Embryonic stem cell-derived osteocytes are capable of responding to mechanical oscillatory hydrostatic pressure.
Osteoblasts can be derived from embryonic stem cells (ESCs) by a 30 day differentiation process, whereupon cells spontaneously differentiate upon removal of LIF and respond to exogenously added 1,25α(OH)2 vitamin D3 with enhanced matrix mineralization. However, bone is a load-bearing tissue that has to perform under dynamic pressure changes during daily movement, a capacity that is executed by osteocytes. At present, it is unclear whether ESC-derived osteogenic cultures contain osteocytes and whether these are capable of responding to a relevant cyclic hydrostatic compression stimulus. Here, we show that ESC-osteoblastogenesis is followed by the generation of osteocytes and then mechanically load ESC-derived osteogenic cultures in a compression chamber using a cyclic loading protocol. Following mechanical loading of the cells, iNOS mRNA was upregulated 31-fold, which was consistent with a role for iNOS as an immediate early mechanoresponsive gene. Further analysis of matrix and bone-specific genes suggested a cellular response in favor of matrix remodeling. Immediate iNOS upregulation also correlated with a concomitant increase in Ctnnb1 and Tcf7l2 mRNAs along with increased nuclear TCF transcriptional activity, while the mRNA for the repressive Tcf7l1 was downregulated, providing a possible mechanistic explanation for the noted matrix remodeling. We conclude that ESC-derived osteocytes are capable of responding to relevant mechanical cues, at least such that mimic oscillatory compression stress, which not only provides new basic understanding, but also information that likely will be important for their use in cell-based regenerative therapies.
['Ehnes|D D|DD|', 'Price|F D|FD|', 'Shrive|N G|NG|', 'Hart|D A|DA|', 'Rancourt|D E|DE|', 'zur Nieden|N I|NI|']
D000818:Animals D001842:Bone and Bones D002117:Calcitriol D002454:Cell Differentiation D019245:Compressive Strength D015536:Down-Regulation D053595:Embryonic Stem Cells D004867:Equipment Design D006874:Hydrostatic Pressure D051379:Mice D052247:Nitric Oxide Synthase Type II D009991:Oscillometry D010006:Osteoblasts D010011:Osteocytes D044968:Regenerative Medicine D013314:Stress, Mechanical D013997:Time Factors D058125:Transcription Factor 7-Like 1 Protein D015854:Up-Regulation D016474:Weight-Bearing D051176:beta Catenin
Osteoblast Embryonic stem cell Beta-catenin Mechanotransduction Nitric oxide synthetase