Short cord-like structures formed from HAECs on the scaffolds by day 4, and a complex interconnecting network of capillary tubes with identifiable lumens was demonstrated by day 7. The preservation of cell phenotype on the silk fibroin scaffolds was confirmed by the presence of cell-specific markers, including CD146, VE-cadherin, PECAM-1 and vWF for HAECs, and SM-MHC2 and SM-actin for HCASMCs at both protein and transcription levels using immunocytochemistry and real-time RT-PCR, respectively. Formation of ECM was also demonstrated for the HCASMCs, based on the quantification of collagen type I expression at protein and transcription levels.