title: Effects of hypoxia on differentiation from human placenta-derived mesenchymal stem cells to nucleus pulposus-like cells.
abstract: BACKGROUND
  Low back pain is a frequently occurring disease caused by intervertebral disc degeneration. Mesenchymal stem cells (MSCs) are a possible treatment modality. Studies have shown MSCs can be transformed into nucleus pulposus-like cells under normoxic conditions. However, this is not a true representation of the hypoxic environment nucleus pulposus cells experience during in vivo growth and differentiation.
  
  
  OBJECTIVE
  To determine the effects of a hypoxic environment on the differentiation of human placenta-derived mesenchymal stem cells (PMSCs) to nucleus pulposus-like cells.
  
  
  METHODS
  An experimental study.
  
  
  METHODS
  Placenta-derived mesenchymal stem cells were cultured and the mesenchymal lineage was confirmed by flow cytometry. Two groups of PMSCs were then cultured under different oxygen concentrations creating a hypoxic group and normoxic group. The proliferation of cells in each group was compared by cell counting kit-8 on Day 1, 3, 5, and 7. Real-time polymerase chain reaction on Days 3 and 7 compared the expressions of Sox-9, Type II collagen, aggrecan, and hypoxia inducible factor-1α (HIF-1α) between the two groups. Immunofluorescence was used to compare the expression of Type II collagen between the two groups after 14 days.
  
  
  RESULTS
  Placenta-derived mesenchymal stem cells were successfully isolated and cultured. Mesenchymal markers were positive. On Days 3 and 5, the hypoxic group had a significantly higher proliferation rate than the normoxic group (p<.05). The expression of Sox-9 and HIF-1α was significantly higher (p<.05) in the hypoxic group at Days 3 and 7. Type II collagen and aggrecan expressions were significantly higher (p<.05) in the hypoxic group at Day 7. The hypoxic group stained more positive for Type II collagen at Day 14.
  
  
  CONCLUSIONS
  Hypoxic conditions lead to an increased differentiation and proliferation of nucleus pulposus-like cells. Placenta-derived mesenchymal stem cells cultured in nucleus pulposus inducing media and a hypoxic environment show enhanced expression of the nucleus pulposus-like cell markers, Sox-9, Type II collagen, aggrecan, and HIF-1α.
authors.affiliation: The First Affiliated Hospital of Suzhou University, 188 Shizi St., Suzhou, 215006, China.
authors.forename: Li
authors.initials: L
authors.lastname: Ni
authors.affiliation: University of Toledo Medical Center, 3000 Arlington Ave., Toledo, OH 43614, USA.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Liu
authors.affiliation: University of Toledo Medical Center, 3000 Arlington Ave., Toledo, OH 43614, USA.
authors.forename: Kyle R
authors.initials: KR
authors.lastname: Sochacki
authors.affiliation: University of Toledo Medical Center, 3000 Arlington Ave., Toledo, OH 43614, USA.
authors.forename: Miranda
authors.initials: M
authors.lastname: Ebraheim
authors.affiliation: University of Toledo Medical Center, 3000 Arlington Ave., Toledo, OH 43614, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Fahrenkopf
authors.affiliation: The First Affiliated Hospital of Suzhou University, 188 Shizi St., Suzhou, 215006, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Shi
authors.affiliation: The First Affiliated Hospital of Suzhou University, 188 Shizi St., Suzhou, 215006, China; University of Toledo Medical Center, 3000 Arlington Ave., Toledo, OH 43614, USA.
authors.forename: Jiayong
authors.initials: J
authors.lastname: Liu
authors.affiliation: The First Affiliated Hospital of Suzhou University, 188 Shizi St., Suzhou, 215006, China. Electronic address: suzhouspine@163.com.
authors.forename: Huilin
authors.initials: H
authors.lastname: Yang
mesh_terms: D053674:Aggrecans / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D024043:Collagen Type II / Q000378:metabolism; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007403:Intervertebral Disc / Q000166:cytology* / Q000378:metabolism; D055959:Intervertebral Disc Degeneration / Q000628:therapy; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D010920:Placenta / Q000166:cytology* / Q000378:metabolism; D011247:Pregnancy
chemical_list: D053674:Aggrecans; D024043:Collagen Type II; D051795:Hypoxia-Inducible Factor 1, alpha Subunit
keywords: HIF-1α; Hypoxia; Intervertebral disc degeneration; Nucleus pulposus cells; Placenta-derived mesenchymal stem cells; Sox-9; Transforming growth factor-β1; Type II collagen