Objective To investigate the effect of canine decellularized tendon slices (DTSs) on tendon-bone healing in repairing rotator cuff injury of rabbit. Methods Canine DTSs were prepared by repetitive freeze/thaw 5 times combined with nuclease processing for 12 hours from the adult Beagles Achilles tendons. Histological observation and cytocompatibility evaluation for the canine DTSs were performed in vitro. Twenty-four mature male New Zealand white rabbits, weighing 2.5-3.0 kg, were randomly selected. U-shaped defect of more than 50% of normal tendon in width and 8 mm in length was made in infraspinatus tendons of unilateral limb as the experimental group; the canine DTSs were used to repair defect, and the insertion of infraspinatus tendon on greater tuberosity of humerus was reconstructed in the experimental group. No treatment was done on the contralateral limb as the control group. At 4, 8, and 12 weeks after operation, the specimens were harvested for histological observation and biomechanical test. Results Histological examination showed that collagen fibers of canine DTSs were well preserved, without residual cells. The cytocompatibility examination showed that fibroblasts attached well to canine DTSs. Biomechanical test showed that the maximum load and stiffness increased significantly with time, and the maximum load and stiffness at 12 weeks were significantly higher than those at 4 and 8 weeks (P lt; 0.05). The maximum load and stiffness of the experimental group at 4 and 8 weeks were significantly lower than those of the control group (P lt; 0.05). The stiffness of the experimental group at 12 weeks was significantly lower than that of the control group (t= — 5.679, P=0.000), but no significant difference was found in the maximum load at 12 weeks between 2 groups (t=0.969, P=0.361). Histological observation showed that the control group displayed a 4-layer structure of the tendon-bone insertion. In the experimental group at 4 weeks, the tendon-bone interface was filled with granulation tissue, and a small amount of Sharpey’s fibers-like connected the tendon to bone; granulation tissue disappeared, and fibroblasts, Sharpey’s fiber, new cartilage, and chondrocytes significantly increased with time; tendon-bone interface became mature, but the tide line was not observed between the unmineralized fibrocartilage and mineralized fibrocartilage. Conclusion Canine DTSs prepared by repetitive freeze/thaw 5 times combined with nuclease processing for 12 hours, can enhance the healing of host tendon-bone and improve the biomechanical characteristics of the rabbit infraspinatus tendon.
Objective?To analyze the effect of different surgery techniques on the tendon-bone healing of rotator cuff insertion.?Methods?Forty-two adult Japanese rabbits, weighing 2.0-2.5 kg and male or female, were selected. Thirty-six rabbits were given a sharply left-lateral tenotomy of the supraspinatus tendon with subsequent re-attachment of the tendon. According to the depth of re-attachment, 36 rabbits were equally randomized into the cancellous-fixation group (a cancellous bed was prepared with a dental burr) and the cortical-fixation group (the same treatment was performed except the preparation of the bone bed). Six rabbits served as the controls without treatment (control group). At 4 and 8 weeks after operation, the general observation, HE staining, and the biomechanical test were performed.?Results?At 4 weeks after operation, the supraspinatus-humerus specimens morphologically showed atrophy and vague between tendon and new bone in the cancellous-fixation group and the cortical-fixation group; at 8 weeks, no obvious difference was observed between 2 groups and the control group. The histological results of the cortical-fixation group at 4 weeks revealed the interface between tendon and new bone became smooth. The interface became transitional at 8 weeks, and the shape of bone tissue was nearly normal. The interface obtained from the cancellous-fixation group at 4 weeks became sclerotic, and collagen fibers formed in disorder. With ingrowth of new bone and re-establishment of collagen-fiber continuity at 8 weeks, thickness of interface became thin, and bone tissue was remodeling. The ultimate load were significantly higher in the cortical-fixation group than in the cancellous-fixation group at both 4 and 8 weeks, and the results gained at 8 weeks is significantly higher than that at 4 weeks in each group (P lt; 0.05). Except rupture strength at 4 weeks between 2 groups and all tensile strength (P gt; 0.05), there were significant differences in the results of others (P lt; 0.05).?Conclusion?In this model, the tendon-bone healing process and the biomechanical properties of cortical-fixation is superior to those of cancellous-fixation.
ObjectiveTo investigate the effect of hamstring tendon transfected with adenovirus-mediated transforming growth factor β1 (AdTGF-β1) genes on the histomorphology of tendon-bone interface healing after anterior cruciate ligament (ACL) reconstruction in rabbits. MethodsAdTGF-β1 and AdGFP were diluted to 5×108 PFU/mL with DMEM. Forty-eight New Zealand white rabbits were divided into 3 groups randomly (n=16), weighing 1.6-2.5 kg for ACL reconstruction with hamstring tendon autograft. Hamstring tendon was cultured and transfected with AdTGF-β1 (group A) and AdGFP (group B) for 12 hours before ACL reconstruction, and was cultured with DMEM in group C. After 12 hours of transfection, the expression of green fluorescence was observed in groups A and B under fluorescence microscopy; TGF-β1 protein level was detected by ELISA in group A. At 2, 4, 8, and 12 weeks after operation, the specimens were harvested for HE and Masson staining; the number of fibroblasts was counted, and the Buark grading was used to evaluate tendon-bone interface healing. ResultsGreen fluorescence was observed after 12 hours of transfection in groups A and B. TGF-β1 protein level reached (221.0±12.2) ng/mL at 12 hours in group A. The histological observation showed that few fibroblasts and collagen fibers were found, and Sharpey fibers appeared in group A; regular Sharpey fibers were seen in the interface, and integrity interface in some areas at 12 weeks. But fibroblasts of groups B and C were less than those of group A, with loose tendon-bone interface; no integrity interface was observed at 12 weeks. The number of fibroblasts and Buark grading of group A were significantly higher than those of groups B and C (P<0.05), but no significant difference was found between groups B and C (P>0.05). ConclusionHamstring tendon transfected with AdTGF-β1 gene can promote the healing of tendon-bone interface after ACL reconstruction.