In situ prevascularization designed by laser-assisted bioprinting:effect on bone regeneration

摘要

Vascularization plays a crucial role in bone formation and regeneration process. Development of afunctional vasculature to improve survival and integration of tissue-engineered bone substitutesremains a major challenge. Biofabrication technologies, such as bioprinting, have been introduced aspromising alternatives to overcome issues related to lack of prevascularization and poor organizationof vascular networks within the bone substitutes. In this context, this study aimed at organizingendothelial cellsin situ, in a mouse calvaria bone defect, to generate a prevascularization with a definedarchitecture, and promote in vivo bone regeneration. Laser-assisted bioprinting (LAB)was used topattern Red Fluorescent Protein-labeled endothelial cells into a mouse calvaria bone defect of criticalsize, filled with collagen containing mesenchymal stem cells and vascular endothelial growth factor.LAB technology allowed safe and controlled in vivo printing of different cell patterns. In situ printingof endothelial cells gave rise to organized microvascular networks into bone defects. At two months,vascularization rate (vr) and bone regeneration rate (br)showed statistically significant differencesbetween the ‘random seeding’ condition and both ‘disc’ pattern (vr = +203.6%; br = +294.1%) and‘crossed circle’ pattern (vr = +355%; br = +602.1%). These results indicate that in vivo LAB is avaluable tool to introduce in situ prevascularization with a defined configuration and promote boneregeneration.