title: Mesenchymal stem cells/multipotent stromal cells (MSCs) are glycolytic and thus glucose is a limiting factor of in vitro models of MSC starvation.
abstract: Mesenchymal stem/multipotent stromal cells (MSCs) contribute to tissue repair but are challenged during wound healing when the blood supply is disrupted, thereby limiting nutrient delivery. Survival mechanisms against 'starvation' include autophagy, which we previously found to enhance differentiation efficiency. MSC response to models of in vitro nutrient deprivation are of great interest for improving MSC survival and therapeutic efficacy; however, the rate-limiting nutrients are unknown.
  
  
  
  MSC responses to culture nutrient and/or serum deprivations were assessed through light microscopy, cell survival, and measurements of metabolic levels. Glucose uptake was determined through conditioned media analyses over 3 days of culture. The Seahorse XF24 Flux analysis system was used to determine oxygen consumption and extracellular acidification for glycolytic metabolism. MSC autophagic response to these conditions was assessed via immunoblots for LC3-I and LC3-II, markers of autophagosome turnover.
  
  
  
  We more closely examined limiting nutritional factors to MSC survival in vitro, finding that glucose is rapidly utilized/depleted whereas amino acids and other required nutrients were used sparingly. This finding concurred with metabolic analyses that showed a primarily glycolytic character to the MSCs at steady state. MSC autophagy, previously linked to MSC function through a unique accumulated autophagosome phenotype, also responded quickly to changes in glucose concentration, with drastic LC3-II changes within 24 h of glucose concentration shifts.
  
  
  
  Our results demonstrated a rapid uptake of glucose in MSC cultures that was due to a highly glycolytic phenotype for the cells; MSC starvation with serum or other nutrients appears to have a less notable effect on the cells. These findings highlight the importance of glucose and glucose metabolism on MSC function. The conditions and cellular responses outlined here may be essential in modeling MSC nutrient deprivation.
authors.affiliation: Department of Pathology, University of Pittsburgh School of Medicine, Scaife Hall, 3550 Terrace St, Pittsburgh, PA, 15261, USA.|McGowan Institute for Regenerative Medicine, University of Pittsburgh, 450 Technology Drive, Pittsburgh, PA, 15219, USA.
authors.forename: Austin
authors.initials: A
authors.lastname: Nuschke
authors.affiliation: Department of Pathology, University of Pittsburgh School of Medicine, Scaife Hall, 3550 Terrace St, Pittsburgh, PA, 15261, USA.|Present Address: Department of Plastic and Reconstructive Surgery, Stanford University, Palo Alto, CA, USA.
authors.forename: Melanie
authors.initials: M
authors.lastname: Rodrigues
authors.affiliation: Taylor Allderdice High School, 2409 Shady Ave, Pittsburgh, PA, 15217, USA.
authors.forename: Albin W
authors.initials: AW
authors.lastname: Wells
authors.affiliation: Department of Pathology, University of Pittsburgh School of Medicine, Scaife Hall, 3550 Terrace St, Pittsburgh, PA, 15261, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Sylakowski
authors.affiliation: Department of Pathology, University of Pittsburgh School of Medicine, Scaife Hall, 3550 Terrace St, Pittsburgh, PA, 15261, USA. wellsa@upmc.edu.|McGowan Institute for Regenerative Medicine, University of Pittsburgh, 450 Technology Drive, Pittsburgh, PA, 15219, USA. wellsa@upmc.edu.|VA Pittsburgh Health System, University Drive A, Pittsburgh, PA, 15261, USA. wellsa@upmc.edu.
authors.forename: Alan
authors.initials: A
authors.lastname: Wells
mesh_terms: D000071182:Autophagosomes / Q000187:drug effects / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects* / Q000235:genetics; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002461:Cell Line, Transformed; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D005786:Gene Expression Regulation; D005947:Glucose / Q000172:deficiency / Q000494:pharmacology*; D006019:Glycolysis / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D003470:Culture Media; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D005947:Glucose
keywords: Glucose metabolism; Mesenchymal stem cells; Multipotent stem cells; Nutrient starvation; Stem cell survival