Abstract
Ammonia is a toxic substance that results from the metabolism of proteins. The liver is responsible for the metabolism of ammonia, which can be harmful to the body. Within hepatocytes, toxic ammonia is converted into urea, by the action of the multiple enzymes involved in the urea cycle, and subsequently excreted in urine. However, patients with gene mutations in their urea cycle enzymes have abnormal ammonia metabolism, which leads to hyperammonemia. While liver transplantation is the best option for treating urea cycle disorders, it is limited by donor availability. Following the advances in stem cell technology, a new method has been developed to create a three-dimensional tissue (an organoid) with functional liver characteristics. Because this organoid is generated from human iPS cells, using it avoids donor availability issues. In this paper, we outline the research progress on urea cycle disorders and discuss the possibility of treating them using organoids derived from human iPS cells.
