Funding opportunities

Human Embryonic Stem Cell for Myocardial Restoration

Funding Type: 
Comprehensive Grant
Grant Number: 
Funds requested: 
$2 636 900
Funding Recommendations: 
Not recommended
Grant approved: 
Public Abstract: 
Coronary artery disease (CAD) is the leading cause of death in the Western world and consumes approximately fifty billion dollars annually in the United States. CAD is the most common cause of congestive heart failure (CHF), which is now the leading diagnosis associated with hospital admission afflicting over 5 million people in this country. Despite aggressive treatment of CHF with advanced medical regimen and implantable devices, the average five-year survival is a dismal 50%. Congestive heart failure is primarily a disease of tissue loss, with an overall decrease in functional capacity and residual structural deformity that can further impair remaining pump function. Medical therapies to stimulate compensatory function of the remaining myocardial tissue and surgical attempts to remodel the remaining heart tissue have been largely unsuccessful. While regeneration approaches to the treatment of decompensated heart function have been attempted for some time, only recently has a source of cellular building blocks with demonstrable ability to generate functional heart tissue become widely available, human embryonic stem cells (hESCs). This Program brings together a committed group of physicians and scientists at {REDACTED} who share a keen interest in the basic research of regeneration and functional restoration of cardiac tissue, and who firmly believe that the ultimate outcome of this collaboration will be the transplantation of hESC-derived cells for the treatment of human heart disease. The leaders of the various portions of this proposal have complementary strengths, which include expertise in stem cell biology and stem cell purification, in vivo assays that assess cardiac repair, histology and specialized microscopy, and state of the art imaging of small and large animals, as well as humans. We have come together to answer the critical questions that need to be addressed prior to investigation of this approach in human clinical studies. The work proposed in this application will teach us how to isolate the heart cells that spontaneously form from hESC when they differentiate in the laboratory, how to track and optimize survival of the hESC-derived heart cells, and how to delivery the cells and monitor their function in large animal models of heart disease. Upon completion of the proposed work, we will have established a rational protocol for the safe clinical study of embryonic stem cell therapy as a treatment of end-stage congestive heart failure
Statement of Benefit to California: 
Coronary artery disease (CAD) is the leading cause of death in California and consumes approximately 6 billion dollars annually in this state, representing a large portion of our annual health care budget. One of the common causes of death from CAD is congestive heart failure (CHF). CHF is now the leading diagnosis associated with hospital admission in this state, afflicting over 550,000 people in California. Despite aggressive treatment of CHF with advanced medical regimens and implantable devices, the average five-year survival is a dismal 50%, even in the finest tertiary heart care centers in this state. Cardiac transplantation is an established treatment for end-staged CHF but is limited to a few hundred patients per year in California. The benefit to citizens of California of the work proposed in this application is the development of tools and methodology leading to a novel and effective treatment for CHF. This treatment will be the replacement or regeneration of dead or diseased heart tissue with new and functional tissue that is derived from human embryonic stem cells. While there is still some debate, most scientists now believe that such cells are the only possible source for replacement heart tissue. Many issues need to be addressed before such therapy can be implemented. The scientists at {REDACTED} who have created this application are experts in the areas of research and clinical care that are required to create the replacement tissues, deliver the tissues to the injured heart, and monitor the treatment to optimize clinical utility.
Review Summary: 
SYNOPSIS: The average 5-year survival rate for individuals with congestive heart failure is < 50%. Attempts to compensate for the loss of cells or cellular function have been largely unsuccessful. The Specific Aims in this proposal are designed to isolate cardiomyocyte committed cells from hES cells and administer them into animal models of mycocardial infarction (MI). Cardiomyocyte progenitors will be marked using GFP expression driven by a cardiomyocyte-specific promoter. Optimal culture conditions for driving progenitor cells towards myocardial differentiation will be identified, and the ability to image these cells and track survival in murine models will be examined in Specific Aim 2. In Specific Aim 3, the safety and efficacy of the differentiated, tagged cardiomyocytes will be tested in porcine models of MI. The ultimate goal of these studies is to develop a rational clinical protocol for testing hESC-derived cardiomyocytes (hESC-CM) as therapeutics for congestive heart failure. IMPACT AND SIGNIFICANCE: This study addresses an important medical problem related to the isolation of cardiac progenitors from human ES cells, directing their differentiation, and then studying their localization and fate with advanced imaging techniques in well-defined small and large animal model systems. The significance and interest are therefore high. The investigators have identified three issues of interest in bringing hESCs to myocardial repair and, while they do not imply that these are the only important issues, they focus their attentions on them. Hence, they propose: 1) in vitro enrichment of hESC-CM; 2) in vivo small animal multi-modality imaging of hESC-CM survival, and 3) in vivo large animal delivery and multi-modality imaging of survival and functional improvement with hESC-CM. The significance of these steps is that they impact first on making sufficient numbers of appropriately differentiated cells available for the purpose of implantation, and second that they consider means for imaging the localization of cells and their functionality in situ. The successful performance of these studies should have a major impact on both our understanding of the differentiation of hESCs into myocytes and on our abilities to study the fate of the cells and of the organs in which they reside. The approach is interdisciplinary, and incorporates existing strengths on site at Stanford. QUALITY OF THE RESEARCH PLAN: There are both positive and negative aspects in the research plan. On the positive side, the investigators clearly enunciate the general tendency in the field to confuse cells being differentiated towards a functional cardiac lineage and the need to actually obtain a cell line that functions as a surrogate/replacement for lost myocardium. They have a clear understanding of the markers to be used to follow cell differentiation, and a strategy via the use of embryoid bodies. Based on preliminary data they anticipate 30-50% purification will be attained for murine and porcine studies, respectively (although it is not clear why this isn’t greater). The development of the chip array cell differentiation system in collaboration with Pat Brown to establish the appropriate conditions to optimize hESC differentiation is a major plus. Also the use of in vivo MRI and PET imaging should provide the information needed about cell localization in the murine model. Finally, the studies of functionality in the porcine heart are well-described and appear do-able. Overall, the plan includes experiments that focus on important steps on the way to myocardial repair and assessment of its efficacy. The data gathered and the technology being developed all should be of use. On the negative side, while the goals of the study are admirable, and the plan is solid, focused and logical, it is not terribly inspired in terms of the cellular isolation and other approaches. The proposal for cell isolation would gain from further depth, preliminary data, and a better consideration of alternative approaches. It is entirely possible that the methods proposed will not result in a sufficient number of cardiovascular progenitors or their progeny to allow subsequent study in vivo. Again, the preliminary data here could be stronger. In addition, important and very relevant subject areas are not carefully considered (e.g. amount of rejection, migration of cells elsewhere in the body). These areas are beyond the intent and the time frame allotted, but perhaps could be addressed in later (or parallel) work. The study as written is extremely ambitious, and it is not clear that the goals can be fully realized within the time span of the proposal. Finally, the experience of the investigators in the human ES cell arena is rather limited to date, although the existing expertise is available on site at Stanford. STRENGHTS: While this is a high risk project, the goals are meritorious and the quality of the preliminary data suggests that one may be justified in taking the risk. The major strengths are the experimental plan itself, and the preliminary data provided, which do a great deal to assuage concerns. Specifically the results studying mES cells transfected with the Nkx2.5:GFP construct, and the tracking of meschenymal cells in the porcine system are quite strong. The PI has made a reasonable choice of the markers for cell isolation, though they are identical to that of others. That this investigator is a highly respected cardiovascular researcher strengthens the feasibility of the proposed studies. They have assembled a good team of cardiologists, cardiac surgeons, and imagers, and the environment for these studies, particularly the in vivo imaging studies, is very solid. WEAKNESSES: The overriding weakness of this proposal is that it is not clear that the experimental approach will result in the isolation of sufficient quantities of the cardiac cell types of interest with preservation of their differentiation potential to allow the completion of Specific Aims II and III. To the extent that either in robustness or number the study falls short, this is a major weakness. Further, there is nothing very original in the work plan or its execution. The aims are quite ambitious and somewhat diffuse, and the investigator may have underestimated the difficulty of accomplishing the first specific aim. Another concern is that the protocols, while strongly “result-oriented” are not as strongly “mechanism-oriented.” In other words, while there may be useful outcomes, obtaining such outcomes may not be strongly associated with an understanding of why they have come out in this fashion. If results are positive, this may not be seen as a compelling flaw. If they are negative, it is difficult to understand how the investigators will use what they have learned to come up with alternative approaches. DISCUSSION: The techniques in this proposal are beautiful, but the proposal is results-oriented and not hypothesis-driven. Insofar as the robustness and number of isolated cells is critical, there are no guarantees they’ll get what they need for the animal studies, and the proposal lacks sufficient consideration of alternative plans for cell isolation. The team and environment are outstanding, and the preliminary data are strong; however, Reviewers feel that the applicants have underestimated the difficulty of achieving success in Aim 1. Should future funding opportunities arise, it would be best to focus a proposal the goals related to Specific Aim 1, and to attack this problem with multiple alternative and/or synergistic approaches and a new set of specific aims.

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