Strategies for liver support: from stem cells to xenotransplantation

Xenotransplantation of human cultured parathyroid progenitor cells into mouse peritoneum does not induce rejection reaction

INTRODUCTION

Parathyroid progenitor cells devoid of immunogenic antigens were used for human allotransplantation. Although there were many potential reasons for the expiry of transplant activity in humans, we decided to exclude a subclinical form of rejection reaction, and test the rejection reaction in an animal model.

MATERIAL AND METHODS

Experiments were carried out on 40 conventional male mice in their third month of life. The animals were housed in groups of 10 per cage in 4 cages with fitted water dispensers and fed a conventional diet based on standard pellet food. They were divided into four groups of 10 animals each, three experimental groups and one control group. Identified progenitor cells were stored in a cell bank. After testing the phenotype, viability, and absence of immunogenic properties, the cells were transplanted into mouse peritoneum cavity.

RESULTS

Animals were observed for 9 weeks. At 9 weeks of observation, the mean serum PTH concentration in the experimental groups was 2.0-2.5 pg/ml, while in the control group it did not exceed 1.5 pg/ml. The immunohistochemical assays demonstrated that millions of viable cells with a phenotype identical to the endocrine cells had survived in the peritoneum. Histologic specimens from different internal organs stained for PTH revealed positive cells labelled with anti-PTH Ab in the intestinal lamina, brain, liver, and spleen.

CONCLUSIONS

In the present paper we have demonstrated that xenotransplantation may be used as a model for an explanation of the immunogenic properties of cells generated from postnatal organs for regenerative therapy.

Experimental hepatology applied to stem cells

Transplantation is an accepted treatment today for many people suffering from organ failure. More and more patients are referred for transplant surgery, and the waiting lists are growing longer because not enough organs and tissues are donated for transplantation. This has led to several potentially viable alternatives being considered, including bio-artificial support devices, the transplantation of mature cells or stem/progenitor cells and the potential transplantation of xenogenic organs and cells [Burra P, Samuel D, Wendon J, Pietrangelo A, Gupta S. Strategies for liver support: from stem cells to xenotransplantation. J Hepatol 2004;41:1050-9]. Numerous investigators around the world are engaged in these investigations and the pace of discovery has begun to accelerate in recent years. To take stock of the achievements of recent years, the AISF sponsored a Single-Topic Conference, held in Padua on 26-27 May, 2006, with the participation of many leading investigators from various parts of Italy and Europe. This present paper summarizes the content of the Conference. Different issues were analysed, from the biology of stem cells to the possible use of gene therapy. The speakers were clinicians and scientists interested in diseases not only of the liver but also of other organs such as the kidney or heart. The fact that numerous specialties were represented helped the audience to understand the stem cell research area from different standpoints, and what research has achieved so far.