Derivation of Human Embryonic Stem Cell-Like Cells from the Testis

Funding Type: 
SEED Grant
Grant Number: 
ICOC Funds Committed: 
Stem Cell Use: 
Embryonic Stem Cell
Public Abstract: 
Although the potential of embryonic stem cell-based therapy to cure disease is tremendous, its progress has been hampered by the biological complexity of stem cells and by limited federal research support. We propose to develop “embryonic stem cell-like” cells, that have been shown in animal models to have pluripotency properties similar to true embryonic stem cells, using adult testis tissue, and not human embryos, as the cell source. This research is based on the recognition that early germ cells (cells later destined to become sperm) in the testis are likely to be pluripotent, unlike other cells in the body. In other words, they have the power to either self-renew or to generate another cell type. As shown in mouse studies, it is possible to extract and culture the critically important testis stem cell (spermatogonial stem cells) in a Petri dish for prolonged periods of time. Under specific and precise culture conditions, it is also possible to “reprogram” these stem cells, or to uncover their pluripotency potential, so that they the gain the properties of true embryonic stem cells. Although these cells are not actually obtained from embryos, these “embryonic stem cell-like” cells perform many activities of true embryonic stem cells, including self-renewal or the ability to develop into other cell types in the body. Work in our laboratory suggests that we also can obtain these early germ (spermatogonial) stem cells from adult men after a testis biopsy. Additionally, in specific culture conditions, we were able to coax these stem cells into cells that looked identical to embryonic stem cells. Despite early success, our first attempts to grow these cells for prolonged periods to verify their identity was not successful. We reasoned that we had not created the optimal culture conditions for these cells to “reprogram” or to uncover their pluripotency. Thus, one aim of this proposal is to study culture conditions, including systems that employ embryonic stem cells, to generate an optimal environment for reprogramming testis stem cells into embryonic stem cell-like cells. Since one goal stem cell therapy is to repair damaged tissues in diverse diseases and individuals, another aim of this study addresses this issue. Because diseases are not limited by age or ethnicity, we will derive embryonic stem cell-like cells from individuals of various ages and ethnicities. We will determine whether the age or ethnicity of the stem cell donor affects our ability to generate embryonic stem cell-like cells. Perhaps it is more difficult to generate stem cells from men who are older compared to younger, or men of certain ethnicities compared to others. This information will have important clinical implications if testis based stem cell therapy is used to treat disease in the future. In summary, through this research we hope to obtain pluripotent stem cells that could potentially be used to treat disease in half the world’s population, without using embryos.
Statement of Benefit to California: 
Five decades ago, a fledgling electronics and computer chip industry began to flourish in California. Known now as Silicon Valley, it was the vanguard of one of the world’s greatest industrial revolutions. Three decades ago, biotechnology also found a stronghold in California, and since then has blossomed into an industry of similarly profound size and productivity. Research in stem cell biology, enabled by Proposition 71, is yet another example of a burgeoning revolution that will maintain California’s competitiveness and reputation as the nation’s premier state for biomedical research. As Florence served as a magnet for education and the arts during the Renaissance, California, with its long history of entrepreneurial energy and new interest in funding stem cell research, now has the ability to draw into its fold the best minds in biomedical science with the potential for research funding in one of the most promising fields that biomedical research has ever witnessed. The research, which will use known hESC lines to help create and characterize patient-specific, embryo-free, pluripotent stem cells of potential benefit to half of the world’s population, is uniquely suited for CIRM funding and will benefit the California on several fronts. Through its broad scientific approach and requirement for a highly skilled, broadly trained and multidisciplinary team, this proposal assembles a cohesive group of talented clinicians and scientists, including the hiring of others (post-doctoral fellow), who will work together to improve our ability to recruit and retain premier scientific minds in California. In addition, the mentoring abilities of the lead scientist and the project collaborator are robust, further contributing to the training of future stem cell scientists in California. Lastly, multidisciplinary interactions are essential not only for solving today’s problems in stem cell biology, but they also form a crucible for gestating the next generation of ideas and discoveries. In this way, California’s reputation at the premier state for stem cell research will be maintained, even as other states including Massachusetts, New Jersey, Connecticut, Maryland and Illinois consider similar state-supported, stem cell propositions. In addition to the importance of a broadly trained team to the discovery “process” in the proposed research, the “content” of this proposal will add value to California in the form industry collaborations and patents. Given that a vibrant biotechnology industry coexists with academic centers in California, one can foresee this research in non-embryo-based, pluripotent stem cell technology being carried to its full clinical potential as cell-based therapy through academic-industry collaboration. Finally, by funding this proposal with limited federal funding opportunities, California will maintain its competitiveness as a global leader in high quality, clinically driven, embryonic and non-embryonic stem cell research.
Progress Report: 
  • Stem cell quality and safety for regenerative medicine therapies is of utmost importance. Poor outcomes include inadequate functionality, exhaustion, immune rejection, cancer development, and others. Recent studies strongly support our core hypothesis that mitochondrial function determines stem cell quality and safety. Dysfunctional mitochondria foster cancer, diabetes, obesity, neurodegeneration, immunodeficiency, and cardiomyopathy. Unlike whole genome approaches, methodological hurdles for evaluating mitochondria in human embryonic stem cells (hESCs) and in reprogrammed human induced pluripotent stem cells (hIPSCs) are significant and techniques developed or adapted for stem cells are almost non-existent. With this 2-year CIRM Seed Grant, we developed new approaches for analyzing respiration (oxygen consumption that drives energy production) in hESCs and hIPSCs in a series of 4 invited publications for the stem cell scientific community (; 2008). We showed that mitochondria are capable of respiring and utilizing oxygen for energy generation but do this at a very limited level compared to mature tissue cells of an adult. We speculate that this is because the cells from which hESC are derived exist physiologically in a low oxygen environment and require a switch to be turned on to facilitate oxygen consumption during development. We are working hard on understanding this switch and believe we have one of the components identified. We showed that mitochondria in reprogrammed hIPSCs are not completely reset to the embryonic state seen in hESCs, which may have implications for the use of hIPSCs in regenerative medicine. A manuscript describing the function of hESC and hIPSC mitochondria in low oxygen tension (hypoxia), in normoxia (room air), and during differentiation is being prepared for manuscript submission. We also collaboratively developed small molecule inhibitors of specific mitochondrial functions, thereby providing new essential tools to the scientific community for interrogating the function of stem cell mitochondria- this work is being continued under a new funding mechanism from CIRM. Unlike current inhibitors of mitochondrial function, with are generally non-specific, irreversible, and toxic over time, our novel inhibitors are reversible, non-lethal, and target a range of specific mitochondrial functions. These inhibitors are undergoing continuous molecular refinement and validation studies for use in basic studies and can potentially lead to insights for clinical application in common diseases, such as diabetes and cancer. They may also find utility in interrogating hESC and hIPSC mitochondria function to pick the best stem cell lines for developing future cellular therapies.

© 2013 California Institute for Regenerative Medicine