Bone or Cartilage Disease

Coding Dimension ID: 
279
Coding Dimension path name: 
Bone or Cartilage Disease
Funding Type: 
Preclinical Development Awards
Grant Number: 
PC1-08128
Investigator: 
Institution: 
Type: 
PI
ICOC Funds Committed: 
$7 660 211
Disease Focus: 
Bone or Cartilage Disease
Stem Cell Use: 
Embryonic Stem Cell
Public Abstract: 

Surgical approaches to the treatment of focal cartilage defects can be classified into repair, replacement, and regeneration therapies. Marrow stimulation procedures such as microfracture result in a repair tissue that is predominantly fibrocartilaginous in nature, which is mechanically less durable than articular cartilage and survives on average 7 years before requiring another procedure. Osteochondral grafting (autologous or allogeneic) replaces the defect with fresh mature cartilage and bone. While the tissue replicates natural cartilage, the grafted cartilage does not integrate or bond with the host tissue. Autologous chondrocyte implantation (ACI) attempts to regenerate tissue by injecting chondrocytes into the defect. Results with this technique are mixed with several randomized clinical trials failing to find a clinically and statistically significant benefit over microfracture or other procedures.
Our approach is to advance third-generation cell therapy by constructing scaffolds that are seeded with chondroprogenitor cells programmed to undergo differentiation into bone and cartilage cells. If successful, this will be the first-in-man embryonic stem-cell-based treatment of an orthopaedic disease that has challenged repeated attempts over the last 400 years. The product has the unique advantage that the same material is universally applicable in all patients with a range of different defect shapes and sizes. The preclinical development, characterization, efficacy, and safety will also support and advance stem-cell-based regenerative medicine in general.

Statement of Benefit to California: 

Arthritis is a common disease and increases with age. The annual cost of treating arthritis in the US is estimated to be over $200B in 2013. Over a million joint replacements are performed in the US alone for end-stage arthritis. However, for younger patients with severe arthritis or impending arthritis there is as yet no treatment that can prevent, cure, or even slow the progression of this disease. In this proposal. we target bone and cartilage defects that are a major factor in contributing to early osteoarthritis in patients less than 55 years of age. Our approach is to advance third-generation cell therapy by constructing scaffolds that are seeded with chondroprogenitor cells programmed to undergo differentiation into bone and cartilage cells. This proposal falls under the mission statement of CIRM for funding innovative research. A stem-cell-based approach for treating articular cartilage defects in not represented in CIRM’s current portfolio. If successful, this will be the first-in-man embryonic stem-cell-based treatment of an orthopaedic disease that has challenged repeated attempts over the last 400 years. This will further validate the significance of the CIRM program and help maintain California’s leading position at the cutting edge of biomedical research.

Funding Type: 
Tools and Technologies III
Grant Number: 
RT3-07804
Investigator: 
Name: 
Institution: 
Type: 
PI
ICOC Funds Committed: 
$1 452 708
Disease Focus: 
Bone or Cartilage Disease
Stem Cell Use: 
Adult Stem Cell
Public Abstract: 

Despite the great promise stem cells hold for regenerative medicine, the efficacy of stem cell-based therapies is greatly limited by poor cell engraftment and survival. To overcome this major bottleneck, the goal of this proposal is to validate the efficacy of novel microribbon (µRB)-based scaffolds for cell delivery. These scaffolds combine the injectability and cell encapsulation of conventional hydrogels with macroporosity, which facilitates nutrient transfer, cell survival, proliferation, and tissue formation. In preliminary studies, our µRB-based scaffolds markedly enhanced the survival of human stem cells and accelerated bone repair in vivo. Thus, here we propose to validate the efficacy of µRB-like hydrogels with tunable stiffness and macroporosity as cell-delivery matrices that enhance the engraftment and survival of stem cells for both soft and hard tissue reconstruction using relevant animal models in vivo. Our results will significantly accelerate clinical translation of stem cell-based therapy by enhancing cell delivery, survival, and integration, thus improving therapeutic outcomes, reducing the number of cells needed for transplantation, and reducing the associated time and cost to produce these cells. Our validated platform will be broadly applicable to diverse cell types, and its wide dissemination will crucially advance the translation of stem cell-based therapies to combat both acute and degenerative human conditions

Statement of Benefit to California: 

Tissue loss and organ failure represents a substantial socioeconomic burden to the State of California, with increasing medical costs for treating patients suffering from various degenerative disease, trauma and congenital defects. Furthermore, the average life-span and percentage of aging population in California is expected to grow, with increasing needs for better therapeutic strategies for caring these patients. Stem cell-based therapies hold great promise for treating tissue loss and enhancing tissue regeneration, often via direct injection of cells at the target site. However, the majority of transplanted cells die shortly after transplantation, which greatly diminishes the efficacy of stem cell-based therapies. Poor cell engraftment and survival remain a major bottleneck to fully exploiting the power of stem cells for regenerative medicine. Here we propose to validate the efficacy of novel µRB-like hydrogels as cell-delivery matrices that enhance the engraftment and survival of stem cells for both soft and hard tissue reconstruction. Our results will significantly accelerate clinical translation of stem cell-based therapy for residents in California by enhancing cell delivery, survival, and integration, thus improving therapeutic outcomes. Our validated platform will be broadly applicable to diverse cell types, and its wide dissemination will crucially advance the translation of stem cell-based therapies to combat both acute and degenerative human conditions.

Funding Type: 
Disease Team Therapy Development - Research
Grant Number: 
DR2A-05302
Investigator: 
Name: 
Type: 
PI
Name: 
Type: 
Co-PI
ICOC Funds Committed: 
$19 999 867
Disease Focus: 
Bone or Cartilage Disease
Stem Cell Use: 
Adult Stem Cell
oldStatus: 
Active
Public Abstract: 

Although most individuals are aware that osteoporosis is disease of increased bone fragility that results from estrogen deficiency and aging, most are unaware of the high risk and cost of the disorder. It is estimated that close to 30% of the fractures that occur in the United States each year are due to osteoporosis (Schwartz & Kagan 2002). California, with one of the largest over-age-65 populations, is expected to double the fracture rate from 1995 to 2015 (Schwartz & Kagan 2002). Current treatment of osteoporosis is focused on anti-resorptive agents that prevent further bone loss. These agents and are effective in reducing new vertebral fractures but less effective for the prevention of hip fractures, and the duration of use of one anti-resorptive class, the bisphosphonates, is limited due to a concern about weakening of the cortical bone with longterm use. The only bone growing agent that is approved by FDA is the protein, hPTH 1-34, which requires two years of daily injections, is only approved by the FDA for one course of treatment, is only effective in about 60% of treated individuals for reduction of vertebral fractures, and has not been shown to be effective in reducing new hip fractures. This leaves an unmet medical need for an anabolic or agent that stimulates bone formation for millions of elderly Californians that suffer or will suffer from this disease.

We have developed a small molecule, LLP2A-Ale that directs endogenous mesenchymal stem cells (MSCs), the cells that have the potential to grow bone tissue, to the bone surface to form new bone. We propose a development plan for this small molecule, LLP2A-Ale for the treatment of osteoporosis in both postmenopausal women and men.

Yrs. 1-2: These 2 years will be spent with optimizing the manufacturing and packaging of the small molecule, obtaining information about the efficacy and toxicity in preclinical models, and preparing documents for an FDA meeting when the preclinical studies are completed to provide comment on the proposed Phase I clinical trials.

Yrs. 3-4. We plan perform a Phase I study with two parts. Part I will study postmenopausal women with osteopenia and a fracture risk (3% for hip fracture and 20% for major nonvertebral fractures over the next 10 years). After the initial Phase I study in postmenopausal women we will perform Part 2 and study both postmenopausal women and men with similar inclusion and exclusion criteria. The primary endpoint of these studies will be change in biochemical markers of bone turnover (PINP, BSAP, osteocalcin), and secondary endpoints will be bone mineral density of the lumbar spine measured by DXA and trabecular bone volume measured by QCT. The Phase I trials will also include required pharmacokinetic and pharmacodynamic measures to obtain information about the action of this small molecule and to inform us for Phase II clinical studies in the future.

Statement of Benefit to California: 

Osteoporosis is a disease of the elderly that results from a process of age related bone loss that renders the bone fragile. Current osteoporosis treatments have relatively good efficacy in reducing incident fractures. However these agents (anti-resorptive agents or the anabolic agent rhPTH (1-34) only reduce the risk of vertebral fractures about 60%, and hip fractures only 40%, and these agents require years of treatment to be effective. The goal of this project is to increase bone homing of the endogenous MSCs with a small molecule (LLP2A-Ale) to form new bone as a novel treatment for osteoporosis that could cure osteoporosis with only 3-4 injections by mobilizing the endogenous MSCs to build bone. Our molecule would be highly competitive in this market as the efficacy of increasing bone mass and bone strength would be high and the risks in a very acceptable range.

The market potential for bone tissue regeneration is large as it is estimated that close to 1/3 of fractures that occur in the US each year are due to osteoporosis (Schwartz & Kagan (2002). California, with one of the largest over-age-65 populations, is expected to double the fracture rate from 1995 to 2015 (Schwartz & Kagan 2002). One study places the cost per year in osteoporotic fractures at 2.4 billion dollars (Schwartz & Kagan 2002), establishing it as one of the highest health care costs for older individuals. The prevalence of osteoporosis is projected to increase with increasing lifespan globally both from age related bone loss and from secondary causes of bone loss including inflammatory diseases and cancer. The market potential for bone tissue regeneration is large, an estimated 2 million fractures and $19 billion in costs annually. By 2025, experts predict that osteoporosis will be responsible for approximately 3 million fractures and $25.3 billion in costs each year (publication from National Osteoporosis Foundation). The osteoporotic patients spend about $10 a month for the generic version of Fosamax, at the lower end, to about $80 a month for brand-name Fosamax or Actonel to $900 or more a month for Forteo (rhPTH (1-34).

Therefore, once validated in osteoporosis patients, this form of tissue regeneration would be effective in patients with primary osteoporosis, in patients with secondary osteoporosis due to long term glucocorticoid treatment or after chemotherapy in both men and women and to augment peak bone mass in children in whom current osteoporosis medications are contraindicated, in individuals who have had radiation to their skeletons in whom rhPTH (1-34) is contraindicated and to augment fracture healing in the elderly. Our agent would have the potential to save the State of California millions of dollars in health care and would allow these osteoporotic individuals to live longer and be independent longer.

Progress Report: 
  • One of the early goals for this project is the successful development and clinical grade manufacturing of the drug LLP2A-Alendronate (LLP2A-Ale). We are pleased that we now have a robust stability indicating method that has been transferred for use in drug product development. We are currently working with our collaborators on stability maintenance and monitoring of the compound.
  • At the annual CIRM advisory committee review in late October 2013, the reviewers liked the "hybrid" compound. However, they also felt that the project would benefit from additional preclinical studies to compare two treatments for osteoporosis that are currently available, alendronate and PTH. Therefore, based on the advisory committee's comments, we will conduct further studies that confirm and support our original hypotheses. We are looking forward to beginning clinical trials soon after those studies are completed.
  • This past year, on the advice of CDAP, we completed the recommended additional proof of concept studies with LLP2A-Ale for age related osteoporosis and other indications. These new studies have demonstrated that LLP2A-Ale can also be effective in fracture healing and osteonecrosis. In addition, we completed the requested drug stability testing of LLP2A-Ale.
  • At this time we are awaiting decision by CIRM/CDAP regarding continuation of our Disease Team project for the use of LLP2A-Ale for the treatment of bone diseases.
  • During this reporting period we completed the repeat-dose rat and dog GLP toxicology studies, and a mouse glucocorticoid induced osteoporosis study in which multiple treatments and doses of LLP2A-Ale were assessed.
Funding Type: 
Disease Team Therapy Planning I
Grant Number: 
DR2-05368
Investigator: 
Name: 
Institution: 
Type: 
PI
ICOC Funds Committed: 
$99 110
Disease Focus: 
Bone or Cartilage Disease
oldStatus: 
Closed
Public Abstract: 

There are over 1.5 million osteoporotic fractures annually in the USA alone, at a cost of approximately $15 billion each year. The majority of these fractures occur in the spine, followed by the hip and wrist. Incidence varies according to age; vertebral fracture rates increase rapidly by the sixth decade of life, whereas the risk of hip fracture rises markedly by the eighth decade and beyond.

Current treatment is focused on prevention using osteoclast inhibitors, hormone therapy, diet and exercise. When a fracture occurs current therapies involve injection of cement into the vertebral body and/or open surgery with implants. Unfortunately, these procedures do not regenerate bone tissue, often fail and incur risks of leakage and emboli. The clinical and economic impact associated with these fractures is substantial. Following a fragility fracture, significant pain, disability, and deformity can ensue. If fracture union is not achieved, the patient may suffer long-term disability. This is exacerbated because there is a five-fold increase in the risk for sustaining a subsequent vertebral fracture and the odds that a neighboring vertebrae will fail within one year is >20%. We propose to add a noninvasive anabolic option to the treatment and prevention of osteoporotic fractures. This therapy utilizes a novel small molecule Wnt pathway activator that drives the endogenous stem cells in the bone compartment to differentiate into bone forming osteoblasts thereby increasing bone mass and reducing the risk of fracture. This therapy will be administered 1-2X/year by injection, eliminating the concerns over patient compliance and revolutionizing the treatment of vertebral and hip fractures in patients suffering from osteoporosis.

Statement of Benefit to California: 

There are over 25 million osteoporosis patients in the US alone, leading to 1.5 million osteoporotic fractures annually at a cost of approximately $17 billion per year. The lifetime incidence of fragility fractures secondary to osteoporosis in females over fifty years of age is approximately 1 in 2, and in males over the age of fifty, is 1 in 4. Osteoporosis-related vertebral compression fractures are the most common fragility fractures in the United States, accounting for more than 79% of the total. Approximately 70,000 OVCFs result in hospitalization each year with an average hospital stay per patient of 8 days. Current treatment is focused on prevention using osteoclast inhibitors, hormone therapy, diet and exercise. When a fracture occurs, current therapies involve injection of cement into the vertebral body and/or open surgery with implants. Unfortunately, these procedures do not regenerate bone tissue, often fail, incur risks of leakage and emboli, and suffer significant side effects. The clinical and economic impact associated with these fractures is substantial. Following a fragility fracture, significant pain, disability, and deformity can ensue. If fracture union is not achieved, the patient may suffer long-term disability. This is exacerbated because there is a five-fold increase in the risk for sustaining a subsequent vertebral fracture after the first fracture, and the odds that an adjacent vertebrae will fail within one year is >20%. We propose to add a noninvasive anabolic option to the treatment and prevention of osteoporotic fractures, with minimal to no side effects or systemic safety concerns. This therapy utilizes a novel small molecule Wnt pathway activator that drives the endogenous stem cells in the bone compartment to differentiate into bone forming cells, thereby increasing bone mass and reducing the risk of fracture. This therapy will be administered 1-4 times per year by injection, eliminating the concerns over patient compliance and revolutionizing the treatment of vertebral and hip fractures in patients suffering from osteoporosis. This will benefit the citizens of California by reducing hospitalization periods, operative costs and loss of workdays, and by improving quality of life for Californians with osteoporosis that are at risk for OVCFs.

Progress Report: 
  • This project is working to advance a first-in-class, small molecule Wnt pathway activator through IND-enabling and Phase I/II clinical studies for treatment of osteoporotic hip fractures. During this reporting period, quotes were solicited from drug manufacturing companies for the manufacture of the drug compound, a manufacturer was selected and the drug is presently in the GMP manufacturing process. In addition, international thought leaders were identified to act as clinical consultants and with their input the outline of a Phase I/II clinical trial plan was drafted and submitted to the FDA for comment. Beyond that, a pre-IND briefing document was prepared that described the clinical product’s known pharmacology, pharmacokinetic, toxicology and chemical characteristics. After preparing and submitting the clinical plan outline and pre-IND briefing document to the FDA, the team had a successful pre-IND meeting on January 30, 2012. IND filing is proposed for the first half of 2013. Currently, quotes have been requested for contract research organizations (CROs) who offer appropriate preclinical fracture model studies and a decision on the most suitable vendor for the study will be determined shortly.
  • In addition, the CIRM disease team application detailing known properties of the drug, along with a 4 year development plan and associated budget was drafted and completed during the reporting period.
Funding Type: 
Early Translational II
Grant Number: 
TR2-01821
Investigator: 
Name: 
Type: 
Co-PI
ICOC Funds Committed: 
$5 391 560
Disease Focus: 
Bone or Cartilage Disease
Stem Cell Use: 
Adult Stem Cell
Cell Line Generation: 
Other
oldStatus: 
Active
Public Abstract: 

Like most tissues of the body, bone possesses a natural regenerative system aimed at restoring cells and tissues lost to natural cell aging, disease or injury. These natural regenerative systems are complex combinations of cell growth factors and support structures that guide and control the development of specialized bone stem cells. However, the regeneration process may still fail, for multiple reasons. For instance, the degree of skeletal injury may be so great that it overwhelms the natural regenerative capacity. Alternatively, the natural regenerative capacity may be defective; this is exemplified by osteoporosis, a frequent condition affecting post-menopausal females and elderly males and females. Osteoporotic individuals have severe declines in stem cell numbers (10-fold decrease from age 30 to 80) and stem cell function (tendency of stem cells to turn into fat rather than bone cells with age), leading to bone loss and “fragility fractures” that typically would not occur in persons with normal stem cell number and function. Thus, there is a tremendous need for therapies to increase the number and function of endogenous adult stem cells with the potential to build new bone.

One option is to introduce so called mesenchymal stem cells (MSC) from the patient to bone repair sites. However, significant hurdles to autologous MSC use include the need for 2-3 week culture times to isolate MSC before application. Moreover culturing introduces infectious and immunogenic risks from prolonged exposure to animal products and cancerous risks from cellular gene changes in culture. In addition, once isolated, MSC require appropriate growth factor stimulation to form bone. Finally, MSC isolated from patient tissues such as fat or bone marrow are heterogenous and of undetermined composition—making growth factor dosing and conformance with FDA regulations for defining target product identity, purity, and potency more difficult.

To circumvent these problems, we have identified and purified the cells at the origin of human MSC. We have termed these perivascular stem cells (PSC) because they are natively localized around all arteries and veins, forming the key cellular component of the natural regenerative system. In a significant breakthrough, we are able to isolate these cells within hours from adipose tissues in sufficient numbers for therapy without the need for culture. This realizes the possibility of harvesting and implanting stem cells during the same operative period. In another breakthrough, we have identified a potent growth factor NELL-1 that potently amplifies the ability of PSC to form bone and vascular structures. This has led to the development of our target PSC+NELL-1 product, which effectively stimulates and augments the body’s natural bone regenerative system by providing all the components (stem cells, growth factor, and allograft bone support structure) necessary to “jump start” as well as maintain the function of bone stem cells.

Statement of Benefit to California: 

This FDA oriented proposal focuses on crucial preparatory work required before IND-enabling preclinical studies on our Developmental Candidate for bone formation and regeneration. Our Developmental Candidate provides a complete package of stem cells, bone growth factors, and scaffold to build an optimized microenvironment to “jump start” bone formation in normal and impaired bone healing conditions. We have generated very promising preclinical data on our Developmental Candidate’s superior bone formation and regeneration efficacy. In addition to its significant impact on health care, this highly multi-disciplinary project by our team has many near-term and long-term benefits to the State of California.

1. Besides direct health costs, musculoskeletal injuries and diseases are the leading cause of work-related and physical disability in the United States. Hard working Californians are responsible for California’s annual gross domestic product of $1.8 trillion, which rank our state among the top eight largest economies in the world. By promoting the repair of both normal and healing-impaired bone in a safe and effective manner, our mature technology will reduce the loss of work productivity at the front end, reduce work disability costs, and reduce the loss of state income tax.

2. Local osteogenic stem cells decline with age (from 1/10,000 in newborns to 1/250,000 by age 30 and 1/2,000,000 by age 80), leading to osteoporosis, poor bone quality, and fragility fractures. In 1998, the health care burden for osteoporosis exceeded $2.4 billion in California alone. A whopping 64% of the $2.4 billion was caused by hip fracture. If our Development Candidate is successful in healing existing fractures in impaired bone, it may also translate to therapies to prevent fractures in impaired bone. This will significantly reduce the long-term health care burden for California’s public health insurance program.

3. This project directly adds jobs at [REDACTED] and at the California-based companies that are involved in this project.

4. This project will produce intellectual property that is owned by t [REDACTED]. Our team has a track record of attracting out of state private investment to invest in California and of procuring supplies and equipment from strategic California-based companies.

5. This mature project is precisely the type of cutting-edge, multi-disciplinary stem cell project that Californians imagined when they approved proposition 71 in 2004. The establishment of CIRM has transformed the research infrastructure at [REDACTED], increased our ability to recruit world class stem cell scientists, and attracted the attention of superb scientists from other disciplines to this new field. Working together, our team has compiled an impressive list of accomplishments and we are confident in our abilities to take this project to IND submission in a timely fashion. Funding of this project will fulfill the promise of proposition 71.

Progress Report: 
  • Background: unsuccessful bone repair
  • Most organs can regenerate cells lost to ageing, exposure to adverse conditions, ephemeral lifespan, disease or injury. Regenerative systems are complex combinations of growth factors and anchorage molecules which support, guide and control the maturation of specialized stem cells. The regenerative process may still fail, for multiple reasons. Bone fractures will sometimes not heal spontaneously because parts of the broken bone do not join anymore, or because bone regeneration itself is impaired, like in osteoporosis, a frequent condition that affects post-menopause females and elderly people of both genders.
  • A novel class of bone-healing stem cells
  • Since specialized bone-forming cells have not been identified, which stem cells could be used for the cell therapy of bone fractures? We have identified and purified novel stem cells, localized around blood vessels and therefore named perivascular stem cells (PSCs). We have also demonstrated that Nell-1, a potent osteogenic growth factor we have developed, efficiently turns PSCs into bone cells. In 2011, we have been granted support by the California Institute for Regenerative Medicine to develop a product to heal critically fractured bones in osteoporotic – or not – patients or to perform spine fusion in order to correct skeletal defects. PSCs will be purified from the patient’s own fat tissue, a well-documented, rich source of these cells, and embedded in a biocompatible scaffold in the presence of the bone forming growth factor. The resulting compound, inserted at the site of the fracture, will provide bone-forming stem cells 1-precisely characterized in terms of origin and identity; 2- derived from the patient, hence not rejected; 3- not cultured, therefore similar to their natural counterparts.
  • Progress after one year of research supported by CIRM
  • We are now close to the end of the first year of our CIRM supported studies. In this initial period we have, first, validated the stem cells of use with regard to stringent biologic criteria: how many of these cells can be purified from fat tissue? How viable and pure are these cells after the sorting process? Do stem cell numbers and quality depend on the age, sex and corpulence of the donor? Following analysis of about 80 distinct fat harvests (lipoaspirates) we have determined that robust bone forming PSC can be reliably purified, in sufficient numbers, from male and female donors in all age and weight ranges. We have also shown that PSC are at least as good, in terms of bone forming potential, than conventional mesenchymal stem cells (the candidate stem cells, so far, to be used for cell therapies of bone defects amd injuries), while being significantly superior regarding purity and safety.
  • Transplantation experiments in mice and rats have revealed that the combination of PSC and the Nell-1 growth factor ensures the most efficient bone regeneration, but that PSC do not give rise to tumors, an important verification in any protocol involving transplantation. These experiments have also demonstrated that PSC stimulate the formation of new blood vessels, an essential requisite for efficient wound healing and tissue repair.
  • Finally, we have embarked on the development of a larger animal model of bone regeneration, that will be used in the second and third years of the projects.
  • In summary, we have reached all the milestones and met the deadlines planned in the original project. The next year will see the further validation of the protocol and the beginning of the development of a stem cell/scaffold/growth factor combination product in the perspective of trials in human patients.
  • Our research group has identified in the human body a novel class of stem cells endowed with strong osteogenic potential, which means capacity to produce bone. These stem cells are attached to the outer aspect of blood vessels, and therefore present in all organs. Our ultimate goal is to use these stem cells in human beings, to perform for instance spine fusion, a procedure used to treat spine deformities (scoliosis) or faulty vertebrae, or to heal complicated bone fractures, especially in patients suffering from osteoporosis, a condition where spontaneous bone repair is compromised. We shall harvest stem cells from the patient’s own abdominal adipose (fat) tissue, a rich source of these cells which is also easy and safe to collect. Stem cells will be purified on an automated machine, named fluorescence activated cell sorter, and immobilized on an engineered biocompatible scaffold in the presence of a novel osteogenic growth factor, that is a sort of hormone which stimulates stem cell development into bone. We have won an Early Translational grant (2011-2014) from the California Institute for Regenerative Medicine to develop this project to the stage where the first clinical trials can be engaged into. In the first year, we had fully validated the stem cell population of use on a large number of human adipose samples and clearly documented the availability, efficiency and safety of these cells independently of the age, sex and weight of the donor. We had also initiated experiments in mice and rats which have been pursued during the second year, finally demonstrating unequivocally the outstanding bone forming ability of these cells in the presence of the appropriate scaffold and osteogenic hormone. We have also, during this 2nd year, developed a large animal model of stem cell mediated bone regeneration which will be indispensable prior to the inception of human treatments. Finally, we have refined the physicochemical properties of the scaffold for optimal osteogenic factor availability and bone growth. In conclusion, all milestones and deadlines included in this grant have been met and our team is steadily progressing toward the medical “translation” of these novel stem cells.
  • Our research group has identified in the human body a novel class of stem cells endowed with strong osteogenic potential, which means capacity to produce bone. These stem cells are attached to the outer aspect of blood vessels, and therefore present in all organs. Our ultimate goal is to use these stem cells in human beings, to perform for instance spine fusion, a procedure used to treat spine deformities (scoliosis) or faulty vertebrae, or to heal complicated bone fractures, especially in patients suffering from osteoporosis, a condition where spontaneous bone repair is compromised. We shall harvest stem cells from the patient’s own abdominal adipose (fat) tissue, a rich source of these cells which is also easy and safe to collect. Stem cells will be purified on an automated machine, named fluorescence activated cell sorter, and immobilized on an engineered biocompatible scaffold in the presence of a novel osteogenic growth factor, that is a sort of hormone which stimulates stem cell development into bone. We have won an Early Translational grant (2011-2014) from the California Institute for Regenerative Medicine to develop this project to the stage where the first clinical trials can be engaged into. In the first year, we had fully validated the stem cell population of use on a large number of human adipose samples and clearly documented the availability, efficiency and safety of these cells independently of the age, sex and weight of the donor. We had also initiated experiments in mice and rats which have been pursued during the second year, finally demonstrating unequivocally the outstanding bone forming ability of these cells in the presence of the appropriate scaffold and osteogenic hormone. We have also, during this 2nd year, developed a large animal model of stem cell mediated bone regeneration which will be indispensable prior to the inception of human treatments. Finally, we have refined the physicochemical properties of the scaffold for optimal osteogenic factor availability and bone growth. In conclusion, all milestones and deadlines included in this grant have been met and our team is steadily progressing toward the medical “translation” of these novel stem cells.
Funding Type: 
New Faculty II
Grant Number: 
RN2-00916
Investigator: 
ICOC Funds Committed: 
$2 396 871
Disease Focus: 
Bone or Cartilage Disease
Trauma
Stem Cell Use: 
Embryonic Stem Cell
oldStatus: 
Active
Public Abstract: 

The goal of this proposal is to develop cell-based therapies that lead to the better healing of traumatic head injuries. Our first strategy will be to use genetics and embryology in zebrafish to identify factors that can convert human embryonic stem cells into replacement skeleton for the head and face. Remarkably, the genes and mechanisms that control the development of the head are nearly identical between fish and man. As zebrafish develop rapidly and can be grown in large numbers, a growing number of researchers are using zebrafish to study how and when cells decide to make a specific type of tissue – such as muscle, neurons, and skeleton - in the vertebrate embryo. Recently, we have isolated two new zebrafish mutants that completely lack the head skeleton. By studying these mutants, we hope to identify the cellular origins and genes that make head skeletal precursors in the embryo. These genes will then be tested for their ability to drive human embryonic stem cells along a head skeletal lineage. Our second strategy will be to test whether a population of cells, similar to the one that makes the head skeleton in the embryo, exists in the adult face. We have found that adult zebrafish have the extraordinary ability to regenerate most of their lower jaw following amputation. In this proposal, we use sophisticated imaging and transgenic approaches to identify potential adult stem cells that can give rise to new head skeleton in response to injury. Traumatic injuries to the face are common, and treatment typically involves grafting skeleton from other parts of the patient to the injury site. Unfortunately, the amount of skeleton available for grafts is in short supply, and surgeries often result in facial disfigurement that causes psychological suffering for the patient for years to come. Here we propose two better treatments that would lead to more efficient healing and less scarring. The first treatment would be to differentiate human embryonic stem cells, a potentially limitless resource, into skeletal precursors that can be grafted into the head injury site. By understanding the common pathways by which head skeletal cells are specified in the zebrafish embryo and human embryonic stem cells, we will be able to generate skeletal replacement cells in large quantities in cell culture. The second treatment would be to stimulate adult stem cells already in the face to regenerate the injured head skeleton. If successful, our experiments on zebrafish jaw regeneration will allow us to devise strategies to augment the natural skeletal repair mechanisms of humans.

Statement of Benefit to California: 

Traumatic injuries to the head, such as those caused by car accidents and gunshot wounds, are commonly seen in emergency rooms throughout California. Current treatments for severe injuries of the head skeleton involve either grafting skeleton from another part of the body to the injury site or, in cases where there is not sufficient skeleton available for grafts, implanting metal plates. Although these operations save lives, they often result in facial disfigurement that causes psychological suffering for the patient for years to come. For this reason, there is enormous interest in cell-based skeletal replacement therapies that will heal the face without leaving disfiguring scars. Remarkably, the genes and mechanisms that control the development of the head are nearly identical between fish and man. Thus, we are using the zebrafish embryo to rapidly identify factors that can make head skeletal precursors, and then asking if these same factors can instruct human embryonic stem cells to form skeletal replacement cells. In addition, we have found that adult zebrafish have the extraordinary ability to regenerate most of their lower jaw following amputation, and we will use sophisticated imaging and transgenic approaches to identify potential adult stem cells that can regenerate the face. The successful completion of these experiments would allow us to both generate unlimited amounts of head skeletal precursors for facial repair and stimulate latent skeletal repair mechanisms. The combination of these approaches will lead to therapies that promote a more natural healing of the face, thus allowing Californians to eventually resume normal lives after catastrophic accidents.

Progress Report: 
  • A major aim of this grant is to investigate the developmental origin of the skeleton-forming cells in the head. An understanding of how these skeletal cells form in the embryo will aid in our long-term goal of producing skeletal replacement cells in culture and stimulating new skeleton to form after traumatic head injuries.
  • In the first year of this award, we have made a landmark discovery concerning how the skeletal-forming cells arise in the head. The head skeleton arises from an unusual cell population called the neural crest, which is characterized by its ability to form a very wide diversity of cell types in the embryo. We had previously described the isolation of two mutant lines of zebrafish that completely and specifically lack the head skeleton. We have now identified a mutation in a variant histone protein as the genetic basis for the lack of head skeleton in one of these lines. Histone proteins play a central role in not only wrapping our DNA but also controlling which genes are active in different cell types. Despite the fact that histones are expressed in every cell in the body, we have found that variant histones are uniquely required for neural crest cells to acquire skeleton-forming potential. In particular, our findings indicate that the head skeleton forms by a process of developmental reprogramming, in which precursor cells with a limited potential undergo large-scale changes in their DNA packaging such that they are able to form a much wider array of cell types.
  • Controlled cell reprogramming is becoming one of the most promising directions of regenerative medicine. For example, there is enormous therapeutic potential in being able to take cells from a patient, reprogram these cells back to a naïve state with defined factors, and then induce these cells to form replacement cells of any type that can be introduced back into the patient. Our discovery that the vertebrate embryo uses a similar process of reprogramming to generate head skeletal cells during development provides us an opportunity to better understand how reprogramming works at a molecular level. In addition, our finding that head skeletal cells form by developmental reprogramming suggests that adult patient-specific cells can be directly reprogrammed to form head skeletal precursors. Moreover, as the variant histone we have identified is identical at the protein level between zebrafish and humans, it is likely that the reprogramming process we have discovered operates in humans as well. Thus, in the coming years of this grant we are excited to develop methods of reprogramming adult patient-specific cells to a head skeletal fate, such that we can generate large quantities of replacement cells to repair the face and skull.
  • A major aim of this grant is to investigate the developmental origin of the skeleton-forming cells in the head. An understanding of how these skeletal cells form in the embryo will aid in our long-term goal of producing skeletal replacement cells in culture and stimulating new skeleton to form after traumatic head injuries.
  • In the second year of this award, we have extended our initial findings that variant histones play an essential role in the generation of head skeletal cells. Skeletal cells usually arise from a cell population called the mesoderm. However, in the head a unique population of ectoderm cells, which normally forms derivatives such as neurons and skin, has an added ability to form skeletal cells. How these cranial neural crest cells acquire this extra potential remains unclear. Here we show that variant histones function within the ectoderm to give cranial neural crest cells skeletal-forming ability. In addition, we have used biochemical analysis in a human cell line to demonstrate how mutations in a particular H3.3 type of variant histone disrupt the association of histones with DNA. Furthermore, we have developed tools which allow us to analyze how variant histone changes throughout the genome endow neural crest ectoderm cells with mesoderm-like skeletal-forming potential.
  • Variant histones have been implicated in cell reprogramming, whereby a mature cell regains the ability to form many more cells that can repair a damaged tissue. As we find that variant histones are required for reprogramming of the ectoderm to form neural crest during early development, we believe that we can use this pathway to convert patient-specific cells to neural crest and skeletal cells that can be used for facial repair. To test this, we have developed a mouse model in which we can detect the ability of neural crest genes to convert mature cells to neural crest and skeletal fates. In parallel, we have developed a model of jaw regeneration in zebrafish that will allow us to test whether adult cells within the animal can be reprogrammed to repair the skeleton in response to injury. During this period, the generation of transgenic tools has allowed us to begin to address which cell types can give rise to new skeleton in response to injury. In the coming years, we hope that our work in model systems will lead to therapies for head skeletal injuries on two fronts: the generation of large amount of head skeletal precursors from patient-specific cells and the induction of increased regenerative ability of cells within the patient.
  • A major aim of this grant is to investigate the developmental origin of the skeleton-forming cells in the head, as well as their ability to regenerate craniofacial skeleton in adults after injury. The head skeleton derives from a special population of cells, the neural crest, which has the remarkable ability to form not only neurons but also skeletal tissues. We have previously described that zebrafish with a mutant form of a variant histone H3.3 protein have very specific defects in the ability of neural crest cells to form skeleton. As histone H3.3 is a core component of the chromatin around which DNA is wrapped, our findings suggest a novel mechanism by which changes in chromatin structure endow the neural crest with the ability to form a wide array of derivatives. In the third year of this award, we have expanded our analysis to examine how the incorporation of histone H3.3 is regulated specifically in the neural crest population. Our data suggest that such H3.3 incorporation may depend on a novel chaperone protein as reducing the function of several known H3.3 chaperone proteins does not lead to specific neural crest or head skeletal defects. A clue to what regulates H3.3 activity comes from a second zebrafish mutant – called myx - that we are studying, which has head skeletal defects similar to what we see in our H3.3 mutant. We have mapped the myx mutant interval to a very small region that contains a putative H3.3 chaperone protein. We are currently establishing whether loss-of-function of this chaperone accounts for myx defects. Together, our studies of H3.3 and myx mutants will shed light on how to generate cells with the ability to form replacement head skeleton in patients. To this aim, we have also begun experiments to use our findings in zebrafish to directly convert mammalian cells (initially mouse but then in humans) to a neural crest and skeletal fate.
  • A parallel strategy that we are taking towards regenerative strategies for facial skeleton is to stimulate endogenous neural crest cells to make replacement skeleton. We have a limited ability to repair defects in our skeleton, for example after bone fracture. However, we have found that adult zebrafish have the remarkable ability to regenerate nearly their entire lower jaw following amputation. By studying why zebrafish regenerate facial skeleton to a much greater extent than humans, we hope to devise molecular strategies to augment skeletal repair/regeneration in patients. In particular, we have found that the zebrafish lower jaw bone regenerates through a cartilage intermediate, in contrast to the direct differentiation to bone during development. Hence, our findings indicate that bone regeneration in zebrafish is a cellularly distinct mechanism than bone development. Furthermore, we have found that the FGF signaling pathway is greatly upregulated during early jaw regeneration. FGF signaling also mediates the regeneration of the heart and other organs in zebrafish, and thus jaw regeneration may rely on a common regenerative program throughout the zebrafish. In the coming period, we plan to test the functional requirements of FGF signaling in mediating jaw regeneration, as well as identifying the stem cell populations that are the FGF-dependent source of new bone.
  • A major aim of this grant is to investigate the developmental origin of the skeleton-forming cells in the head, as well as their ability to regenerate craniofacial skeleton in adults after injury. The head skeleton derives from a special population of cells, the neural crest, which has the remarkable ability to form not only neurons but also skeletal tissues. In the previous grant cycle, we published a manuscript in PLoS Genetics describing the role of a variant histone H3.3 protein in controlling the ability of neural crest cells to form the head skeleton of zebrafish. As histone H3.3 is a core component of the chromatin around which DNA is wrapped, our findings suggest a novel mechanism by which changes in chromatin structure endow the neural crest with the ability to form a wide array of derivatives. In addition, we published a separate study in PLoS Genetics that showed a critical role of Twist1 in guiding these neural crest cells to make head skeleton at the expense of other cell types such as neurons. Together, our studies of H3.3 and Twist1 in zebrafish will shed light on how to generate cells with the ability to form replacement head skeleton in patients. In ongoing experiments, we are using principles from our zebrafish system to directly convert mammalian cells (initially in mouse but then in humans) to a neural crest and skeletal fate.
  • A parallel strategy that we are taking towards regenerative strategies for facial skeleton is to stimulate endogenous neural crest cells to make replacement skeleton. We have a limited ability to repair defects in our skeleton, for example after bone fracture. However, we have found that adult zebrafish have the remarkable ability to regenerate nearly their entire lower jaw following amputation. By studying why zebrafish regenerate facial skeleton to a much greater extent than humans, we hope to devise molecular strategies to augment skeletal repair/regeneration in patients. In particular, we have found that during zebrafish lower jawbone regeneration, an unusual cartilage intermediate is able to directly make replacement bone, which is in marked contrast to the way bone is made during development. Furthermore, we have found a potentially critical role of the Ihh signaling pathway in allowing regenerating cartilage cells to directly make replacement bone. In the coming period, we plan to test the functional requirements of Ihh signaling in mediating jaw regeneration, as well as identifying the cellular source of bone-producing cartilage cells during jaw regeneration. As similar bone-producing cartilage cells may also be present in human fractures, lessons learned from zebrafish may allow us to stimulate these cells and hence augment bone repair in patients.
  • A major aim of this grant is to investigate the developmental origin of the skeleton-forming cells in the head, as well as their ability to regenerate craniofacial skeleton in adults after injury. The head skeleton derives from a special population of cells, the neural crest, which has the remarkable ability to form not only neurons but also skeletal tissues. We had previously identified a unique role of histone replacement within the neural plate precursor cells that allows neural crest to make skeletal derivatives. In the current grant cycle, we now find that misexpression of groups of neural plate transcription factors is able to convert cells to a neural crest fate, and we are currently exploring whether this occurs by stimulating the histone replacement program we found to be so important for neural crest development. We are also testing whether similar neural plate transcription factors can convert mammalian cells to a neural crest fate, with the eventual goal to use this technique to generate an unlimited supply of patient-specific bone and cartilage replacement cells for skeletal repair.
  • A parallel strategy that we are taking towards regenerative strategies for facial skeleton is to stimulate endogenous neural crest cells to make replacement skeleton. While we have a limited ability to repair defects in our skeleton, for example after bone fracture, we have found that adult zebrafish have the remarkable ability to regenerate nearly their entire lower jawbone following amputation. By studying why zebrafish regenerate facial skeleton to a much greater extent than humans, we hope to devise molecular strategies to augment skeletal repair/regeneration in patients. In particular, we have found that during zebrafish lower jawbone regeneration, cartilage cells are able to change their fate to directly make replacement bone, which is in marked contrast to the way bone is made during development. We have also identified a critical role of the Ihh signaling pathway in bone regeneration and in particular the generation of the critical cartilage intermediate. In adults lacking the Ihha protein, no cartilage forms after jawbone amputation and the jawbone fails to heal properly. Moreover, in collaborative work we find that such bone-producing cartilage cells may also be present in a mammalian model of bone healing. We are therefore excited by the prospects of using similar bone-producing cartilage cells to repair large skeletal wounds in patients.
Funding Type: 
Late Stage Preclinical Projects
Grant Number: 
CLIN1-08309
Investigator: 
ICOC Funds Committed: 
$1 667 832
Disease Focus: 
Bone or Cartilage Disease
Public Abstract: 
Statement of Benefit to California: 

Osteoarthritis (OA) is the most prevalent musculoskeletal disease and globally the 4th leading cause of Years Lost to Disease (YLD). The annual economic impact of arthritis in the U.S. is estimated at over $100 billion. No disease-modifying OA drugs are approved for clinical use. Clearly the development of a new disease-modifying therapeutic would have a significant impact on the well-being of Californians and reduce the negative economic impact on the state.

Funding Type: 
Preclinical Development Awards
Grant Number: 
PC1-08142
Investigator: 
ICOC Funds Committed: 
$2 633 592
Disease Focus: 
Bone or Cartilage Disease
Stem Cell Use: 
Adult Stem Cell
Public Abstract: 

Osteoarthritis (OA) is the most prevalent musculoskeletal disease affecting nearly 27 million people in the United States, and is the leading cause of chronic disability in the United States. Current therapeutic options are limited to pain or symptom-modifying drugs and joint replacement surgery; no disease-modifying drugs are approved for clinical use. OA is characterized by progressive degeneration of the articular cartilage, resulting from abnormal activation, differentiation and death of cartilage cells. A unique and unexplored therapeutic opportunity exists to induce somatic stem cells to regenerate the damaged tissue and reverse the chronic destructive process. Cartilage contains resident mesenchymal stem cells (MSCs) that can be differentiated in vitro to form chondrocytes. This observation suggests that intra-articular injection of a small molecule that promotes chondrogenesis in vivo will preserve and regenerate cartilage in OA-affected joints. Targeting resident stem cells pharmacologically also avoids the risks and costs associated with cell-based approaches. In previous preclinical studies we have identified a small molecule drug candidate that specifically induces chondrocyte differentiation in culture and improves cartilage repair in OA animal models. In the proposed study we will optimize the regimen for dose, frequency and duration. We will also profile the preclinical candidate (PCC) for physicochemical, pharmacological and toxicological properties, draft a detailed plan for phase 1 clinical trial, and prepare documents and conduct a pre-IND meeting with the FDA. If successful, we will initiate IND-enabling studies and subsequent phase 1 clinical trial for the PCC.

Statement of Benefit to California: 

Osteoarthritis (OA) is the most prevalent musculoskeletal disease and globally the 4th leading cause of Years Lost to Disease (YLD). OA affects over 40 million Americans and the magnitude of the problem is predicted to increase even further with the obesity epidemic and aging of the baby boomer generation. It is estimated that 80% of the population will have radiographic evidence of OA by age 65 years. The annual economic impact of arthritis in the U.S. is estimated at over $100 billion, representing more than 2% of the gross domestic product. OA accounts for 25% of visits to primary care physicians. In 2004 OA patients received 650,000 knee and hip replacements at a cost of $26 billion. Without change in treatment options 1.8 million joint replacements will be performed in 2015. OA is a painful, degenerative type of arthritis; physical activity can become difficult or impossible. Some patients with osteoarthritis are forced to stop working because their condition becomes so limiting. OA can interfere with a patient's ability to even perform routine daily activities, resulting in a decrease in quality of life. The goals of osteoarthritis treatment are to relieve pain and other symptoms, preserve or improve joint function, and reduce physical disability. Current therapeutic options are limited to pain medications and joint replacement for patients with advanced disease. No disease-modifying OA drugs are approved for clinical use. OA is thus a major unmet medical need with a huge clinical and socioeconomic impact and a complete absence of effective therapies. Clearly the development of a new therapeutic that is both symptom and disease modifying would have a significant impact on the well-being of Californians and reduce the negative economic impact on the state resulting from this highly prevalent disease.

Funding Type: 
Tools and Technologies III
Grant Number: 
RT3-07981
Investigator: 
Name: 
Type: 
PI
Type: 
Co-PI
ICOC Funds Committed: 
$1 846 529
Disease Focus: 
Bone or Cartilage Disease
Stem Cell Use: 
Adult Stem Cell
Public Abstract: 

Stem cell technologies hold great promise for engineering replacement tissues for repairing functional loss from trauma or disease. Such therapies are particularly important for replacing bone and cartilage in the aging population to maintain an active quality of life. However, the application of stem cells to generate individualized implantable grafts suffers from patient-to-patient variability that is unpredictable and immeasurable without destructive techniques, representing a major bottleneck in translating stem cell technologies to the clinic and delivering a quality product. This process could be markedly improved by the availability of nondestructive, non- or minimally invasive methods to measure dynamic changes in tissue development, thereby reducing the quantity of tissue collection for sufficient cell numbers and cutting costs that do not directly benefit the patient. During tissue formation, cells deposit extracellular matrix molecules that possess a unique fluorescence signature, which can be detected by light, while matrix quantity, detectable by ultrasound, correlates with mechanical strength. We propose the development and application of a multi-modal imaging probe that uses light and sound to detect changes in engineered bone and cartilage, which reflect maturity and mechanical properties. The availability of this tool will advance the personalized medicine aspect of stem cell-based tissue formation while providing new insight into dynamic tissue development.

Statement of Benefit to California: 

The aging population of California, 20% of whom will be over 65 in 2025, will require functional replacement tissues to maintain their quality of life. The promise of using stem cells to generate individualized grafts suffers from donor variability that is unpredictable and immeasurable without destructive techniques. The development of a nondestructive, minimally invasive tool enabling the dynamic assessment of tissue maturation and remodeling would provide users unparalleled insight without destructive biopsies. Herein, we aim to develop a multi-modal imaging probe that uses light and sound to measure the maturity of stem cell-generated bone and cartilage by detecting unique signatures of extracellular matrix components and observing matrix deposition. After optimizing the probe for these tissues, we will characterize maturation of engineered tissues in vitro and after implantation. This tool will reduce the number of cells required to create tissues by eliminating destructive biopsies and provide an individualized tissue product to maximize clinical outcome, resulting in reduced healthcare costs. The technology will be invaluable to clinicians and biotechnology companies pursuing regenerative medicine in California. Finally, the exposure of trainees to new stem cell-related research may provide the greatest benefit to California by inspiring future scientists to pursue their research efforts within the state or develop therapies at California-based companies.

Funding Type: 
Early Translational IV
Grant Number: 
TR4-06713
Investigator: 
Name: 
Type: 
PI
Name: 
Type: 
Co-PI
ICOC Funds Committed: 
$5 185 487
Disease Focus: 
Arthritis
Bone or Cartilage Disease
Stem Cell Use: 
Adult Stem Cell
Cell Line Generation: 
Adult Stem Cell
oldStatus: 
Active
Public Abstract: 

Segmental bone fractures are a complex medical condition. These injuries cause great suffering to patients, long-term hospitalization, repeated surgeries, loss of working days, and considerable costs to the health system. It is well known that bone grafts taken from the patient (autografts) are considered the gold-standard therapy for these bone defects. Yet these grafts are not always available, and their harvest often leads to prolonged pain. Allografts, are "dead" bone grafts, which are readily available from tissue banks, but have very low potential to induce bone repair. We have previously shown that stem cells from human bone marrow, engineered with a bone-forming gene, can lead to complete repair of segmental fractures. However, such an approach requires several steps, which could complicate and prolong the pathway to clinical use. An alternative approach would be to gene-modify stem cells that already reside in the fracture site. We were the first to show, in a rodent model, that a segmental bone defect can be completely repaired by recruitment stem cells to the defect site followed by direct gene delivery. In the proposed project we aim to further promote this approach to clinical studies. The project will include the development of a direct gene delivery technology, based on ultrasound. We will test the efficiency of the method in repairing large bone defects and its safety. If successful, we will be able to proceed to FDA approval towards first-in-human trials.

Statement of Benefit to California: 

Segmental bone defects are a complex medical problem that often requires bone grafting. Autografts are considered the gold standard for these defects, but their usage is limited by availability and donor-site morbidity and supply. Allografts are more available but often fail to integrate with the host bone. Thus there is an unmet need in the field of orthopedic medicine for novel therapies for segmental bone fractures. We propose to develop a novel approach for the treatment of such fractures without the need for a bone graft. Specifically, we will utilize ultrasound to deliver a bone-forming gene to stem cells that will be recruited to the defect site. As we have already shown, the gene would trigger the cells to regenerate the bone that had been lost due to trauma or cancer. If successful, this project could lead to the development of a simple treatment for massive bone loss. Such a treatment will benefit the citizens of California by reducing loss of workdays, duration of hospital stays, and operative costs, and by improving quality of life for Californians with complex segmental bone fractures.

Progress Report: 
  • Segmental bone fractures constitute a complex medical condition with no effective treatment. These injuries cause great suffering to patients, long-term hospitalization, repeated surgeries, loss of working days, and considerable costs to the health system. It is well known that autologous bone grafts (autografts) that are harvested from the patient, are considered the gold-standard therapy for these bone defects. Yet these grafts are not always available, and their harvest often leads to prolonged postoperative pain and comorbidity at the donor site. Bone allografts obtained from tissue banks are readily available, but lead to poor graft-host integration resulting in numerous failures. We have previously shown that mesenchymal stem cells (MSCs) engineered with a specific bone-forming gene can be used to achieve complete regeneration of segmental fractures in long bones. However, such an approach requires several steps—cell isolation, expansion, and engineering—which could complicate and prolong the regulatory pathway to clinical use. An alternative approach would be to gene-modify endogenous stem cells that reside within in the body. We were the first to show, in a rodent model, that a segmental bone defect can be completely repaired by recruitment of endogenous stem cells to the fracture site followed by direct gene delivery. In this research project we aimed to further promote this therapeutic approach to clinical studies. During the first year of the project we investigated the use of an ultrasound system to deliver genes to feature sites. Our results showed that we were able to deliver the genes to 40-50% of the cells residing in the fracture site. Moreover, 70-90% of the cells that received the genes were identified as stem cells, which are the target of the therapeutic approach. Our next goal would be to deliver bone-forming genes to stem cells in the fracture site in order to induce complete defect repair.
  • Our goal was to develop a novel therapy for complex bone fractures that do not spontaneously heal and require bone grafting. Bone grafts can be harvested from the patient or obtained from tissue banks. Both approaches entail hazardous disadvantages such as prolonged pain, infection and graft failure. We proposed to recruit the body's own stem cells to the fracture site and then to activate them to rapidly form bone by delivering a bone-inducing molecule using ultrasound. In the 1st year of the project we established the model and therapeutic protocol. During the 2nd year we tested the protocol in a bone fracture model that mimics the clinical scenario in trauma patients. Our results so far have been very encouraging indicating that we were able to repair all fractures after one treatment. Our results are based on x-ray imaging and biomechanical testing analyses performed 6 weeks post treatment.

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