Biophysical factors in the regulation of asymmetric division of stem cells.

Stem cells are a promising cell source for regenerative medicine due to their characteristics of self-renewal and differentiation. The intricate balance between these two cell fates is maintained by precisely controlled symmetric and asymmetric cell divisions. Asymmetric division has a fundamental importance in maintaining tissue homeostasis and in the development of multi-cellular organisms. For example, during development, asymmetric cell divisions are responsible for the formation of the body axis. Mechanistically, mitotic spindle dynamics determine the assembly and separation of chromosomes and regulate the orientation of cell division. Interestingly, symmetric and asymmetric cell division is not mutually exclusive and a range of factors are involved in such cell-fate decisions, the measurement of which can provide efficient and reliable information on the regenerative potential of a cell. The balance between self-renewal and differentiation in stem cells is controlled by various biophysical and biochemical cues. Although the role of biochemical factors in asymmetric stem cell division has been widely studied, the effect of biophysical cues in stem-cell self-renewal is not comprehensively understood. Herein, we review the biological relevance of stem-cell asymmetric division to regenerative medicine and discuss the influences of various intrinsic and extrinsic biophysical cues in stem-cell self-renewal. This review particularly aims to inform the clinical translation of efforts to control the self-renewal ability of stem cells through the tuning of various biophysical cues.