It's part of the hot field of tissue regeneration, trying to regrow all kinds of body parts.

WSJ: Scientists use 3-D printing to help grow an ear

"Advances in medicine are being made every day in different areas, whether it's tissue transplantation or tissue regeneration, " he said.

CNN: Iraq vet undergoes successful double-arm transplant

"It was a mixture of elation and, for lack of a better word, terror, " said Hollister, a professor of biomedical and mechanical engineering who has been studying tissue regeneration for more than 15 years.

CNN: 3-D printer helps save dying baby

Investors should take careful notice of the field of tissue regeneration: companies like Advanced Tissue Sciences (nasdaq: ATIS - news - people ) and Organogenesis (amex: ORG - news - people ) that try to use skin stem cells to create replacement skin for burn victims.

FORBES: Hold Off On Investing In Stem Cells