Table 1.

Cell types with mesenchymal phenotypes detected in the kidneya

Cell TypeMarkersSpecific CharacteristicsReferences
Resident FibroblastsFSP1, HSP47, 5′ectonucleotidase, CD44, ICAM, DDR2Phenotypic variability between cortical and medullary fibroblasts41, 44, 63
Pericytesα-SMA, NG2, PDGFR-2, DesminAssociated capillaries and venoles64, 65
Vascular smooth muscle cellsα-SMA, caldesmon, calponinAssociated arteries, arterioles, veins64
EMT-derived fibroblastsFSP1 (residual epithelial markers?)Exclusively found in fibrotic kidneys41, 44
Mesenchymal stem cellsFSP1?44
  • a At least 6 distinct cell types with mesenchymal phenotypes can be detected in the kidney. Due to the lack of specific markers, identification of the different lineages can be challenging. In the normal kidney, myofibroblasts can be distinguished from vascular smooth muscle cells and pericytes based on topographical criteria. Without genetic markers, indisputable identification of EMT-derived cells and mesenchymal stem cells is not feasible as of yet. HSP47, heat shock protein 47; ICAM, intracellular adhesion molecule; DDR2, discoidin domain receptor; α-SMA, α-smooth muscle actin; NG2, neuron glial antigen 2; PDGFR, PDGF receptor; EMT, epithelial–mesenchymal transition.