Researchers have demonstrated a novel way of using porous structures as a drug-delivery vehicle that can help boost the integration of host tissue with surgically implanted titanium, according to an article published online Jan. 15 in The Journal of the Federation of American Societies for Experimental Biology.
Instead of being acted on by the body as an impenetrable foreign object, the synthetic bone replacement—currently being tested in rabbits—features a porous material that allows for the delivery of "micro-encapsulated bioactive cues" that speed up the growth of host tissue at the site and allow for the growth of new bone.
Dr. Jeremy Mao, professor, Columbia University College of Dental Medicine, New York City, and colleagues reported that after just four weeks, the porous implants showed a 96 percent increase in bone-to-implant contact and a 50 percent increase in the growth of new bone over placebos.
A critical finding, according to the investigators, is that the drug dose needed for host tissue integration by this controlled-release approach is about one-tenth of that needed by the traditional technique of simple adsorption of the growth factor.
Because stem cells play a vital role in the growth of new bone, Dr. Mao and colleagues have focused on impregnating the titanium implants with a factor that "homes" the body’s own regenerating cells to the potential growth site to create and build on a platform for new bone.
This new approach may eliminate the need to harvest bone from a noninjured site in the body for grafting into the site of injury, as is commonly performed now. This work suggests that it should be possible to harness the body’s natural tissue regeneration capacity to recruit the right cells to the site where new bone tissue is needed.
Implants that naturally attract the mesenchymal stem cells that can differentiate readily into bone, fat, cartilage and other types of cells could be the way of the future, said Dr. Mao. "In comparison with donor site morbidity and pain in association with autologous tissue grafting, synthetic materials have the advantage of ready and endless supply without any sacrifice of donor tissue," he added.
"This is a hybrid approach releasing biological cues from existing orthopedic and dental implants to recruit the body’s own stem cells," Dr. Mao said.
This research was supported by U.S. National Institutes of Health grants DE015391 and EB02332 to Dr. Mao and colleagues.
