Repair of cartilage defect in the rabbit with cultured mesenchymal stem cells from bone marrow

In 16 mature New Zealand white rabbits mesenchymal stem cells were aspirate d from the bone marrow, cultured in monolayer and implanted on to a full-th ickness osteochondral defect artificially made on the patellar groove of th e same rabbit. A further 13 rabbits served as a control group. The rabbits were killed after 14 weeks, Healing of the defect was investigated histolog ically using haematoxylin and eosin and Safranin-O staining and with immuno histochemical staining for type-II collagen. We also used a reverse transcr iption-polymerase chain reaction (RT-PCR) to detect mRNA of type-I and type -II collagen. The semiquantitative histological scores were significantly higher in the e xperimental group than in the control group (p < 0.05). In the experimental group immunohistochemical staining on newly formed cartilage was more inte nse for type-II collagen in the matrix and RT-PCR from regenerated cartilag e detected mRNA for type-II collagen in mature chondrocytes. These findings suggest that repair of cartilage defects can be enhanced by the implantati on of cultured mesenchymal stem cells.