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- Professor of Experimental Hepatology
- Inst for Liver and Digestive Hlth
- Div of Medicine
- Faculty of Medical Sciences
1. A Bioartificial Liver machine: There is a therapeutic need for functional liver capacity in patients with acute fulminant liver failure (FHF). It is now possible to grow human hepatocytes and hepatocyte cell lines in vitro. Monolayer cultures are disappointing since differentiated function is lost after a few days of culture. We developed a three-dimensional culture system, encapsulating human hepatocyte celllines in alginate without imposing diffusion barriers, in which liver function is markedly upregulated. This novel culture system uses a hydrogel without polymer coating with several advantages: better mass-transfer between cells and the macro-environment outside the beads; cryopreservation and recovery of function; proliferation and cell polarisation of cell spheroids with permanent cell-to-cell interactions via desmosomes, junctional-complexes and microvilli. This culture system forms the biological component of a bioartificial liver device (BAL), envisaged to treat patients with FHF, by extracorporeal hepatic perfusion. Our approach characterised at the gene, protein and metabolic expression levels, the function achieved in this 3-D culture system, and modulated the extracellular matrix environment to provide a cellular component capable of replacing sufficient functional liver capacity to tide a patient over whilst the damaged liver repairs and regenerates. The Bioartificial Liver project is supported in part by funds raised by The Liver Group Charity in the "Liver for Life" Appeal. (www.ucl.ac.uk/livergroup ).
We successfully tested this system in a large model and are now funded by a Technology Transfer award (Wellcome Trust) to make this system clinically ready, prior to regulatory authority approval, research ethics and first-in- man trials.
2. Growth factors: As a post-doc I showed HGF was generated in the liver after partial hepatectomy. and upregulated in oetal human liver by 19-21 wk gestation, compared with adult human liver. We mapped the HGF gene to Chromosome 7q22-ter in man. Recently it has been demonstrated that HGF can reverse aspects of liver fibrosis in experimental models. We have explored the use of engineered proteins which are HGF analogues in human hepatocytes in vitro and in situ, as well as in a spectrum of fibrotic and acute liver disease rodent models.
3. Gene transfer: I demonstrated, in murine histidinaemia, the first complete amelioration of the biochemical phenotype of an inborn error of metabolism, by co-transplantation of isolated hepatocytes and non-parenchymal cells into the peritoneum where they survived, proliferated and functioned as normal hepatocytes. More recent techniques enabled an alternative approach to enhance hepatocyte function in situ by gene transfer. We constructed retroviral vectors containing the corrected murine histidase gene to use in the histidinaemic mouse model, in order to correct the biochemical defect. We demonstrated an improvement in the in vivo response to a histidine load, albeit transient. In a study aimed at improving gene transfer efficiency in human hepatocytes I demonstrated that growth factors eg. HGF markedly improve the uptake, integration and expression of proteins when lentiviral vectors were used for transfection. This has implications for clinical gene therapy protocols since it may allow lower titres of viral vectors, thereby reducing the potential risk from viral load.
My teaching commitment is both formal and informal in nature. Formally, I organise and teach on the Special Study module "The Liver: from Science to Clinical Practice". I also teach on the Intercalated Clinical Sciences BSc for medical students. In the laboratory my teaching concerns predominantly our team of ten research staff, with all of whom I interact to show and help with appropriate experimental techniques for their particular projects. This "teaching" includes introducing doctors, from here and abroad, to laboratory based research, many of whom have had no experience of benchwork, as well as supervising science and medical students and recent graduates starting their research careers as PhD Students. In addition I supervise BSc and MSc students during their degree projects, and take undergraduate students for one year placements during their sandwich year when applicable.