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Transplantation of Non-expanded Adipose Stromal Vascular Fraction and Platelet-Rich Plasma for Articular Cartilage Injury Treatment in Mice Model（2）

In the next experiment, we evaluated the efficiency of SVF transplantation in articular cartilage injury. The results showed that the SVF plus PRP transplantation significantly improved the articular cartilage injury compared to control. In the treated group, mice exhibited a reduction of the time required that mice could move on the table by injured hind limb compared to control. In the control group, mice can move by injured legs after days, while in the treated group, mice could move by injured legs after days.

About histological analysis, in the treated group, an average area of the cartilage damage was 62.60%, and there was 35.5% of neocartilage formation after 45 days ( ). While in the control group, average area of cartilage lesions was 53.13%, but only 15.5% of neocartilage formation after 45 days (Figure 3).

Figure 3: HE staining of articular cartilage. Mature cartilage layer was recorded in normal mouse (a). Mature cartilage was thinned by needle (b). Injured cartilage was regenerated in negative control group (c, e) and treated group (d, f). However, the neocartilage in treated group was thicker than in negative control group.

The grade of cartilage injury between two experimental groups was different due to the effects of the dissimilar force from needle. After 45 days, results showed that 35.5% of neocartilage formed in treated group, while only 15.5% of neocartilage formed in the negative control group. This suggested that SVF and PRP gave benefit effects on the enhancement as well as trigger the neocartilage forming. More importantly, the articular cartilage in both of groups completed at the same level after 45 days with 12 cell layers. These results demonstrated that the SVF and PRP could participate in the process of self-renewal of joint cartilage at the joint microenvironment. Especially, there were no scar tissues or tumors forming at the graft sites. This result was similar to the previous publications about SVF plus PRP transplantation in the treatment of cartilage injury in dog [31–33], rabbits [34, 61], horses [14, 61], rat [35], mice [36], and goats [37]. For example, in joint injured mice model by collagenase, Ter Huurne et al. (2011) showed that the level of damage nearly 50% reduction in ADSC transplanted mice compared to control after 42 days [36]. Specifically, knee injury went down to 25% in treated mice compare to 88% in controls. They suggested that the transplanted ADSC protected and healed of injured cartilage [37]. The findings of Dragoo et al. (2007) showed that autologous ADSCs could reestablish the joint surface in rabbits, in which 100% of rabbits (12/12) had the occurrence of neocartilage, while only 8% rabbit (1/12) in the control had the appearance of neocartilage ( ) [62].

Roles of SVF or ADSCs in cartilage regeneration were recorded with many different effects. In fact, similar to MSCs derived from bone marrow, ADSC had anti-inflammatory properties [63, 64] and inhibition of graft versus host disease (GVHD) [65]. The transplantation of ADSC could successfully treat graft versus host disease with steroid-resistant form [66, 67]. All of these roles could add more effects to trigger rapid cartilage regeneration in this study.

Besides, in this study, ingredients from PRP also had important roles in stimulated grafted cells as well as endogenous cells growth and differentiation. There are at least six known growth factors such as platelet-derived growth factor (PDGF) that promotes blood vessel growth, cell division, and forming the skin; transforming growth factor-beta (TGF-b) that promotes cell division mitosis and bone metabolism; vascular endothelial growth factor (VEGF) that promotes the blood vessel formation; epidermal growth factor (EGF) that promotes cell growth and differentiation, angiogenesis, and collagen formation; fibroblast growth factor-2 (FGF-2) that promotes the growth of cell differentiation and angiogenesis; and insulin-like growth factor (IGF) that is a regulator in all cell types of the body [68, 69]. PRP injection also showed that improvements in knee injury and osteoarthritis score, including pain and symptom relief [70, 71].

Combining effect of SVF and PRP has a positive effect on the stimulation of proliferation, differentiation, and regeneration of cartilage in a mouse model. However, SVF also has a few limitations, notably the relatively low presence of ADSCs in the SVF. Therefore, SVF cultured to enrich ADSC before being transplanted may be essential, especially a little obtained fat cases.

Adipose tissue provides a rich source of MSCs. The SVF and PRP injection are a promising therapy in injured articular cartilage regeneration. This therapy significantly improved the injured articular cartilage. However, this study only assesses the ability of tumorigenicity and efficiency in mouse. Some side effects such as fever and muscle pain as well as the tumorigenicity in human being when using SVF and PRP could not be checked in this research.