title: High ambient glucose is effect neutral on cell death and proliferation in human proximal tubular epithelial cells.
abstract: In vitro models of diabetic nephropathy that assess the role of hyperglycemia on proximal tubular cell turnover commonly compare cells in a high-glucose medium (25 or 30 mM) with a low-glucose medium (5 to 6.1 mM). Any cellular growth changes observed are usually attributed to the effect of high glucose. We hypothesize that in such experiments, glucose concentrations in the low-glucose medium may decline during the course of the experiments to levels that inhibit cell growth leading to the comparative conclusion that high glucose induces hyperplasia and/or hypertrophy. In this study, primary cultures of human proximal tubular epithelial cells (PTEC) and immortalized HK-2 cells were exposed to low (5 mM) or high (17, 30, or 47 mM) glucose for up to 6 days (PTEC) and 48 h (HK-2). When culture media were not replenished, low glucose induced a significant increase in necrosis and release of lactate dehydrogenase and a decrease in proliferation, metabolic activity, and protein content without any changes in apoptosis. High-glucose media failed to induce any of these changes. Glucose was undetectable in the low-glucose culture medium after 72 h. No significant differences were observed between any of the treatment groups when culture media were replenished daily. We conclude that regular replenishment of culture media is necessary to prevent the emergence of artifactual and misleading differences between high- and low-glucose groups. The current knowledge of the pathophysiology of high glucose based on cell culture systems may need to be reevaluated.
authors.affiliation: Conjoint Renal Laboratory, Queensland Health Pathology Service, Royal Brisbane, Australia.
authors.forename: Christudas
authors.initials: C
authors.lastname: Morais
authors.forename: Justin
authors.initials: J
authors.lastname: Westhuyzen
authors.forename: Betty
authors.initials: B
authors.lastname: Pat
authors.forename: Glenda
authors.initials: G
authors.lastname: Gobe
authors.forename: Helen
authors.initials: H
authors.lastname: Healy
mesh_terms: D000963:Antimetabolites / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001973:Bromodeoxyuridine / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D002469:Cell Separation; D003470:Culture Media; D004847:Epithelial Cells / Q000187:drug effects*; D005434:Flow Cytometry; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D020287:In Situ Nick-End Labeling; D007687:Kidney Tubules, Proximal / Q000166:cytology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009336:Necrosis; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D000963:Antimetabolites; D003470:Culture Media; D013778:Tetrazolium Salts; D013844:Thiazoles; D007770:L-Lactate Dehydrogenase; C022616:thiazolyl blue; D001973:Bromodeoxyuridine; D005947:Glucose