189 The Effect of Vitamin K on the Differentiation of Adipose-Derived Stem Cells into Osteoblasts

Abstract

Tissue engineering offers a viable alternative to bone grafts in repairing large bone defects. This involves using scaffolds of various sizes and shapes that contain stem cells and other osteoinductive molecules. The aim of this project was to evaluate the effects of vitamin K in osteogenic medium and its effect on the differentiation of adipose-derived stem cells (ASC) into osteoblasts. Vitamin K has been shown to increase bone mineral density by acting as a coenzyme in the γ-carboxylation of osteocalcin, a protein involved in bone mineralization (Weber 2001 Nutrition 11–12, 1024). Our hypothesis was that the presence of vitamin K in the osteogenic medium would positively influence the number of osteoblastic nodules formed. Swine ASC were isolated as described (Monaco et al. 2009 Open Tissue Eng. Regen. Med. J. 2, 20–33). The ASC were divided into 7 different treatments: 5 concentrations of vitamin K in the osteogenic medium (10, 50 100, 500, 1000 nM) plus 2 control treatments (osteogenic medium without vitamin K and a negative control, DMEM). The media was changed twice a week for 4 weeks. The experiment was replicated 6 times. At the end of the culture period, cells were stained with Alizarin Red S and Von Kossa. In each well, we counted the nodules and then divided them in 2 categories: formed and forming nodules. Data were analysed by analysis of variance using the generalized linear model (GLM) procedure of SPSS (IBM/SPSS, Armonk, NY, USA); the least significant difference (l.s.d.) post hoc test was used to perform statistical multiple comparison, and the α-level was set at 0.05. The results showed (in Table 1) that there was no positive effect on nodule formation when vitamin K was added to the medium; however, when 1000 nM vitamin K was added, nodule formation decreased. More experiments need to be conducted to determine if vitamin K can act synergistically with other vitamins to produce a significant role in ASC differentiation into osteoblasts. This preliminary experiment is the first step towards the analysis of the behaviour of ASC on scaffolds with vitamin K incorporated into their matrix. Table 1.The average number of formed and forming osteoblast nodules compared between treatment groups (SD in parentheses)