RESUMO
The development of bioartificial liver (BAL) systems has required detailed information about the functional capabilities of cultured hepatocytes during blood or plasma passage. In this study we investigated the effects of porcine plasma and various supplements on the viability and function of adult rat hepatocytes in vitro. Primary rat hepatocytes cultured in porcine plasma supplemented with various substances showed albumin synthesis rates and viability equal to or higher than those of controls. Supplementation with calcium chloride, magnesium sulfate, trace elements, amino acids, insulin, and epidermal growth factor were essential to maintain viability and high albumin synthesis. Especially, trace elements showed significantly higher and longer albumin secretion. Isolated rat hepatocytes were cultured in Spinner flasks for 24 hours to form spheroids that were harvested and encapsulated with chitosan-alginate solution before transfer to the bioreactor in the BAL system. Encapsulated rat hepatocyte spheroids cultured with porcine plasma including trace elements showed higher viability (57%) than controls (40%) after 24 hours, with ammonia removal values of 30.92 µg/10(6) cells versus the control 9.04 µg/10(6) cells. After 24 hours of operation the urea secretion value of encapsulated rat hepatocyte spheroids cultured in porcine plasma in the presence versus absence of trace elements was 76.73 µg/10(6) cells and 18.80 µg/10(6) cells, respectively. We concluded that encapsulated hepatocyte spheroids in a packed-bed bioreactor operated with human plasma including trace elements enhanced cell viability and liver function as a bases for an in vivo clinical trial of the BAL system.
Assuntos
Meios de Cultura/metabolismo , Hepatócitos/metabolismo , Falência Hepática Aguda/sangue , Fígado Artificial , Albuminas/metabolismo , Alginatos , Animais , Reatores Biológicos , Sobrevivência Celular , Células Imobilizadas , Quitosana , Meios de Cultura/química , Modelos Animais de Doenças , Ácido Glucurônico , Ácidos Hexurônicos , Humanos , Masculino , Plasma/metabolismo , Ratos , Ratos Sprague-Dawley , Esferoides Celulares , Suínos , Fatores de Tempo , Ureia/metabolismoRESUMO
Hepatocyte and various hepatic stem cell transplantations have been studied as alternative therapies to orthotopic liver transplantation for liver injury. The engraftment of transplanted cells into the parenchyma requires transmigration through sinusoidal endothelial cells (SECs), the only cellular barrier. In this study, we constructed a SEC-imaging perfusion culture system that mimics sinusoids with respect to hemorheologic properties. SECs were successfully maintained for 24 hours. Human liver stem cells (HLSCs) were used as a model of transplanted cells for in vitro engraftment to SECs under perfusion culture conditions. Conditions of high shear stress perfusion with 0.34 dyne/cm(2) significantly reduced cell adhesion in contrast to lower shear stress conditions of 0.1 and 0.03 dyne/cm(2). Among the biologic perfusion fluids, namely, fetal bovine serum (FBS), pig plasma, and 5% human albumin solution, HLSCs showed significantly greater attachment to SECs when perfused with FBS, which is well known to contain abundant amounts of adhesion molecules. This biomimetic SEC perfusion culture system may provide a useful tool to study engraftment mechanisms and to evaluate the effects of various enhancers as an alternative to animal models.