Disease Team Planning
The incidence of adult-onset Diabetes Mellitus (DM)(T2DM) has been rapidly increasing in California and throughout the world. T2DM commonly runs in families, indicating a genetic predisposition, but human genes do not change as fast as the incidence of T2DM is increasing. Therefore, much of the increase in T2DM incidence must be the result of the faulty interaction between ancient genes and recent changes in our environment. DM patients have high levels of sugar (glucose) in their blood. This glucose comes from our food and is used as fuel to generate energy by the power plants of our cells, the mitochondria. If an individual that eats a higher sugar diet than the mitochondria can burn, glucose builds up in the blood. Mitochondrial deficiencies have been found in T2DM patients, thus limiting their capacity to metabolize today’s rich diets. Like industrial power plants, our mitochondrial power plants contain their own blueprints located inside the mitochondrion, the mitochondrial DNA. Damage to the mtDNA means that damaged power plants can not be repaired and go offline. In a number of instances, T2DM has been associated with defects in the mtDNA blueprints. Therefore, T2DM is associated with an underlying mitochondrial defect. When we eat a high sugar meal, our blood sugar level rises. Cells in the pancreas, the beta cells, sense the high blood glucose and secrete a hormonal signal, insulin. Insulin enters the blood stream and instructs the cells in our body to start burning the glucose. However, if the mitochondrial furnace is damaged, the glucose fuel can not be burned and both glucose and insulin build up in the blood. As long as the blood glucose is high, the beta cells will keep producing and secreting insulin. However, this puts an enormous stress on the beta cells, and eventually they burn out and die. Consequently, the patient’s cells are not informed when fuel is available and thus don’t burn it. This leads to end stage T2DM. If we wish to effectively treat people for T2DM, we must first correct the mitochondrial defect so that the cells can again convert the glucose into energy. Then we can replenish the patient’s beta cells using stem cells so that the rest of the body’s cells know when to burn the glucose. Therefore, we propose to develop a drug and neutriceutical procedure to repair and reactivate the mitochondria throughout the body. In addition, we propose to create individualized replacement Beta cells by converting the patient’s skin cells into stem cells. These patient stem cells will then be converted into functional beta cells for introduction back into the liver of the patient. The new beta cells should colonize the liver, secreting insulin and regulating blood glucose.
Statement of Benefit to California:
Diabetes Mellitus (DM) currently affects 4 to 5% of the world population and the incidence of DM has been projected to increase 50% between 2000 and 2030. By 2010, approximately 350 million individuals will suffer from DM (1, 2). DM patients are also at increased risk of developing renal, visual, and peripheral neuropathy symptoms, and the relative risk of developing DM and the associated complications varies among California’s ethnic groups (3). Hence, the health burden of DM in California is enormous. Diabetes is traditionally divided into two classes: an early-onset, HLA class I associated form presenting with a complete absence of endogenous insulin production (Type I DM, T1DM) and a later-onset, non-HLA associated form frequently associated with the retention of some endogenous insulin production (Type II DM, T2DM). In the U.S. T1DM patients account for about 5 to 10% of DM. T2DM patients then account for the remaining 90 to 95% of cases (2). Since T1DM is assumed to result from the autoimmune destruction of the pancreatic beta cells, it is thought that this disease might be treated by suppression of the immune system and infusion of functional pancreatic islets into the liver (4). By contrast, the etiology of T2DM is less well understood, and its treatment might be more complex. Still, the health burden of T2DM vastly overshadows that of T1DM. Hence, the search for a cure for T2DM must be a high priority. A recent series of discoveries may have brought T2DM into the realm of treat-ability. A rising tide of evidence has appeared that indicates that most T2DM patients have an underlying defect in mitochondrial oxidative phosphorylation (OXPHOS) (5-10). Moreover, the discovery of T2DM cases caused by mtDNA mutations (11, 12) has stimulated the active search of pharmacological and neutraceutical approaches to treat mitochondrial dysfunction (13-19). Therefore, it follows that T2DM could be effectively treated by a combination of metabolic treatment to resuscitate faltering mitochondria plus replacement of lost beta cells through stem cell-derived beta cell replacement, which is what we proposed here. However, the significance of this project goes far beyond treatment of T2DM. Certainly, the beta cells could be used to treat T1DM patients. More importantly, however, it is becoming increasingly clear that mitochondrial dysfunction underlies the etiology a broad spectrum of metabolic, neurological, and cardiovascular diseases as well as cancer and aging (13, 20, 21). Hence, an effective mitochondrial resuscitation cocktail might be an essential adjunct of many of the cell based therapies that are being considered by CIRM including those for treating Parkinson Disease, Alzheimer Disease, Amyotrophic Lateral Sclerosis (ALS), retinal degeneration, deafness, cardiomyopathy, etc.
Executive Summary This proposal is focused on developing a treatment for Type II Diabetes Mellitus (T2DM). The treatment design is based on the premise that T2DM is caused by a systematic mitochondrial defect. One goal will be the development of a mitochondrial resuscitation cocktail that stimulates mitochondrial function and optimizes mitochondrial activity. A second goal will be to replace lost or damaged pancreatic islet cells with patient-specific cells derived via induced pluripotency followed by in vitro differentiation and maturation. The efficacy and safety of these approaches will be tested first in mouse models. The proposal is focused on a very significant disease, with an incidence that has been increasing rapidly in California and throughout the world. The proposed approach is directed at both correcting systemic metabolic defects associated with T2DM and replacing lost pancreatic beta cells. Although reviewers felt that the proposal outlined an interesting and innovative approach, they had strong doubts about the underlying premise that most T2DM is caused by a mitochondrial defect reversible by mitochondrial resuscitation, even though T2DM is associated with significant oxidative stress. Considerable published clinical evidence supports the heterogeneous, complex nature of the disease and reviewers felt that the complexity would not be captured by a purely mitochondrial pathophysiological focus. Consequently, the proposed therapeutic intervention was not viewed as likely to cure most cases of T2DM. Furthermore, the major focus of the proposal could be achieved independent of stem cell biology, by developing mitochondrial cocktails for diabetes independent of stem cells; stem cells are not the foundation of the proposal. Reviewers had two additional concerns that limited their enthusiasm for the proposal. First, the development, optimization, potential side effects, and regulatory approval for the resuscitation cocktail were viewed as serious obstacles. Second, the generation of mature pancreatic islet cells from patient-specific induced pluripotent stem cells has yet to be achieved, with a variety of steps in the process and appropriate conditions for development unknown. The prospect for these challenges being addressed within the five year time-frame was judged highly unlikely. The PI is a widely recognized leader in the field of mitochondrial disease. He/she has a superb record of productivity and collaboration and has substantial experience in assembling and managing team-based research programs. The PI is a clear strength of the proposal. The planning approach is well organized and structured. Prospective team members with appropriate expertise are identified. Seven subcommittees are assigned distinct responsibilities in formulating and guiding the planning process. Reviewer Synopsis The premise of this proposal is that Type II Diabetes Mellitus (T2DM) is caused by a systemic mitochondrial defect that could be corrected by developing a mitochondrial resuscitation cocktail that up-regulates OXPHOS, reduces oxygen radicals, inhibits apoptosis, and optimizes mitochondrial autophagy. Then to replace the lost cells, the applicant proposes to genetically induce patient cells into pluripotent stem (iPS) cells and use the Novocell differentiation procedure to generate immature cells, and to apply insights from mouse studies to induce the maturation of the human cells. The efficacy and safety of the cocktail and cells will be tested in mouse models of T1DM and mitochondrially-induced T2DM. Preclinical testing of the mitochondrial cocktail will be performed on patients with known mtDNA defects and on IR and NIDDM patients. Preclinical tests of the iPS cell-derived cells will apply the Edmonton transplantation protocol to IDDM patients in combination with mitochondrial resuscitation. Reviewer One Comments Concept: The proposal focuses on a very significant disease (T2DM), even though the clinical definition seems to capture a number of diseases with different pathophysiological etiology. The concept underlying this proposal is that mitochondria cause T2DM. This is an interesting idea; however this is unlikely to be ultimately the sole cause of T2DM. Thus treatment with iPS cured for mitochondrial defects is a very preliminary idea, especially since T2DM is treatable with other approaches. Another important consideration is that it is unclear and unknown how well the Novocell protocol works for the production of pancreatic islet-like cells. Principal Investigator: The PI is a pioneer in the field of mitochondrial disease. He is not an MD. Planning Approach: The planning approach is divided up into individual planning committees. It seems very organized and structured. The host institution is an excellent environment for the project. Reviewer Two Comments Concept: The premise of this proposal is that type 2 diabetes is a mitochondrial disease in that insulin resistance is the result of the inability of the mitochondria to oxidize all the calories consumed leading to ROS that cause mitochondrial damage; cells are then stressed by the extra glucose causing their dysfunction and loss. Thus, the concept is that a cure for type 2 diabetes would be two pronged: a cocktail to resuscitate the mitochondria and then replacement of cells using a patient’s own induced pluripotent stem (iPS) differentiated to functional mature cells ex vivo. While a small proportion of type 2 diabetes patients clearly have a mitochondrial defect (along with deafness), type 2 diabetes is a heterogeneous disease that may arise from many different genes contributing to cell inability to compensate for the functional demand of insulin resistance. Two arguments against the mitochondrial basis of type 2 diabetes as defined here are : 1) most obese persons have significant insulin resistance but are not diabetic (actually have normal glucose tolerance); 2) 70% of type 2 patients who undergo gastric bypass become non diabetic within a week of surgery. The generation of a mitochondrial resuscitation cocktail is imaginative and based on the research of the PI and his collaborators. As suggested it might include resveratrol (to increase SIRT1 activation and OXPHOS energy output), bezefibrate (to increase fatty acid metabolism), natural or catalytic antioxidants (to ameliorate mitochondrial oxidative damage), a modified cyclosporine (to inhibit apoptosis) and PI3K antagonists and agonists to regulate mitochondrial turnover. It is frightening what side effects could be seen from these numerous drugs. While there are mouse models to test the effectiveness of the variations of this cocktail, it is hard to conceive of FDA approval for all within the desired time frame. The second prong is equally problematic: generation of patient specific-induced pluripotent stem cells, then using the Novocell protocol to generate cells from these and some yet to be discovered protocol for inducing functional maturity in these cells. Each of these steps is unproven and will need extensive development. Thus the feasibility in the time frame for this prong is doubtful. Principal Investigator: Dr. Wallace is Director of the Center for Molecular and Mitochondrial Medicine and Genetics and Professor of Molecular Medicine, of Biological Chemistry and of Ecology and Evolutionary Biology UC Irvine. A member of the National Academy of Sciences, he is a well recognized expert on mitochondrial dysfunction and disease. He not only is an excellent scientist but he has many years of experience in building and managing a group of basic, translational and clinical researchers. He and several of the other involved already have CIRM grants. He is clearly a strength of this proposal. Planning Approach: The planning approach is for 7 subspecialty groups with specific responsibilities to meet together monthly to define the goals and plans to achieve those goals. The groups include: mitochondrial medicine, hES cells, cell development, mouse diabetes models, patient recruitment and evaluation, transplantation and evaluation, and regulatory and commercial. The individuals who are core to these groups are named and provide a large range of necessary expertise. It is likely that these committees will be able to define the goals and steps to get to clinical trials.