The Nobel Prize for Medicine was jointly awarded Monday to Shinya Yamanaka of Japan and John Gurdon of Britain for their groundbreaking contribution to stem cell research.

The two scientists discovered the missing part of the equation on regenerative medicine crucial to replacing tissue for victims of Alzheimer’s, Parkinson’s and other diseases, AFP reports.

“Their findings have revolutionised our understanding of how cells and organisms develop,” the Nobel jury said.

Gurdon, 79, had long researched stem cells. “I’m amazed and immensely grateful and astonished that they should recognize work done such a long time ago,” Gurdon told Swedish Radio.

Yamanaka, 50, left his profession to become a researcher after realizing he was not good at it. He recalls his failure to remove a benign tumor in his first operation as an orthopedic intern fresh out of Kobe University’s School of Medicine. A good doctor could finish the procedure in 10 minutes, Yamanaka said he had fumbled for more than an hour.

Yamanaka told reporters that he was “just an obscure researcher” determined to carry on his work. “I really feel that I have to realize a medical application and contribute to society as soon as possible”.