This application is focused on a development candidate and describes studies to investigate the potential of amniotic fluid-derived stem cells (AFSCs) and amniotic fluid kidney progenitor cells (AFKPCs) to mediate kidney repair in animal models of Alport’s syndrome, and to develop human AFSC’s or AFKPCs for clinical use. Currently, dialysis and kidney transplantation remain the only viable treatments for end-stage renal disease, and significant complications are associated with both therapies. Stem cells are, then, attractive and rational potential therapeutic tools. The applicant intends to determine whether different treatment regimens, specifically early versus later treatment and single versus multiple treatments of stem cells, can improve renal outcome. Safety and efficacy of AFSC/AFKPC in the Alport animal model will be examined. To facilitate progress toward the early clinical development phases for AFSCs and AFKPCs, the applicant proposes to fulfill all of the requirements for scalability under Good Manufacturing Practice (GMP) conditions as a prerequisite to testing the safety and activity of the stem cells in human phase I trials.
The principal investigator has chosen an important health care problem to address, one that has not been seriously impacted by stem cell biology--deterioration of kidney function that leads to kidney failure. If stem cells of any type could home to the kidney and replace or augment the function of the injured or dysfunctional cells, kidney failure might be potentially slowed, thus improving the lives of many patients and saving billions of dollars in health care costs. The use of AFSCs as opposed to embryonic stem cells has several potential advantages, since AFSCs do not rely on embryonic sources for isolation, and are considered less likely to generate teratomas. Thus, the development candidate(s) could address an unmet medical need and potentially have significant impact. However, a lack of consideration of issues of immunogenicity relating to the use of allogeneic stem cells limits the potential of this approach, and reviewers were surprised that extensive discussion of this issue was missing from the application. There was no consideration of the fact that human AFSC’s or AFKPCs from allogeneic donors have potential to elicit an immune response, especially upon differentiation into renal lineage cells. The preliminary data were obtained in either syngeneic models or immunodeficient mice, although little detail was provided.
In Alport’s syndrome, podocytes (part of the glomerular filtration apparatus) fail to make the appropriate collagen IV network, which leads to glomerular injury, decreased renal perfusion, and kidney failure. If the defective podocytes could be replaced with genetically normal cells, they may synthesize the correct collagen IV network, leading to a halt in disease progression. One reviewer stated that the dependence of Aim 2 on Aim 1’s success was a drawback, as the applicant acknowledges that Aim 1 may consume considerable amounts of time and that alternative approaches may be required as the applicant works through the disease model. In short, reviewers felt there was a disproportionate reliance in the proposed work on the mouse model. Although there were good preliminary data to suggest the model would be useful, reviewers were concerned that potential pitfalls and alternatives to the mouse work were not adequately addressed. In addition, there was a lack of detail for reviewers in the description of purification of the bone marrow stem cells, which is the control cell population. Finally, one reviewer felt that interpretation of some figures in the proposal was unconvincing and not clearly aligned with the hypothesis. In addition, reviewers interpreted the data as showing only few AFSCs in the glomeruli of treated animals, which may suggest that regenerative processes may be insufficient to restore sufficient collagen to address functional glomerular rescue.
The principal applicant is an internationally recognized researcher with an outstanding publication and funding track record. The assembled team of investigators is outstanding, and covers expertise in kidney physiology and in isolation and handling of human stem cells. Thus, the expertise is in place to carry out these studies, with the exception of immunology where the team lacks domain expertise. The budget proposed by the principal applicant is extremely high for the work proposed. The amount of work is no more than proposed in a typical R01, as a benchmark. Inflated FTEs, travel ($5000 per year for each individual paid from the grant), mouse, microarray charges, etc. appeared inflated. Given the risky nature of the work and the lack of consideration to important immunologic issues, a more modest budget is appropriate especially for the first two years of proposed work.
In summary, this application focuses on creation of a development candidate to address Alport Syndrome as a model kidney disease, using stem cells from the amniotic fluid and kidney progenitor cells from the amniotic fluid as therapies. Although the reviewers praised the rationale and the enormous need for new approaches to end-stage renal disease, this application had several issues that detracted from its appeal, most importantly the lack of sufficient consideration of thorny immunological issues. Enthusiasm for the proposal was also dampened by vague and unconvincing presentation of some preliminary data, and major concerns over construction of the budget.