In utero hepatocellular transplantation in rats.

This work represents a step forward in the experimental design of an in utero hepatocellular transplantation model in rats. We focused on the enrichment optimization of isolated fetal hepatocytes suspension, arranging the surgery methodology of in utero transplantation, monitoring the biodistribution of the transplanted hepatocytes, and assessing the success of the transplants. Rat fetuses have been transplanted at the 17th embryonic day (ED17) with fetal hepatocytes isolated from rats at the end of pregnancy (ED21). We assessed possible differences between lymphocyte population, CD4 positive, CD8 positive, double-positive T-cells, and anti-inflammatory cytokines interleukins 4 and 10 (IL4 and IL10) as well. Cellular viability reached the rates of 90-95%. Transplanted groups had a limited success. Transplanted hepatocytes were not able to pass through the hematoplacental barrier. The hepatocytes injected were primarily located in the liver. There was an upward trend in the whole amount of T CD4 and T CD8 cells. There was an increased IL4 in the transplanted groups observed in the pregnant rats. The possibility to induce tolerance in fetuses with a hepatocyte transplant in utero could be a key point to avoid the immunosuppression treatments which must be undergone by transplanted patients.

Survival of allogeneic hepatocytes transplanted into the thymus.

BACKGROUND/AIM: Currently, when cell therapy is being considered instead of liver transplantation to treat terminal liver diseases, complete knowledge of the evolution and behavior of ectopically transplanted hepatocytes is a subject of utmost interest in the design of clinical trials. Hepatocytes survive in ectopic locations and have a therapeutic effect in different experimental models. Although it offers remarkable advantages over liver transplantation, hepatocyte transplantation presents several problems, among them the number of cells that can be injected at once and their rejection. Our main objective was to study the survival and functionality of hepatocytes transplanted into the thymus and, secondarily, to test whether the intrathymic transplant could induce any tolerogenic effect. METHODS: Hepatocytes from F344 rats were transplanted into thymuses of Gunn rats, half of which received a unique dose of cyclosporine A. The recipients were sacrificed at different times. Light microscopy was performed and bilirubin levels were determined in serum and bile. RESULTS/CONCLUSIONS: Transplanted hepatocytes survive for at least 6 weeks in the thymus of allogeneic animals without immunosuppressive therapy. The work provides interesting data about the behavior of hepatocytes injected into this unique ectopic site and shows that the thymus can be used as a recipient organ for cell therapy.

Functional response of hepatocytes transplanted into Gunn rats stimulated with thyroid hormone.

In the attempt to translate laboratory studies into clinical practice, the small number of cells that can be transplanted is currently a problem to be solved. The aim of this work is to study the functional response of intrasplenically transplanted syngeneic rat adult and fetal hepatocytes to a proliferative stimulus, 3,5,3'-triiodothyronine. Total serum bilirubin significantly decreased from 7 to 90 days after fetal hepatocyte transplantation and from 24 hr to 30 days after adult hepatocyte transplantation. Concomitant with these changes, bile conjugated bilirubin increased from 7 to 90 days after fetal and from 24 hr to 30 days after adult hepatocyte transplantation. In both cases, administration of thyroid hormone enhances this effect. We conclude that although adult and fetal hepatocytes correct the hyperbilirubinemia, fetal cells function longer than adult hepatocytes. Thyroid hormone is a powerful stimulator of function of hepatocytes since it improves both adult and fetal response.