(149a) Dissecting the Role of Asymmetric Division in Control of Stem Cell Lineage Specification

Human pluripotent stem cells (hPSCs) have proven to be a promising tool for biomedical researchers due to their capabilities of self-renewal, almost indefinite proliferation, and ability to give rise to all human cell types.  Regarding self-renewal, stem cells also have the ability to give rise to daughter cells with a committed cell fate as well as an undifferentiated and uncommitted cell. To accomplish this feat, cells intrinsically organize polarity proteins and cell fate determinants into only one dividing daughter cell and divide asymmetrically with the cell fate determinants segregated. In observing this asymmetric division, cytoskeletal organization has proven to be a critical factor for polarization as well as many other stem cell behaviors including cellular organization and adhesion. This study will outline the role of cell polarization in hPSC function and stem cell lineage commitment. Deep ultraviolet (UV) lithography was utilized to create patterns with symmetrical and non-symmetrical features to display and promote polarization of stem cells. This process was accomplished by utilizing a photomask with microfeatures to irradiate an already passivated substrate with low wavelength UV light making is possible to attach proteins selectively to irradiated areas. These studies showed cells were able to adhere and display prominent stress fibers while certain patterns were able to show segregation of polarity protein GPSM2. Cell polarity, spindle orientation, cell division, and lineage specification of dividing and daughter cells were then quantified on adherent cells and correlated to illicit the roles of asymmetric division in hPSCs. Understanding the mechanisms by which cell shape and cell division can control lineage specification has the ability to provide great insight for the rational design of biomaterials and usage in regenerative medicine.