Stem Cell 'Homing' Fixes Joints in Rabbit Experiments

July 29, 2010— -- Researchers are reporting they have successfully persuaded damaged joints to regrow cartilage and bone using a novel "cell homing" approach.

The experiments, conducted in rabbits, are a proof of concept of a method that may one day replace artificial joint transplants in humans, according to Jeremy Mao of Columbia University and colleagues.

The method uses a carefully constructed "bioscaffold," impregnated with a natural substance called a growth factor. the growth factor in the scaffold causes precursor cells to migrate to the site and become cartilage and bone cells, Mao and colleagues wrote online in The Lancet.

In contrast with previous attempts to regrow tissue in joints, the researchers reported that they did not transplant any cells.

Animals treated with the method fully recovered weight-bearing and locomotion within a month, and the regenerated tissue was similar to naturally occurring cartilage and bone, the researchers said.

The findings are "a substantial step" toward being able to grow individually customized replacement joints for patients who now would be treated with total joint replacement, according to Dr. Patrick Warnke of Bond University in Gold Coast, Australia.

Warnke led researchers who in 2004 reported growing a mandible bone in the muscle tissue of a man who had a defect in the mouth after cancer surgery. The bone was later transplanted successfully to the man's jaw.

The new research, Warnke wrote in an accompanying editorial, "offers new insights into in-vivo tissue engineering."

In the experiments, the researchers first used laser scanning and computer-aided design to construct an anatomically correct model of the surface of a joint found in the front legs of rabbits out of a mixture of polyester and bone.

In 20 animals, the entire joint surface of this leg joint was surgically removed and replaced with these bioscaffolds. Half of these contained the growth factor, while half did not. Three other animals underwent the surgery and had no implant.