title: Reversal of the detrimental effects of simulated microgravity on human osteoblasts by modified low intensity pulsed ultrasound.
abstract: Microgravity (MG) is known to induce bone loss in astronauts during long-duration space mission because of a lack of sufficient mechanical stimulation under MG. It has been demonstrated that mechanical signals are essential for maintaining cell viability and motility, and they possibly serve as a countermeasure to the catabolic effects of MG. The objective of this study was to examine the effects of high-frequency acoustic wave signals on osteoblasts in a simulated microgravity (SMG) environment (created using 1-D clinostat bioreactor) using a modified low-intensity pulsed ultrasound (mLIPUS). Specifically, we evaluated the hypothesis that osteoblasts (human fetal osteoblastic cell line) exposure to mLIPUS for 20 min/d at 30 mW/cm(2) will significantly reduce the detrimental effects of SMG. Effects of SMG with mLIPUS were analyzed using the MTS proliferation assay for proliferation, phalloidin for F-actin staining, Sirius red stain for collagen, and Alizarin red for mineralization. Our data showed that osteoblast exposure to SMG results in significant decreases in proliferation (∼ -38% and ∼ -44% on days 4 and 6, respectively; p < 0.01), collagen content (∼ -22%; p < 0.05) and mineralization (∼ -37%; p < 0.05) and actin stress fibers. In contrast, mLIPUS stimulation in SMG condition significantly increases the rate of proliferation (∼24% by day 6; p < 0.05), collagen content (∼52%; p < 0.05) and matrix mineralization (∼25%; p < 0.001) along with restoring formation of actin stress fibers in the SMG-exposed osteoblasts. These data suggest that the acoustic wave can potentially be used as a countermeasure for disuse osteopenia.
authors: Orthopaedic Bioengineering Research Lab, Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-5281, USA.
authors: Sardar M Z
authors: SM
authors: Uddin
authors: Michael
authors: M
authors: Hadjiargyrou
authors: Jiqi
authors: J
authors: Cheng
authors: Shu
authors: S
authors: Zhang
authors: Minyi
authors: M
authors: Hu
authors: Yi-Xian
authors: YX
authors: Qin
mesh_terms: D049109:Cell Proliferation / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D019220:High-Energy Shock Waves; D006801:Humans; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects*; D011829:Radiation Dosage; D013010:Sonication / Q000379:methods*; D014893:Weightlessness