HESCs hold great potential in the treatment of many human disorders for which no effective therapies presently exist. A major challenge in realizing the therapeutic value of these cells is the development of well-defined and optimized conditions by which hESCs can be expanded and differentiated in vitro. To establish the stem cell-based regenerative therapy, it is necessary to generate sufficient number of cells with specific functions. The maintenance of stem cells with pluripotency as well as the control of differentiation under well defined condition without the support of the mouse feeder cells is essential for the safe use of stem cells in therapies. Success of such research activities requires a comprehensive and cost effective platform that can control and direct the fate of the stem cells in terms of proliferation and differentiation. The aim of our proposed research is to establish a platform that allows the systematic investigation of the role of the physicochemical microenvironment in modulating the fate of various types of stem cells. The result will provide a common foundation needed for stem cell research directed at a broad range of diseases.
Our extracellular matrix protein (ECMPs) microarray platform allowed us to use only minute amount of the ECMPS to screen hundreds or thousands of the conditions for hESC growth and differentiation. With such a platform, we have screened 320 unique combinations of 5 different proteins without animal feeder cell supplements. The results suggest that the combination of 4 ECMPs (collagen 1, collagen 4, laminin, and fibronectin) provides excellent support for the long-term growth of three hESC lines (H1, HUES1 and HUES9) tested with prolonged pluripotency. The 4 ECMP-combination was also used for scale-up hESC culture and such a combination supported these cells for more than 10 passages without losing their abilities of proliferation and differentiation. In addition to ECMPs, testing of growth factors indicates that three factors (WNT5A, WNT3A, and FGF) have positive effects on cell pluripotency maintenance, and two factors (BMP4 and RA) affect hESC differentiation. Furthermore, our tests also indicate that mechanical loading can promote cell differentiation. Our systematic study of the roles of microenvironmental factors by using a combinatorial approach can replace the undefined cell culture conditions with the use of mouse feeder cells.
In summary, our results provide new insight on defining the optimum stem cell culture condition, which can be used to customize the parameters for expansion of different types of stem cell culture. Hence, this project has fundamental importance and broad applications. This is a most cost-effective way to pursue hESC research for the improvement of human health and quality of life, and the resulting technology advances would provide financial gain for the people in California.