Objective—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).
Sample—Cells from 6 young adult horses.
Procedures—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.
Results—Monolayer expansion with FGF-2 significantly increased the mean ± SE number of tendon-derived cells (15.3 ± 2.6 × 106), compared with bone marrow–derived cells (5.8 ± 1.8 × 106). 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.
Conclusions and Clinical Relevance—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.
Objective—To determine the effects of sodium hyaluronate (HA) in combination with methylprednisolone acetate (MPA) on interleukin-1 (IL-1)–induced inflammation in equine articular cartilage pellets.
Sample Population—Chondrocytes collected from 7 horses euthanatized for problems unrelated to the musculoskeletal system.
Procedures—Chondrocyte pellets were treated with medium (negative control); medium containing IL-1 (positive control); or medium containing IL-1 with MPA only (0.05 or 0.5 mg/mL), HA only (0.2 or 2 mg/mL), or MPA (0.05 or 0.5 mg/mL) and HA (0.2 or 2 mg/mL) in combination. Proteoglycan (PG) synthesis was determined by incorporation of sulfur 35–labeled sodium sulfate into PGs. Glycosaminoglycan (GAG) content of the media and the pellets and total pellet DNA content were determined.
Results—Methylprednisolone acetate at 0.5 mg/mL caused an increase in PG synthesis, whereas HA had no effect alone. The combination of MPA, both 0.05 mg/mL and 0.5 mg/mL, with HA at 2 mg/mL increased PG synthesis, compared with IL-1–treated control. All treatment groups containing the high concentration of MPA (0.5 mg/mL) and the high concentration of HA (2.0 mg/mL) had pellets with increased GAG content. The addition of HA caused an increase in total GAG content in the media, regardless of MPA treatment. Cyclooxygenase-2 mRNA and aggrecan mRNA expression was significantly reduced with MPA treatment. Total pellet DNA content was unchanged by any treatment.
Conclusions and Clinical Relevance—Our results indicate that MPA in combination with HA has beneficial effects on PG metabolism of IL-1–treated equine chondrocytes.
Objective—To compare viability and biosynthetic capacities of cells isolated from equine tendon, muscle, and bone marrow grown on autogenous tendon matrix.
Sample Population—Cells from 4 young adult horses.
Procedures—Cells were isolated, expanded, and cultured on autogenous cell-free tendon matrix for 7 days. Samples were analyzed for cell viability, proteoglycan synthesis, collagen synthesis, and mRNA expression of collagen type I, collagen type III, and cartilage oligomeric matrix protein (COMP).
Results—Tendon- and muscle-derived cells required less time to reach confluence (approx 2 weeks) than did bone marrow–derived cells (approx 3 to 4 weeks); there were fewer bone marrow–derived cells at confluence than the other 2 cell types. More tendon- and muscle-derived cells were attached to matrices after 7 days than were bone marrow–derived cells. Collagen and proteoglycan synthesis by tendon- and muscle-derived cells was significantly greater than synthesis by bone marrow–derived cells. On a per-cell basis, tendon-derived cells had more collagen synthesis, although this was not significant. Collagen type I mRNA expression was similar among groups. Tendon-derived cells expressed the highest amounts of collagen type III and COMP mRNAs, although the difference for COMP was not significant.
Conclusions and Clinical Relevance—Tendon- and muscle-derived cells yielded greater cell culture numbers in shorter time and, on a per-cell basis, had comparable biosynthetic assays to bone marrow–derived cells. More in vitro experiments with higher numbers may determine whether tendon-derived cells are a useful resource for tendon healing.