title: Proliferation of dental follicle-derived cell populations in heat-stress conditions.
abstract: OBJECTIVE
  Isolation and purification of adult stem cells (ASC) are a great challenge. Our objectives were to determine whether ASC are more heat-tolerant than non-stem cells, and to explore if ASC could be enriched by heat-stress treatments.
  
  
  METHODS
  Rat dental follicle cells were cultured in a variety of media to obtain either a heterogeneous cell population (H-DFC) consisting of stem cells and non-stem cells, or a homogenous cell population (DFC) containing non-stem cells only. Real-time RT-PCR was conducted to compare expression of heat-shock proteins (HSPs) between the two populations. To study heat tolerance, H-DFC and DFC were incubated under heat-stress conditions and cell proliferation was evaluated by alamar blue reduction assay. Furthermore, cells resulting from heat-stress treatments were evaluated for differentiation capability and expression of stem cell markers.
  
  
  RESULTS
  H-DFC expressed higher levels of HSP110, HSP70s and HSP27s than did DFC. H-DFC increased levels of proliferation at 40 °C compared to controls grown at 37 °C; no significant reduction in proliferation occurred at temperatures below 40.5 °C. In contrast, DFC showed significant reduction in proliferation under all heat-stress treatments. Heat-stressed H-DFC had increased differentiation capability and increased expression of stem cell markers.
  
  
  CONCLUSIONS
  Stem cells appear to be more tolerant to heat stress than non-stem cells. Incubation of a heterogeneous cell population in heat-stress conditions resulted in increased stem cell numbers.
authors.affiliation: Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA. shaomia@lsu.edu
authors.forename: S
authors.initials: S
authors.lastname: Yao
authors.forename: D L
authors.initials: DL
authors.lastname: Gutierrez
authors.forename: H
authors.initials: H
authors.lastname: He
authors.forename: Y
authors.initials: Y
authors.lastname: Dai
authors.forename: D
authors.initials: D
authors.lastname: Liu
authors.forename: G E
authors.initials: GE
authors.lastname: Wise
mesh_terms: D053687:Adult Stem Cells / Q000166:cytology* / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D049109:Cell Proliferation; D017931:DNA Primers / Q000235:genetics; D003795:Dental Sac / Q000166:cytology* / Q000378:metabolism; D015870:Gene Expression; D005819:Genetic Markers; D050957:HSP110 Heat-Shock Proteins / Q000235:genetics; D055551:HSP27 Heat-Shock Proteins / Q000235:genetics; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D018869:Heat-Shock Response; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D005819:Genetic Markers; D050957:HSP110 Heat-Shock Proteins; D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; C494655:Hspa4 protein, rat; C486114:Hspb1 protein, rat