USE OF MESENCHYMAL STEM-CELLS IN A COLLAGEN MATRIX FOR ACHILLES-TENDON REPAIR

This investigation tested the hypothesis that delivering mesenchymal s tem cell-seeded implants to a tendon gap model results in significantl y improved repair biomechanics. Cultured, autologous, marrow-derived m esenchymal stem cells were suspended in a collagen gel delivery vehicl e; the cell-gel composite was subsequently contracted onto a pretensio ned suture. The resulting tissue prosthesis was then implanted into a l-cm-lon,a gap defect in the rabbit Achilles tendon. Identical procedu res were performed on the contralateral tendon, but only the suture ma terial was implanted. The tendon-implant constructs were evaluated 4, 8, and 12 weeks later by biomechanical and histological criteria. Sign ificantly greater load-related structural and material properties were seen at all time intervals in the mesenchymal stem cell-treated tendo ns than in the contralateral, treated control repairs (p < 0.05), whic h contained suture alone with natural cell recruitment. The values wer e typically twice those for the control tissues at each time interval. Load-related material properties for the treated tissues also increas ed significantly over time (p < 0.05). The treated tissues had a signi ficantly larger cross-sectional area (p < 0.05), and their collagen fi bers appeared to be better aligned than those in the matched controls. The results indicate that delivering mesenchymal stem cell-contracted , organized collagen implants to large tendon defects can significantl y improve the biomechanics, structure? and probably the function of th e tendon after injury.