HYALURONAN DURING LIVER REGENERATION AFTER PARTIAL HEPATECTOMY: TRANSIENT ACCUMULATION IN THE TISSUE AND ELEVATION OF THE SERUM CONCENTRATION.

Abstract

Hyaluronan (HA) is a widely distributed nonsulfated glycosaminogtycan with many physiological and biological functions including promotion of cell proliferation and migration. Accumulation of HA in extracellular matrix is an early event in tissue repair, and also the appearance and removal of HA at specific loci are precisely controlled during embryogencsis. Liver regeneration following partial hepatectomy (PH) is well established in vivo system to study cell proliferation and tissue reorganization. Therefore we studied tissue distribution of HA, its serum level, and the expression patterns of the genes of HA synthases (HAS1, HAS2, HAS3) in regenerating rat liver after PH. In the regenerating liver, HA were transiently accumulated along sinusoid from 24 hour to 48 hour after PH. Normally, low concentrations of HA circulate in the blood, but, during the liver regeneration serum concentration of HA was transiently elevated with the same temporal pattern as the tissue accumulation of HA. Semi-quantitative RT-PCR analyses showed expression level of HAS1 in regenerating liver was elevated immediately after PH and was kept at high level for 1 week. Transient accumulation and synthesis of HA may play important roles in liver regeneration by remodeling the microenvironment.