# Metabolic priming alters the morphology and metabolism of human dermal fibroblasts

## TL;DR

Changing the glucose levels in culture media alters the shape and energy use of human skin cells, showing how metabolic conditions affect cell behavior.

## Contribution

This study demonstrates how metabolic priming induces structural and metabolic changes in fibroblasts through redox signaling.

## Key findings

- Cells in glucose-free medium showed increased metabolic activity and structural enlargement.
- Oxygen consumption nearly doubled in glucose-free conditions, indicating mitochondrial adaptation.
- NAC reduced metabolic changes, highlighting the role of oxidative stress in adaptation.

## Abstract

The metabolic environment provided by the culture medium plays a critical role in shaping cellular function and mitochondrial activity in vitro. In this study, we investigated the effects of metabolic priming on the metabolism and morphology of Normal Human Dermal Fibroblasts (NHDFs) by manipulating glucose availability in the culture medium. Our strategy involved transitioning NHDFs from traditional high-glucose medium (HGm) to either a medium with physiological glucose levels (LGm) or a glucose-free, galactose-containing medium (OXm). Prior to cellular characterization, we confirmed the absence of glucose in the culture media and fetal bovine serum using 1H nuclear magnetic resonance (NMR) spectroscopy. Given previous observations of elevated reactive species under glucose-free conditions, we explored the cellular adaptations associated with a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS). Cells cultured in OXm exhibited increased metabolic activity, elevated protein content, and substantial metabolic remodeling. Morphological analysis revealed enlargement of the cell body, cytoplasm, mitochondria, and nuclei, indicative of extensive structural adaptation. Notably, oxygen consumption rate (OCR) nearly doubled within 24 h of exposure to OXm, reflecting a rapid mitochondrial response to metabolic stress. The presence of the antioxidant N-acetyl cysteine (NAC) attenuated this increase, suggesting that redox signaling plays a key role in mitochondrial bioenergetic adaptation. These findings underscore the complex interplay between metabolic context, oxidative stress, and cellular morphology, and highlight the importance of appropriate normalization strategies in metabolic studies.

See also the graphical abstract(Fig. 1).