| Embryonic stem cells have the ability to differentiate into virtually any cell type. They provide a powerful cell source for replacement therapies, especially for diseases and injuries in organ systems whose cells have limited ability to regenerate. The majority of the work done to guide the differentiation of stem cells has been to inoculate stem cells with potent differentiation chemokines and growth factors. However, it is still difficult to generate pure populations of cells for replacement therapies, and moving these approaches in vivo has added difficulties. The niche surrounding the cells also provides cues that may guide differentiation of stem cells. Incorporating these differentiation cues into in vitro systems may lead to purer population of cells for replacement therapies, and potentially the ability to move the niche in vivo. Herein, we modulate the differentiation of stem cells by controlling the ECM surrounding the cell. We grafted peptide sequences that resemble the active regions of noggin and wnt antagonist proteins to collagen scaffolds and assayed the differentiation of stem cells into ectodermal lineage. Peptides were presented both in uniform concentrations and in a gradient to mimic the in vivo condition. The extent of differentiation was assayed using immunohistochemistry and quantitative, real-time PCR. |
