Nomenclature clarification: synovial fibroblasts and synovial mesenchymal stem cells

Abstract

Synovial-derived cells, found in the synovial membrane of human joints, were obtained by digestion of the synovial membrane and were subsequently expanded in vitro. The identity of synovial-derived cells has long been a topic of debate. The terms “type B synoviocytes,” “fibroblast-like synoviocytes (FLS),” “synovium-derived mesenchymal stem cells (MSCs),” and “synovial fibroblasts (SF)” appeared in different articles related to human synovial-derived cells in various disease models, yet they seemed to be describing the same cell type. However, to date, there is no clear standard to distinguish these terms; thus, the hypothesis that they represent the same cell type is currently inconclusive. Therefore, this review aims to clarify the similarities and differences between these terms and to diffuse the chaotic nomenclature of synovial-derived cells.

Identification of putative master regulators in rheumatoid arthritis synovial fibroblasts using gene expression data and network inference

“…In RA, inflammation and cellular infiltration cause hyperplasia of the synovial tissue leading to the pannus formation. The pannus is a tissue composed of MLS, FLS, leucocytes, plasma cells and mastocytes that mediates cartilage damage and bone erosion [7][8][9][10] .…”

The human arthritic hip joint is a source of mesenchymal stromal cells (MSCs) with extensive multipotent differentiation potential

“…While MSC-like cells have also previously been obtained from the joint capsule of the human hip, interestingly, the tissue utilized for the isolation of cells was exclusively derived from the synovial stratum [33]. Within the synovial stratum MSC-like cells are believed to reside within the intimal layer of the synovial membrane [34]. In addition, there is no data exclusively describing the characterization of MSC-like cells isolated from the LCF.…”

Infrapatellar Fat Pad/Synovium Complex in Early-Stage Knee Osteoarthritis: Potential New Target and Source of Therapeutic Mesenchymal Stem/Stromal Cells

“…Located within the synovial intima and sub-intima lie distinct MSC populations similar to IFP-MSC, with an origin still debated (Li et al, 2019;Sivasubramaniyan et al, 2019). Though not populous within the tissue, these cells maintain high proliferative capacity and can differentiate into osteoblasts, adipocytes, and chondrocytes in vitro (Ferro et al, 2019).…”