The influence of polymer blend coatings on the differentiation of mouse mesenchymal stem cells was investigated.  Polymer blending is a common means of producing new coating materials with variable properties.  Stem cell differentiation is known to be influenced by both chemical and mechanical properties of the underlying scaffold.  We therefore selected to probe the response of stem cells cultured separately on two very different polymers, and then cultured on a 1:1 blend.  The response to mechanical properties was probed by culturing the cells on polybutadiene (PB) films, where the film moduli was varied by adjusting film thickness.  Cells adjusted their internal structure such that their moduli scaled with the PB films.  These cells expressed chondrocyte markers (osterix (OSX), alkaline phosphatase (ALP), collagen X (COL-X), and aggrecan (ACAN)) without mineralizing.  In contrast, cells on partially sulfonated polystyrene (PSS₂₈) deposited large amounts of hydroxyapatite and expressed differentiation markers consistent with chondrocyte hypertrophy (OSX, ALP, COL-X, but not ACAN).  Cells on phase-segregated PB and PSS₂₈ films differentiated identically to those on PSS₂₈, underscoring the challenges of using polymer templates for cell patterning in tissue engineering.

*Bherwani A, Chang C, Pelled G, Gazit Z, Gazit D, Rafailovich M, Simon M. Coatings 2019; 9:451