Stem cells are the building blocks of the human body. They play a major role in the regeneration of tissues, and in the development of the human embryo. Stem cells are now at the center of world attention, since it has become evident that they possess the potential to change the face of transplantation medicine. A pluripotent stem cell that may differentiate in culture to all cell types is the ”Holy Grail” of cell-based therapy and the new area of disease modeling. Human embryonic stem cells and human induced-pluripotent stem cells are a unique scientific and medical resource. These cells may give rise to many cell types of the body, such as nerve, muscle, liver, heart, and blood, and thus they hold the promise to treat many human diseases. However, the potential of pluripotent stem cells to create tumors is currently the most major safety concern in their use in the clinic and could affect how they are used to model human diseases in the dish. Our research is aimed at the characterization of abnormal cells generated from the naive cells and after their continuous growth in culture. Our unique repository of pluripotent cell lines will enable us to discover the chromosomal regions that may control the aggressiveness of the tumors and how the cells change in culture. In addition, we will attempt to identify the protein/s that characterize the tumors and use the data to generate new ways to reduce the risk of tumor formation and produce more normal culture systems.
Statement of Benefit to California:
California is now in a special position to lead the research on stem cells for years to come. Research with human embryonic stem cells has the capacity to change the face of regenerative medicine. Our study will focus on the number one concern in the use of pluripotent stem cells in transplantation medicine and disease modeling. When the cultures are expanded in the dish some cells become abnormal and dangerous for transplantation. Furthermore, these cells may make it difficult to produce good models of human disease. Our research will characterize the abnormal cells in culture, the tumors generated from the them and furthermore generate methodologies to reduce the risk of tumor formation. Through this basic research we hope to understand more about stem cell biology which in turn will allow all CIRM funded scientists to work with the best quality, normal cells for their laboratory and clinical studies. Together [REDACTED] represent over 50 years of stem cell experience. Now working together at the [REDACTED] their labs will work together in synergy to tackle one of the most fundamental problems in the field. This will be of great benefit to the state of California and its citizens.
This application proposes to investigate the effects of aneuploidy (abnormal numbers of chromosomes) on tumorigenicity and differentiation capacity in human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs). In Aim1, the incidence of recurring aneuploidies will be examined in pluripotent stem cells, neural stem cells and mesenchymal stem cells to determine if these aberrations differ between pluri- and multipotent stem cells, and to identify the smallest aberration unique to pluripotent stem cells. The goals of Aims 2 and 3 are to explore the effects of aneuploidy on the aggressiveness of teratomas and on differentiation capacity, respectively. In Aim 4, the applicants propose to investigate whether specific genes that are affected by the chromosomal aberrations contribute to oncogenic transformation of stem cells.
Significance and Innovation:
- Reviewers expressed mixed opinions regarding the significance of this proposal.
- Some reviewers felt that the analysis of aneuploid pluripotent stem cells is not a high priority in the field. For example, the applicant intends to gain clinically relevant insights by studying the tumorigenicity of transplanted neural cells derived from aneuploid stem cells. However, aneuploid cells will not be utilized in clinical settings.
- Other reviewers felt that this proposal addresses important, mechanistic questions and has the potential to make a significant impact. Defining chromosomal abnormalities and specific genes associated with increased tumorigenicity may enable the development of methods to reduce the risk of tumor formation. This could significantly enhance the safety of stem cell-based therapeutics.
- Given the high frequency of chromosomal changes that develop during the culturing or reprogramming process, delineation of their functional consequences is significant.
- Some of the proposed methodologies are innovative. However, the overall novelty is limited as many of the proposed studies are an extension of work that has already been published.
Feasibility and Experimental Design:
- The proposal is poorly written, the approach is only superficially described, and very little experimental detail is provided. Thus, the feasibility of the research plan is difficult to assess.
- Potential pitfalls and alternative plans are not discussed.
- In order to correlate tumorigenicity with the level of aneuploidy, it must be assumed that the genome of aneuploid cells remains stable during the many cell divisions that generate a tumor. However, this may not be the case.
- Data obtained from publicly available databases, to be included in the search for common aneuploidies, may vary due to differing experimental conditions. It is unclear how this will be taken into account to allow effects solely due to aneuploidy to be distinguished with any confidence.
- The preliminary data are strong and support the ability of the applicants to perform sophisticated analyses of chromosomal abnormalities in stem cell cultures. They further support the hypothesis that these abnormalities occur with high enough frequency to cause concern.
Principal Investigator (PI) and Research Team:
- The PI has published a number of seminal papers on stem cells in the last several years and has a track record of grant support for stem cell-related research.
- The PI and co-investigator are well suited to carry out the proposed studies and the research team has all the expertise necessary to perform the experiments.
- The budget is appropriate.
Responsiveness to the RFA:
- The proposed studies are responsive to the RFA, as they explore fundamental processes of in vitro adaptation of human stem cells.