UPDATE: Instalanche! Thanks for the links, Glenn, both here and on the new Better All the Time, which features a roundup of good news related to that most irreplaceable of parts -- the human brain.

This really got my attention:

In his lab at Wake Forest University, a lab he calls a medical factory, Dr. Anthony Atala is growing body parts.

Atala and his team have built, from the cell level up, 18 different types of tissue so far, including muscle tissue, whole organs and the pulsing heart valve of a sheep.

"And is it growing?"...

"Absolutely," Atala said, showing him, "All this white material is new tissue."

"When people ask me 'what do you do,' we grow tissues and organs," he said. "We are making body parts that we can implant right back into patients."

Dr. Atala, one of the pioneers of regeneration, believes every type of tissue already has cells ready to regenerate if only researchers can prod them into action. Sometimes that prodding can look like science fiction.

Emerging from an everyday ink jet printer is the heart of a mouse. Mouse heart cells go into the ink cartridge and are then sprayed down in a heart shaped pattern layer by layer.

Dr. Atala believes it's a matter of time before someone grows a human heart.

How big a deal is this? Consider this analysis, found on Dr. Atala's site at Wake Forest University:

The Joint Commission for Health Care Organizations (JCAHO) recently declared the shortage of transplantable organs and tissues a public health crisis. There is about one death every 30 seconds due to organ failure, and complications and rejection are still significant problems. The national cost of caring for persons who might benefit from engineered tissues or organs has reached $600 billion annually.

If this research leads to the ability to grow new kidneys, patients with severe kidney disease will be able to get replacement kidneys without a healthy person having to give one of theirs up. If this research leads to the ability to grow new hearts, patients with severe heart disease will be able to get replacement hearts without someone having to die.

Call me easily excited, but that strikes me as a distinct improvement.

Plus the patients will benefit from the elimination of all the complications associated with organ rejection. I don't think there will be much of a problem with people's bodies rejecting their own organs.

Additionally, this research seems likely to lead to some breakthroughs in life extension -- at least a stop-gap version of life extension wherein patients can replace parts as they go and keep the overall system functioning. Moreover, there may be some key parts of the body which, if replaced with new versions, can "trick" the body into thinking its younger than it really is. Clearly a new heart or kidney won't have that effect, but what would a brand new pituitary gland do? Also, could regeneration techniques help mitigate damage to the brain cause by Alzheimer's or Parkinson's?

Stay tuned.