To harness the regenerative capabilities of stem cells we need to understand both their broad potential and limitations. There are two camps on how to achieve the greatest clinical benefit using stem cells as a therapy. One wants to isolate embryonic stem cells and inject them into patients where they are expected to ‘home’ only to the exact spot in the body where they are needed, and in this case relatively few biologically powerful cells are needed. The second wants to engineer tissues in the lab made out of stem cells that can be transplanted to specific locations in patients, where the cells used are likely larger numbers of adult stem cells which may or may not be derived from embryonic cells. Our effort is more directed to this later possibility. We tap into an existing protocol developed to isolate cells that work in tissue engineered skin, and seek to expand this protocol’s capability by maximizing the number of times we get the cells to replicate, and by branching out to get it to work with other cell types. Our goal is to enhance the quantity, quality, and diversity of stem cell types available while contributing to knowledge about any unique properties of these cells. So far we can successfully isolate and expand cells from the outer layer of the skin and have documented that they make proteins characteristic of adult stem cells, and therefore may have future applications in wound healing. Surprisingly, fat cells isolated in the same way were able to store more fat than others have seen in culture, indicating that our conditions may be inherently better than those used by others. The fat cultures could provide tests for understanding obesity and diabetes. Neurons are another cell type that could provide benefits but they are nearly impossible to grow. Neurons actually derive from epithelial cells, so there is a chance that the prolific epithelial stem cells we isolate could be converted to neurons, creating a nearly limitless supply of a valuable cell type that might be used to cure paralysis or other neurological problems. A recent breakthrough in stem cell research is the identification of a set of proteins that can actually convert regular cells into the functional equivalent of embryonic stem cells without destroying embryos. A subset of these proteins may operate in adult stem cells also and we have a novel test that may indicate which proteins are important for which adult stem cell types. We want to understand which proteins control how often stem cells divide and which ones impart their ability to convert into other cell types. We will make the cells we grow available to other researchers in California.
Statement of Benefit to California:
For the citizens of the State of California there are multiple benefits to the quality of life experienced by all that would be positively impacted by the support of stem cell research, and our project in particular should lead to practical solutions and products in the shorter term. The use of stem cells actually has the potential to multiply the positive impact of modern medicine because it opens up a new type of treatment – cell based therapies. In human history drugs, at first derived from plants, were the category of treatments developed for what ails us, in essence you give the body a dose of a chemical that can reset living cells back onto a healthy course. But there is only so much you can accomplish with a chemical, i.e., living tissues are sometimes too damaged to respond to the quick fix of drugs, and they sometimes have dangerous side effects. So what if you could actually replace living tissues? Stem cells are the most powerful biological units for regrowing parts of the body, and their use will lead to the most powerful medicine ever made available to humanity. We link our effort into a local effort to grow human skin in plastic dishes. There is an immediate need to replace animal testing for cosmetics and personal care products with lab tests, and skin grown in the lab is a product today that has broad uses. The European Economic Community has a complete ban on animal testing for these uses by January 2009, and companies worldwide must comply if they wish to sell products there. The best skin products lead naturally into applications in wound healing of all types, from surgeries, for burns etc. Their application will reduce hospital stays by reducing recovery times. Skin grafting is currently 90% of all cell-based therapy, so our project is linked to the area of greatest success, but we are rapidly branching out. Skin biopsies are rich in blood vessels so we are learning how to revascularize wounds, and the fat layer just under the skin can be made to grow, or we can learn to control its proliferation to reduce obesity and diabetes. We are all touched by the suffering and paralysis of neuronal disease. Surprisingly, neurons derive biologically from the same layer as the outer skin, so we are also trying to accomplish this in the lab to yield a profusion of neurons. The treatment is living cells, so growing up a large supply of the right ones is a main point, and a major part of our emphasis. We can train students to become the skilled workforce to apply science, techniques, and procedures that yield living cells as a valuable resource. The technology is clean and nonpolluting, using reagents that sustain life by their very nature.
In this proposal the investigators seek to scale-up an existing protocol to isolate and propagate adult stem cells from skin that produce keratinocytes capable of incorporating into 3D skin constructs, and apply these methods to the production and characterization of additional cell types such as adipocytes, endothelial cells, and epithelial-derived neural cells. Using proprietary technology they propose to expand progenitor cells from skin biopsies with the goal of banking the cells and making them available to researchers in the stem cell community for use in studies aimed at, for instance, creation of skin grafts.
The isolation and propagation of high quality skin cells capable of use in artificial 3D skin constructs could lead to potential improved therapies in wound healing, for example. The applicant also alludes to the use of skin-derived stem and progenitor cells to replace animals currently used to test chemicals in cosmetics and other home products and to treat burn victims, a currently-used application of these cells. However, there is no explicit statement in the proposal of the intended uses of the cells generated from these studies other than to make them available to the scientific community. Hence, the impact of completing the proposed studies is unclear.
Reviewers agreed that this proposal is poorly written, vague, and disjointed, which makes discerning the intent of the experiments difficult. The proposed experiments are not described with adequate detail and the rationale for pursuing some of them is not clear. For example, the specific rationale for preparing a cell bank is not clearly stated, nor is it clear what the relevance of the proposed transcription factor assays are or how these data will be used in the context of the majority of the proposed experiments. The preliminary data is also vaguely described and therefore reviewers were unable to adequately judge the feasibility of these studies. For instance, the number keratinocyte stem cells that can actually be generated from skin biopsies is not described, much less are numbers of adipocytes, endothelial or neural stem cells. The applicant aims to establish a cell bank for the use by CIRM-funded investigators, however it is not clear how many investigators would be interested in obtaining the cells, and such a survey is important to judge the need for the planned cell production and storage.
The PI brings experience as head of a small start-up biotechnology company, which developed the 3D skin construct technology, and as a faculty investigator at a California university. It is not clear how long the PI has held an adjunct faculty position at the applicant institution. The PI has a limited publication record and it is not clear from the proposal what are the impact and function of the 3D skin constructs previously generated by the PI, information that would have helped in evaluating the PI’s team leadership skills.
Overall, reviewers felt that the proposal lacked a clear and compelling research plan. Unfortunately, the proposal attempts to draw on the varied research interests of the PI and co-investigators, rather than to focus on a clear, primary tools & technology objective.