title: Multipotent mesenchymal stem cells from human placenta: critical parameters for isolation and maintenance of stemness after isolation.
abstract: OBJECTIVE
  This study was undertaken to isolate and characterize multipotent mesenchymal stem cells from term human placenta (placenta-derived mesenchymal stem cells, PD-MSCs).
  
  
  METHODS
  Sequential enzymatic digestion was used to isolate PD-MSCs in which trypsin removes the trophoblast layer, followed by collagenase treatment of remaining placental tissue. Karyotype, phenotype, growth kinetics, and differentiability of PD-MSC isolates from collagenase digests were analyzed.
  
  
  RESULTS
  PD-MSC isolation was successful in 14 of 17 cases. Karyotyping of PD-MSC isolates from deliveries with a male fetus revealed that these cells are of maternal origin. Flow cytometry and immunocytochemistry confirmed the mesenchymal stem cell phenotype. Proliferation rates of PD-MSCs remained constantly high up to passage 20. These cells could be differentiated toward mesodermal lineage in vitro up to passage 20. Nonconfluent culture was critical to maintain the MSC stemness during long-term culture.
  
  
  CONCLUSIONS
  Term placenta constitutes a rich, very reliable source of maternal mesenchymal stem cells that remain differentiable, even at high passage numbers.
authors.affiliation: Department of Obstetrics, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Semenov
authors.forename: Sonja
authors.initials: S
authors.lastname: Koestenbauer
authors.forename: Mariluce
authors.initials: M
authors.lastname: Riegel
authors.forename: Nikolas
authors.initials: N
authors.lastname: Zech
authors.forename: Roland
authors.initials: R
authors.lastname: Zimmermann
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Zisch
authors.forename: Antoine
authors.initials: A
authors.lastname: Malek
mesh_terms: D000071916:AC133 Antigen; D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D002454:Cell Differentiation; D002469:Cell Separation / Q000379:methods*; D005260:Female; D006023:Glycoproteins / Q000032:analysis; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D039902:Multipotent Stem Cells / Q000166:cytology*; D010455:Peptides / Q000032:analysis; D010920:Placenta / Q000166:cytology*; D011247:Pregnancy
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D006023:Glycoproteins; D010455:Peptides