Regeneration of Musculoskeletal Tissues by Prolonged Low-Grade Inflammation.

摘要

Inflammation is a defense mechanism to injury that contains infection and initiates tissue repair. A potential outcome of the inflammatory process is granulomatous inflammation characterized by a large collection of macrophages. In a previous study, we observed a low-grade inflammation around a pure collagen based scaffold on implantation into the rabbit patellar tendon. Additionally, the cross-sectional areas of the tendons treated with the implant were about 40% greater compared to the shamoperated controls. In the current study, we hypothesized that soft connective tissue such as tendon can be regenerated by creation of a granulomatous inflammation. To test this hypothesis, the collagen bioscaffold was implanted into the rat patellar tendon using a minimally invasive technique and the inflammation was blocked using liposomal clodronate. The control group animals were operated in a similar manner but did not receive the drug. The animals were euthanized 1 month postimplantation, tissues were harvested and tendon cross-sectional area and the area of the granulomatous inflammatory core was determined using quantitative histology. The results revealed that the presence of granulomatous inflammation was observed around the implant in the rat model similar to our previous results in the rabbit model. However, the tendon crosssectional area was comparable between tendons treated with the implant and the sham-operated control. Furthermore, no difference in tendon area was observed between the experimental group (with clodronate) and control group (no clodronate). Together, these results refute the hypothesis of the current study possibly due to species related differences between rats and rabbits.