Responses of equine tendon- and bone marrow–derived cells to monolayer expansion with fibroblast growth factor-2 and sequential culture with pulverized tendon and insulin-like growth factor-I

Abstract

To compare in vitro expansion of equine tendon- and bone marrow-derived cells with fibroblast growth factor-2 (FGF-2) supplementation and sequential matrix synthesis with pulverized tendon and insulin-like growth factor-I (IGF-I). Cells from 6 young adult horses. Progenitor cells were expanded in monolayers with FGF-2, followed by culture with autogenous acellular pulverized tendon and IGF-I for 7 days. Initial cell isolation and subsequent monolayer proliferation were assessed. In pulverized tendon cultures, cell viability and expression of collagen types I and III and cartilage oligomeric matrix protein (COMP) mRNAs were assessed. Collagen and glycosaminoglycan syntheses were quantified over a 24-hour period. Monolayer expansion with FGF-2 significantly increased the mean ± SE number of tendon-derived cells (15.3 ± 2.6 × 10(6)), compared with bone marrow-derived cells (5.8 ± 1.8 × 10(6)). Overall, increases in collagen type III and COMP mRNAs were seen in tendon-derived cells, compared with results for bone marrow-derived cells. After IGF-I supplementation, increases in collagen type I and type III mRNA expression were seen in bone marrow-derived cells, compared with results for unsupplemented control cells. Insulin-like growth factor-I significantly increased collagen synthesis of bone marrow-derived cells. Monolayer expansion with FGF-2 followed by IGF-I supplementation significantly increased glycosaminoglycan synthesis in tendon-derived cells. Tendon-derived cells had increased cell numbers and matrix synthesis after monolayer expansion with FGF-2, compared with results for bone marrow-derived cells. In vivo experiments with FGF-2-expanded tendon-derived cells are warranted to evaluate effects on tendon healing.