Experimental Study Of The Possibility Of Using Chondrocyte From Epiphyseal Plate Cultured In Vitro As Seed Cell For Meniscus

Objective:Seed cell was the most important factor restricting the clinical application of meniscal tissue engineering,and it was also the premise ensuring further study of tissue engineeering.At present ,mesenchymal stem cell,multi-functional fibrocyte,meniscal fibrochondrocyte and transgenic cell have been used popularly as the cell source.Epiphyseal plate(growth plate) was a kind of hyaline cartilage that located between metaphysis and osteoepiphysis,possessing longitudinal growth ability.From the proliferation of embryonic stem cell forming cartilage frame to the differentiation of articular cartilage,meniscus and epiphyseal plate,those three cartilages had the same origin of cytogenesis.This study was aimed to compare the bionomics between chondrocyte from epiphyseal plate and meniscal fibrochondrocyte cultured in vitro and to investigate the possibility of using chondrocyte from epiphyseal plate cultured in vitro as the seed cell of meniscus. Methods:Chondrocyte isolated from epiphyseal plate and meniscus of New Zealand rabbits aged 4 weeks were respectively passaged in monolayer and cultured in centrifuge tube.The biological charicteristics of these two chondrocytes were observed by inverted phase contrast microscop,growth curves of these two chondrocytes were compared,the ultrastructure of chondrocytes from epiphyseal plate and meniscus in passage 2 and 4 were separately compared by transmission electronic microscopy. Articular cartilage of distal femur, epiphyseal plate of proximal tibia and meniscus were collected from a 6-week-old New Zealand rabbit.The ultrstructure of chondrocytes and extracellular matrix in the three cartilages and the cultured cartilage were observed by transmission elctron microscopy and histological examinations including immunohistochemical dyeing of type two collagen, toluidine dyeing and safranine"O"dyeing.Result:Chondrocytes from epiphyseal plate and meniscal fibrochondrocytes in passage 4 were dedifferentiated.Chondrocytes from epiphyseal plate formed cartilage 2 weeks after cultivation in centrifuge tube,but meniscal fibrochondrocytes could not generate cartilage.Cartilage cultured in centrifuge tube has unique ultrastructure and was similar to articular chondrocyte and epiphyseal plate,but it was markedly different from meniscus.These four kinds of cartilages were characteristic of respectively different chondrocyte and extracellular matrix.The ultrastructure of chondrocytes from epiphyseal plate and meniscal fibrochondrocytes in passage 2 and 4 were respectively different.Conclusion: Meniscal fibrochondrocytes could not form cartilage after cultivation in centrifuge tube,while cartilage cultured in centrifuge tube from passage-one chondrocytes of epiphyseal plate has unique ultrastructure. Cartilage cultured in centrifuge tube may be used as graft materials for epiphyseal plate and articular cartilage, but not for meniscus. The chondrocytes from epiphyseal plate and meniscal fibrochondrocytes dedifferentiate and lose their special phenotypes gradually with passage.