Effects of BMP-7 and low molecular weight peptide solution on healing in rotator cuff tear model: histopathological and biomechanical study in rats

Effects of BMP-7 and Low Molecular Weight Peptide Solution on Healing in Rotator Cuff Tear Model: Histopathological and Biomechanical Study in Rats Introduction: Rotator cuff tears're the most common shoulder pathology requiring surgery. Retear rates after surgery can be around 70%. The search for additional medications that'll help reduce these rates continues. Bone morphogenetic protein(BMP)-7's begun to be investigated for its potential benefits on bone-tendon healing by stimulating synthesis, organization and retention of matrix molecules. Low molecular weight peptide solution(LMWPS)'s a new medical device obtained by hydrolyzing collagen chains and dimensional filtration of peptides.This study aimed to evaluate the in-vivo effectiveness of this 2 different agents after rotator cuff repair. Material& Method: Three groups were created using 24 Wistar Albino rats.Supraspinatus tendon(SS) was separated from the humeral attachment site by entering through craniolateral incision and deltoid split approach in both shoulders.Tendon was sutured with 3-0 polyprolene suture with Mason-Allen technique and ligated by passing through 0.5mm tunnel in humerus, primary repair was performed. The operation was completed for Group-1(control); for Group- 2(LMWPS), after the repair was completed, 1μg/μl,5μl LMWPS was applied; for Group-3(BMP7), 200μl (2.5ng/μl) BMP7 was applied on the tendon in both shoulders. After 4 weeks,animals were sacrificed and shoulder joints were resected leaving the scapula, humerus and SS intact.Right shoulders were evaluated in the biomechanics laboratory for maximum-load, maximum-tension, stiffness and Young modulus. Left shoulders were examined histopathologically for tendon-bone healing. Results: Histopathological:Healing parameters were evaluated with Tendon Healing Scoring System.Group-3 and 2 was statistically better than Group-1 in terms of tenocyte-like cells,parallel lining cells,large diameter fibers resembling mature tendon fibers,parallel lining fiber ratios,ensuring tendon-bone transition.For vascularity,Group-2 showed significant increase. Biomechanics: The 3 groups were similar for max-load and max-stress. Stiffness was significantly lower in Group-2.For Young's modulus Group-3 was significantly better than Group-2. Conclusion: Although BMP7 and DMAPS improved histological healing parameters in rotator cuff repair, no early benefit was shown in terms of biomechanical values. Further studies are needed to determine the optimal biological augments.