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 ma y be site-specific. We have compared the dose-response effects of platelet- derived growth factor-BB (PDGF-BB) on proteoglycan, collagen, noncollagen p rotein and DNA synthesis between intrasynovial intermediate and proximal se gments of deep flexor tendons, and extrasynovial peroneal tendons of rabbit s during short-term cultures. PDGF-BB stimulated matrix and DNA synthesis o f the three types of tendon segments in a dose-dependent manner in the rang e from 0.1 to 100 ng/mL, PDGF-BB stimulated collagen synthesis and noncolla gen protein synthesis (calculated from LogED(50)) in proximal intrasynovial tendon segments more than in extrasynovial peroneal tendon segments, and D NA synthesis less in proximal than in intermediate intrasynovial tendons. H owever, the estimated maximal stimulations (E-max) by PDGF-BB were similar in the three types of tendon segments. These findings show that PDGF-BB sti mulates DNA and matrix synthesis differently in various types and regions o f tendons during short term explant culture and suggests that there may be differences in cellular responsiveness during tendon healing.