PEG matrix enables cell-mediated local BMP-2 gene delivery and increased bone formation in a porcine critical size defect model of craniofacial bone regeneration

Purpose This study addressed the suitability of a polyethylene glycol (PEG) matrix as scaffold for cell‐mediated local BMP‐2 gene transfer in a calvarial critical size defect (CSD) model. Materials and methods PEG matrix (degradation time 10 days) and PEG membrane (degradation time 120 days) were used in the pig calvarial model. Cylindrical (1 × 1 cm) CSD (9 per animal; 20 animals) were filled with: (i) HA/TCP, covered by PEG membrane (group 1); (ii) HA/TCP, mixed with PEG matrix (group 2); and (iii) HA/TCP mixed with BMP‐2 transfected osteoblasts and PEG matrix (group 3). BMP‐2/4 gene transfer: liposomal in vitro transfection of BMP‐2/V5‐tag fusion‐protein. Quantitative histomorphometry (toluidine blue staining) after 2, 4 and 12 weeks assessed bone formation. Semiquantitative immunohistochemistry estimated the expression of BMP‐2 and V5‐tag. Results Group 3 showed significantly higher new bone formation than groups 1, 2 at 4 (P