Fig. 5

Mitochondrial transfer improves the severity of collagenase I-induced Achilles tendinopathy in rats. A In vivo experimental protocol. B Representative image of the tendon tissue after injection of MSC: red and green indicate MSC mitochondria (MitoTracker Red CMXRos) and harvested tendon tissue mitochondria (MitoTracker Green), respectively, on day 5 after collagenase injection with DAPI nuclear staining (blue). CB was used to block mitochondrial transfer. Mitochondria of MSCs (white arrowheads) localized in tenocytes within the tissue. Scale bars: 100 × , 25 µm; 400 × , 5 μm (magnified graphs). Relative Scx (C), TN-C (D), and Tnmd (E) mRNA levels in tendon tissue assessed by RT-qPCR (C-E, n = 3). F Level of proliferation factor Ki67 assessed by RT-qPCR (n = 3). G H&E staining of the tendons in each group (n = 3). Scale bars: 100 × , 200 μm; 400 × , 50 μm (magnified graphs). H Collagen was evaluated with PSR staining (n = 3). Scale bars: 100 × , 100 μm; 200 × , 50 μm (magnified graphs). I Masson staining (n = 3). Blue indicates collagen matrix disruption, whereas red indicates collagen fibers. Scale bars: 100 × , 100 μm; 200 × , 50 μm (magnified graphs). Data represent means ± SD. Statistical significance of the differences among groups was determined by ANOVA (LSD method). ^*P < 0.05, ^**P < 0.01, ^***P < 0.001