Here. I agree with their choice for number one.

1. Researchers Turn Skin Cells to Stem Cells

Using a virus to reprogram skin cells, two teams of scientists managed to skirt the greatest ethical issue facing regenerative medicine — the destruction of human embryos. Groups led by Shinya Yamanaka of Kyoto University and Junying Yu of the University of Wisconsin coaxed a type of skin cell called fibroblasts into forming muscle, heart, fat and nerve tissues without using any eggs. Unfortunately, the hijacked cells often became tumors. Following up on his initial discovery this November, Yamanaka told Nature Biotechnology that by inserting three growth genes instead of four, the lab-grown flesh can be controlled without becoming cancerous.