Poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) scaffolds coated with PhaP-RGD fusion protein promotes the proliferation and chondrogenic differentiation of human umbilical cord mesenchymal stem cells in vitro.

Human umbilical cord blood-derived mesenchymal stem cells (hUC-MSCs) have been widely used in tissue engineering. The aim of this study is to evaluate the ability of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) scaffolds coated with polyhydroxyalkanoate binding protein fused with arginyl-glycyl-aspartic acid (PhaP-RGD) to promote the proliferation and chondrogenic differentiation of hUC-MSCs seeded on them. The PhaP-RGD fusion protein was expressed by Escherichia coli. PHBHHx films were coated with PhaP-RGD fusion protein and the physiochemical properties were examined. hUC-MSCs were seeded on PHBHHx films with or without PhaP-RGD precoating and tested for changes in morphology, viability, and chondrogenic differentiation. We found that PhaP-RGD-coated PHBHHx films had similar surface morphology to uncoated PHBHHx. The water contact angle of the coated PHBHHx surface was lower than that of the uncoated surface (10.63° vs. 98.69°). At 7 and 14 days after seeding, the PhaP-RGD-coated PHBHHx group showed greater numbers of viable cells compared to the uncoated PHBHHx group. The expression levels of aggrecan and collagen II were enhanced in the PhaP-RGD-coated PHBHHx group relative to the uncoated PHBHHx group. Histological analysis using toluidine blue staining showed elevated formation of proteoglycan producing chondrocytes in the PhaP-RGD-coated PHBHHx group. Additionally, the synthesis of proteoglycan and collagen was significantly enhanced within the PhaP-RGD constructs. Taken together, PhaP-RGD coating promotes the proliferation and chondrogenic differentiation of hUC-MSCs seeded on PHBHHx films. PhaP-RGD-coated PHBHHx may be a useful scaffold for cartilage tissue engineering.