Creating a bank to store a new type of stem cell produced from donors' ordinary skin cells could help reduce time and money for treating patients with regenerative medicine in the future, a Japanese researcher said on Wednesday.

This would be more practical than tailor-made treatments for individual patients, said Shinya Yamanaka of Kyoto University.

Yamanaka led one of two teams that in November unveiled how to transform ordinary human skin cells into cells that look and act like embryonic stem cells, but without using cloning technology or human embryos.

Stem cell research has stirred up ethical debate, though the field received a boost when Yamanaka's team and another from the United States reported their findings separately last year.

The new cell type, called induced pluripotent stem cells (iPS cells), have fuelled hopes for regenerative medicine, although researchers say it will take years before such medicine can be used to treat people. "It may be a good idea to make an iPS cell bank," Yamanaka told a news conference.

"By making such a bank, we can cut down the cost of treatment and also we can shorten the period which is required for the generation of iPS cells," he said.

"In reality, tailor-made medicine using iPS cells is not so ideal."

Scientists hope iPS cells will improve disease research and pave the way for treating people with injuries as well as diseases such as Parkinson's and diabetes.

But Yamanaka said it takes about three months to transform a patient's skin cells into iPS cells, which is too much time when considering that these cells may be needed within 10 days to treat a spinal cord injury.

Yamanaka said it may take 10 years, or even longer for some diseases, before iPS cells can be used to treat humans.