Human hepatocytes in mice receiving pre-immune injection with human cord blood cells.
ABSTRACT It is well established that certain subpopulations of human adult stem cells can generate hepatocyte-like cells when transplanted into adult immunosuppressed mice. In the present study, we wanted to explore whether xeno-transplantation of human cord blood CD34(+) (hCBCD34(+)) cells during pre-immune stages of development in immunocompetent mice might also lead to human-mouse liver chimerism. Freshly isolated hCBCD34(+) cells were xeno-transplanted into non-immunosuppressed mice by both intra-blastocyst and intra-fetal injections. One and four weeks after birth, immunostaining for different human-specific hepatocyte markers: human hepatocyte-specific antigen, human serum albumin, and human alpha-1-antitrypsin indicated the presence of human hepatocyte-like cells in the livers of transplanted animals. Detection of human albumin mRNA further corroborated the development of pre-immune human-mouse chimeras. The current report, besides providing new evidence of the potential of hCBCD34(+) cells to generate human hepatocyte-like cells, suggests novel strategies for generating immunocompetent mice harboring humanized liver.
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ABSTRACT: Introduction: The mouse is a common model used in evaluating drug metabolism and hepatitis infectivity. However, these models have limited value due to species difference in hepatic functions, leading to the creation of the chimeric mouse 12 years ago. These models were unique in that their hepatocytes had been replaced with human (hu) hepatocytes (dubbed the 'first-generation chimeric mouse'). Since then, the chimeric mouse has become a practical tool for this area of studies. However, some shortcomings have also been recognized. One major shortcoming is that the mouse cannot mimic hu-liver diseases due to immunodeficiency and also it is unable to provide sufficient amounts of blood for analysis compared to the rat. There are also issues around donor-to-donor variability of hu-hepatocytes such as variable engraftment efficiency. Areas covered: This review provides the current status of the first-generation chimeric mouse. Furthermore, the authors review studies intended to create a 'second-generation of the chimeric mouse' in which inflammation/immune-response cells as well as hepatocytes are humanized. A brief comment is also made on studies aiming at producing chimeric rats. Finally, the authors consider induced pluripotent stem cells (iPS cells) as new sources of hu-hepatocytes. Expert opinion: The authors believe that the current rapid progress in the field of biotechnology should enable us to create a mouse model with a humanized liver that is made by iPS-derived hu-hepatocytes and hu-immune cells. This development will provide researchers with a model that will be able to effectively mimic human liver disease under experimental conditions.Expert Opinion on Drug Metabolism & Toxicology 08/2013; DOI:10.1517/17425255.2013.826649 · 2.93 Impact Factor
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ABSTRACT: The liver has an enormous potential to restore the parenchymal tissue loss due to injury. This is accomplished by the proliferation of either the hepatocytes or liver progenitor cells in cases where massive damage prohibits hepatocytes from entering the proliferative response. Under debate is still whether hepatic stem cells are involved in liver tissue maintenance and regeneration or even whether they exist at all. The definition of an adult tissue-resident stem cell comprises basic functional stem cell criteria like the potential of self-renewal, multipotent, i.e. at least bipotent differentiation capacity and serial transplantability featuring the ability of functional tissue repopulation. The relationship between a progenitor and its progeny should exemplify the lineage commitment from the putative stem cell to the differentiated cell. This is mainly assessed by lineage tracing and immunohistochemical identification of markers specific to progenitors and their descendants. Flow cytometry approaches revealed that the liver stem cell population in animals is likely to be heterogeneous giving rise to progeny with different molecular signatures, depending on the stimulus to activate the putative stem cell compartment. The stem cell criteria are met by a variety of cells identified in the fetal and adult liver both under normal and injury conditions. It is the purpose of this review to verify hepatic stem cell candidates in the light of the stem cell definition criteria mentioned. Also from this point of view adult stem cells from non-hepatic tissues such as bone marrow, umbilical cord blood or adipose tissue, have the potential to differentiate into cells featuring functional hepatocyte characteristics. This has great impact because it opens the possibility of generating hepatocyte-like cells from adult stem cells in a sufficient amount and quality for their therapeutical application to treat end-stage liver diseases by stem cell-based hepatocytes in place of whole organ transplantation. © 2012 International Society for Advancement of Cytometry.Cytometry Part A 01/2013; 83A(1). DOI:10.1002/cyto.a.22232 · 3.07 Impact Factor
Article: Hepatozytentransplantation*[Show abstract] [Hide abstract]
ABSTRACT: Hintergrund:Die Transplantation von Hepatozyten stellt heute eine aussichtsreiche experimentelle Methode zur Zelltherapie bei Lebererkrankungen dar. Dabei werden die Zellen aus Organen, die nicht für die Lebertransplantation freigegeben werden, isoliert und einem geeigneten Empfänger in die Leber implantiert. Im Idealfall übernehmen die transplantierten Zellen die Funktion des erkrankten Organs und stellen somit die Organleistungen entweder dauerhaft oder für die Zeit der Überbrückung bis zur Lebertransplantation wieder her. Methodik und Ergebnisse:Obwohl weltweit bisher ca. 50 Fälle der klinischen Anwendung der Hepatozytentransplantation dokumentiert sind, ist der therapeutische Erfolg bis heute zweifelhaft. Die Ursachen dafür sind weitgehend unbekannt, liegen aber möglicherweise in der unzureichenden Qualität der aus marginalen Lebern gewonnenen transplantierten Zellen. Deshalb werden zurzeit im Tiermodell neue Verfahren zur Transplantation erprobt, die u. a. auch Aufschluss über den Mechanismus der Integration der transplantierten Zellen in der Empfängerleber geben sollen. Diese Kenntnis wird es ermöglichen, in Abhängigkeit von der Grunderkrankung der Leber individualisierte Methoden zu entwickeln, die den transplantierten Zellen einen Wachstumsvorteil verschaffen und so die effiziente Besiedlung der Empfängerleber ermöglichen. Perspektiven:Stammzellen scheinen aufgrund ihrer Plastizität und ihrer Proliferationsfähigkeit zur Herstellung von Hepatozyten besonders gut geeignet zu sein. Deshalb wird auch die Möglichkeit untersucht, aus Stammzellen unterschiedlicher Herkunft Hepatozyten zu generieren, die künftig in der Zelltherapie bei Lebererkrankungen Verwendung finden könnten. Background:Transplantation of hepatocytes is considered a promising technology for the cell therapy of liver diseases. Cells are isolated from donor livers, which are not allocated for organ transplantation and transplanted into the liver of a suitable recipient. Ideally, the transplanted cells functionally replace the hepatocytes of the diseased organ and restore its metabolic capacity either permanently or for a period of bridging to organ transplantation. Methods and Results:Although about 50 cases of clinical hepatocyte transplantation have been documented, therapeutic benefit is doubtful, and the reasons for this are largely unknown. Minor quality of the transplanted cells isolated from marginal donor livers may be a major cause. Therefore, animal models have been established, which enable scientists to develop novel procedures of hepatocyte transplantation and to specifically study the mechanisms of hepatocyte integration in the host liver. Hopefully, results generated in animal models will set the basis for the design of novel procedures of hepatocyte transplantation individualized to the underlying disease in order to provide a growth advantage for donor over host cells. Perspectives:The plasticity of stem cells and their proliferative potential is the basis for current efforts to generate stem cell-derived hepatocytes of transplantation quality for the treatment of liver diseases.09/2005; 100(10):650-655. DOI:10.1007/s00063-005-1088-z