الفهرس 
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Abstract
OLT is now regarded as the treatment of choice for a number of otherwise irreversible forms of acute and chronic liver disease. OLT involves the substitution of a diseased liver with a normal one (or part of it) taken from a diseased or living donor .
Patient survival at one year and five years is 85–90% and 75–80%,
respectively; graft survival is 80–85% and 70–75%, respectively. The main factor limiting further growth in liver transplantation worldwide is shortage of donor . Liver transplantation is indicated for adults and children with acute or chronic liver disease that cannot be treated medically or with alternative forms of surgery .
Growth factors are proteins that bind to receptors on the cell surface, with the primary result of activating cellular proliferation and/or differentiation. Many growth factors are essential in stimulating cellular division in numerous different cell types e.g. Epidermal growth factor (EGF), platelet-derived growth factor (PDGF), Transforming growth factor-α (TGF-α), transforming growth factors-β (TGFs-β), Insulin-like growth factor-I (IGF-I), insulin-like growth factor-II (IGF-II),Colony stimulating factors (CSFs) and vascular endothelial growth factor (VEGF) .
Cytokines are small secreted proteins which mediate and regulate immunity, inflammation, and hematopoiesis. They stimulate both the humoral and cellular immune responses, as well as the activation of phagocytic cells. A large family of cytokines are produced by various cells of the body.
Liver is an organ of high regenerative capacity. The hepatocytes are able to reconstruct the liver tissue after the occurrence of any damages. The regenerative process requires a close interplay between the signals of the extracellular matrix and the intracellular means .
The extent of the resection and tissue damage remarkably influence the initiation and synchronization of replication in different types of hepatic cells, after a massive resection, up to 90% of the hepatocytes appear to replicate.
Eventually the liver should reach the normal liver/body mass ratio to enable proper function, even if a small-sized graft is implanted into a larger recipient .
The liver regeneration is divided into three phases (1) Initiation (2) Proliferation and (3) Inhibition. The mitogenic response divides into two phases, first due to cytokines,which is cytokine - mediated phase that stimulate the G0-G1transition, and then the progression until phase S ,and second phase due to growth factors,which is called growth factors- mediated pathway .