Human Cartilage Oligomeric Matrix Protein, COMP ELISA Kit

Several studies have indicated that dietary silicon (Si) is beneficial for bone homeostasis and skeletal health. Furthermore, Si-containing bioactive glass biomaterials have positive effects on bone regeneration when used for repair of bone defects. Si has been demonstrated to stimulate osteoblast differentiation and bone mineralisation in vitro. However, the mechanisms underlying these effects of Si are not well understood. The aim of the present study was to investigate the effects of soluble Si on osteogenic differentiation and connexin 43 (CX43) gap junction communication in cultured pluripotent cells from human dental follicles (hDFC). Neutral Red uptake assay demonstrated that 25 mu g/ml of Si significantly stimulated hDFC cell proliferation. Dosages of Si above 100 mu g/ml decreased cell proliferation. Alizarin Red staining showed that osteogenic induction medium (OIM) by itself and in combination with Si (25 mu g/ml) significantly increased mineralisation in hDFC cultures, although Si alone had no such effect. The expression of osteoblast-related markers in hDFC was analysed with RT-qPCR. OSX, RUNX2, BMP2, ALP, OCN, BSP and CX43 genes were expressed in hDFC cultured for 1, 7, 14 and 21 days. Expression levels of BMP-2 and BSP were significantly upregulated by OIM and Si (25 mu g/ml) and were also induced by Si alone. Notably, the expression levels of OCN and CX43 on Day 21 were significantly increased only in the Si group. Flow cytometric measurements revealed that Si (50 mu g/ml) significantly increased CX43 protein expression and gap junction communication in hDFC. Next-generation sequencing (NGS) and bioinformatics processing were used for the identification of differentially regulated genes and pathways. The influence of OIM over the cell differentiation profile was more prominent than the influence of Si alone. However, Si in combination with OIM increased the magnitude of expression (up or down) of the differentially regulated genes. The gene for cartilage oligomeric matrix protein (COMP) was the most significantly upregulated. Genes for the regulator of G protein signalling 4 (RGS4), regulator of G protein signalling 2 (RGS2), and matrix metalloproteinases (MMPs) 1, 8, and 10 were also strongly upregulated. Our findings reveal that soluble Si stimulates Cx43 gap junction communication in hDFC and induces gene expression patterns associated with osteogenic differentiation. Taken together, the results support the conclusion that Si is beneficial for bone health.

Lewis Victor Heilbrunn has been called the pioneer of Ca2+ as an intracellular regulator (Campbell AK. Cell Calcium 7: 287-296, 1986; Campbell AK. Intracellular Calcium, 2015). In 1947, he was the first to provide convincing evidence that Ca2+ triggered muscle contraction (Heilbrunn LV, Wiercinski FJ. J Cell Comp Physiol 29: 15-32, 1947). Yet his work was met mostly with silence and neglect. One wonders why. Heilbrunn was a general physiologist who believed in the uniformity of nature with regard to movement. He believed that "... the theory of what makes cells divide should not be very different from the theory of what makes muscle contract..." (Heilbrunn LV. The Dynamics of Living Protoplasm, 1956). He did not believe that one could understand how the living machine worked by investigating its parts. He believed that, to understand life, one must study the dynamics of living protoplasm. The origin and evolution of Heilbrunn's thought process regarding the role of Ca2+ as a physiological activator will be traced back to the 1920s. The ways in which he tested the Ca2+ hypothesis in sea urchin eggs in the 1920s and 1930s will be explored. This work shaped Heilbrunn's thinking about the role of Ca2+ in muscle contraction. Importantly, why he and his results were ignored for years will be examined. It turned out that being right was not enough. Bad luck and a stubborn belief in an outmoded scientific philosophy contributed to the neglect.