Efficient hepatocyte engraftment and long-term transgene expression after reversible portal embolization in nonhuman primates

Abstract

The feasibility of ex vivo gene therapy as an alternative to liver transplantation for the treatment of liver metabolic diseases needs to be analyzed in large animal models. This approach requires appropriate gene transfer vectors and effective hepatocyte engraftment. Lentiviral vectors have the ability to transduce nondividing differentiated cells, such as hepatocytes, and portal vein occlusion increases hepatocyte engraftment. We investigated whether reversible portal vein embolization combined with ex vivo lentivirus-mediated gene transfer is an effective approach for successful hepatocyte engraftment in nonhuman primates and whether the transgene remains expressed in the long term in transplanted hepatocytes in situ. Simian hepatocytes were isolated after left lobe resection, and the left and right anterior portal branches of animals were embolized with absorbable material. Isolated hepatocytes were labeled with Hoechst dye or transduced in suspension with lentiviruses expressing green fluorescent protein under the control of the human apolipoprotein A-II promoter and transplanted via the inferior mesenteric vein. The whole procedure was well tolerated. The embolized liver was revascularized within 2 weeks. The volume of nonembolized liver increased from 38.7% ؎ 0.8% before embolization to 55.9% ؎ 1% after embolization and hepatocytes significantly proliferated (10.5% ؎ 0.4% on day 3 after embolization). Liver repopulation after transplantation with Hoechst-labeled hepatocytes was 7.4% ؎ 1.2%. Liver repopulation was 2.1% ؎ 0.2% with transduced hepatocytes, a proportion similar to that obtained with Hoechst-labeled cells, given that the mean transduction efficacy of simian hepatocyte population was 34%. Transgene expression persisted at 16 weeks after transplantation. Conclusion: We have developed a new approach to improve hepatocyte engraftment and to express a transgene in the long term in nonhuman primates. This strategy could be suitable for clinical applications. (HEPATOLOGY 2009;49: 950-959.)O rthotopic liver transplantation is the only available curative treatment for various liver diseases and genetic metabolic disorders. Owing to the limited availability of donor livers, alternative approaches such as hepatocyte transplantation have been proposed. 1,2 However, the increasing organ shortage makes the supply of tissue for cell transplantation very limited. 3 There are often no unused donor livers available when a patient requires cell transplantation; most patients therefore receive cryopreserved cells, the functionality of which remains lower than that of freshly isolated hepatocytes.

Chemokine-Mediated Robust Augmentation of Liver Engraftment: A Novel Approach

“…Usually major loss of transplanted cells is thought to be due to failure in entering sinusoids and crossing the sinusoidal-endothelial barrier [40]. In a nonhuman primate model, liver repopulation with transplanted hepatocytes was approximately 2%-7% [40], whereas in our study, robust engraftment was recorded (34.14%, 37.34%, 45.25%, and 26.16% engraftment in groups 4, 5, 6, and 7, respectively). Transplantation of stem and progenitor cell populations, rather than mature hepatocytes, has been investigated recently, exploiting their known proliferative potential.…”

“…In rats, transplantation of 2 3 10 7 hepatocytes results in engraftment of approximately 0.5% of the total recipient liver cells [39], and this hepatocyte loss occurs during the early stages of transplantation [40,41]. Usually major loss of transplanted cells is thought to be due to failure in entering sinusoids and crossing the sinusoidal-endothelial barrier [40].…”

“…In rats, transplantation of 2 3 10 7 hepatocytes results in engraftment of approximately 0.5% of the total recipient liver cells [39], and this hepatocyte loss occurs during the early stages of transplantation [40,41]. Usually major loss of transplanted cells is thought to be due to failure in entering sinusoids and crossing the sinusoidal-endothelial barrier [40]. In a nonhuman primate model, liver repopulation with transplanted hepatocytes was approximately 2%-7% [40], whereas in our study, robust engraftment was recorded (34.14%, 37.34%, 45.25%, and 26.16% engraftment in groups 4, 5, 6, and 7, respectively).…”

Development of a portocaval shunt using a small intestinal segment in rats

“…12 Although we did not confirm the feasibility of the small intestine as an effective PCS component, as well as a scaffold for liver regeneration, in this study, we showed that the transplanted graft met the requirement to maintain the blood circulation and its structure for 1 month, which is needed for our strategy.…”

Morbidity and Mortality of Hepatic Right Lobe Living Donors: Systematic Review and Perspectives

“…The aim of this technique is to induce the atrophy of the ipsilateral liver and thus the hypertrophy of the future remnant liver before hepatectomy. Based on these results, some teams have developed reversible portal vein embolization to avoid liver atrophy [51][52][53].…”