Evaluation of 2-Year-Old Intrasplenic Fetal Liver Tissue Transplants in Rats

Abstract

Liver cell transplantation into host organs like the spleen may possibly provide a temporary relief after extensive liver resection or severe liver disease or may enable treatment of an enzyme deficiency. With time, however, dedifferentiation or malignant transformation of the ectopically transplanted cells may be possible. Thus, in the present study syngenic fetal liver tissue suspensions were transplanted into the spleen of adult male rats and evaluated 2 years thereafter in comparison to orthotopic livers for histopathological changes and (as markers for preneoplastic transformation) for cytochrome P450 (P450) and glutathione S-transferase (GST) isoform expression. Because inducibility of P450 and GST isoforms may be changed in preneoplastic foci, prior to sacrifice animals were additionally treated either with beta-naphthoflavone, phenobarbital, dexamethasone, or the respective solvent. In the 2-year-old grafts more than 70% of the spleen mass was occupied by the transplant. The transplanted hepatocytes were arranged in cord-like structures. Also few bile ducts were present. Morphologically, no signs of malignancy were visible. With all rats, transplant recipients as well as controls, however, discrete nodular structures were seen in the livers. Due to age, both livers and transplants displayed only a low P450 2B1 and 3A2 and GST class alpha and mu isoform expression. No immunostaining for P450 1A1 was visible. At both sites, beta-naphthoflavone, phenobarbital, or dexamethasone treatment enhanced P450 1A1, P450 2B1 and 3A2, or P450 3A2 expression, respectively. No immunostaining for GST class pi isoforms was seen in the transplants. The livers of both transplant recipients and control rats, however, displayed GST pi-positive foci, corresponding to the nodular structures seen histomorphologically. Compared to the surrounding tissue, these foci also exhibited a more pronounced staining for GST class alpha and mu isoforms and a stronger inducibility of the P450 1A1 expression due to beta-naphthoflavone. In conclusion, in contrast to the livers, no preneoplastic foci seem to appear in the intrasplenic transplants even 2 years after transplantation. This may be due either to the protection of these transplants by the orthotopic livers or to the different humoral and nerval influences at the ectopic site.

Phases I-II Matched Case-Control Study of Human Fetal Liver Cell Transplantation for Treatment of Chronic Liver Disease

“…Immunosuppression was well tolerated, and no neoplasm developed in 1-year follow-up, as already found in clinical experience (16). No oncogenic transformation at least 2 years after intrasplenic fetal HT has been reported in animal models, or in culture, despite acquisition of cytogenic aberrations (17,27).…”

Surgical Model of in Vivo Culture of Stem Cells by Implantation of Fetal Organs into Adult Animals

“…Important too that the implantation site was well vascularized: under gland capsules or visceral peritoneum, or within the ear pavilion. Localizations in the spleen or liver or kidney superficial parenchyma are well known and also satisfy to the same criteria [23][24][25][26][27][28][29]. The subcutaneous ear pavilion seems to be an original implantation site and has shown different advantages: simple, easy to perform and not very traumatic operation, well tolerated by animals, allowing visual observation, measures, biochemical and physiological investigations of the implant, procurement of biopsy material.…”

“…They are low cost and simple execution. They are not exclusive: a lot of foetal organs was not tested here such as brain, kidney, lung, and other implantation sites are also possible, many of them having been mentioned in literature [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Our studies have many common features with organoid creation studies, except that the last are started in vitro and their growth can be obtained from other organs of the same embryonic sheet (for instance intestine crypt cells can give growth to pancreas) by experimental monitoring means [32].…”

Clinical applications of hepatocyte transplantation

“…Fetal liver cells have several advantages compared to adult liver cells: greater availability, proliferative capacity and plasticity, less immunogenicity, good adaptation and integration capacity, and greater resistance to cryopreservation and ischemia. Moreover, there are no reports of oncogenic transformation, at least 2 years after intrasplenic fetal hepatocyte transplantation, in animal models [25] . The use of cell transplantation for liver disease raises a number of expectations, though it is important that controlled studies designed on the principles of evidence-based medicine be done in order to guarantee the reproducibility of results.…”