"When I saw the embryo, I suddenly realized there was such a small difference between it and my daughters. I thought, we can't keep destroying embryos for our research. There must be another way," this was Dr Shinya Yamanaka, a father of two, in an interview in The New York Times in 2007.

These words of Dr Shinya Yamanaka, the winner of Nobel Prize for Physiology or Medicine in 2012, sum up the reason that inspired him to discover that adult skin cells can be reprogrammed into embryonic-like stem cells. The discovery, a revolutionary work in the field of stem cell research, gave an alternative to using human embryos for growing stem cell, allowing researchers to side-step the ethics debate related to the use of embryos and heralded a new era of research into regenerative medicine.

Dr Yamanaka, director of Center of iPS Cell Research and Application, Kyoto University, Japan, shared the Nobel Prize with British researcher Sir John B Gurdon who established the principle of gene conservation in differentiated cells. Sir Gurdon's work was published in 1962, the year Dr Yamanaka was born in Osaka, Japan. Half a century later and taking forward the work started by Sir Gurdon, Dr Yamanaka achieved a technological feat in 2006 when he and Dr Kazutoshi Takahashi generated what they named induced pluripotent stem cells or iPS cells by introducing four genes (now referred to as the Yamanaka factors) into mouse fibroblasts, which are a kind of connective-tissue cell (in this case, they were skin cells). They repeated the same feat with human cells, reprogramming adult skin cells into iPS cells that are comparable to human embryonic stem cells.

Dr Yamanaka, who is also a senior investigator at Gladstone Institutes in San Franscisco, California, US, described a modified protocol for generation without the c-Myc retrovirus, which is capable of forming tumors. Later he used this protocol to generate virus-free iPS cells in 2008. In another breakthrough in July of 2012, Dr Yamanaka's laboratory at Gladstone Institutes provided an insight into how iPS cells develop and proved that environmental factors critically influence their growth. This is a significant step towards using stem cell-based therapies for combating diseases.

"I will bring this technology to clinics. I really want to help as many patients as possible. As you may know, I started my career as a surgeon 25 years ago. But it turned out that I am not talented as a surgeon. So I decided to change my career, from clinics to laboratories. But I still feel that I am a doctor, I am a physician, I really want to help patients," said Dr Yamanaka after he was named the winner of Nobel Prize for Physiology on October 8, 2012.