돼지 간세포를 이용한 체외 순환형 생인공간 개발

Bioartificial Liver System using a Fluidized-Bed Bioreactor

Purpose: Acute fulminant hepatic failure (FHF) is associated with high mortality. Recent studies have shown that a liver support system based on viable hepatocytes can prolong life in animal models of FHF and also in some FHF patients who were successfully bridged to liver transplantation. To be applied in humans, the bioartificial liver (BAL) system should have sufficient liver cell mass to provide adequate bioactive support. The most widely investigated bioreactor at present is based on hollow fiber membrane. However, it is difficult to build a scaled-up module of this model. We devised a fluidized-bed bioreactor that is packed with isolated porcine hepatocytes, and these hepatcytes are immobilized in Ca-alginate hydrogel. Methods: We isolated fresh porcine hepatocytes using a 2-step collagenase perfusion method, and they were suspended in 1.5% alginate solution. Through a drop-generator, this mixture was gelled in 135mM $Cacl_2$. The resulting spherical beads (mean size: 500${\mu}m$) were embedded in a module. An average of $2{\times}10^{10}$ hepatocytes were present in the module. The efficacy of our design was tested in pigs that had undergone total hepatic devascularization and portocaval shunt. Results: The BAL-treated group showed a significantly lower ammonium build-up rate compared to the control group (598.6${\pm}$344.2${\mu}g$/dl vs 1937.6${\pm}$744.1${\mu}g$/dl, respectively, at 8 hours after connecting to BAL). In addition, the intracranial pressure was well controlled in the BAL-treated group, whereas the control group showed a progressive increase of the intracranial pressure (16.9${\pm}$1mm$H_2O$ vs 21.9${\pm}$2.6mm$H_2O$, respectively, at 8 hours after connecting to BAL). Conclusion: Our bioartificial liver system is a fluidized-bed bioreactor packed with immobilized porcine hepatocytes, and it seems to be a more effective scaled-up module.