Sheep as a Model for Liver Transplantation.

OBJECTIVE: Experimental animal liver transplantation is the initial step, before the application of the procedure on humans. Canine and swine transplantation were used to perfect the technical aspects of the procedure. Small animals such as rats were mainly utilized to study the metabolic and immunological aspects of liver transplantation. In this paper, we describe our experience with attempting liver transplantation in a sheep animal model. MATERIAL AND METHOD: The animal model used for both donor and recipient was outbred male weanling sheep of Naimi strain (Ovis aries, Awassi). They weigh between 25 and 35 kg. They were put under general anesthesia. Harvested livers were kept in cold storage. Recipients underwent hepatectomy, after construction of an active portal systemic bypass using a Medtronic pump. The implantation was done with caval replacement and direct portal anastomosis. The hepatic artery with its attachments to the aortal was anastomosed directly to the recipient aorta. RESULT: Twelve pairs (24 sheep) were utilized for donor and recipient surgery. Donor surgery was completed successfully in all 12 cases. Recipient surgery was not completed in three cases, when animals were lost in the implantation phase, before reperfusion mainly due to uncontrolled bleeding, resulting in hemodynamic instability. We also lost five recipients immediately after reperfusion, mainly due to post-perfusion bleeding and hemodynamic instability. Four recipients stayed alive after the implantation. CONCLUSION: We demonstrated the feasibility of using sheep as an animal model for liver transplantation. We described the similarities of sheep liver to that of humans, as well as the technical difficulties. This model is suitable in situations where other well-established models are not available for cultural or religious reasons. Further refinement in the technical aspects will be needed, as well as investigation of the biochemical outcome and long-term survival.

Tacrolimus-Induced Neurotoxicity in Early Post-Liver Transplant Saudi Patients: Incidence and Risk Factors.

BACKGROUND Tacrolimus is a calcineurin inhibitor (CNI) commonly used as an immunosuppressant to prevent the rejection of organ transplants. After liver transplantation, it can cause early neurological complications, known as early calcineurin inhibitor-induced neurotoxicity (ECIIN). Its management requires CNI withdrawal, a measure that can affect post-transplant outcomes, primarily allograft rejection. In addition, it can negatively impact the quality of life. The incidence and risk factor of ECIIN has not been reported in the Saudi population. We investigated the incidence and risk factors of ECIIN after liver transplant in Saudi patients. We also looked at the length of stay in the Intensive Care Unit, hospital, and 30-day mortality as secondary endpoints. MATERIAL AND METHODS This was a retrospective cohort study of adult patients on tacrolimus with mild, moderate, or severe neurological events within the first month after liver transplantation at a single center of patients who meet the inclusion criteria and were over age 14 years. A total of 338 patients were included in the analysis, and the sample size was calculated based on a pilot study. RESULTS Among 338 liver transplantation patients, 63 patients (19%) developed ECIIN. Forty-eight percent of patients had seizures, 23% had agitation, 21% had psychosis, 10% had severe tremors, 13% had confusion, and 6% developed coma. The median time of the incident to develop ECIIN was 9 (IQR: 5-13.5) days after transplant. Thirty-eight patients were managed by switching to cyclosporine, 12 required a reduction in the dose, and 3 were managed temporarily by discontinuing therapy. Autoimmune hepatitis as an underlying liver disease was one of the statistically significant risk factors (P=0.0311). The median length of hospital stay was 31 (IQR: 21-75.5) days, ICU length of stay was 10 (IQR: 5-20.5) days, and 8 patients died within 30 days after transplant. CONCLUSIONS The incidence of ECIIN in Saud Arabia was similar to that reported in other populations with similar risk factors. Electrolyte imbalance, mainly hyponatremia, was significantly associated with developing ECIIN. Therefore, ECIIN may potentially increase hospital and ICU length of stay.

Mycobacterium tuberculosis DNA in living donor transplanted livers and donor-related tuberculosis in recipients: A retrospective longitudinal cohort study.

OBJECTIVES: Mycobacterium tuberculosis DNA has been detected in multiple organs in people without active tuberculosis or a history of tuberculosis. Molecular testing for metabolic activity has suggested that M tuberculosis DNA represents viable bacilli. Whether transplanted organs with M tuberculosis DNA can result in tuberculosis in recipients has not been assessed. METHODS: Biopsies obtained at the time of living donor liver transplantation were tested for the presence of M tuberculosis DNA using in situ PCR. The cohort of recipients was longitudinally followed for the development of tuberculosis. RESULTS: Living donor liver transplantation was performed for 270 patients. Mean age was 33 years (median: 41 years, range: 1-80 years). Recipients were followed for a mean of 68 months (median: 72 months, range: 1-138 months) after transplantation. Mycobacterium tuberculosis DNA was detected in 25 of 155 donated livers (16%) with liver biopsies available for testing. None of the recipients of these livers received tuberculosis chemoprophylaxis and only one (4%) developed tuberculosis 15 months after transplantation. Among the entire cohort of 270 patients, post-transplant tuberculosis was diagnosed in four patients (1.48%) at an incidence rate of 2.61 cases per 1000 transplant-years. No factors associated with developing tuberculosis were identified, including positive M tuberculosis DNA in transplanted livers. CONCLUSIONS: Mycobacterium tuberculosis DNA in living donor transplanted livers did not result in tuberculosis despite post-transplant immunosuppression.