Enhancement Of Meniscal Tearing Damage Repair In The Avascular Zone Using Connective Tissue Growth Factor (CTGF) In The Rabbit Model

Objective: To test whether connective tissue growth factor CTGF is required forextracellular matrix synthesis of meniscal fibrochondrocytes and/or angiogenesis duringthe repair of meniscal tearing damage.Methods: Meniscal fibrochondrocytes were isolated from the inner-1/2of rabbits'meniscus by trypsine collagenase treatment, and treated with100ng/ml CTGF in vitro.Characterization of fibrochondrocytes was identified by flow cytometry analysising CD44,CD45and CD105, and was further tested by type II collagen Immunocytochemistry.Changes in gene expression of meniscal fibrochondrocytes were monitored by quantitativereal-time polymerase chain reaction. In vivo, the sections of the3mm of the longitudinaltearing defect in the avascular zone of the rabbit's meniscus after treatment of1.5ug CTGF,which were subjected to fluorescence-immuno-histochemisty analysis at the1st week, the4th week and the10th week.Results:(1) Quantitative RT-PCR assays showed that type I collagen, type II collagen,and VEGF mRNA expression in the100ng/ml CTGF group have been remarkablyenhanced than in the no-dose group at the fourteen day,2.38±0.63fold,2.96±0.87fold,2.14±0.56fold respectively.(2) Consistent with these effects in vitro, fluorescence-immuno-histochemical analysis revealed that in the group implanted with CTGF-fibringlue, type I collagen, type II collagen and capillaries completely lled the defect at the10th week postoperatively. In contrast, only soft tissue repair occurred when the PBS-fibringlue was implanted.Conclusion: These ndings suggest that CTGF can significantly promote extracellularmatrix (I collagen, II collagen) of the meniscal avascular zone synthesis, and CTGF cangreatly heighten the expression of VEGF activity at the same time in vivo, so that it canfurther enhance the repair of meniscal tearing damage in the avascular zone.