Bone growth is induced by nail transplantation in amputated proximal phalanges

Mammals are able to regrow the tips of amputated fingers and toes. However, regrowth is limited to regions covered by, and is dependent upon, the presence of the nail organ. If the nail organ is responsible for bone growth in digit-tips, we reasoned that transplanted nail organ might also be able to induce outgrowth from other levels of the digit. Partial nail organ has been transplanted to amputated proximal phalanges of young rats. To date, six transplants have successfully produced outgrowth of nail. New bone growth, not seen in control amputated digits, was documented by x-ray and by alizarin red and calcein injections to be directed toward implanted nail organ. These results support an inductive role for nail organ epithelium in bone growth after amputation and provide encouragement for attempts to enhance a positive outcome after appendage amputation.