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Mesenchymal stem cells (MSCs) are the most promising seed cells for cell therapy. Comparing the biological and transcriptome gene characteristics of MSCs from different sources provides an important basis for the screening of clinically used cells. The main purpose of this experiment was to establish methods for the isolation and culture of MSCs from five different canine sources, including adipose tissue, bone marrow, umbilical cord, amniotic membrane, and placenta, and compare biological and transcriptome characteristics of MSCs, in order to provide a basis for the clinical application of canine MSCs. MSCs were isolated from Chinese pastoral dogs, and the following experiments were performed: (1) the third, sixth, and ninth generations of cells were counted, respectively, and a growth curve was plotted to calculate the MSC population doubling time; (2) the expression of CD34 and CD44 surface markers was studied by immunofluorescence; (3) the third generation of cells were used for osteogenetic and adipogenic differentiation experiments; and (4) MSC transcriptome profiles were performed using RNA sequencing. All of the five types of MSCs showed fibroblast-like adherent growth. The cell surface expressed CD44 instead of CD34; the third-generation MSCs had the highest proliferative activity. The average population doubling time of adipose mesenchymal stem cells (AD-MSCs), placenta mesenchymal stem cells (P-MSCs), bone marrow mesenchymal stem cells (BM-MSCs), umbilical cord mesenchymal stem cells (UC-MSCs), and amniotic mesenchymal stem cells (AM-MSCs) were 15.8 h, 21.2 h, 26.2 h, 35 h, and 41.9 h, respectively. All five types of MSCs could be induced to differentiate into adipocytes and osteoblasts in vitro, with lipid droplets appearing after 8 days and bone formation occurring 5 days after AD-MSC induction. However, the multilineage differentiation for the remaining of MSCs was longer compared to that of the AD-MSCs. The MSC transcriptome profiles showed that AD-MSC and BM-MSCs had the highest homology, while P-MSCs were significantly different compared to the other four types of MSCs. All the isolated MSCs had the main biological characteristics of MSCs. AD-MSCs had the shortest time for proliferation, adipogenesis, and osteogenic differentiation.

Objective. The aim of this study was to assess the efficacy of canine umbilical cord mesenchymal stem cells (UC-MSCs) on the treatment of knee osteoarthritis in dogs. Methods. Eight dogs were evenly assigned to two groups. The canine model of knee osteoarthritis was established by surgical manipulation of knee articular cartilage on these eight dogs. UC-MSCs were isolated from umbilical cord Wharton’s jelly by 0.1% type collagenase I and identified by immunofluorescence staining and adipogenic and osteogenic differentiation in vitro. A suspension of allogeneic UC-MSCs (1 × 106) and an equal amount of physiological saline was injected into the cavitas articularis in the treated and untreated control groups, respectively, on days 1 and 3 posttreatment. The structure of the canine knee joint was observed by magnetic resonance imaging (MRI), B-mode ultrasonography, and X-ray imaging at the 3rd, 7th, 14th, and 28th days after treatment. Concurrently, the levels of IL-6, IL-7, and TNF-α in the blood of the examined dogs were measured. Moreover, the recovery of cartilage and patella surface in the treated group and untreated group was compared using a scanning electron microscope (SEM) after a 35-day treatment. Results. Results revealed that the isolated cells were UC-MSCs, because they were positive for CD44 and negative for CD34 surface markers, and the cells were differentiated into adipocytes and osteoblasts. Imaging technology showed that as treatment time increased, the high signal in the MRI T2-weighted images decreased, the echo-free space in B ultrasonography images disappeared basically, and the continuous linear hypoechoic region at the trochlear sulcus thickened. On X-ray images, the serrate defect at the ventral cortex of the patella improved, and the low-density gap of the ventral patella and trochlear crest gradually increased in the treated group. On the contrary, the high signal in the MRI T2-weighted images and the echo-free space in B ultrasonography images still increased after a 14-day treatment in the untreated control group, and the linear hypoechoic region was discontinuous. On the X-ray images, there was no improvement in the serrate defect of the ventral cortex of the patella. Results for inflammatory factors showed that the blood levels of IL-6, IL-7, and TNF-α of the untreated control group were significantly higher than those of the treated group (P<0.05) 7–14 days posttreatment. The result of SEM showed that the cartilage neogenesis in the treated group had visible neonatal tissue and more irregular arrangement of new tissue fibers than that of the untreated control group. Furthermore, more vacuoles but without collagen fibers were observed in the cartilage of the untreated control group, and the thickness of the neogenetic cartilage in the treated group (65.13 ± 5.29, 65.30 ± 5.83) and the untreated control group (34.27 ± 5.42) showed a significant difference (P<0.01). Conclusion. Significantly higher improvement in cartilage neogenesis and recovery was observed in the treated group compared to the untreated control group. The joint fluid and the inflammatory response in the treated group decreased. Moreover, improved recovery in the neogenetic cartilage, damaged skin fascia, and muscle tissue around the joints was more significant in the treated group than in the untreated control group. In conclusion, canine UC-MSCs promote the repair of cartilage and patella injury in osteoarthritis, improve the healing of the surrounding tissues, and reduce the inflammatory response. [ABSTRACT FROM AUTHOR]