A synthetic bridging patch of modified co-electrospun dual nano-scaffolds for massive rotator cuff tear

Massive rotator cuff tears (MRCTs) are difficult to repair because of the retraction and poor mobility of torn tendons. In the current study, co-electrospun dual nano-scaffolds of poly(lactic-co-glycolic acid)/collagen I-polycaprolactone/nanohydroxyapatite (PLGA/Col-PCL/nHA) were fabricated and used to bridge MRCTs of infraspinatus tendons in a rabbit model. PLGA-PCL served as a control. The PLGA or the PLGA/Col sides of the dual scaffolds connected the tendon stumps. The PCL or PCL/nHA side was inserted into the bone tunnel at the insertion of the infraspinatus tendon. Fibroblasts showed higher viability and collagen secretion when seeded on a PLGA/Col scaffold compared to a PLGA scaffold. Osteoblasts seeded on a PCL/nHA scaffold grew better with higher mineralization than on a PCL scaffold. Histologically, collagen regenerated along PLGA scaffolds, but showed poor ingrowth to scaffolds compared with the PLGA/Col group. Newly formed bone was observed on the PCL scaffold, but was less than that on the PCL/nHA scaffold. At 6 weeks post repair, the regenerated tendon in both groups had similar maximum load to failure and ultimate stress but significantly lower stiffness in the PLGA-PCL group and a higher cross-sectional area in the PLGA/Col-PCL/nHA group compared with normal values. At 12 weeks, the maximum failure load, ultimate stress and cross-sectional areas of the regenerated tendon in the PLGA/Col-PCL/nHA group were significantly higher than in the PLGA-PCL and normal groups. The biomechanical properties of the PLGA-PCL group were similar to normal except for a larger cross-sectional area. Our data showed that the co-electrospun dual nano-scaffolds are promising in bridging MRCTs. Doping with Col and nHA further strengthens tissue regeneration.