Bone Abstracts

see PP494....

The in vitro culture of calvarial osteoblasts from neonatal rodents remains an important method for studying the regulation of osteoblast function. Widespread use of transgenics has created a particular need for a reliable, simple method that allows the differentiation and bone-forming activity of mouse osteoblasts to be studied directly. We have established such a method and have identified key differences in optimal culture conditions between mouse and rat osteoblas...

The process of vascular calcification shares many similarities with that of skeletal mineralisation, and involves the deposition of hydroxyapatite crystals in arteries and cardiac muscle. However, the cellular mechanisms responsible have yet to be fully elucidated. BMP-9 has been shown to exert direct effects on both bone development and vascular function. In the present study, we have investigated the role of BMP-9 in vascular smooth muscle cell (VSMC) calcification. Murine V...

The process of vascular calcification shares many similarities with that of skeletal mineralisation, and involves the phenotypic trans-differentiation of vascular smooth muscle cells (VSMCs) to osteoblastic and chondrocytic cells within a calcified environment. Various microRNAs (miRs) are known to regulate cell differentiation, however their role in mediating VSMC calcification has yet to be fully understood.Murine VSMCs were cultured for up to 28 days ...

Ecto-nucleotide pyrophosphatase/phosphodiesterases (NPPs) hydrolyse nucleotide triphosphates to the corresponding nucleotide monophosphate and the mineralisation inhibitor, pyrophosphate (PPi). This investigation examined the role of NPP1 in bone and soft tissue mineralisation using a mouse model lacking NPP1(Enpp1−/−). At physiological pH 7.35, cultured Enpp1−/...

Increasing interest is focusing on the role of the FGF-23/Klotho axis in mediating vascular calcification. However, the underpinning mechanisms have yet to be fully elucidated. Murine VSMCs were cultured in calcifying medium for a 21-day period. FGF-23 mRNA expression was significantly up-regulated by 7 days (1.63-fold; P<0.001), with a concomitant increase in protein expression. mRNA and protein expression of both FGFR1 and Klotho were confirmed. Increased FGF-23...

Extracellular nucleotides stimulate both the formation and resorptive activity of osteoclasts. Ecto-nucleotide pyrophosphatase/phosphodiesterases (NPPs) hydrolyse extracellular nucleotide triphosphates to their corresponding monophosphate and pyrophosphate (PPi). We investigated if osteoclasts express functional NPPs and whether Enpp1 gene deletion influenced osteoclast formation and activity. Osteoclasts were formed from the bone marrow of 8 and 15 week old knockou...

Vascular calcification (VC) involves hydroxyapatite deposition in the arteries and cardiac muscle. VC is thought to share some outward similarities to skeletal mineralisation and has been associated with the transdifferentiation of vascular smooth muscle cells (VSMCs) to an osteoblast-like phenotype. We have previously shown that ATP, UTP and synthetic ATP-analogues (α, β-meATP, β, γ-meATP, Bz-ATP) (≥1 μM) act to potently inhibit both bone minera...

Bone has recently emerged as a novel endocrine organ regulating glucose metabolism. Ectonucleotide pyrophosphatase/phosphodiesterase-1 (NPP1) controls bone mineralisation by generating the mineralisation inhibitor pyrophosphate. In clinical studies increased activity of NPP1 has been found in patients with insulin resistance, and it has been shown to directly inhibit the insulin receptor. We hypothesised that mice lacking NPP1 (Enpp1−/−) would exhibit im...

Genetic approaches to bone physiology utilising judicious gain and loss of function models have identified bone as an endocrine organ, being involved in the regulation of energy metabolism and reproduction. Recent advances expand our understanding and identify a new and unconventional role of bone beyond its classical functions. PHOSPHO1 is a bone specific phosphatase with a recognised role in bone mineralisation, but our present studies have now identified a novel role for PH...