2015 ISAKOS Biennial Congress ePoster #411

Platelet-Rich Plasma (PRP) Accelerates Murine Patellar Tendon Healing Through Enhancement of Angiogenesis and Collagen Synthesis

Yohei Kobayashi, MD, PhD, Tokyo JAPAN
Yoshitomo Saita, MD, PhD, Tokyo JAPAN
Masashi Nagao, MD, PhD, Tokyo JAPAN
Hiroshi Ikeda, MD, PhD, Tokyo JAPAN
Kazuo Kaneko, MD, PhD, Prof., Tokyo JAPAN
Department of Orthopaedics, Juntendo University School of Medicine, Tokyo, Please Select, JAPAN

FDA Status Cleared

Summary: We demonstrated that the local application of PRP gel on the murine patellar tendon defect model enhanced tendon healing trough acceleration of vascularization and collagen synthesis.

Abstract:

Introduction

Platelet-rich plasma (PRP) is an autologous platelet concentrates that contains diverse growth factors and cytokines that would stimulate tissue healing. Although PRP has been frequently used as one of the therapeutic applications in the field of orthopedics and sports medicine, the molecular mechanisms of PRP on tissue healing process remain poorly understood. The aims of this study were to confirm the efficacy of PRP therapy on murine patellar tendon healing, and elucidate the mechanisms of its healing processes.

Methods

Forty female C57BL/6 mice (12-week old) were used in this study. Full thickness defects were created in the central third of patellar tendon of their right hind limb under microsurgery technique. PRP was obtained from whole blood of C57BL/6 donor mice (n=7) by double spinning method. Isolated PRP was then activated and gelled with calcium chloride. Prepared allogeneic PRP gel (50µl) was applied on the defect of patellar tendon in twenty mice (PRP group), while remaining twenty mice served as an untreated control group (control group). Mice were sacrificed at 2, 4, 6, 8 and 10 weeks after the operation and histological sections with HE, Alcian-blue, and Azan stain were obtained in each time point (n=4 / time point / group) . Semi-quantitative histological evaluation was performed in accordance with Bonar score. The variables included in this scoring system were cell morphology, ground substance, collagen arrangement, and vascularity with higher grades indicating worse tendon structure (each factor; 0-4 points, total score; 0-12 points). In addition, the ratio of collagen fibers stained with Azan to the entire tendon tissue (FT ratio) was measured using KS400 software (Carl Zeiss, Germany) as a quantitative histological evaluation. Mann-Whitney U test was used for statistical analysis and p-values of less than 0.05 were considered to be statistically significant.

Results

The total Bonar score in the PRP group was significantly lower than control group (p=0.029). With regard to the variables in Bonar score, the vascularity score was significantly higher in the PRP group at 2 and 4 weeks (p=0.029), and the collagen arrangement score was significantly lower in the PRP group at 8 weeks (p=0.029). In a quantitative evaluation, recovery speed of patellar tendon determined by FT ratio was significantly faster in the PRP group than control group at 6 weeks. (p=0.008)

Discussion

Tendon injuries often become refractory due to poor vascurality. In our present study, administration of PRP significantly increased angiogenesis during early phase of tendon healing process. In addition, we revealed that collagen re-arrangement after tendon injury was shorten in the PRP group. These results suggest that local application of PRP could enhance tissue healing process via not only direct action on localized cells (mediated by repairing growth factors such as TGF-beta, IGF) but also indirect manner (recruitment of reparative cells through blood flow mediated by angiogenic growth factors such as VEGF, PDGF). Further investigations will be needed to confirm the mechanisms of PRP on tissue healing processes.