Objective
To investigate the synergic therapeutic effects of Co-injection of intra-lesional human umbilical cord blood-derived mesenchymal stem cells (SC) and polydeoxyribonucleotide (PDRN) combined with microcurrent therapy (MIC) on 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 supraspinatus tendon was created by excision, the wound was immediately covered by silicone tube to prevent natural healing. After 6 weeks, 4 types of procedures (0.2 mL normal saline injection, group 1 (G1-NS); 0.2mL SC injection, group 2 (G2-SC); 0.2 mL SC and weekly four injections of 0.2 mL PDRN with sham MIC, group 3 (G3-SC+PDRN+sham MIC); and 0.2 mL SC and weekly four injections of 0.2 mL PDRN with MIC for four weeks, group 4 (G4-SC+PDRN+MIC)) were performed into FTRCTT. All injections were performed under ultrasound guidance. In group 3 and 4, sham MIC or MIC was applied daily for 4 weeks after the first SC injection. We evaluated gross morphologic changes on all rabbits after euthanize. Proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF) and platelet endothelial cell adhesion molecule (PECAM-1) stains were performed to evaluate histological changes. Motion analysis was also performed. We used chi-square test and analysis of variance (ANOVA) to determine statistical differences among intra- and inter-groups.
Results
There was significant difference in gross morphologic changes between baseline and 4 weeks after treatment in group 4 compared to other three groups (p = .01, Table 1). In group 4, at 4 weeks after first treatment, full-thickness tendon tear (FTT) was observed in one rabbit (12.5%), partial-thickness tendon tear (PTT) in four rabbits (50.0%), and nearly complete healing (CH) in three rabbits (37.5%) (Table 1). Mean tendon tear size in group 2, group 3, and group 4 was significantly smaller than that in group 1 (p < .05, Figure 1, Table 1). In histochemical and motion analysis, PCNA, VEGF, PECAM-1 stained cells and walking distance, fast walking time, mean walking speed in group 2, group 3, and group 4 were greater than those in group 1 (p < .05, Figure 2, Table 1). In group 3 and 4, all parameters of histochemical and motion analysis showed significantly greater than those in group 2 (p < .05, Table 1). In group 4, PCNA, VEGF, PECAM-1 stained cells and walking distance showed significantly greater than those in group 3 (p < .05, Table 1).
Conclusions
SC alone and SC combined with PDRN with/without MIC showed effective in tendon healing as demonstrated by improvement in gross morphologic, histological, and motion analysis. SC with PDRN and MIC seems more effective in improving activity level, tendon tear severity, and angiogenesis than SC alone and SC with PDRN in traumatic full thickness rotator cuff tendon tear in a rabbit model.
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Figure 1. Gross morphology of the supraspinatus tendon. Gross morphological (A-H) findings of the supraspinatus tendons in G1-NS, G2-SC, G3-SC+PDRN+sham MIC, and G4-SC+PDRN+MIC. (A-D) Pre-treatment images; (E-H) Post-treatment images. Mean tendon tear size in group 2, group 3, and group 4 was significantly smaller than that in group 1 (p < .05). Abbreviations are NS, Normal saline; SC, human umbilical cord blood-derived mesenchymal stem cell; PDRN, polydeoxyribonucleotides; MIC, Microcurrent therapy;
Figure 2. Histologic findings of the supraspinatus tendon. Numerus cell proliferating PCNA stained cells (black arrow, x 100) were observed in regenerated tendon fibers in G4-SC+PDRN+MIC. Lesser PCNA stained cells were observed in G2-SC, G3-SC+PDRN+sham MIC and few PCNA stained cells were observed in G1-NS (A to D). Numerous VEGF-positive cells and PECAM-1 positive microvascular angiogenesis densities (black arrow, x 100) were observed in G4-SC+PDRN+MIC. In G4-SC+PDRN+MIC, VEGF-positive cells and PECAM-1 positive densities are significantly greater than those of G3-SC+PDRN (E to L). Abbreviations are NS, Normal saline; SC, human umbilical cord blood-derived mesenchymal stem cell; PDRN, polydeoxyribonucleotides; MIC, Microcurrent therapy; PCNA, proliferating cell nuclear antigen; VEGF, Vascular endothelial growth factor; PECAM-1, Platelet endothelial cell adhesion molecule.
Values are mean±SD. The proportion of positive cells of PCNA, VEGF, PECAM-1 was scored as 0 = no cells stained positive, 1 = between 1% and 10%, 2 = between 11% and 33%, 3 = between 34% and 66%, and 4 = between 67% and 100%. NS, Normal saline; SC, human umbilical cord blood-derived mesenchymal stem cell; PDRN, polydeoxyribonucleotides; MIC, Microcurrent therapy; CH, complete healed; PTT, partial-thickness tear; FTT, full-thickness tear; PCNA, proliferating cell nuclear antigen; VEGF, Vascular endothelial growth factor; PECAM-1, Platelet endothelial cell adhesion molecule. *) p < .05 one-way ANOVA, Tukey's post hoc test among group 1 and 2. †) p < .05 one-way ANOVA, Tukey's post hoc test among group 1 and 3. ‡) p < .05 one-way ANOVA, Tukey's post hoc test among group 1 and 4. §) p < .05 one-way ANOVA, Tukey's post hoc test among group 2 and 3. ∥) p < .05 one-way ANOVA, Tukey's post hoc test among group 2 and 4. ¶) p < .05 one-way ANOVA, Tukey's post hoc test among group 3 and 4.
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