Allogeneic Dermal Fibroblasts Improve Tendon-to-Bone Healing in a Rabbit Model of Chronic Rotator Cuff Tear Compared With Platelet-Rich Plasma.

PURPOSE: To compare the effects of allogeneic dermal fibroblasts (ADFs) and platelet-rich plasma (PRP) on tendon-to-bone healing in a rabbit model of chronic rotator cuff tear. METHODS: Thirty-two rabbits were divided into 4 groups (8 per group). In 2 groups, the supraspinatus tendon was detached and was left as such for 6 weeks. At 6 weeks after creating the tear model, we performed transosseous repair with 5 × 106 ADFs plus fibrin injection in the left shoulder and PRP plus fibrin in the right shoulder. The relative expression of the COL1, COL3, BMP2, SCX, SOX9, and ACAN genes was assessed at 4 weeks (group A) and 12 weeks (group B) after repair. Histologic and biomechanical evaluations of tendon-to-bone healing at 12 weeks were performed with ADF injection in both shoulders in group C and PRP injection in group D. RESULTS: At 4 weeks, COL1 and BMP2 messenger RNA expression was higher in ADF-injected shoulders (1.6 ± 0.8 and 1.0 ± 0.3, respectively) than in PRP-injected shoulders (1.0 ± 0.3 and 0.6 ± 0.3, respectively) (P = .019 and P = .013, respectively); there were no differences in all genes in ADF- and PRP-injected shoulders at 12 weeks (P > .05). Collagen continuity, orientation, and maturation of the tendon-to-bone interface were better in group C than in group D (P = .024, P = .012, and P = .013, respectively) at 12 weeks, and mean load to failure was 37.4 ± 6.2 N/kg and 24.4 ± 5.2 N/kg in group C and group D, respectively (P = .015). CONCLUSIONS: ADFs caused higher COL1 and BMP2 expression than PRP at 4 weeks and showed better histologic and biomechanical findings at 12 weeks after rotator cuff repair of the rabbit model. ADFs enhanced healing better than PRP in the rabbit model. CLINICAL RELEVANCE: This study could serve as a transitional study to show the effectiveness of ADFs in achieving tendon-to-bone healing after repair of chronic rotator cuff tears in humans.