Liver cell created from subcutaneous fat
A team of doctors has succeeded in creating a hepatic cell out of subcutaneous fat, a development that might lead to a regenerative medicine technique that would enable patients with hepatitis or cirrhosis to have their livers repaired.
More than 3.5 million people in Japan suffer from the diseases, and clinical application of the team's findings is being eyed for sometime in the next few years.
According to the National Cancer Center Research Institute and the International Medical Center of Japan, the doctors used a cell called mesenchymal stem cell that accounts for about 10 percent of the subcutaneous fat tissue of a human body, believing the cell has the potential to change into different cells that make up various organs or other tissues. In the research, five grams of subcutaneous fat was taken from each of seven patients who underwent abdominal surgery at the International Medical Center of Japan, and the mesenchymal stem cells were extracted from the fat tissues.
The researchers added three types of proteins that prompt growth to the stem cells, and incubated them for about 40 days.
As a result, nearly all cells turned into hepatic cells, according to the doctors.
At least 14 types of proteins, including albumin--one of the major components of blood--and drug-metabolizing enzyme, that are known to be synthesized only in the human liver, were detected in the incubated cells, the doctors said. Then the researchers injected about 1 million incubated cells into lab mice that were artificially made to develop liver malfunctions.
The ammonia level in the mice, which had been rising before injection, dropped to a normal level in one day, the doctors said.
Regenerated subcutaneous fat cells have already been used in some clinical practices such as breast reconstruction, but this is the first time in the world that more than one function for the human liver has been observed in the regenerated cells, according to the research team.
While the most highlighted technique in regenerative medicine is embryo-stem cell development, it has been criticized because it utilizes fertilized egg cells.
The use of subcutaneous fat cells, on the other hand, faces fewer obstacles in terms of life ethics, and are advantageous because they can be taken from patients' own bodies to eliminate the risk of rejection, the doctors said.
Takahiro Ochiya, head of the Section for Studies on Metastasis Research at the National Cancer Center Research Institute, who led the team of researchers, said: "I would give 60 out of 100 if I were to grade the hepatic cells we made from subcutaneous fat for their performance. They barely pass the test at the moment, but we would like to go on working to make cells that perform like real hepatic cells."
Yasuyuki Sakai, associate professor of the Center for Disease Biology and Integrative Medicine at the University of Tokyo, hailed the team's findings as a "remarkable achievement," but pointed out that several issues need to be addressed before clinical application. "To achieve a certain level of therapeutic effect from a patient with liver disease, more than 10 billion hepatic cells have to be implanted into his or her liver. To reach the goal of clinical application, researchers must develop a technique to more efficiently make hepatic cells from a large amount of subcutaneous fat," Sakai said.
