Impact of PDGF‐BB on cellular distribution and extracellular matrix in the healing rabbit Achilles tendon three weeks post‐operation

Current methods for tendon rupture repair suffer from two main drawbacks: insufficient strength and adhesion formation, which lead to rerupture and impaired gliding. A novel polymer tube may help to overcome these problems by allowing growth factor delivery to the wound site and adhesion reduction, and by acting as a physical barrier to the surrounding tissue. In this study, we used a bilayered DegraPol(®) tube to deliver PDGF‐BB to the wound site in a full‐transection rabbit Achilles tendon model. We then performed histological and immunohistochemical analysis at 3 weeks postoperation. Sustained delivery of PDGF‐BB to the healing Achilles tendon led to a significantly more homogenous cell distribution within the healing tissue. Lower cell densities next to the implant material were determined for +PDGF‐BB samples compared to −PDGF‐BB. PDGF‐BB application increased proteoglycan content and reduced alpha‐SMA(+) areas, clusters of different sizes, mainly vessels. Finally, PDGF‐BB reduced collagens I and III in the extracellular matrix. The sustained delivery of PDGF‐BB via an electrospun DegraPol(®) tube accelerated tendon wound healing by causing a more uniform cell distribution with higher proteoglycan content and less fibrotic tissue. Moreover, the application of this growth factor reduced collagen III and alpha‐SMA, indicating a faster and less fibrotic tendon healing.