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Platelets Infused via the Portal Vein Promoted Liver Regeneration in Rats
Posted on: March 3, 2011

Platelets, or thrombocytes, are small, regularly-shaped clear cell fragments (i.e. cells that do not have a nucleus containing DNA), 2-3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes. The average lifespan of a platelet is normally just 5 to 9 days.

Platelets play a fundamental role in hemostasis and are a natural source of growth factors. They circulate in the blood of mammals and are involved in hemostasis, leading to the formation of blood clots. Platelets release a multitude of growth factors including Platelet-derived growth factor (PDGF), a potent chemotactic agent, and TGF beta, which stimulate the deposition of extracellular matrix. Both of these growth factors have been shown to play a significant role in the repair and regeneration of connective tissues.

Other healing-associated growth factors produced by platelets include basic fibroblast growth factor, insulin-like growth factor 1, platelet-derived epidermal growth factor, and vascular endothelial growth factor. Local application of these factors in increased concentrations through Platelet-rich plasma (PRP) has been used as an adjunct to wound healing for several decades.

The objective of this scientific study examines the applicability of platelet infusion therapy for liver regeneration in vivo. It was reported that platelets accumulate in the liver immediately after extended hepatectomy and promote residual liver regeneration. Liver regeneration depends on the number of accumulated platelets in the sinusoids.

To evaluate regenerative potential of platelets, male Sprague-Dawley rats underwent 70% hepatectomy and were then assigned to groups that were infused with 1 mL of either platelet-rich plasma (PRP; 1 × 10 platelets/mL) in normal saline (NS) or NS via the portal vein. Liver regeneration and the signaling pathways that are related to liver regeneration and function have been analysed. The dynamics of platelets infused via the portal vein were visualized before and after hepatectomy.

It was shown that the liver/body weight ratio after 70% hepatectomy was significantly higher and the Ki-67 labeling index was higher in the PRP, than in the NS group. The Akt pathway was activated earlier in the PRP, than in the NS group with concurrent ERK1/2 pathway activation, but this was prolonged in the PRP group.

Many more platelets infused via the portal vein accumulated in the sinusoid after 70% hepatectomy, and serum liver function tests and histological findings revealed that portal infusion did not cause liver damage. This means that platelets infused via the portal vein promoted liver regeneration after 70% hepatectomy in rats without liver damage.

These findings indicate that PRP administration could be a useful part of liver regeneration therapy.

Source: Matsuo R, Nakano Y, Ohkohchi N.; Platelet Administration Via the Portal Vein Promotes Liver Regeneration in Rats After 70% Hepatectomy.; Ann Surg. 2011 Feb 21.
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