Electrospun polyacrylonitrile-based nanofibers maintain embryonic stem cell stemness via TGF-beta signaling

Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are capable of self-renewal and differentiation into any cell type, thus making them the focus of many clinical application studies. Culturing ESCs on mouse embryonic fibroblast-derived and cell-based feeder layers to maintain pluripotency is a standard laboratory procedure. However, xenogeneic contamination and the large amount of time required for feeder cell preparation are two challenges that encourage the use of a murine-based feeder layer. A novel biomaterial is required to replace the current cell-based feeder system. Toward this goal, we applied a combination of biocompatible polyacrylonitrile (PAN) and electrospinning technology to establish a non-cell-based feeder layer. According to results from stem cell marker staining, scanning electron microscopy, and embryoid body formation tests, optimal ESC stemness and pluripotency were noted in three electrospun groups (2, 4, and 8 minutes), with the longer electrospinning times producing higher feeder-layer densities. KEGG pathway microarray results identified TGF-beta signaling as one of the major deregulatory pathways on electrospun-based feeder layers. Western blot data indicate significant increases in TGF-beta receptor II, phosphorylated Smad3, and Nanog protein levels in the 4- and 8-minute electrospun-based feeder layer groups compared to the non-feeder layer group. Combined, the data suggest that electrospun-based feeder layers are good candidates for maintaining ESC and iPSC pluripotency in clinical applications.