Man Grows Own Replacement Thumb (With a Little Help From Science)

As reported in the May 17, 2001 issue of the New England Journal of Medicine, doctors have successfully grown a replacement thumb bone using tissue from the patient's own body. Our health correspondent Dr. Emily Senay explains.

Raul Murcia became the first human to undergo the experimental procedure after losing his thumb in a machine accident. Doctor Charles Vacanti at the University of Massachusetts pioneered the procedure.

To engineer new bone, Vacanti first placed a small sample of cells from the patient's arm bone in the laboratory to culture and multiply. Then during surgery, a sea coral scaffold was sculpted into the shape of the missing thumb bone and implanted into Mercia's thumb. The patient's own bone cells grown in the lab were then injected onto the scaffold. The hope was that the bone cells would grow a blood supply and the coral scaffold would slowly melt away, leaving behind a new living thumb bone.

Now, 28 months after the surgery, the patient is able to use his thumb relatively normally, though there is some decreased sensation on one side. And the doctors say the experiment in tissue engineering is working! The patient's own bone cells are slowly taking over the coral scaffold and the researchers predict that this will continue so that eventually all that will be left will be a thumb bone with healthy bone cells and no coral.

So essentially, this guy grew a new thumb? Why use coral?

Coral is very much like human bone actually, and the body does not reject it. It is conducive to allowing new bone growth.

Why not use bone from cadavers?

That has been tried and there are several shortcomings, one of which is the possibility to exposing the recipient to disease. In addition, the body can reabsorb cadaver bones taken from one part of a patient's body and put in another part. So tissue-engineered bone that could be used as replacement bone for damaged or diseased bones would be very useful.

Will this be commonly used now?

This case is proof of the principle of tissue-engineered bone. What must happen now is, additional experiments must be done that perfect the procedure. Vacanti's team is applying to the Food and Drug Administration to do additional procedures on larger bones so that more can be learned.

Does this mean we will eventually be seeing the regeneration of amputated limbs?

Tissue-engineered body parts are increasingly the focus of research. This area is still in its infancy but the whole area of research has been given a big boost with the discovery of stem cells--cells that can be grown in the lab to become any type of cell. So I suspect that this area will continue to provide advances that not only allow replacement bone but also replacement heart tissue, liver tissue, etcetera.

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