Paracrine effect of the stromal vascular fraction containing M2 macrophages on human chondrocytes through the Smad2/3 signaling pathway

Abstract

The adipose-derived stromal vascular fraction (SVF) is composed of a heterogeneous mix of adipose-derived stem cells (ADSCs), macrophages, pericytes, fibroblasts, blood, and other cells. Previous studies have found that the paracrine effects of SVF cells may be therapeutic, but their role in osteoarthritis treatment remains unclear.This study aimed to investigate the therapeutic effect of SVF cells on chondrocytes.Chondrocytes were seeded on culture plates alone (control) or cocultured with SVF or ADSCs on cell culture inserts. After 48 h of coculture, chondrocyte collagen II, tissue inhibitors of metalloproteinases-3 (TIMP-3), and matrix metalloproteinases-13 (MMP-13) messenger RNA (mRNA) expression levels were evaluated using reversetranscription polymerase chain reaction, and the transforming growth factor-β (TGF-β) levels in the supernatant were measured using ELISA. Immunohistochemical staining and flow cytometry were used to evaluate the macrophages in the SVF.These macrophages were characterized according to phenotype using the F4/80, CD86, and CD163 markers. To determine whether the Smad2/3 signaling pathways were involved, the chondrocytes were pre-treated with a Smad2/3 phosphorylation inhibitor and stimulated with the SVF, and then Smad2/3 phosphorylation levels were analyzed using western blot. The mRNA expression levels of various paracrine factors and chondrocyte pellet size were also assessed. Collagen II and TIMP-3 expression were higher in the SVF group than in the ADSC group and controls, while MMP-13 expression was the highest in the ADSC group and the lowest in the controls. TGF-β levels in the SVF group were also elevated. Immunohistochemical staining and flow cytometry revealed that the macrophages in the SVF were of the anti-inflammatory phenotype. Western blot analysis showed that the SVF increased Smad2/3 phosphorylation, while Smad2/3 inhibitors decreased phosphorylation. Smad2/3 inhibitors also reduced the expression of various other paracrine factors and decreased chondrocyte pellet size. These findings suggested that the paracrine

Human uncultured adipose-derived stromal vascular fraction shows therapeutic potential against osteoarthritis in immunodeficient rats by enhancing anabolism-promoting and catabolism-inhibiting effects via direct effects of transplanted M2 macrophages

“…M2Φ secrete TGF-β and IL-10, induce collagen II expression in chondrocytes, and decrease MMP-13 expression [50]. Previous studies have reported that co-culture of the SVF or ADSCs with isolated pellets produces notably larger pellets in the SVF group than in the ADSC group [30,32]. Our results support these ndings: moreover, the M2Φ group showed a larger pellet size than the ADSC group.…”

“…The rats were divided into three groups and received injections of the SVF containing 1 × 10 5 cells (SVF group), 1 × 10 4 ADSCs (ADSC group), or 100 µL of PBS (control group). Based on previous reports [32], in this study, the SVF/ADSC ratio was set at 10%, and the SVF and ADSC groups included equivalent amounts of ADSCs to determine the therapeutic potential of the heterogeneous cells in SVF.…”

Clinical use of autologous adipose-derived stromal vascular fraction cell injections for hip osteoarthritis

“…Another study showed that SVF was superior to platelet-rich plasma for reducing pain associated with knee OA from 1 month to 1 year postoperatively [ 29 ]. This may be because SVF cells promote inhibitory macrophages and T-regulatory cells, which have stronger pain-relieving effects because of reduced inflammatory markers [ 30 , 31 ]. Experiments involving animal models have confirmed the anti-inflammatory effects of SVF on knee OA [ 32 , 33 ].…”

Therapeutic effects of the stromal vascular fraction and adipose-derived stem cells on osteoarthritis in an experimental rabbit model

“…M2 macrophages secrete TGF-β and IL-10, induce collagen II expression in chondrocytes, and decrease MMP-13 expression [53]. Additionally, TGF-β has been recently reported to contribute to chondrocyte regeneration partially through the Smad2/3 signaling pathway [54]. Macrophages that have acquired the M2 phenotype upregulate the expression of anti-in ammatory cytokines, including IL-10 and TGF-β, when co-cultured with MSCs and ADSCs [55].…”