Adhesion Topology Guides Stem Cell Fate

The design of novel biomaterials for regenerative medicine requires incorporation of well-defined physical and chemical properties that mimic the native extracellular matrix (ECM), including the presentation of discrete receptor binding sites on a substrate's surface. To accomplish this, porous foams were synthesized by high internal phase emulsion templating using mixtures diblock copolymers. These different copolymers were confined to the oil−water interface where they phase separated, and depending on the mixture, adhesion topology was engineered from the nanoscopic domains of cell inert and active chemistries of the copolymers (Viswanathan et al, JACS 2012). Human mesenchymal stem cells (hMSCs) were cultured on these foams and found to adhere in a topology dependent manner: foams with nano-scopic adhesive domains randomly spaced 0.6 um apart supported the most robust hMSC adhesion and most closely mimicked the discrete receptor binding sites of native matrix. These foams, when pores were interconnected, also supported the greatest cell spreading and osteogenises, while the same foams with closed pores supported robust adhesion put prevented spreading, which ultimately directed hMSCs into a more adipogenic fate. This process, which occurred without specific induction media, underscores the need to develop materials with appropriate cell adhesion for regenerative applications with stem cells.