(A) rVEGF stability in silk solution overtime. rVEGF was resuspended in PBS or in 2% silk solution and the concentration was assessed by Elisa overtime (16 days). (B) PG-Silk samples, upon gelation, were re-suspended in PBS or silk solution and TGFbeta1 release was measured after 7 days. (C) Growth factors in plasma, obtained from PG, were diluted 1:1 in PBS or 1:1 in 1% silk solution and maintained at 37°C, or room temperature, or 4°C. After 2 weeks the concentration of TGFbeta1 was assessed by Elisa.