Study of Human Chondrocyte Redifferntiation Capacity in Three-Dimensional Hydrogel Culture

Objective(s) Articular cartilage tissue defects cannot be repaired by the proliferation of resident chondrocytes. Autologous chondrocyte transplantation (ACT) is a relatively new therapeutic approach to cover full thickness articular cartilage defects by in vitro grown chondrocytes from the joint of a patient. Therefore, we investigated the redifferentiation capability of human chondrocytes maintained in alginate culture. Materials and Methods The cartilage specimens obtained from 50 patients who underwent total knee and hip operations at the teaching hospital of Isfahan University of Medical Sciences, Isfahan Iran. Isolated primary chondrocytes were first grown in monolayer cultures for 1 to 6 passages (each passage lasting about 3 days). At each passage, monolayer cells seeded in alginate culture and investigated morphologically and immunocytologically for expression of cartilage-specific markers (collagen type II and cartilage-specific proteoglycans). Results The chondrocytes from monolayer passages P1 to P4 introduced in alginate cultures regained a chondrocyte phenotype. Cells were interconnected by typical gap junctions and after few days, they produced a cartilagespecific extracellular matrix (collagen type II and cartilage-specific proteoglycans). In contrast, cells from monolayer passages P5 and P6 did not redifferentiate to chondrocytes in the alginate cultures. Conclusion Chondrocyte culture was established for the first time in Iran. The alginate culture conditions promote the redifferentiation of dedifferentiated chondrocytes that have still a chondrogenic potential. This procedure opens up a promising approach to produce sufficient numbers of differentiated chondrocytes for ACT. Indeed, in some patients the harvested cells were used immediately and successfully for transplantation