Mechanosensory Pathways in Angiocrine Mediated Tissue Regeneration

Abstract Endothelial cells not only form the vascular networks that deliver nutrients and oxygen throughout the body, they also establish instructive niches that stimulate organ regeneration through elaboration of paracrine trophogens. Priming of the vascular niche promotes repair and regeneration of damaged tissues by establishing an inductive vascular network that temporally precedes new tissue formation. This induction of endothelial cells provides a platform for essential instructive cues. Tissue regeneration in certain organs such as the liver, involves cell mitosis and expansion, which is orchestrated by a dynamic interplay between cytokines, growth factors, and metabolic pathways. Although the intrinsic events of cell mitosis have been thoroughly studied, the extrinsic triggers for initiation and termination of liver regeneration, especially the set points rendered by the original liver size, are unknown. Furthermore, the gatekeepers that control organ size remain unidentified. The prevailing dogma states that liver regeneration involves the proliferation of parenchymal hepatocytes and nonparenchymal cells such as biliary epithelial cells. However, recent findings also implicate hepatic sinusoidal endothelial cells (SECs) as drivers of this process. In the classic liver regeneration model, in which 70 % partial hepatectomy induces regeneration, the abrupt increase in blood flow into the sinusoidal vasculature of the liver’s remaining lobes correlates with initiation of the regeneration cascade. As such, the shear stress and mechanical stretch exerted on the endothelial cells may activate mechanosensory mediated molecular programs, and may be involved in the elaboration of endothelial cell-derived angiocrine growth cues that suppor