Single-Cell Analysis of ADSC Interactions with Fibroblasts and Endothelial Cells in Scleroderma Skin

Abstract

Adipose-derived stem cells (ADSCs) as part of autologous fat grafting have anti-fibrotic and anti-inflammatory effects, but the exact mechanisms of action remain unknown. By simulating the interaction of ADSCs with fibroblasts and endothelial cells (EC) from scleroderma (SSc) skin in silico, we aim to unravel these mechanisms. Publicly available single-cell RNA sequencing data from the stromal vascular fraction of 3 lean patients and biopsies from the skin of 10 control and 12 patients with SSc were obtained from the GEO and analysed using R and Seurat. Differentially expressed genes were used to compare the fibroblast and EC transcriptome between controls and SSc. GO and KEGG functional enrichment was performed. Ligand–receptor interactions of ADSCs with fibroblasts and ECs were explored with LIANA. Pro-inflammatory and extracellular matrix (ECM) interacting fibroblasts were identified in SSc. Arterial, capillary, venous and lymphatic ECs showed a pro-fibrotic and pro-inflammatory transcriptome. Most interactions with both cell types were based on ECM proteins. Differential interactions identified included NTN1, VEGFD, MMP2, FGF2, and FNDC5. The ADSC secretome may disrupt vascular and perivascular inflammation hubs in scleroderma by promoting angiogenesis and especially lymphangiogenesis. Key phenomena observed after fat grafting remain unexplained, including modulation of fibroblast behaviour.

Lymphatic Endothelial-to-Myofibroblast Transition: A Potential New Mechanism Underlying Skin Fibrosis in Systemic Sclerosis

“…Together with such morphofunctional changes, HdLy-MVECs challenged with SSc serum also exhibited a reduction in the expression of the lymphatic markers Prox1 and LYVE-1 accompanied by a robust increase in the myofibroblast markers S100A4, α-SMA, COL1A1, and nuclear Snail1. In agreement with our data, lymphatic ECs were found to exhibit a profibrotic transcriptome profile featuring a significant upregulation of the myofibroblast marker S100A4 in a very recent single-cell analysis of SSc skin biopsies [35].…”

Exploring Anti-Fibrotic Effects of Adipose-Derived Stem Cells: Transcriptome Analysis upon Fibrotic, Inflammatory, and Hypoxic Conditioning

“…FGF2 and HGF are believed to act together in an anti-fibrotic pathway [48]. While HGF is implicated in various anti-fibrotic effects of ADSCs [16], our recent research indicates a lack of high HGF expression by any cell type in the SVF [23]. In this study, HGF was significantly downregulated in both TGF-β1 and IL1-β.…”

“…However, their paracrine signalling or secretome is considered the most dominant mechanism by which they counteract inflammation, promote wound healing, and possibly reverse fibrosis. ADSCs interact with a variety of cell types including immune cells, endothelial cells, and fibroblasts-all key drivers of fibrosis [16][17][18]22,23]. They are believed to exert their anti-fibrotic effects by the secretion of growth factors including basic fibroblast growth factor (FGF2), platelet derived growth factor (PDGF) and hepatocyte growth factor (HGF) immunomodulatory molecules (IDO, PGE2, IL10, CSF2), proangiogenic factors including vascular endothelial growth factor (VEGF), matrix remodelling enzymes, e.g., matrix metalloproteinases (MMPs), pro-apoptotic factors, and extracellular mi-crovesicles [16][17][18]22,24].…”