title: Regulation of mesenchymal stem cell chondrogenesis by glucose through protein kinase C/transforming growth factor signaling.
abstract: OBJECTIVE
  Effective induction of human mesenchymal stem cell (hMSC) differentiation for regenerative medicine applications remains a great challenge. While much research has studied hMSC activity during differentiation, it is unclear whether pre-differentiation culture can modulate differentiation capacity. We investigate the effect of glucose concentration in pre-differentiation/expansion culture on modulating chondrogenic capacity of hMSCs, and explore the underlying molecular mechanism.
  
  
  METHODS
  The extent of chondrogenesis of hMSCs previously cultured with different concentrations of glucose was evaluated. Transforming growth factor-beta (TGF-β) signaling molecules and protein kinase C (PKC) were analyzed to identify the role of these molecules in the regulation of glucose on chondrogenesis. In addition, hMSCs in high-glucose expansion culture were treated with the PKC inhibitor to modulate the activity of PKC and TGF-β signaling molecules.
  
  
  RESULTS
  High-glucose maintained hMSCs were less chondrogenic than low-glucose maintained cells upon receiving differentiation signals. Interestingly, we found that high-glucose culture increased the phosphorylation of PKC and expression of type II TGF-β receptor (TGFβRII) in pre-differentiation hMSCs. However, low-glucose maintained hMSCs became more responsive to chondrogenic induction with increased PKC activation and TGFβRII expression than high-glucose maintained hMSCs during differentiation. Inhibiting the PKC activity of high-glucose maintained hMSCs during expansion culture upregulated the TGFβRII expression of chondrogenic cell pellets, and enhanced chondrogenesis.
  
  
  CONCLUSIONS
  Our findings demonstrate the effect of glucose concentration on regulating the chondrogenic capability of pre-differentiation hMSCs, and provide insight into the mechanism of how glucose concentration regulates PKC and TGF-β signaling molecules to prime pre-differentiation hMSCs for subsequent chondrogenesis.
authors.affiliation: Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI 53705, USA. tsai@ortho.wisc.edu
authors.forename: T-L
authors.initials: TL
authors.lastname: Tsai
authors.forename: P A
authors.initials: PA
authors.lastname: Manner
authors.forename: W-J
authors.initials: WJ
authors.lastname: Li
mesh_terms: D000328:Adult; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D020219:Chondrogenesis / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects; D008875:Middle Aged; D011493:Protein Kinase C / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
chemical_list: D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D000077294:Receptor, Transforming Growth Factor-beta Type II; D005947:Glucose