Dose-related cellular effects of platelet-derived growth factor-BB differ in various types of rabbit tendons in vitro

Cellular responsiveness to growth factors that can affect tendon healing may be site-specific. We have compared the dose-response effects of platelet-derived growth factor-BB (PDGF-BB) on proteoglycan, collagen, noncollagen protein and DNA synthesis between intrasynovial intermediate and proximal segments of deep flexor tendons, and extrasynovial peroneal tendons of rabbits during short-term cultures. PDGF-BB stimulated matrix and DNA synthesis of the three types of tendon segments in a dose-dependent manner in the range from 0.1 to 100 ng/mL. PDGF-BB stimulated collagen synthesis and noncollagen protein synthesis (calculated from LogED50) in proximal intrasynovial tendon segments more than in extrasynovial peroneal tendon segments, and DNA synthesis less in proximal than in intermediate intrasynovial tendons. However, the estimated maximal stimulations (Emax) by PDGF-BB were similar in the three types of tendon segments. These findings show that PDGF-BB stimulates DNA and matrix synthesis differently in various types and regions of tendons during short term explant culture and suggests that there may be differences in cellular responsiveness during tendon healing.