First note

سلام

مقاله ای که امروز خلاصه کرده ام ، اشاره به اثرات و کاربردهای ساخت رگ با تکنولوژی های تازه است. 

Endothelial cells are the great goal of recent research, because of their ability to cure some vascular diseases and also to stimulate the growth in some ischemic tissues. The first step in vascular development is related to progenitor endothelial cells or angioblasts that are influenced by sonic hedgehog signalling by the endoderm and vascular endothelial growth factor A (VEGF A) which acts through its receptor (FIK-1/KDR). These angioblasts differentiate from the mesoderm and form into tubes and fuse to form a continuous network. In addition, vascular development is influenced by Fibroblast growth factors (FGFs), extra cellular matrix (ECM), transforming growth factor B  and platelet-derived growth factor

Although, angiogenesis is the formation of new vessels by proliferation and migration of endothelial cells, vasculogenesis is migration of circulating cells into ischemic sites to contribute the neovascularisation. These are influenced by several ways. Firstly, hemangioblasts were found from bone marrow and express CD34 or CD133 and mobilize to the peripheral blood under effect of VEGF and travel to the ischemic tissues or tumours. Secondly, mesenchymal stem cells inside bone marrow differentiate into endothelial cells. Thirdly, haematopoietic stem cell derived myeloid cells can give rise to endothelial cells. Finally, other kinds of cells from fat tissue, cardiac tissue and neural stem cells, can give rise to endothelial cells

Many studies show several markers are expressed in sequential steps to produce endothelial cells from embryoid bodies (EBs). On the other hand, seeding embryonic stem cells differentiate to endothelial cells on an extra cellular matrix. In this assay, two types of cell population differing by size were identified. The small cells were changed to endothelial cells and the additions of cells were induced differentiation into smooth muscle cells

Endothelial cells are derived engineering vessels. In this method isolated endothelial cells, growth on scaffolds in vitro, followed by invivo implantation. For example, pulmonary arterial cells were grown on PLGA for one week before transplantation into pulmonary arteries of lamb by Shinoko in 1998. Another method was to culture bovine aortic smooth muscle cells into PGA in pulsating flow manner that increased wall thickness and collagen content of vessels after eight weeks by Niklason in 1999. The next method was explained to migrating of circulating endothelial progenitor cells to traumatic or ischemic sites. These studies (Takahashi, 1999 and Kaushal, 2001) show endothelial cells have both the structural and functional capabilities of blood vessels in vitro. Another method was explained by Hibino in 2005, showed that bone marrow cells can be used directly in vascular graft without any culturing and also used to engineer vascular patches on decellularized tissue matrices (Cho, 2005). Finally, Poh used human vascular cells that isolated from elderly patients to engineer blood vessels in 2005

Endothelial cells have the ability to organize vessels networking in vitro by forming tube like structures. In addition, the co-culture of endothelial cells with embryonic fibroblasts induces the differentiation of fibroblasts into smooth muscle cells (Darland, 2003

In this article, researchers hypothesized those embryonic endothelial cells in the appropriate environment are used to induce endothelial vessels networking in engineered skeletal muscle tissue in vitro. They used mouse myoblasts and hESG-drived endothelial cells or HUVEGs in a co-culture system. Another approach was to produce scaffolds to include channels that later filled by endothelial cells

In conclusion, there are still remaining challenges that need to be considered producing engineering of single vessel in vitro or networks to the invivo neovascularisation of various tissues. It is necessary to be identified which progenitor is optimal for specific clinical solutions

Reference

SHULAMIT, L. (2005) Engineering blood vessels from stem cells: recent advances and applications. Current Opinion in Biotechnology, 16, 516-523

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