Abstract
Objective The aim of this study was to investigate regenerative effects of ultrasound- (US-) guided injection with human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) and/or polydeoxyribonucleotide (PDRN) injection in a chronic traumatic full-thickness rotator cuff tendon tear (FTRCTT) in a rabbit model. Methods Rabbits (n = 32) were allocated into 4 groups. After a 5 mm sized FTRCTT just proximal to the insertion site on the subscapularis tendon was created by excision, the wound was immediately covered by a silicone tube to prevent natural healing. After 6 weeks, 4 injectants (0.2 mL normal saline, G1-SAL; 0.2 mL PDRN, G2-PDRN; 0.2 mL UCB-MSCs, G3-MSC; and 0.2 mL UCB-MSCs with 0.2 ml PDRN, G4-MSC + PDRN) were injected into the FTRCTT under US guidance. We evaluated gross morphologic changes on all rabbits after sacrifice. Masson's trichrome, anti-type 1 collagen antibody, bromodeoxyuridine, proliferating cell nuclear antigen, vascular endothelial growth factor, and platelet endothelial cell adhesion molecule stain were performed to evaluate histological changes. Motion analysis was also performed. Results The gross morphologic mean tendon tear size in G3-MSC and G4-MSC + PDRN was significantly smaller than that in G1-SAL and G2-PDRN (p < 0.05). However, there were no significant differences in the tendon tear size between G3-MSC and G4-MSC + PDRN. In G4-MSC + PDRN, newly regenerated collagen type 1 fibers, proliferating cell activity, angiogenesis, walking distance, fast walking time, and mean walking speed were greater than those in the other three groups on histological examination and motion analysis. Conclusions Coinjection of UCB-MSCs and PDRN was more effective than UCB-MSC injection alone in histological and motion analysis in a rabbit model of chronic traumatic FTRCTT. However, there was no significant difference in gross morphologic change of tendon tear between UCB-MSCs with/without PDRN injection. The results of this study regarding the combination of UCB-MSCs and PDRN are worth additional investigations.
Highlights
Rotator cuff tendon tears (RCTTs) are the most common tendon injury in adults and affect about 30% of people over 60 years of age [1]
There were no significant differences in gross morphologic changes and tendon tear size between G3-Mesenchymal stem cells (MSCs) and G4-MSC + PDRN (Figures 3 and 5)
We previously demonstrated that the injection of UCB-MSCs under US guidance has a regenerative effect for chronic full-thickness RCTTs
Summary
Rotator cuff tendon tears (RCTTs) are the most common tendon injury in adults and affect about 30% of people over 60 years of age [1]. Surgical repair of a RCTT is one of the most common orthopedic procedures, the failure rate for rotator cuff tendon repair ranges widely from 20% to 90% [2]. The current therapeutic approaches do not achieve physiological restoration of the RCTT, and the quality of the repaired tendon is not optimal [3]. These deficiencies have driven attempts to regenerate RCTT with the use of biological adjuvants. The function of autologous MSCs in patients with advanced age or significant comorbidities is impaired, and allogeneic UCB-MSCs may be of particular benefit
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