A group of researchers in Japan says it is a step closer to applying iPS cell technology to help people with liver diseases. It says it has successfully created tiny livers that function as efficiently as human livers.

The group at Yokohama City University is led by Professor Hideki Taniguchi. It is working on creating "mini livers" with a size of several millimeters, using iPS cells. The induced pluripotent stem cells can develop into various kinds of body tissue.

The researchers say they have succeeded in improving the function of mini livers by using blood vessel cells also generated from iPS cells.

They say the mini livers can convert ammonia into harmless substances at the same level as cells in human livers.

They also say the capability of the mini livers to generate albumin, a type of protein in blood, doubled.

The team hopes to start a clinical study in fiscal 2019. They plan to transplant multiple tiny livers into patients with severe liver failure.

Professor Taniguchi says his team will further study how to control the risk of iPS cells generating tumors.