Abstract:

Objective  To construct an double-layered tube-shaped poly (lactic-co-glycolic acid) (PLGA) scaffold composited with vascular endothelial growth factor (VEGF) / platelet-derived growth factor (PDGF) , and to evaluate in vivo the axial vascularization from femoral arteriovenous bundle encapsulated. Methods   Eighteen male adult New Zealand rabbits were assigned randomly into 3 groups: Experimental group (n=8) , experimental control group (n =8), empty control group (n=2). The femoral arteriovenous bundle were separated and encapsulated in double-layered tubeshaped PLGA scaffold prepared by solution casting and particle leaching. According to the way of cell factors being composited to the prepared double-layered scaffold: 1) experimental group: VEGF in inner layer and PDGF in outer layer; 2) experimental control group: VEGF in inner layer with blank outer layer; 3) empty control group: Pure blank. Specimens were retrieved at 7, 10, 14, 21 days postoperatively (7, 10 days in empty control group) . The histological evaluation was performed. Results  At 7 days postoperatively, blood vessel sprouts were observed in experimental group and experimental control group, radially from the central femoral arteriovenous bundle. At 10 days postoperatively, completely penetrations of the double-layered scaffold by abundant new generated blood vessel sprouts were observed, and density descended gradiently from inside to outside. At 14 days postoperatively, new blood vessels in experimental group showed more thickness and layered structure of the wall, while monolayer endothelial cells in experimental control group. At 21 days postoperatively, new blood vessels in experimental group showed more mature characteristics,while less density of blood vessels in experimental control group. There was no obvious blood vessel structure in empty control group. Conclusion  The double -layered tube-shaped PLGA scaffold composited with VEGF/PDGF could induce early angiogenesis.

Key words: bone tissue engineering, vascularization, arteriovenous bundle, angiogenesis