Almost a real liver "in vitro"
Takanori Takebe from Yokohama City University presented the results of the work devoted to the creation of liver tissue from induced pluripotent stem cells (iPSC) at the X Congress of the International Society for the Study of Stem Cells (ISSR) held on June 13-16 in Yokohama.
As part of the study, scientists working under the leadership of Hideki Taniguchi obtained induced pluripotent stem cells by reprogramming adult human skin cells. After 9 days of cultivation in a specially selected medium, iPSCs began to express a marker of maturing hepatocyte liver cells.
At this stage, scientists introduced two additional types of cells into the cultures, known for their ability to stimulate the regeneration of organs: endothelial cells lining the inner walls of blood vessels isolated from umbilical cord blood, and mesenchymal stem cells derived from bone marrow, capable of differentiating into cells of bone, cartilage and adipose tissue. Within two days, the cells formed a five–millimeter three-dimensional fragment of tissue - the rudiment of the liver, corresponding to the early stage of development of this organ.
The rudimentary liver obtained by the authors is still very far from a full-fledged organ: it does not have bile ducts, and its cells do not form neat plates that make up the tissue of a mature liver. At the same time, it is permeated with blood vessels, the functionality of which was confirmed during transplantation of the rudiment of the liver under the skin of a mouse.
The results of genetic testing indicate that the cells of the resulting tissue express many genes active in the cells of the real liver. When transplanted to mice, this tissue provided the metabolism of a number of drugs that are usually cleaved by human, but not cleaved by mouse liver.
According to Takebe, the success of creating functioning liver tissue from induced pluripotent stem cells depends on the exact timing of the introduction of additional cells into the culture, and the development of an appropriate protocol required more than a year and several hundred experiments.
The developers expect that in the future, the three-dimensional tissue structures obtained using the method they developed can be used to temporarily replace the non-functional liver of patients waiting for suitable donor organs for transplantation, or in cases where doctors hope for the restoration of the patient's own liver. However, to do this, it is necessary to improve the technology, including to ensure that the emerging rudiment of the liver contains bile ducts. Scientists plan to devote their further work to this, and at this stage they hope that the rudiment of the liver can be used for toxicity testing during screening of potential pharmacological drugs.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on Nature news: Rudimentary liver grown in vitro.
26.06.2012