title: The assessment of the in vivo to in vitro cellular transition of human umbilical cord multipotent stromal cells.
abstract: BACKGROUND
  Human umbilical cord stroma is a rich source of primitive multipotent stromal cells (hUC-MSCs). However, the methods for hUC-MSC isolation and propagation remain controversial and vary among laboratories. Our group previously demonstrated that two cell types emerge upon enzymatic isolation of hUC-MSCs, which subsequently undergo a transition towards a fibroblastoid phenotype in later passages. The aim of this study was to further analyse cultured hUC-MSCs by evaluating the cytoskeletal and cell adhesion proteins and by comparing the remodelling of those proteins in umbilical cord sections to determine the cell alterations due to enzymatic and explant methods.
  
  
  METHODS
  Tissue sections and cultured cells isolated by enzymatic or explant methods were analysed morphologically and by labelling cytokeratin, vimentin, alpha-smooth muscle actin, E-cadherin and N-cadherin profiles.
  
  
  RESULTS
  The present observations confirmed that wide, flat cells (type-1) share myofibroblastic features, appear exclusively in enzymatically isolated early cultures; gradually diminish or are replaced by fibroblastoid cells (type-2) in later passages. In contrast, the explant method does not result in the existence of type-1 cells in vitro. Among the tested CK subtypes, CK18 expression is upregulated, whereas CK19 expression is downregulated upon culturing after both protocols. Vimentin and α-SMA, as the major intermediate filaments of hUC-MSCs were found unaltered throughout the culturing period regardless of the cell isolation technique used.
  
  
  CONCLUSIONS
  The data presented confirm and further elucidate the previously observed phenotypic change in hUC-MSCs as illustrated by alterations in structural proteins during enzymatic isolation and subsequent culturing of cells compared with in situ equivalents.
authors.affiliation: Ankara University Biotechnology Institute, Tandogan, Besevler, 06110 Ankara, Turkey.
authors.forename: H
authors.initials: H
authors.lastname: Coskun
authors.affiliation: Ankara University School of Medicine, Department of Histology and Embryology, Laboratory for Stem Cells and Reproductive Medicine, Sihhiye, Ankara 06100, Turkey. Electronic address: alpcan@medicine.ankara.edu.tr.
authors.forename: A
authors.initials: A
authors.lastname: Can
mesh_terms: D015820:Cadherins / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D039902:Multipotent Stem Cells / Q000166:cytology / Q000502:physiology*; D010641:Phenotype; D011247:Pregnancy; D014470:Umbilical Cord / Q000166:cytology*
chemical_list: D015820:Cadherins
keywords: Alpha-smooth muscle actin; Cadherin; Cytokeratin; Mesenchymal stem cell; Umbilical cord; Vimentin