Segmental bone repair by tissue-engineered periosteal cell transplants with bioresorbable fleece and fibrin scaffolds in rabbits

The biological bone healing depends on the presence of osteochondral progen itors and their ability for proliferation. Isolated periosteal cells were s eeded into biodegradable PGLA polymer fleece or fibrin beads and cultivated for 14 days after prior monolayer culture. On 12 New Zealand white rabbits 8 mm metadiaphyseal ulna defects were created bilaterally and subsequently filled with cell-fibrin beads, with polymers seeded with cells compared to controls with fibrin beads and polymers alone and untreated defects. A sem iquantitative grading score was applied for histomorphological and radiolog ical analysis after 28 days. Histologically intense bone formation was obse rved in both experimental groups with cell transplants only. The histologic al and radiological scoring was superior for both experimental groups. Cont rol groups revealed only poor healing indices and untreated defects did not heal. The highest histological score was noted in the group with polymer f leeces containing periosteal cells. Applying the radiographic score system we determined a significant difference between experimental groups and cont rols without cells. The radiographic and histological scores for both exper imental groups containing periosteal cells differed not significantly. The results strongly encourage the approach of the transplantation of pluripote nt mesenchymal cells within a suitable carrier structure for the reconstruc tion of critical size bone defects. (C) 2000 Elsevier Science Ltd. All righ ts reserved.