Photoencapsulated-mesenchymal stromal cells in biodegradable thiol-acrylate hydrogels enhance regeneration of craniofacial bone tissue defects.

This study investigated biodegradable thiol-acrylate hydrogels as stem cell carriers to facilitate cranial bone regeneration. Two formulations of thiol-acrylate hydrogels (5 and 15 wt% Poly[ethylene glycol]-diacrylate [PEGDA] hydrogels) were used as stem cell carriers. Bone marrow mesenchymal stromal cells and dental pulp mesenchymal stromal cells were photoencapsulated and cultured in basal or osteogenic medium 3 days before the surgery. Using New Zealand White Rabbits, four defects (5 mm diameter and 2 mm thickness) were created and hydrogel scaffolds were implanted in each rabbit cranium for 6 weeks. AlamarBlue assay showed increasing metabolic activity levels in 5 wt% PEGDA hydrogels than 15 wt% PEGDA hydrogels. Photoencapsulated-mesenchymal stromal cells in 15 wt% PEGDA hydrogels demonstrated significantly increasing alkaline phosphatase activity levels on day 7 compared with days 1 and 3. Histological diagnosis showed 5 wt% PEGDA hydrogels resulted in lower averaged residual gel areas than 15 wt% PEGDA hydrogel specimens and control groups 6 weeks postimplantation.