Towards Bioengineered Liver Stem Cell Transplantation Studies in a Preclinical Dog Model for Inherited Copper Toxicosis

Machine perfusion of the liver and bioengineering

With the increasing number of accepted candidates on waiting lists worldwide, there is an urgent need to expand the number and the quality of donor livers. Dynamic preservation approaches have demonstrated various benefits, including improving liver function and graft survival, and reducing liver injury and post-transplant complications. Consequently, organ perfusion techniques are being used in clinical practice in many countries. Despite this success, a proportion of livers do not meet current viability tests required for transplantation, even with the use of modern perfusion techniques. Therefore, devices are needed to further optimise machine liver perfusion - one promising option is to prolong machine liver perfusion for several days, with ex situ treatment of perfused livers. For example, stem cells, senolytics, or molecules targeting mitochondria or downstream signalling can be administered during long-term liver perfusion to modulate repair mechanisms and regeneration. Besides, today's perfusion equipment is also designed to enable the use of various liver bioengineering techniques, to develop scaffolds or for their re-cellularisation. Cells or entire livers can also undergo gene modulation to modify animal livers for xenotransplantation, to directly treat injured organs or to repopulate such scaffolds with "repaired" autologous cells. This review first discusses current strategies to improve the quality of donor livers, and secondly reports on bioengineering techniques to design optimised organs during machine perfusion. Current practice, as well as the benefits and challenges associated with these different perfusion strategies are discussed.

Transplantable Liver Organoids, Too Many Cell Types to Choose: a Need for Scientific Self-Organization

Purpose of Review

Liver stem cells have been proposed as alternatives or additions for whole liver transplantations to accommodate the donor liver shortage. Various sources of liver stem cells have been described in experimental animal studies. Here we aim to compare the various studies.

Recent Findings

Irrespective of the experimental design, the percentage of long-lasting survival and functional recovery of transplanted cells is generally very low. An exception to this are the proliferating hepatocytes transplanted into Fah(-/-) Rag2−/−IL2rg−/− mice; here 4-month post-transplantation around 65% repopulation was observed, and 11/14 mice survived in contrast to zero survival in sham-treated animals.

Summary

Taking the different cellular sources for the organoids, the different maturation status of the transplanted cells, and the variable animal models into account, a paper-to-paper comparison is compromised. This lack of objective comparison restricts the translation of these model studies into clinical practice.

Bioengineering Liver Transplantation

Since the first in-man liver transplantation was performed by Starzl et al [...].