The National Center for Child Health and Development in Tokyo announced it has successfully conducted a clinical trial to transplant liver cells created from human embryonic stem cells into a baby with a serious liver condition.
It is the first clinical trial in Japan to use human embryonic stem cells, and is also believed to be the first case in the world of liver cells produced from embryonic stem cells being transplanted into a person.
The baby that received the transplant had hyperammonemia, a condition in which an abnormality in the natural urea cycle prevents toxic ammonia from being broken down in the liver. The abnormality is said to be prevalent in between one in 8,000 and one in 44,000 people.
In serious cases a liver transplant is required to treat it, but newborns have a high risk of experiencing major side effects. As a result, transplants cannot be conducted safely until several months after birth, when the baby weighs 6 kilograms or more.
In Europe and North America, doctors have utilized translational medicine, in which normally functioning liver cells are transplanted into newborns, to keep the liver functioning until an organ transplant can be carried out. In Japan, the National Center for Child Health and Development has previously transplanted liver cells from living donors into newborns with the condition soon after birth, but it has had difficulty in steadily securing liver cells.
Because of this, the center drew up plans to create liver cells from embryonic stem cells and transplant them. Over a period of two days in October 2019, it injected about 190 million liver cells into blood vessels in the umbilical cord of a 6-day-old newborn with hyperammonemia. The ammonia concentration in the infant's blood then stopped rising, enabling researchers to confirm that the liver cells had reached the newborn's liver, and the baby was temporarily discharged from the hospital.
Five months later, when the baby weighed 7 kilograms, a living donor liver transplant was carried out with the baby's father serving as the donor. The baby was again able to be discharged from the hospital in late April.
The center has received approval from the national government to use liver cells derived from embryonic stem cells in regenerative medicine, and plans to transplant them into several people subject to clinical trials in the future.
Center official Mureo Kasahara of the national center's organ transplant center commented, "It was often the case that babies with this condition died from seizures or suffered brain damage before the liver transplant could take place. The latest case is hugely significant in that we have proved the effectiveness of the method."
(Japanese original by Ayumu Iwasaki, Science & Environment News Department)