Mechanisms protecting self-renewal of human hematopoietic stem cells
Blood stem cells have already been used in the clinic to treat patients suffering from blood cancers or inherited blood disorders. However, only a fraction of patients can be treated as there are not enough compatible bone marrow donors, and it has not been possible to create more blood stem cells in culture by using expansion protocols, or by generating them from undifferentiated pluripotent stem cells. The limited success in creating blood stem cells in culture stems from our incomplete understanding of the regulatory mechanisms that protect their unique properties. This is especially challenging in human, as there is insufficient knowledge of how to identify human blood stem cells, and as there have not been good experimental models to manipulate human blood stem cells or their niche cells for mechanistic studies. We have overcome these bottlenecks and identified a human HSC surface protein GPI80 that allows purification of blood stem cells during human fetal development from multiple blood forming tissues. Our data also indicate that GPI80 is necessary for blood stem cell self-renewal and interaction with their niche cells. With these findings and the tools we have established, we are in a unique position to define the key pathways active in GPI80+ blood stem cells that maintain their unique properties. Identification of these factors will ultimately help us create more blood stem cells in culture for therapeutic applications.
The goal of this proposal is to identify regulatory molecules that could be used in the future to help expand hematopoietic stem cells in culture, or even to generate them from pluripotent stem cells. Thus, the results of this work could help develop better treatment for patients in California suffering from various blood diseases such as leukemia and inherited blood/immune disorders.
This study may also lead to the development of commercial applications for molecules that could be used for future clinical HSC culture protocols, and thereby this work may boost the biotech industry in California.
This work will also serve as an outstanding training tool for students and post-doctoral fellows in California who aim to learn human hematopoietic stem cell manipulation and state of the art assays to investigate their function and molecular regulation. This training will provide an outstanding foundation for a career in either academia or biotech industry.