Morphological and immunocytochemical characterization of cultured fibroblast-like cells derived from adult human synovial membrane

Arch Histol Cytol. 2003 May;66(2):145-53. doi: 10.1679/aohc.66.145.


The synovial membrane (SM) is a source of multipotent mesenchymal stem cells (MSCs), which appeared microscopically to be a relatively homogeneous population of fibroblast-like cells (FCs) in culture (De Bari et al., 2001). The aim of this study was to investigate phenotypic characteristics of the SM-derived FCs (SD-FCs) that could elucidate their origin inside the synovial tissue. Morphological characterization of SD-FCs was assessed by electron microscopy and by expression of surfactant protein A (SPA). This study, yielded substantial evidence that SD-FCs show ultrastructural and immunocytochemical features of type B synoviocytes; they contained characteristic lamellar bodies (LBs) that are secreted by exocytosis. LB secretion ability was maintained upon passaging (P3-P10). Immunocytochemistry showed that SD-FCs express surfactant protein A (SP-A). Taken together, these results indicate that multipotent SD-MSCs may originate from the synovial lining, having a phenotype highly similar to that of type B synoviocytes. We believe our data highlight the potent ability of type B synoviocytes to have a multilineage differentiation potential.

MeSH terms

  • Adipocytes / chemistry
  • Adipocytes / cytology
  • Adipocytes / metabolism
  • Cell Differentiation
  • Cell Lineage
  • Cells, Cultured
  • Chondrocytes / chemistry
  • Chondrocytes / cytology
  • Chondrocytes / metabolism
  • Exocytosis
  • Fibroblasts / cytology*
  • Fibroblasts / metabolism
  • Fibroblasts / ultrastructure
  • Humans
  • Immunohistochemistry
  • Mesoderm / cytology
  • Oligodendroglia / chemistry
  • Oligodendroglia / cytology
  • Oligodendroglia / metabolism
  • Pseudopodia / ultrastructure
  • Pulmonary Surfactant-Associated Protein A / metabolism
  • Stem Cells / cytology
  • Stem Cells / physiology
  • Synovial Membrane / cytology*


  • Pulmonary Surfactant-Associated Protein A