The African Liver Tissue Biorepository Consortium: Capacitating Population-Appropriate Drug Metabolism, Pharmacokinetics, and Pharmacogenetics Research in Drug Discovery and Development.

Pharmaceutical companies subject all new molecular entities to a series of in vitro metabolic characterizations that guide the selection and/or design of compounds predicted to have favorable pharmacokinetic properties in humans. Current drug metabolism research is based on liver tissue predominantly obtained from people of European origin, with limited access to tissue from people of African origin. Given the interindividual and interpopulation genomic variability in genes encoding drug-metabolizing enzymes, efficacy and safety of some drugs are poorly predicted for African populations. To address this gap, we have established the first comprehensive liver tissue biorepository inclusive of people of African origin. The African Liver Tissue Biorepository Consortium currently includes three institutions in South Africa and one in Zimbabwe, with plans to expand to other African countries. The program has collected 67 liver samples as of July 2023. DNA from the donors was genotyped for 120 variants in 46 pharmacogenes and revealed variants that are uniquely found in African populations, including the low-activity, African-specific CYP2C9*5 and *8 variants relevant to the metabolism of diclofenac. Larger liver tissue samples were used to isolate primary human hepatocytes. Viability of the hepatocytes and microsomal fractions was demonstrated by the activity of selected cytochrome P450s. This resource will be used to ensure the safety and efficacy of existing and new drugs in African populations. This will be done by characterizing compounds for properties such as drug clearance, metabolite and enzyme identification, and drug-drug and drug-gene interactions. SIGNIFICANCE STATEMENT: Standard optimization of the drug metabolism of new molecular entities in the pharmaceutical industry uses subcellular fractions such as microsomes and isolated primary hepatocytes, being done mainly with tissue from donors of European origin. Pharmacogenetics research has shown that variants in genes coding for drug-metabolizing enzymes have interindividual and interpopulation differences. We established an African liver tissue biorepository that will be useful in ensuring drug discovery and development research takes into account drug responses in people of African origin.

Hyperreduced left lateral living donor liver transplant in a 4.5 kg child-A first in Africa.

BACKGROUND: Supply-demand mismatch in solid organ transplantation is particularly pronounced in small children. For liver transplantation, advanced surgical techniques for reducing deceased and living donor grafts allow access to life-saving transplantation. Living donor left lateral segment liver grafts have been successfully transplanted in small children in our center since 2013, the only program providing this service in Sub-Saharan Africa. This type of partial graft remains too large for children below 6 kg body weight and generally requires reduction. METHODS: A left lateral segment graft was reduced in situ from a directed, altruistic living donor to yield a hyperreduced left lateral segment graft. RESULTS: The donor was discharged after 6 days without complications. The recipient suffered no technical surgical complications except for an infected cut-surface biloma and biliary anastomotic stricture and remains well 9 months post-transplant. CONCLUSIONS: We report the first known case in Africa of a hyperreduced left lateral segment, ABO incompatible, living donor liver transplant in a 4,5 kg child with pediatric acute liver failure (PALF).

Living donor liver transplant from an HIV-positive mother to her HIV-negative child: opening up new therapeutic options.

OBJECTIVE: Transplant a liver from an HIV-positive mother to her HIV-negative child to save the child's life. DESIGN: A unique case of living donor liver transplantation from an HIV-positive mother to her HIV-negative child in South Africa. Two aspects of this case are ground-breaking. First, it involves living donation by someone who is HIV-positive and second it involves controlled transplant of an organ from an HIV-positive donor into an HIV-negative recipient, with the potential to prevent infection in the recipient. METHODS: Standard surgical procedure for living donor liver transplantation at our centre was followed. HIV-prophylaxis was administered preoperatively. Extensive, ultrasensitive HIV testing, over and above standard diagnostic assays, was undertaken to investigate recipient serostatus and is ongoing. RESULTS: Both mother and child are well, over 1 year posttransplantation. HIV seroconversion in our recipient was detected with serological testing at day 43 posttransplant. However, a decline in HIV antibody titres approaching undetectable levels is now being observed. No plasma, or cell-associated HIV-1 DNA has been detected in the recipient at any time-point since transplant. CONCLUSION: This case potentially opens up a new living liver donor pool which might have clinical relevance in countries where there is a high burden of HIV and a limited number of deceased donor organs or limited access to transplantation. However, our recipient's HIV status is equivocal at present and additional investigation regarding seroconversion events in this unique profile is ongoing.

Paediatric liver transplantation in Johannesburg revisited: 59 transplants and challenges met.

BACKGROUND: A paediatric liver transplant programme was started at the Wits Donald Gordon Medical Centre, Johannesburg, South Africa (SA), in November 2005. We reported on the first 29 patients in 2012. Since then we have performed a further 30 transplants in 28 patients, having met the major challenge of donor shortage by introducing a living related donor programme and increasing the use of split liver grafts. OBJECTIVE: To review the Wits Donald Gordon Medical Centre paediatric liver transplant programme to date. We describe how the programme has evolved and specifically compare the outcomes of the first cohort with the most recent 28 patients. METHODS: Case notes of all paediatric liver transplants performed between 14 November 2005 and 30 June 2014 were retrospectively reviewed. Data were analysed for age and weight at transplantation, indication and type of graft. Morbidity and mortality were documented, specifically biliary and vascular complications. Comparison was made between Era 1 (November 2005 - October 2012) and Era 2 (November 2012 - June 2014). RESULTS: A total of 59 transplants were performed in 57 patients. Age at transplantation ranged from 9 months to 213 months (mean 82.39 months) and weight ranged from 5 kg to 62 kg (mean 21 kg). A total of 23 whole livers, 10 reduced-size grafts, 14 split liver grafts and 12 living donor liver transplants (LDLTs) were performed. Eight patients were referred with fulminant hepatic failure (FHF), all in Era 2. Of these, three patients were successfully transplanted. Of the 57 patients, 45 are alive and well with actuarial 1-year patient and graft survival of 85% and 84%  and 5-year patient and graft survival of 78% and 74%, respectively. Sixteen (25.42%) biliary complications occurred in 15 of our 59 transplants. Seven patients developed significant vascular complications. Comparing Era 1 with Era 2, mean age at transplant decreased from 100.86 months to 64.73 months, mean weight from 25.2 kg to 16.9 kg, and type of graft utilised changed with a trend away from the use of whole livers and reduced-sized grafts to split livers and segment 2,3 LDLT grafts. CONCLUSION: Initially limited by a shortage of donor organs, we aggressively explored optimal utilisation, splitting liver grafts from deceased donors as often as possible and establishing an LDLT programme. This increased access to donor livers allowed us to include patients with FHF and to perform retransplantation in recipients with early graft failure. It remains to offer liver transplantation to the entire paediatric community in SA, in conjunction with the only other established paediatric liver transplant unit, at Red Cross War Memorial Children's Hospital in Cape Town.

Combined paediatric liver-kidney transplantation: analysis of our experience and literature review.

BACKGROUND: Renal insufficiency is increasingly common in end-stage liver disease and allocation of livers to this category of patient has escalated. The frequency of combined liver-kidney transplantation (CLKT) has consequently increased. Indications for CLKT in children differ from those for adults and typically include rare congenital conditions; subsequently limited numbers of this procedure have been performed in paediatric patients worldwide. Scant literature exists on the subject. METHODS: Subsequent to institutional approval, a retrospective chart analysis of all paediatric CLKTs performed at the Transplant Unit, Wits Donald Gordon Medical Centre, University of the Witwatersrand, Johannesburg, South Africa between January 2005 and July 2013 was conducted. RESULTS: Defining children as younger than 18 years of age, 43 patients had received a liver transplant since 2005, of whom 8 received a CLKT. Indications included autosomal recessive polycystic kidney disease (n=3), primary hyperoxaluria type 1 (n=4) and heterozygous factor H deficiency with atypical haemolytic uraemic syndrome (n=1). Graft combinations included whole liver and one kidney (n=5), whole liver and two kidneys (n=1) and left lateral liver segment and one kidney (n=2), all from deceased donors. Patient age ranged from 4 to 17 years (median 9) and included 4 females and 4 males. Weight ranged from 13 to 42 kg (median 22.5). We describe one in-hospital mortality. The remaining 7 patients were long-term survivors with a survival range from 6 to 65 months. CONCLUSIONS: Although rarely indicated in children, CLKT is an effective treatment option, appropriately utilising a scarce resource and significantly improving quality of life in the recipient.