Effect of moderate treadmill exercise together with modified hydroxyapatite chitosan composite hydrogel implantation on repair of full-thickness defects of articular cartilage in rats

Abstract

Objective To investigate the effect of moderate treadmill exercise together with modified hydroxyapatite chitosan composite hydrogel(CS/HA-g-CS)implantation on repair of full-thickness defects of articular cartilage in rats. Methods Full-thickness cartilage defects were drilled in the patellar groove of bilateral femoral condyles in a total of 24 male SD rats before they were randomly assigned into 4 groups. The control group(BC group)was subjected to no exercise or CS/HA-g-CS implantation; the chitosan group(CHI group)to CS/HA-g-CS implantation without exercise; the moderate treadmill exercise group(MIR group)to exercise 4 weeks after modeling without CS/HA-g-CS implantation; the CHI + MIR group to moderate treadmill exercise plus CS/HA-g-CS implantation 4 weeks after modeling. Half of the animals were sacrificed at week 8 and half at week 16 after operation. Femoral condyles were harvested for gross observation and his-tochemical measurement by O’ Driscoll scoring system. mRNA expressions of glycosaminoglycan, collagen typeⅡ and BMP-2 were detected by RT-PCR. Results Gross observation revealed: at 8 weeks after modeling, the CHI + MIR group was significantly better than the other 3 groups, with the BC group in the poorest(P 0. 05). O' Driscoll scoring revealed: at both 8and 16 weeks after modeling, the CHI + MIR group was significantly better than the other 2 groups and the BC group significantly poorer than the other 3 groups(P 0. 05). The expressions of collagen type Ⅱ, glycosaminoglycan and BMP-2 were significantly higher in the CHI + MIR group than in the other 3 groups(P< 0. 05)and significantly lower in the BC group than in the other 3 groups(P< 0. 05). Conclusions Moderate treadmill exercise together with CS/HA-g-CS implantation has significant positive effects on repair of full-thickness defects of articular cartilage in rats than merely moderate treadmill exercise or CS/HA-g-CS implantation alone. The defective cartilage repaired by moderate treadmill exercise together with CS/HA-g-CS implantation contains more collagen type II and glycosaminoglycan and shows morphology of nearly normal cartilage. Key words: Exercise; Cartilage, articuler; Injuries; Hydroxyapatite chitosan composite hydrogel