[Effect of platelet-rich plasma on tendon healing]

Platelet-rich plasma (PRP) secretes many growth factors, including transforming growth factor beta1 (TGF-beta1), platelet derived growth factor, vascular endothelial growth factor, insulin-like growth factor 1, and so on, which can promote cell proliferation, chemotaxis, and collagen synthesis in wound healing. To investigate the effects of PRP on the tendon healing, and to explore the mechanism of action so as to provide the experimental basis for the tissue engineered tendons.

Forty healthy New Zealand white rabbits, weighing 2.5-3.0 kg and male or female, were randomly divided into the experimental group (n = 20) and the control group (n = 20). PRP was prepared from arterial blood of rabbit's ears through twice centrifugation method of Landesberg. The platelet concentrations of whole blood and PRP were determined. The right achilles tendons of the rabbits were transected to make rupture models. In experimental group, the tendon was sutured after PRP (0.5 mL) was immediately applied at repair site. In control group, the tendon was sutured directly after transection. At 1, 2, 4, and 6 weeks after operation, the tendons of 5 rabbits in each group were harvested for morphological, histological, and immunohistochemical observations; the fibroblast counting, the content of collagen fibers, and the expression of TGF-beta1 were detected.

The concentration of platelet of PRP was 4.03 times of whole blood. All the animals survived till the end of the experiment, and the incision healed well. No death, infection, and other complications occurred. With time, the tendons almost healed in 2 groups, and the fibrous tissue at anastomosis site was more remarkable in control group than in experimental group. The histological observation showed significant differences in fibroblast counting at 1, 2, and 4 weeks after operation between 2 groups (P < 0.05), while no significant difference at 6 weeks (P > 0.05). The contents of collagen fibers in the parenchyma at repair site in experimental group were significantly higher than those in control group at each time point (P < 0.05). Immunohistochemistry staining showed the expression of TGF-beta1 in experimental group was upregulated at 1 week and 2 weeks and reached the peak at the 2nd week, and subsequently downregulated at 4 and 6 weeks in comparison with the control group, showing significant differences between 2 groups at each time point (P < 0.05).

PRP can facilitate rabbit's tendons healing and significantly improve the healing quality, which may be associated with its advancing the peak time of the TGF-beta1 expression in tendon.