FIG. 1.

Extracellular matrix (ECM) and integrin expression in mesenchymal stem cells (MSCs) cultured on poly(lactide-co-glycolide) (PLGA) substrates. (A) MSCs were cultured on non-tissue culture dishes coated with 85:15 PLGA in the presence of normal growth medium (serum medium) or medium containing osteoinductive supplements (OS medium) for 1, 7, 14, or 28 days. At each time point, cell lysates were analyzed using sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blot for levels of fibronectin (FN) and vitronectin (VN). Results shown are from a representative blot, similar to those obtained from multiple experiments. (B) MSCs cultured on thin PLGA films in OS medium were also fixed and fluorescently stained for extracellular type I ollagen, VN, or FN. Images shown are representative of one of the intermediate time points (7 days). Scale bar represents 10 μm. (C) Quantitative flow cytometry was used to assess the relative expression of the α2β1, α5β1, and αvβ3 integrins in MSCs, with mean fluorescent intensities used to determine the relative expression of each integrin.