Intratendon delivery of leukocyte‐rich platelet‐rich plasma at early stage promotes tendon repair in a rabbit Achilles tendinopathy model

摘要

Abstract Tendinopathy is a great obstacle in clinical practice due to its poor regenerative capacity. The influence of different stages of tendinopathy on effects of leukocyte‐rich platelet‐rich plasma (Lr‐PRP) has not been elucidated. The aim of this study is to investigate the optimal time point for delivery of Lr‐PRP on tendinopathy. A tendinopathy model was established by local collagenase injection on the rabbit Achilles tendon. Then after collagenase induction, following treatments were applied randomly on the lesion: (a) 200 μl of Lr‐PRP at 1 week (PRP‐1 group), (b) 200 μl of saline at 1 week (Saline‐1 group), (c) 200 μl of Lr‐PRP at 4 weeks (PRP‐2 group), and (d) 200 μl of saline at 4 weeks (Saline‐2 group). Six weeks after collagenase induction, outcomes were assessed by magnetic resonance imaging, cytokine quantification, gene expression, histology, and transmission electron microscopy. Our results demonstrated that PRP‐1 group had the least cross‐sectional area and lesion percent of the involved tendon, as well as the lowest signal intensity in magnetic resonance imaging among all groups. However, the PRP‐2 group showed larger cross‐sectional area than saline groups. Enzyme‐linked immunosorbent assay indicated that PRP‐1 group had a higher level of interleukin‐10 but lower level of interleukin‐6 when compared with PRP‐2 and saline groups. Meanwhile, the highest expression of collagen (Col) 1 in PRP‐1 and Col 3, matrix metalloproteinase (MMP)‐1, and MMP‐3 in PRP‐2 was found. Histologically, the PRP‐1 showed better general scores than PRP‐2, and no significant difference was found between the PRP‐2 and saline groups. For transmission electron microscopy, PRP‐1 had the largest mean collagen fibril diameter, and the PRP‐2 group showed even smaller mean collagen fibril diameter than saline groups. In conclusion, intratendon delivery of Lr‐PRP at early stage showed beneficial effect for repair of tendinopathy but not at late stage. For translation of our results to clinical circumstances, further studies are still needed.