The aim of this study was to investigate the potential to regenerate of rotator cuff tendon and insertion using a biodegradable scaffold as an acellular matrix. The bilateral infraspinatus tendons and its insertions of Japanese white rabbits were removed to create the defects (10x1Omm). The defects of the right shoulders were closed with a non-woven chitin fabric (NWCF), which was inserted into the bony trough. The contra lateral defects were not treated as a control.
The shoulders were removed at two, four, eight, twelve weeks after surgery. Specimens were evaluated histologically and immunohistochemically. At two weeks, fibroblasts had been inducted into NWCF from the insertion side and deltoid muscle side. At four weeks, collagen fibers were observed. NWCF had expanded near the bony attachment At twelve weeks, the number of fibroblasts had decreased and the collagen tissue had matured. The degradation of NWCF was observed. The regeneration tissues were negative immunostaining in collagen type I and positive in collagen type III. In the control group, a thin membrane, a smaller number of cell and irregular collagen tissue were observed at twelve weeks. Chitin might have a good biocompatibility and contribute to good induction of fibroblast as a biodegradable scaffold material. On the other hand, NWCF had insufficient mechanical properties as a scaffold for regeneration of the rotator cuff tendon and insertion. These findings showed that the biodegradable scaffold had the potential to regenerate the rotator cuff tendon and its insertion. The limitation of this study was to be unable to regenerate normal collagen type in regenerated tissues.
