Characteristics of donor and host cells in the early remodeling process after transplant of Achilles tendon with and without live cells for the treatment of rotator cuff defect -what is the ideal graft for the treatment of massive rotator cuff defects?

Purpose: We examined the characteristics of donor and host cells in the early remodeling process after transplant of Achilles tendon with and without live cells to repair rotator cuff defects. We also clarified which graft with or without live cells was superior in the early remodeling process. Materials and methods: Sprague-Dawley (SD) rats and green fluorescent protein (GFP) rats were used; they were divided into 3 groups: in group SD, the Achilles tendons of GFP rats were transplanted into the defects of SD rats; in group GFP, the Achilles tendons of SD rats were transplanted into GFP rats; in group GFP-Fr, frozen Achilles tendons of SD rats were transplanted into GFP rats. At 3 and 7 days after surgery, these sections were examined histologically and immunohistochemically with anti-heat shock protein (HSP) 47 and antimacrophage antibodies. Results: Donor cells gradually decreased, but HSP47-positive donor cells were detected at 3 days in group SD. Host cells infiltrated into the graft from the surrounding tissue, and their numbers in groups SD and GFP gradually increased more significantly than in group GFP-Fr. Macrophages derived from the donor tissue were absent in all groups. The remodeling process of the frozen graft was slower than that in the case of the graft that was not frozen. Conclusion: These results demonstrate that live donor cells have a positive effect on the remodeling process. Therefore, autografts with live cells considered to be preferred to frozen allografts or synthetic materials without live cells for transplant for rotator cuff defects. Level of evidence: Basic Science Study. (C) 2010 Journal of Shoulder and Elbow Surgery Board of Trustees.