Plasma Membrane Bleb Formation and Rupture: A Common Feature of Hepatocellular Injury

Abstract

Plasma membrane blebbing, the development of blister-like or bubble-like protrusions on the cell surface, is an early morphological alteration of cell injury.During toxic, viral and hypoxic injury to hepatocytes, blebbing is a prominent and virtually universal phenomenon (vide infru).Information regarding blebbing is important to our understanding of the cell biology of liver injury and has many pathophysiological implications.Moreover, many new and recent developments have occurred in this area of hepatology in the past 10 yr.For these reasons, it is timely to summarize current knowledge regarding hepatocellular blebbing.Overall, we have emphasized those aspects of blebbing that are of particular interest to the hepatologist.In addition to being a significant morphological feature of liver injury, bleb formation also occurs in many other tissues during toxic and anoxic injury.Plasma membrane bleb formation has been well described in brain, heart and kidney tissue during cell injury (1-3).The formation of blebs may have unique injurious consequences specific for the organ in which they develop.For example, blebs developing during ischemic injury to proximal renal tubule cells may be shed into the tubules, promoting formation of tubular casts and obstruction of the tubules (3).However, some differences exist in bleb formation between the liver and other organs as will be emphasized in the sections that follow. DEFINITION AND MORPHOLOGYCell surface membrane blebbing was first reported in cultured chick embryo fibroblasts in 1923 by Lewis (4).He described the appearance of "fluid blebs" that flowed out from the edge of the cells in response to an alkaline