Bone morphogenetic protein 13 stimulates cell proliferation and production of collagen in human patellar tendon fibroblasts.

Background: Recombinant human (rh) bone morphogenetic protein 13 (BMP13) has been shown to induce the formation of tendon and ligament tissues in animal experiments. The role of BMP13 in tissue regeneration in human tendons remains unexplored, however.

Material And Methods: We collected healthy human patellar tendon samples for histological examination and tendon fibroblast culture. The cultured cells were incubated in the presence and absence of rhBMP13 and the effect of the protein on cell proliferation was measured using 5-bromo-2'-deoxyuridine uptake.

Results: BMP13 was detectable by immunohistochemical staining in healthy patellar tendon samples, and was located exclusively in active tenoblasts and perivascular mesenchymal cells but not in interstitial tenocytes. The expression of proliferating cell nuclear antigen (PCNA) and pro-collagen type I showed a similar distribution. In vitro studies showed that rhBMP13 can increase proliferation of tendon fibroblasts and increase the gene expression of pro-collagen type I in tendon fibroblast culture.

Interpretation: Our findings indicate that BMP13 may be involved in the matrix remodeling process in adult tendon, and that it may play a role in tissue regeneration in tendons.