Comparison of equine tendon- and bone marrow-derived cells cultured on tendon matrix with or without insulin-like growth factor-I supplementation.

OBJECTIVE: To compare in vitro expansion, explant colonization, and matrix synthesis of equine tendon- and bone marrow-derived cells in response to insulin-like growth factor-I (IGF-I) supplementation.

SAMPLE: Cells isolated from 7 young adult horses.

PROCEDURES: Tendon- and bone marrow-derived progenitor cells were isolated, evaluated for yield, and cultured on autogenous cell-free tendon matrix for 7 days. Samples were analyzed for cell viability and expression of collagen type I, collagen type III, and cartilage oligomeric matrix protein mRNAs. Collagen and glycosaminoglycan syntheses were quantified over a 24-hour period.

RESULTS: Tendon- and bone marrow-derived cells required 17 to 19 days of monolayer culture to reach 2 passages. Mean ± SE number of monolayer cells isolated was higher for tendon-derived cells (7.9 ± 0.9 × 10(6)) than for bone marrow-derived cells (1.2 ± 0.1 × 10(6)). Cell numbers after culture for 7 days on acellular tendon matrix were 1.6- to 2.8-fold higher for tendon-derived cells than for bone marrow-derived cells and 0.8- to 1.7-fold higher for IGF-I supplementation than for untreated cells. New collagen and glycosaminoglycan syntheses were significantly greater in tendon-derived cell groups and in IGF-I-supplemented groups. The mRNA concentrations of collagen type I, collagen type III, and cartilage oligomeric matrix protein were not significantly different between tendon- and bone marrow-derived groups.

CONCLUSIONS AND CLINICAL RELEVANCE: In vitro results of this study suggested that tendon-derived cells supplemented with IGF-I may offer a useful resource for cell-based strategies in tendon healing.