Entry and integration of transplanted hepatocytes in rat liver plates occur by disruption of hepatic sinusoidal endothelium

Abstract

To establish the process by which transplanted cells integrate into the liver parenchyma, we used dipeptidyl peptidase IV-deficient F344 rats as hosts. On intrasplenic injection, transplanted hepatocytes immediately entered liver sinusoids, along with attenuation of portal vein radicles on angiography. However, a large fraction of transplanted cells (Ͼ70%) was rapidly cleared from portal spaces by phagocyte/macrophage responses. On the other hand, transplanted hepatocytes entering the hepatic sinusoids showed superior survival. These cells translocated from sinusoids into liver plates between 16 and 20 hours after transplantation, during which electron microscopy showed disruption of the sinusoidal endothelium. Interestingly, production of vascular endothelial growth factor was observed in hepatocytes before endothelial disruptions. Portal hypertension and angiographic changes resulting from cell transplantation resolved promptly. Integration of transplanted hepatocytes in the liver parenchyma required cell membrane regenesis, with hybrid gap junctions and bile canaliculi forming over 3 to 7 days after cell transplantation. We propose that strategies to deposit cells into distal hepatic sinusoids, to disrupt sinusoidal endothelium for facilitating cell entry into liver plates, and to accelerate cell integrations into liver parenchyma will advance applications of hepatocyte transplantation. (HEPATOLOGY 1999;29:509-519.)

Hepatocyte transplantation activates hepatic stellate cells with beneficial modulation of cell engraftment in the rat

“…15 Cell transplantation is associated with perturbations of additional liver cell compartments, such as those associated with ischemia-reperfu- sion injury, that is, Kupffer cell activation, and endothelial disruption, which increases the potential for cell-cell interactions. [1][2][3][4][5] Activation of HSC is associated early with increased desmin expression and cell cycle entry, which is in agreement with intense and widespread desmin expression in HSC within 3 days after cell transplantation. However, these changes were transient, because the number of desminpositive HSC declined within 7 days after cell transplantation.…”

“…Hepatic DPPIV, adenosine triphosphatase (ATPase) and gamma-glutamyl transpeptidase (GGT) activities were visualized according to published protocols. 1,2 Immunohistochemical methods and assessment of Kupffer cell activity are described in the supplementary material. For morphometric analysis, the number of desmin-positive HSC was determined in 100 microscopic fields centered on portal areas (400ϫ magnification), per time point in multiple animals.…”

“…[1][2][3][4][5] Using DPPIVϪ rats, we demonstrate here that hepatocyte transplantation partially activated HSC, including expression of growth factors and ECM-modifying matrix metalloproteinases (MMPs), which are largely produced in HSC. 7,8 Moreover, depletion of HSC interfered with cell engraftment.…”

“…[6][7][8] HSC are located in the space of Disse, which transplanted cells must circumvent during translocation from liver sinusoids to the parenchyma. 1 HSC regulate multiple physiological processes in the liver, including extracellular matrix (ECM) deposition during the onset, as well as regression, of hepatic fibrosis. 7 Paracrine signals from Kupffer cells, liver sinusoidal endothelial cells (LSEC), and hepatocytes can activate HSC.…”

Liver gene therapy: advances and hurdles

“…78 The remaining cells translocated from sinusoids into liver plates within 20 h after cell transplantation, through a process involving disruption of the sinusoidal endothelium, release of vascular endothelial growth factor (VEGF) by both host and transplanted hepatocytes. 77,79,80 Subsequently, translocated cells integrated into the liver parenchyma, regained their polarity with the formation of gap junctions and bile canaliculi between transplanted and host hepatocytes within about 1 week, without any significant proliferation in adult animals and were functional throughout the life of animals. 74,75,81 Overall, only 20-30% of transplanted hepatocytes integrated into the liver.…”