Abstract
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.
Highlights
Osteoarthritis (OA) is a common clinical disease in dogs affecting several tissues, including joint cartilage, subchondral bone, synovial membrane, and tendons [1]
Cells incubated with antiCD44 antibody and FITC-labeled goat anti-mouse IgG showed a green fluorescence in the membrane (Figure 1(a)), and the nucleus was stained blue by DAPI (Figure 1(b)) indicating that the isolated cells were CD44 positive (Figure 1(c))
The cells incubated with anti-CD34 antibody and FITC-labeled goat anti-rabbit IgG displayed no fluorescence in the cell membrane (Figure 1(d)); only the nucleus was stained blue by DAPI (Figure 1(e)), which showed that the expression of CD34 was negative in these cells (Figure 1(f))
Summary
Osteoarthritis (OA) is a common clinical disease in dogs affecting several tissues, including joint cartilage, subchondral bone, synovial membrane, and tendons [1]. OA is usually caused by injury, old age, and hereditary factors. With the increasing occurrence of OA in dogs, research on canine OA has been increased in the past decade [6,7,8,9,10,11,12]. Among dogs over one year old, almost one out of every five has some degree of OA. OA induces joint swelling, pain, deformation, and effusions, causing motor function obstacles and damage to health and welfare of the pet dogs [14]
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