During spaceflight, crewmembers are subjected to biomechanical and biological challenges including microgravity and radiation. In the skeleton, spaceflight leads to bone loss, increasing the risk of fracture. Studies utilizing hindlimb suspension (HLS) as a ground-based model of spaceflight often neglect the concomitant effects of radiation exposure, and even when radiation is accounted for, it is often delivered at a high-dose rate over a very short period of time, which does not faithfully mimic spaceflight conditions.
Deletion of protein kinase D1 in osteoprogenitor cells results in decreased osteogenesis in vitro and reduced bone mineral density in vivo
Protein kinase D1 (PRKD1) is thought to play a role in a number of cellular functions, including proliferation and differentiation. We hypothesized that PRKD1 in bone marrow-derived mesenchymal stem cells (BMMSC) could modulate osteogenesis. In BMMSCs from floxed PRKD1 mice, PRKD1 ablation with adenovirus-mediated Cre-recombinase expression inhibited BMMSC differentiation in vitro.
Mechanical loading disrupts osteocyte plasma membranes which initiates mechanosensation events in bone
Osteocytes sense loading in bone, but their mechanosensation mechanisms remain poorly understood. Plasma membrane disruptions (PMD) develop with loading under physiological conditions in many cell types (e.g., myocytes, endothelial cells). These PMD foster molecular flux across cell membranes that promotes tissue adaptation, but this mechanosensation mechanism had not been explored in osteocytes. Our goal was to investigate whether PMD occur and initiate consequent mechanotransduction in osteocytes during physiological loading.
Recombinant Human Elafin Promotes Alveologenesis in Newborn Mice Exposed to Chronic Hyperoxia
Elastase inhibitors reverse elastin degradation and abnormal alveologenesis and attenuate the lung structural abnormalities induced by mechanical ventilation with O2-rich gas. The potential of these molecules to improve endothelial function and to ameliorate severe bronchopulmonary dysplasia (BPD) during lung development is not yet understood.
Acceleration of Fracture Healing by Overexpression of Basic Fibroblast Growth Factor in the Mesenchymal Stromal Cells
In this study, we engineered mesenchymal stem cells (MSCs) to over-express basic fibroblast growth factor (bFGF) and evaluated its effects on fracture healing. Adipose-derived mouse MSCs were transduced to express bFGF and green fluorescence protein (ADSCbFGF-GFP). Closed-femoral fractures were performed with osterix-mCherry reporter mice of both sexes.
The Lrp4R1170Q Homozygous Knock-In Mouse Recapitulates the Bone Phenotype of Sclerosteosis in Humans
Sclerosteosis is a rare autosomal recessive bone disorder marked by hyperostosis of the skull and tubular bones. Initially, we and others reported that sclerosteosis was caused by loss-of-function mutations in SOST, encoding sclerostin. More recently, we identified disease-causing mutations in LRP4, a binding partner of sclerostin, in three sclerosteosis patients. Upon binding to sclerostin, LRP4 can inhibit the canonical WNT signaling that is known to be an important pathway in the regulation of bone formation.