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 re-rupture 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 bi-layered DegraPol® tube to deliver PDGF-BB to the wound site in a rabbit full transection Achilles tendon model. We then performed histological and immunohistochemical analysis at 3 weeks post-operation. 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 collagen 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 faster and less fibrotic tendon healing.