Vitamin D: Correlation with biochemical and body composition changes in a southern Brazilian population and induction of cytotoxicity in mesenchymal stem cells derived from human adipose tissue

Studies have shown that metabolic disorders, serum inflammatory markers and weight gain (obesity) are correlated with vitamin D deficiency. Therefore, the present study correlated the serum calcidiol (s25(OH)D3) levels in a sample of individuals from southern Brazil with variables related to metabolic disorders, obesity and lifestyle habits and assessed the cytotoxic effect of calcitriol on adipose tissue-derived mesenchymal stem cells (ADSCs). The results showed a 79.23% prevalence of hypovitaminosis D in the study population and a correlation (p < 0.05) between a low serum vitamin D concentration and an elevated low-density lipoprotein cholesterol (LDL-c) level. Univariate linear regression analysis using 25(OH)D3 as a regressor showed a negative association (p < 0.05) with an indoor work environment (β = −2.305), increased body fat (β = −0.095), age (β = −0.065) and high-density lipoprotein cholesterol (HDL-c; β = −0.109). An in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay performed with ADSCs using five calcitriol concentrations (15.625, 31.25, 62.5, 125 and 250 nM) indicated cytotoxic potential (p < 0.05) at the 62.5 nM concentration at 48 and 72 h and at the 125 and 250 nM concentrations at 24, 48 and 72 h. The results reported herein corroborate one another and suggest a key association between vitamin D deficiency and the development of obesity because ADSCs are involved in adipose tissue hyperplasia and differentiate into adipocytes that can sequester the bioavailable vitamin D necessary for homeostasis.