Adipose-Derived Regenerative Cells Promote Tendon-Bone Healing in a Rabbit Model

Abstract

To evaluate the therapeutic effect of adipose-derived regenerative cell (ADRC) administration on tendon-bone healing in a rabbit anterior cruciate ligament (ACL) reconstruction model. ACL reconstruction with semitendinosus tendon autograft was performed in the right knees of adult white rabbits. Eighty rabbits were divided into 2 groups: the treatment group, in which the graft was coated with ADRCs mixed in a fibrin glue carrier during surgery, and the control group, in which the graft was coated with fibrin glue only. At 2, 4, 6, 8, and 12 weeks postoperatively, 8 rabbits were killed in each group. Three were used for histologic evaluation at the tendon-bone interface and 5 for biomechanical examination. On histologic analysis, chondroid cells appeared more orderly and more regular in size and shape and Sharpey-like fibers, which connected the tendon graft and bone tissue, appeared earlier in ADRC-treated tissues than in control tissues. On biomechanical analysis, the ultimate failure load in the ADRC-treated group was significantly greater than that in the control group at 2 weeks (29.5 ± 7.2 N v 20.9 ± 2.7 N, P= .016) and 4 weeks (32.3 ± 3.9 N v 22.8 ± 5.4 N, P= .016). Stiffness was significantly higher in the ADRC-treated group than in the control group at 6 weeks (21.7 ± 5.9 N/mm v 12.6 ± 4.9 N/mm, P= .037). Although the ultimate failure load and stiffness of the ADRC-treated limbs were higher than those of the limbs in the control group at 8 and 12 weeks, these differences were not significant. Local administration of ADRCs promoted the early healing process at the tendon-bone junction, both histologically and mechanically, in a rabbit ACL reconstruction model. ADRCs could be used to enhance graft healing in ACL reconstruction.