Magnetic Resonance Imaging and Biomechanical Analysis of Adipose-derived Stromal Vascular Fraction Applied on Rotator Cuff Repair in Rabbits.

BACKGROUND: Adipose-derived stromal vascular fraction (ADSVF) can be applied to repair tendon and ligament tears. ADSVF treatment has a better therapeutic potential than adipose stem cells alone in promoting the healing of connective tissue injury in rabbit models. Magnetic resonance imaging (MRI) and biomechanical testing were used in this study to evaluate the efficiency of SVF in the healing of tendon-bone interface of a rotator cuff injury after reattachment. METHODS: A total of 36 rabbits were studied between March and June 2016, 18 rabbits received the SVF-fibrin glue (SVF-FG) treatment and the other 18 formed the control group. ADSVF was isolated from each rabbit. A bilateral amputation of the supraspinatus tendon and parallel reconstruction was also performed on all the 36 rabbits. Then, a mixture of SVF and FG was injected into the tendon-bone interface of the SVF-FG group, whereas the control group only received FG. The animals were randomly sacrificed at 4, 8, and 12 weeks after surgery (n = 6 per group), respectively. The shoulders were prepared for MRI scanning and analysis of biomechanical properties. Analyses of variance were performed using SPSS 13.0. RESULTS: MRI scanning showed that the signal-to-noise quotient of the SVF-FG group was not significantly higher than that of the control group at either 4 (20.1 ± 3.6 vs. 18.2 ± 3.4, F = 1.570, P = 0.232) or 8 weeks (20.7 ± 3.3 vs. 18.0 ± 3.0, F = 2.162, P = 0.117) posttreatment, and only became significant after 12 weeks (27.5 ± 4.6 vs. 22.1 ± 1.9, F = 4.968, P = 0.009). Biomechanical properties such as the maximum load, maximum strength, and the stiffness for the SVF-FG group were significantly greater than that for the control group at 8 weeks' posttreatment (maximum load: 166.89 ± 11.62 N vs. 99.40 ± 5.70 N, P < 0.001; maximum strength: 8.22 ± 1.90 N/mm vs. 5.82 ±0.68 N/mm, P < 0.010; and the stiffness: 34.85± 3.00 Pa vs. 24.57± 5.72 Pa, P < 0.010). CONCLUSION: Local application of ADSVF might lead to better tendon-bone healing in rabbit models.

Effects of canine myoblasts expressing human cartilage­derived morphogenetic protein­2 on the repair of meniscal fibrocartilage injury.

The aim of the present study was to explore the effects of human cartilage-derived morphogenetic protein-2 (hCDMP-2)-expressing canine myoblasts on the repair of meniscal fibrocartilage injury. Purified canine myoblasts were infected with lentiviruses carrying an empty vector or the hCDMP-2 gene. The following four experimental groups were established to study the in vivo meniscal repair in a canine model of meniscal injury: Group A, suture only; group B, suture with the addition of the recombinant hCDMP-2 on a polylactic acid/polyglycolic acid (PLA/PGA) scaffold; group C, a PLA/PGA scaffold with canine myoblasts carrying the empty vector; and group D, a PLA/PGA scaffold with canine myoblasts expressing hCDMP-2. Samples of the regenerated tissue were extracted at weeks 3, 8 and 12 post-repair and analyzed by morphological observation, immunohistochemistry (IHC) and quantitative analysis. At week 12 post-repair, the scaffold material had completely dissolved in the control groups and no changes were observed at the injured area, while regenerated tissue was observed in group D only. Hematoxylin and eosin and Safranin-O staining techniques further revealed cartilage lacunae and fibers present at the red-red zone of the repaired tissue, while cartilage lacunae without fibers were observed at the white-white zone in group D. In addition, IHC studies demonstrated that collagen I and II, and the S-100 protein were expressed at the red­red and the white-white zones of the repaired tissue in group D. It was concluded that purified canine myoblasts expressing the hCDMP-2 gene were able to promote meniscal fibrocartilage healing by regenerating fibrocartilage-like tissue. The tissue in the red-red zone was regenerated more rapidly than that in the white-white zone. Further studies are required to identify the best way to combine hCDMP-2 growth factor with myoblasts for use in the clinic due to the limitations regarding the clinical use of lentiviral infections.