Defining the Most Potent Osteoinductive Culture Conditions for MC3T3-E1 Cells Reveals No Implication of Oxidative Stress or Energy Metabolism.

The MC3T3-E1 preosteoblastic cell line is widely utilised as a reliable in vitro system to assess bone formation. However, the experimental growth conditions for these cells hugely diverge, and, particularly, the osteogenic medium (OSM)'s composition varies in research studies. Therefore, we aimed to define the ideal culture conditions for MC3T3-E1 subclone 4 cells with regard to their mineralization capacity and explore if oxidative stress or the cellular metabolism processes are implicated. Cells were treated with nine different combinations of long-lasting ascorbate (Asc) and ß-glycerophosphate (ßGP), and osteogenesis/calcification was evaluated at three different time-points by qPCR, Western blotting, and bone nodule staining. Key molecules of the oxidative and metabolic pathways were also assessed. It was found that sufficient mineral deposition was achieved only in the 150 µg.mL-1/2 mM Asc/ßGP combination on day 21 in OSM, and this was supported by Runx2, Alpl, Bglap, and Col1a1 expression level increases. NOX2 and SOD2 as well as PGC1α and Tfam were also monitored as indicators of redox and metabolic processes, respectively, where no differences were observed. Elevation in OCN protein levels and ALP activity showed that mineralisation comes as a result of these differences. This work defines the most appropriate culture conditions for MC3T3-E1 cells and could be used by other research laboratories in this field.

Lifelong dietary protein restriction accelerates skeletal muscle loss and reduces muscle fibre size by impairing proteostasis and mitochondrial homeostasis.

The early life environment significantly affects the development of age-related skeletal muscle disorders. However, the long-term effects of lactational protein restriction on skeletal muscle are still poorly defined. Our study revealed that male mice nursed by dams fed a low-protein diet during lactation exhibited skeletal muscle growth restriction. This was associated with a dysregulation in the expression levels of genes related to the ribosome, mitochondria and skeletal muscle development. We reported that lifelong protein restriction accelerated loss of type-IIa muscle fibres and reduced muscle fibre size by impairing mitochondrial homeostasis and proteostasis at 18 months of age. However, feeding a normal-protein diet following lactational protein restriction prevented accelerated fibre loss and fibre size reduction in later life. These findings provide novel insight into the mechanisms by which lactational protein restriction hinders skeletal muscle growth and includes evidence that lifelong dietary protein restriction accelerated skeletal muscle loss in later life.

The Acute Effect of Talocrural Joint Mobilization on Dorsiflexor Muscle Strength in Healthy Individuals: A Randomized Controlled Single-Blind Study.

CONTEXT: Mobilization has been used for enhancing muscle strength. OBJECTIVE: The aim of this study was to investigate the acute effect of talocrural joint mobilization on ankle dorsiflexor muscle strength in healthy individuals, which has not yet been studied. DESIGN: Randomized controlled single-blind study. SETTING: University laboratory. PARTICIPANTS: Forty-eight healthy individuals. INTERVENTIONS: Maitland grade III (study group) versus Maitland grade I (control group) mobilizations. MAIN OUTCOME MEASURES: Muscle strength measurements were performed using a handheld dynamometer at baseline, immediately after the mobilization, and 30 minutes after mobilization. RESULTS: At baseline, the physical characteristics and muscular strength were similar in both groups (P > .05). According to Friedman analysis, a significant difference was detected following the mobilization in the study group (P < .001), and while the muscle strength at immediately after the mobilization and at 30 minutes after mobilization was significantly higher than baseline (P < .001), no significant differences were observed between 30 minutes after mobilization and immediately after the mobilization (P = .17). However, no significant changes were detected in the control group. The study group was found superior to the control group in terms of muscle strength differences following the mobilization (P < .001). CONCLUSION: The ankle dorsiflexor muscle strength might be increased by performing Maitland grade III mobilization, and this increase might be preserved for 30 minutes, while Maitland grade I mobilization did not lead to such an improvement in healthy individuals.