Objective: To explore the effect of platelet-rich plasma (PRP) in treatment of Achilles tendinopathy in rabbits, and provide experimental evidence for the clinical application of PRP in treatment of Achilles tendinopathy.
Methods: Forty-eight adult New Zealand white rabbits, weighing 2.5-3.0 kg, male or female, were randomly divided into model group (group A), model control group (group B), model+treatment control group (group C), model+treatment group (group D), with 12 in each group. The rabbits were injected with type Ⅰ collagenase to prepare Achilles tendinopathy models in groups A, C, and D, and with an equal dose of normal saline in group B. The blood from the central artery of rabbit ear was taken to preprare PRP by secondary centrifugation in group D. The results of platelet counts showed that PRP platelets reached 3 to 5 times the whole blood. After the model was prepared, the rabbits in groups C and D were injected with physiological saline and autologous PRP at the molding site respectively, once a week, 0.8 mL each time for 4 weeks. At 1 week after PRP injection, the relative hardness (expressed as HRD%) of Achilles tendon was evaluated by ultrasound elastic quantitative imaging detection technique; the maximum breaking load of Achilles tendon was measured by universal electronic tensile testing machine; the contents of collagen type Ⅰ and Ⅲ were determined by ELISA; and the morphology of Achilles tendon collagen fibers was observed by HE and Masson stainings.
Results: All animals survived during the experiment. The results of ultrasound elastic quantitative imaging and mechanical tests showed that the HRD% and the maximum breaking load were significantly lower in group A than in group B ( P<0.05) and in group C than in group D ( P<0.05). The results of ELISA showed that the content of collagen type Ⅰ was significantly lower in group A than in group B ( P<0.05) and in group C than in group D ( P<0.05); the content of collagen type Ⅲ was significantly higher in group A than in group B ( P<0.05) and in group D than in group C ( P<0.05). HE and Masson stainings showed that the Achilles tendon collagen fibers were irregularly curled and the structure was severely damaged in group A; the fibers were parallel and ordered, and the structure was complete in group B; the fibers were irregularly curled and structurally disordered in group C; the fibers were slightly curled and the structure was relatively complete in group D.
Conclusion: A rabbit model of Achilles tendinopathy can be reconstructed by type Ⅰ collagenase injection. PRP treatment can increase the Achilles tendon hardness and maximum breaking load, up-regulate the expression level of collagen type Ⅰ and Ⅲ, improve the structure of Achilles tendon collagen fiber, and promote the repair in rabbit Achilles tendinopathy model.
目的: 探讨富血小板血浆（platelet-rich plasma，PRP）治疗兔跟腱病的效果，为 PRP 治疗跟腱病的临床应用提供实验依据。.
方法: 取成年新西兰大白兔 48 只，体质量 2.5～3.0 kg，雌雄不限，随机分为模型组（A 组）、模型对照组（B 组）、模型+治疗对照组（C 组）、模型+治疗组（D 组），每组 12 只。A、C、D 组注射Ⅰ型胶原酶制备兔跟腱病模型，B 组注射等剂量生理盐水。D 组取自体耳中心动脉血，采用二次离心法制备 PRP，血小板计数提示 PRP 血小板达全血的 3～5 倍。模型制备后，C、D 组于造模部位分别注射生理盐水、自体 PRP，每周 1 次，每次 0.8 mL，连续 4 周。于 PRP 注射结束后 1 周，采用超声弹性定量成像检测技术评价各组跟腱相对硬度，以 HRD%（硬度百分比）表示；万能电子拉力试验机测定跟腱最大断裂负荷；ELISA 法测定Ⅰ、Ⅲ型胶原蛋白含量；HE 染色和 Masson 染色观察跟腱胶原纤维形态。.
结果: 各组动物均存活至实验完成。超声弹性定量成像检测及力学试验示，A 组跟腱硬度评价指标 HRD% 及最大断裂负荷显著小于 B 组（ P<0.05），C 组显著小于 D 组（ P<0.05）。ELISA 检测示，A 组Ⅰ型胶原蛋白含量显著低于 B 组、C 组显著低于 D 组，A 组Ⅲ型胶原蛋白含量显著高于 B 组、D 组显著高于 C 组，差异均有统计学意义（ P<0.05）。HE 染色和 Masson 染色示，A 组跟腱胶原纤维呈不规则卷曲，结构严重破坏；B 组呈平行有序排列、结构完整；C 组呈不规则卷曲，结构紊乱；D 组呈轻微卷曲，结构较为完整。.
结论: Ⅰ型胶原酶注射可成功构建兔跟腱病模型，PRP 治疗可增加跟腱硬度和最大断裂负荷，上调Ⅰ、Ⅲ型胶原蛋白表达水平，改善跟腱胶原纤维结构和形态，促进兔跟腱病的恢复。.
Keywords: Achilles tendinopathy; Platelet-rich plasma; rabbit.