慢性腱病模型大鼠肌腱干细胞体外成脂和成肌腱的分化能力

Adipogenic and tenogenic differentiation of tendon-derived stem cells isolated from an animal model of chronic tendinopathy in vitro

背景:慢性腱病是一种常见的肌腱退行性病变,好发于运动员以及肌腱过度劳损的人群。由于慢性腱病的发病机制尚未阐明,临床上还缺乏有效的治疗手段。目的:体外研究比较慢性腱病大鼠和正常大鼠来源肌腱干细胞成脂、成肌腱分化能力。方法:从慢性腱病大鼠以及正常大鼠髌腱中分离培养原代肌腱干细胞,传代培养至第3代,体外观察细胞形态学变化。将两种来源肌腱干细胞(P3)单层培养至细胞融合,分为2组,成脂诱导组用成脂诱导培养基培养,对照组用基础培养基培养。成脂诱导分化21 d后,将两种来源肌腱干细胞的成脂诱导组和对照组分别行油红O染色定量分析。实时荧光定量PCR检测各组细胞成脂性基因C/EBPα和PPARγ2的m RNA的表达。将两种来源的肌腱干细胞体外单层培养至70%-80%融合时,行实时荧光定量PCR检测慢性腱病来源肌腱干细胞以及正常肌腱干细胞成肌腱相关基因Col1a1,Scx,Tnmd和Dcn的m RNA的表达。结果与结论:肌腱干细胞体外培养至第3代时,正常肌腱来源的肌腱干细胞保持细长纺锤形的典型的干细胞形态,而慢性腱病来源的肌腱干细胞虽然形态发生改变,但仍保持纺锤形形态。肌腱干细胞(P3)体外成脂诱导分化21 d后,慢性腱病来源的肌腱干细胞胞体变大、变圆,可见大量油红O染色阳性的细胞,油红O染色阳性率显著高于正常大鼠(P=0.004)。实时荧光定量PCR结果显示,慢性腱病大鼠来源肌腱干细胞的成脂性基因(C/EBPα和PPARγ2)m RNA的表达均显著高于正常大鼠(P=0.004),肌腱特异性基因Col1a1,Scx,Tnmd以及Dcn m RNA表达量均明显低于正常大鼠(P=0.009)。说明与正常大鼠来源的肌腱干细胞相比,慢性腱病来源的肌腱干细胞体外成肌腱分化的能力减弱,而成脂分化的能力增强,此结果为进一步揭示慢性腱病发病机制提供了细胞生物学依据。

BACKGROUND：Chronic tendinopathy is a tendon disorder extremely common in athletes and in the general population with repetitive strain injuries of tendons. The pathogenesis of tendinopathy remains unclear and hence treatment of tendinopathy is usual y pal iative. 〈br〉 OBJECTIVE：To investigate the of adipogenic and tenogenic ability of patel ar tendon-derived stem cel s isolated 〈br〉 from chronic tendinopathy and healthy rats in vitro. 〈br〉 METHODS：Tendon-derived stem cel s were isolated from patel ar tendons of chronic tendinopathy and healthy rats respectively. The tendon-derived stem cel s were cultured to the 3rd passage in complete culture medium, and cel morphology was observed. The cel s were divided into adipogenic induction group and control group. Cel s in the adipogenic induction group were cultured in adipogenic induction medium, while those in the control group cultured in complete culture medium. The ability of adipogenic differentiation between tendon-derived stem cel s isolated from the tendon of chronic tendinopathy and healthy rats in vitro was examined by oil red O staining and quantification assay. The mRNA expressions of C/EBPαand PPARγ2 were detected by real-time quantitative PCR. When 70%-80%cel s were confluent, the mRNA expressions of Col1a1, Scx, Tnmd and Dcn were also detected by real-time quantitative PCR. 〈br〉 RESULTS AND CONCLUSION：At the third passage, slender spindle-shaped cel s were seen in both two groups, but there was a little change in the cel morphology in the chronic tendinopathy group. Lipid droplets were formed after the cel s were cultured in adipogenic induction medium for 21 days. This was not observed in the control group. We observed more oil red O-positive oil droplets in tendon-derived stem cel s from the tendons of chronic tendinopathy rats than healthy rats. The difference between them was statistical y significant （P=0.004）. The results of real-time quantitative PCR showed that the mRNA expressions of C/EBPαand PPARγ2 in the tendon-derived stem cel s from the tendons of chronic tendinopathy rats were significantly higher than those in tendon-derived stem cel s from the tendons of healthy rats （P=0.004）;the mRNA expressions of Col1a1, Scx, Tnmd and Dcn in the tendon-derived stem cel s from the tendons of chronic tendinopathy rats were significantly lower than those in tendon-derived stem cel s from the tendons of healthy rats （P=0.009）. In conclusion, tendon-derived stem cel s from chronic tendinopathy rats showed a higher ability of adipogenic differentiation, but a lower capacity of tenogenic differentiation compared to tendon-derived stem cel s from healthy rats, which might contribute to better understand the pathogenesis of tendinopathy.