title: Spatiotemporal properties of intracellular calcium signaling in osteocytic and osteoblastic cell networks under fluid flow.
abstract: Mechanical stimuli can trigger intracellular calcium (Ca(2+)) responses in osteocytes and osteoblasts. Successful construction of bone cell networks necessitates more elaborate and systematic analysis for the spatiotemporal properties of Ca(2+) signaling in the networks. In the present study, an unsupervised algorithm based on independent component analysis (ICA) was employed to extract the Ca(2+) signals of bone cells in the network. We demonstrated that the ICA-based technology could yield higher signal fidelity than the manual region of interest (ROI) method. Second, the spatiotemporal properties of Ca(2+) signaling in osteocyte-like MLO-Y4 and osteoblast-like MC3T3-E1 cell networks under laminar and steady fluid flow stimulation were systematically analyzed and compared. MLO-Y4 cells exhibited much more active Ca(2+) transients than MC3T3-E1 cells, evidenced by more Ca(2+) peaks, less time to the 1st peak and less time between the 1st and 2nd peaks. With respect to temporal properties, MLO-Y4 cells demonstrated higher spike rate and Ca(2+) oscillating frequency. The spatial intercellular synchronous activities of Ca(2+) signaling in MLO-Y4 cell networks were higher than those in MC3T3-E1 cell networks and also negatively correlated with the intercellular distance, revealing faster Ca(2+) wave propagation in MLO-Y4 cell networks. Our findings show that the unsupervised ICA-based technique results in more sensitive and quantitative signal extraction than traditional ROI analysis, with the potential to be widely employed in Ca(2+) signaling extraction in the cell networks. The present study also revealed a dramatic spatiotemporal difference in Ca(2+) signaling for osteocytic and osteoblastic cell networks in processing the mechanical stimulus. The higher intracellular Ca(2+) oscillatory behaviors and intercellular coordination of MLO-Y4 cells provided further evidences that osteocytes may behave as the major mechanical sensor in bone modeling and remodeling processes.
authors: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
authors: Da
authors: D
authors: Jing
authors: X Lucas
authors: XL
authors: Lu
authors: Erping
authors: E
authors: Luo
authors: Paul
authors: P
authors: Sajda
authors: Pui L
authors: PL
authors: Leong
authors: X Edward
authors: XE
authors: Guo
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D002450:Cell Communication / Q000502:physiology; D002460:Cell Line; D051379:Mice; D010006:Osteoblasts / Q000378:metabolism*; D010011:Osteocytes / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D062211:Spatio-Temporal Analysis