Vitamin D Alleviates Cadmium-Induced Inhibition of Chicken Bone Marrow Stromal Cells’ Osteogenic Differentiation In Vitro

SIMPLE SUMMARY: The most physiologically active form of vitamin D is lα, 25-dehydroxyvitamin D(3) (lα, 25-[OH](2)D(3)), which participates in the bone metabolic homeostasis of animals. In addition to the bone matrix, bone also includes bone-related cells, such as bone marrow stromal cells (BMSCs), osteoblasts, osteoclasts, etc. BMSCs can differentiate into osteoblasts, which are regulated by the Runt-related transcription factor 2 (Runx2) and other factors. Furthermore, type Ⅰ collagen (Col1) is synthesized by osteoblasts and combines with hydroxyapatite to form normal bone matrix. lα, 25-(OH)(2)D(3) promotes the secretion of Col1 in animals and stimulates bone mineralization. In addition, environmental heavy metal has accumulated toxicity in the different organs and tissues of animals, including in bone. Cadmium (Cd) is an element of heavy metals in nature that has osteotoxicity, including the destruction of the bone matrix and damage of bone-related cells (such as BMSCs and osteoblasts), and even inducing the apoptosis of bone-related cells. In this study, despite Cd having a certain toxicity on BMSCs and osteogenic differentiation from chicken embryos, our assessment of Cd osteotoxicity via lα, 25-(OH)(2)D(3) suggested this mitigating effect was, indeed, improved. These signs indicate that lα, 25-(OH)(2)D(3) can alleviate Cd-induced osteogenic toxicity in White Leghorn chickens in vitro. ABSTRACT: Vitamin D is a lipid soluble vitamin that is mostly used to treat bone metabolism-related diseases. In this study, the effect of Cd toxicity in vitro on osteogenic differentiation derived from BMSCs and the alleviating effect of lα, 25-(OH)(2)D(3) were investigated. Cell index in real time was monitored using a Real-time cell analyzer (RTCA) system. The activity of alkaline phosphatase (ALP), and the calcified nodules and the distribution of Runx2 protein were detected using ALP staining, alizarin red staining, and immunofluorescence, respectively. Furthermore, the mitochondrial membrane potential and the apoptotic rate of BMSCs, the mRNA levels of RUNX2 and type Ⅰ collagen alpha2 (COL1A2) genes, and the protein expression of Col1 and Runx2 were detected using flow cytometry, qRT-PCR and western blot, respectively. The proliferation of BMSCs and osteogenic differentiation were enhanced after treatment with different concentrations of lα, 25-(OH)(2)D(3) compared with the control group. However, 5 μmol/L Cd inhibited the proliferation of BMSCs. In addition, 10 nmol/L lα,25-(OH)(2)D(3) attenuated the toxicity and the apoptosis of BMSCs treated by Cd, and also promoted the osteogenic differentiation including the activity of ALP, and the protein expression of Col1 and Runx2. lα, 25-(OH)(2)D(3) can alleviate cadmium-induced osteogenic toxicity in White Leghorn chickens in vitro.