Injectable Tissue-engineered Bone Using Calcium Alginate As Carriers

Objective To investigate the utilization of calciumalginate as carriers for delivering osteoblasts and creating autogenousbone tissue in ectopic site of animal via injection. Methods Bonemarrow cells harvested from tibia bone of New Zealand rabbits wereinduced to differentiate into marrow stromal osteoblasts. Theosteoblasts were mixed with 1.5% alginate sodium solution togenerate three kinds of osteoblasts/ alginate composites with differentfinal cellular density (5 ×105/ ml, 5 ×106/ ml and 5 ×107/ ml).Calcium chloride was used as cross-linking agent to gel aqueousalginate solution. Each marrow stromal osteoblasts/ alginatecomposite was respectively injected into the different position ofdorsal subcutaneous tissue of rabbits with autogenous cellstransplantation. The samples were examined with X-ray andhistological analysis. Results eight and twelve weeks after injection,On X-ray photograph the samples showed calcified image with moredensity than surrounding soft tissue in every group, and the bestdensity belongs to the group of 5×106/ ml. New bone formation can beobserved in the osteoblasts/ alginate composites in histologicalanalysis in every group. The osteogenesis was in association withregenerated hematopoietic bone marrow. Thereinto the group of5×106/ ml is the best. Conclusions These results demonstrate that newbone tissue could be created through the injection of alginate sodiummixed with autogenous marrow stromal osteoblasts. And during thisprocess, the osteoblasts/ alginate composites with final cellular densityof 5×106/ ml have more ideal efficiency of bone formation than others.