Tissue engineering of the liver

  • Nelly Wung

Student thesis: Doctoral ThesisPhD

Abstract

Currently, the only cure for liver failure is orthotopic liver transplantation. However, there are insufficient donor organs available to treat every patient on the transplant list and many die before they are able to receive a liver transplant. The bioartificial liver (BAL) device is a potential extracorporeal treatment strategy utilising hepatocytes or hepatocyte-like cells (HLCs) within a bioreactor to recapitulate normal liver function and therefore ‘bridge’ a patient with liver failure until they receive a transplant. The work in this thesis utilised tissue engineering methods to develop novel approaches to BAL device design through development and characterisation of a polymer membrane scaffold (“PX”) for hollow fibre bioreactor (HFB) culture and a HLC source generated from the transdifferentiation of pancreatic AR42J-B13 (B13) cells. A flat sheet membrane model was used for the development of asymmetrical, hydrophobic polystyrene (PS) phase inversion membranes. Oxygen plasma significantly increased PS membrane surface wettability through addition of oxygen functional groups to create an environment conducive for cell culture. The treated membrane was henceforth referred to as “PX”. The culture medium HepatoZYME+ was investigated for its ability to induce transdifferentiation of B13 cells to HLCs and maintain the hepatic phenotype. Overall, HepatoZYME+-cultured cells experienced viability loss. A diluted version, “50:50”, showed induction of the hepatic markers carbamoylphosphate synthetase-1 (CPS-1) and HNF4α, as well as a change towards a HLC morphology. When using 50:50 as a maintenance medium, transdifferentiated HLCs retained loss of pancreatic amylase and also induction of hepatic markers, with comparable serum albumin secretion to the established Dex + OSM treatment. However, culture viability in 50:50 was still compromised. Therefore, HepatoZYME+ based media were deemed unsuitable for induction and maintenance compared to Dex-based protocols. PX flat sheet membranes were able to support culture of B13 cells and also the human osteosarcoma cell line, MG63, demonstrating improved cell attachment over non-surface treated PS membranes. PX membranes supported transdifferentiation of B13 cells to HLCs, presenting with loss of pancreatic amylase, induction of the hepatic markers transferrin, GS and CPS-1 and serum albumin secretion. Furthermore, PX showed no change in mass or loss of culture surface area over 15 days in culture conditions. Together, the novel membrane material and the media formulation and feeding regime developed have strong potential to be translated to a HFB setting and guide future BAL device design.
Date of Award26 Apr 2017
LanguageEnglish
Awarding Institution
  • University of Bath
SupervisorDavid Tosh (Supervisor) & Marianne Ellis (Supervisor)

Keywords

  • Tissue engineering
  • Regenerative medicine
  • Biomaterials
  • Transdifferentiation
  • Liver
  • Pancreas-to-liver
  • Cell culture
  • Bioreactors (hollow-fiber membrane
  • bioartificial liver

Cite this

Tissue engineering of the liver
Wung, N. (Author). 26 Apr 2017

Student thesis: Doctoral ThesisPhD