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Improved Trabecular Bone Structure of 20-Month-Old Male Spontaneously Hypertensive Rats

Authors

Tzu-Cheng Lee, Andrew J. Burghardt, Wei Yao, Nancy E. Lane, Sharmila Majumdar, Grant T. Gullberg, Youngho Seo

Abstract

A few clinical studies have reported that elderly male participants with hypertensive disease frequently have higher bone mineral density (BMD) than the normotensive participants at several skeletal sites. The detailed mechanism is still unknown; therefore, a study of bone structure and density using the hypertensive animal models could be informative. We used micro-computed tomography to quantitatively evaluate the tibial and 3rd lumbar vertebral bones in the 20-month-old male spontaneous hypertensive rat (SHR). The BMD, volume fraction, and the microarchitecture changes of the SHR were compared to those of same-age normotensive controls (Wistar-Kyoto rat, WKY). We found that in the very old (20 month) male rats, the trabecular bone fraction and microstructure were higher than those in the same-age normotensive controls. The observation of the association of hypertension with BMD and bone strength in hypertensive rats warrants further investigations of bone mass and strength in elderly males with hypertension.

Link To Article

http://dx.doi.org/10.1007/s00223-014-9893-0

Monosodium urate monohydrate crystals inhibit osteoblast viability and function: implications for development of bone erosion in gout

Authors

Ashika Chhana, Karen E Callon, Bregina Pool, Dorit Naot, Maureen Watson, Greg D Gamble, Fiona M McQueen, Jillian Cornish, Nicola Dalbeth

Abstract

Bone erosion is a common manifestation of chronic tophaceous gout. [This study sought] to investigate the effects of monosodium urate monohydrate (MSU) crystals on osteoblast viability and function. The MTT assay and flow cytometry were used to assess osteoblast cell viability in the MC3T3-E1 and ST2 osteoblast-like cell lines, and primary rat and primary human osteoblasts cultured with MSU crystals. Quantitative real-time PCR and von Kossa stained mineralised bone formation assays were used to assess the effects of MSU crystals on osteoblast differentiation using MC3T3-E1 cells. The numbers of osteoblasts and bone lining cells were quantified in bone samples from patients with gout. MSU crystals rapidly reduced viability in all cell types in a dose-dependent manner. The inhibitory effect on cell viability was independent of crystal phagocytosis and was not influenced by differing crystal length or addition of serum. Long-term culture of MC3T3-E1 cells with MSU crystals showed a reduction in mineralisation and decreased mRNA expression of genes related to osteoblast differentiation such as Runx2, Sp7 (osterix), Ibsp (bone sialoprotein), and Bglap (osteocalcin). Fewer osteoblast and lining cells were present on bone directly adjacent to gouty tophus than bone unaffected by tophus in patients with gout. MSU crystals have profound inhibitory effects on osteoblast viability and differentiation. These data suggest that bone erosion in gout occurs at the tophus–bone interface through alteration of physiological bone turnover, with both excessive osteoclast formation, and reduced osteoblast differentiation from mesenchymal stem cells.

Link to Article

http://dx.doi.org/10.1136/ard.2010.144774