Moderate tibia axial loading promotes discordant response of bone composition parameters and mechanical properties in a hindlimb unloading rat model.

OBJECTIVES: The purpose of the present study was to characterize the dynamic alterations of bone composition parameters and mechanical properties to disuse and mechanical intervention. METHODS: A tail suspension hindlimb unloading model and an in vivo axial tibia loading model in rats were used. A moderate mechanical loading that was capable of engendering 800 µÎµ tibia strain was applied to the right tibia of rats in both control and hindlimb unloading group across 28 days of the experimental period. The contralateral tibia served as control. RESULTS: Hindlimb unloading led to bone loss in tibia from day 14. Bone mineral density, mineral content and mechanical properties responded differently with microstructure to disuse in timing course. Mechanical loading of 800 µÎµ tibia strain failed to alter the bone of the control group, but minimized the detrimental effects of unloading by completely prohibiting the decrease of bone mineral content and main mechanical properties after 28 days. Less obvious influence of mechanical loading on bone microstructure was found. CONCLUSIONS: The moderate mechanical loading is not able to stimulate the mechanical response of healthy tibia, but indeed lead to discordant recovery of bone composition parameters and mechanical properties.

Potential role of miR-139-5p in cancer diagnosis, prognosis and therapy.

MicroRNAs (miRNAs) are short non-coding RNAs that regulate the expression of protein-coding genes by partially binding to specific target sites of mRNAs. miRNAs perform important functions in complicated cellular biological processes and their abnormal expression is involved in various disorders, including cancer. Among the miRNAs, differential expression of miR-139-5p serves a significant role in tumorigenesis, metastasis and recurrence, thus suggesting that it may potentially be used as a promising biomarker for cancer diagnosis, prognosis and therapy. miR-139-5p is expected to serve as a biomarker to eventually be implemented in a clinical setting. In the present review, we focus on the importance of miR-139-5p in cancer, summarize the association between miR-139-5p expression level and diagnosis and prognosis, and discuss the potential therapeutic implications for the future.

Response of Osteoblasts to the Stimulus of Fluid Flow.

Bone is an important porous tissue that supports the body, maintains calcium and phosphate homeostasis, protects vital organs, and houses bone marrow. The interaction between hydrostatic pressure and fluid phase, solid phase, cells, and vascular in bone makes bone inevitably bear baseline levels of fluid flow. Fluid flow plays an important role in regulating the proliferation, differentiation, distribution, and apoptosis of osteoblasts in bone. The effect of fluid flow on osteoblasts is dependent on time, velocity, and type. Some response of osteoblasts to fluid flow is closely related to the soluble factors secreted by the osteoblasts themselves or other types of bone cells. When the response is disordered, related bone diseases such as osteoporosis, osteoarthritis, and abnormal osteogenesis probably happen. In this article we review the current progress in the study of the response of osteoblasts to the direct and indirect stimulus of fluid flow and their roles in osteogenesis and related bone diseases.