Although viral
hepatitis treatments have evolved over the years, the resultant
liver cirrhosis still does not completely heal. Platelets contain
proteins required for hemostasis, as well as many
growth factors required for organ development, tissue regeneration and repair.
Thrombocytopenia, which is frequently observed in patients with chronic
liver disease (CLD) and
cirrhosis, can manifest from decreased
thrombopoietin production and accelerated platelet destruction caused by
hypersplenism; however, the relationship between
thrombocytopenia and hepatic pathogenesis, as well as the role of platelets in CLD, is poorly understood. In this paper, experimental evidence of platelets improving
liver fibrosis and accelerating liver regeneration is summarized and addressed based on studies conducted in our laboratory and current progress reports from other investigators. In addition, we describe our current perspective based on the results of these studies. Platelets improve
liver fibrosis by inactivating hepatic stellate cells, which decreases
collagen production. The regenerative effect of platelets in the liver involves a direct effect on hepatocytes, a cooperative effect with liver sinusoidal endothelial cells, and a collaborative effect with Kupffer cells. Based on these observations, we ascertained the direct effect of
platelet transfusion on improving several indicators of liver function in patients with CLD and
liver cirrhosis. However, unlike the results of our previous clinical study, the smaller incremental changes in liver function in patients with CLD who received
eltrombopag for 6 mo were due to patient selection from a heterogeneous population. We highlight the current knowledge concerning the role of platelets in CLD and
cancer and anticipate a novel application of platelet-based clinical
therapies to treat
liver disease.