الفهرس 
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Abstract
latelet Rich Plasma (PRP) has been a breakthrough in the stimulation and acceleration of healing for over 20 years, starting by tissue repair in dentistry and expanding to other clinical fields afterwards. Nowadays, it represents a relatively new biotechnology that is part of growing interest for extensive research in tissue engineering and regenerative medicine.
Platelet-rich plasma is autologous plasma with high platelet concentration. It is easy, cheap, safe, and minimally invasive source for autologous growth factors and cytokines. Several different growth factors and cytokines accelerate healing and help cell proliferation, differentiation, improved synthesis of extracellular matrix (ECM), and angiogenesis (neovascularization and formation of a new conjunctive tissue necessary for healing).
Growth factors (such as PDGF, bFGF, SDF 1α), angiogenic factors (such as VEGF, angiogenin), necrotic factors (such as TNF-α, TNF-β), hemostatic factors (such as factor V, VWF, Fibrinogen), and other cytokines are the important contents of Alpha granules. Alpha (α) granules, dense granules, and lysosomes are found in platelets with α granules - 80 granules per platelet - being most abundant.
The platelets can be activated by thrombin, calcium, collagen, and shear stress. Once activated, morphological changes of platelets and degranulation of their granules occur. GFs are released by degranulation either by fusion with the open canalicular system and extrusion of its contents through small channels in the cell membrane, or by exocytosis and releasing α granules content outside by fusing the granules with the cell membrane.
Recently, platelets have been discovered to have a positive influence on the liver; as they accelerate liver regeneration and have anti-fibrosis and anti-apoptotic activity. Platelets have a direct impact on hepatocytes, a supportive effect with liver sinusoidal endothelial cells, and a cooperative effect with Kupffer cells which accelerates liver regeneration.
The aim of the work was to compare different strategies of PRP activation by evaluating content and release of growth factors for further clinical trials to validate the clinical relevance of best method to help regeneration of liver in hepatic patients.
This study was conducted on 21 participants. Ten ml blood was taken from each one of them divided equally into one EDTA tube and 4 citrated tubes. The collected samples in EDTA group were tested for CBC of each participant. The collected samples in citrated tubes (84 samples, 4 from each participant) were divided into 4 groups: unactivated PRP (group 1), activated PRP with calcium gluconate (group 2), activated PRP with thrombin (group 3), and activated PRP with thrombin plus calcium gluconate (group 4). GFs (PDFG-AB & TGF-β) were measures in each sample using ELISA. Results were compared to each other to get the best activating method.
Results obtained showed significantly higher GF (PDFG-AB & TGF-β) release from group 4 (where PRP activated with calcium gluconate plus thrombin) compared to the other groups. group 3 (where PRP activated with thrombin) showed a higher significant increase in GF (PDFG-AB & TGF-β) release than in group 2 (where PRP activated with calcium gluconate) and group 1 (unactivated PRP group). Also, it has been found that the GF (PDFG-AB & TGF-β) released from group 2 were significantly higher compared to that released from group 1.
Therefore we concluded that:
• Released growth factors using calcium gluconate, and/or thrombin as activators for PRP is more than that released from PRP without activation (high significant difference).
• Released growth factors using thrombin as an activator for PRP is more than that released from calcium gluconate activated PRP (high significant difference).
• Released growth factors using thrombin plus calcium gluconate to activate PRP is more than that released from calcium gluconate or thrombin activated PRP (high significant difference).