BACKGROUND: Large-to-massive rotator cuff tears (L-M RCTs) usually requires a patch to reconstruction. Decellularized tendon patch (DTP) was a biomimetic and effective material for reconstructing L-M RCTs. However, the protocol for DTP sterilization and storage is variable, which may influence their performance. The objective of this study is to optimize the protocol of DTP sterilization and storage and fabricate an off-the-shelf DTP with superior efficacy in enhancing the healing of L-M RCTs. METHODS: DTPs were sterilized by ethylene oxide (EO) or gamma irradiation (GR), then preserved using cryo-preservation (CP) or freeze-drying (FD), thus preparing four kinds of DTPs (EO/CP-DTP, EO/FD-DTP, GR/CP-DTP, GR/FD-DTP). After evaluating their histology, microstructure, biomechanics, biocompatibility, and tenogenic inducibility in-vitro, a total of 88 male SD rats with chronic L-M RCTs were randomly divided into 4 groups, and then reconstructed with one of the four DTPs. At postoperative week 4 or 8, the supraspinatus tendon-to-humerus complexes were harvested for gross, micro-CT, histological, and mechanical evaluations. RESULTS: In-vitro results indicated that the four kinds of DTPs showed excellent biocompatibility, and EO/CP-DTP showed an orderly collagen arrangement and higher tensile properties than the other DTPs. More importantly, the EO/CP-DTP can induce more interacted stem cells toward tenogenic lineages as compared with the other kinds of DTPs. Micro-CT showed that bony footprint in the four groups showed similar value in bone morphological parameters without significant difference. Histologically, the two CP-sterilized DTPs presented significantly higher scores than the FD-sterilized DTPs, while the EO/CP-DTP group exhibited slightly higher scores compared to the GR/CP-DTP group. As for the mechanical strength of the supraspinatus tendon-to-humerus complexes, a significantly higher failure load showed in the CP-sterilized DTPs when compared with the FD-sterilized DTPs at postoperative week 4 or 8. CONCLUSION: DTP should be sterilized by EO and preserved using CP, owing that this type of DTP well preserved the intrinsic bioactivity and mechanical properties as well as showed superior efficacy in enhancing the healing of L-M RCTs. LEVEL OF EVIDENCE: Basic Science Research
Animal Model.