Synthetic Environments to control Human Embryonic Stem Cell Self-Renewal and Fate Determination

K.E. Healy
Departments of Bioengineering and Materials Science and Engineering, University of California at Berkeley, Berkeley, CA

Human embryonic stem (hES) cells are being studied as potential source of cells for the treatment for many diseases (e.g. diabetes, Parkinson’s, leukemia, congestive heart failure). The successful integration of hES cells into such therapies will hinge upon three critical themes: stem cell expansion in number without differentiating (i.e., self-renewal); differentiation into a specific progenitor type or collection of cell types; and, promotion of their functional integration into existing tissue. Precisely controlling each of these steps is essential to maximize the therapeutic efficacy of hES cells, as well as to minimize potential side effects that can occur when cells numbers and types are not properly controlled. However, this has been difficult to achieve in practice, since environmental conditions for self-renewal and differentiation are incompletely understood and still suffer from many drawbacks. Control of hES cell self-renewal and differentiation within a synthetic system offers several advantages. If hES cells can be derived and maintained within a completely synthetic environment, then it will be possible to eliminate pathogen transmission associated with mouse or human feeder layers, provide a scalable basis for large-scale production of hES cell, and provide precise methodology for controlling hES cell differentiation.

My group is developing novel platform technologies consisting of a completely synthetic environment to precisely control hES self-renewal and subsequent differentiation into a defined phenotype. We aim to engineer a tunable and well-defined environment presenting a completely synthetic extracellular matrix, chemically defined media, and environmental conditions (e.g., media pH & pO2, bioreactor physical conditions, etc.). This presentation will focus on the following three main themes related to creating synthetic environments to control of hES cell self-renewal and differentiation:
1) control of hES cell interaction with biomimetic matrices [i.e., mechanically and chemically tunable materials];
2) development of chemically defined hES cell culture media; and,
3) fate determination from chemically and mechanically defined environmental conditions.
By emphasizing these themes, we can create biomaterials, synthetic media, and cell culture protocols that can increase the reproducibility of culture conditions and elucidate the requirements for hES cell maintenance and differentiation. This approach will also yield novel insights into environmental regulation of hES cell biology, provide novel systems for in vitro hES expansion, and create methods that enhance control of transplanted stem cell populations to develop into specific tissues.

This research was supported in part by grants from Berkeley Futures and the NIH EB005812.