Coming Soon: Grow Your Own Joint Replacement
In the next few weeks, the researchers in Dr. Farshid Guilak’s lab at Duke University, which is funded, in part, by the Arthritis Foundation, aim to take stem cells that they have culled from body fat, bathe them in growth factors that will instruct them to form cartilage, and then seed them in a three dimensional scaffold made of polyester fibers that will slowly dissolve in the body.
The scaffold will be woven in a hemispheric shape meant to mirror the curve of the natural cartilage pad, or “ball”, that caps the end of a dog’s femur where it attaches to the “socket” of the hip.
After the scaffolds are surgically implanted, the researchers will watch to see if the cells are growing properly and if the scaffold they have built can withstand the biomechanical wear and tear of a working joint while stem cells are building new cartilage.
If the experiment is successful, Dr. Guilak and his team will be among the first to grab an important brass ring in biomedical engineering – the regeneration of tissue that looks and acts like natural cartilage to replace worn out or damaged surfaces in joints.
“Our goal is to try to totally replace the joint biologically,” Dr. Guilak, who is director of orthopedic research at Duke University Medical School, said. “We want to treat osteoarthritis with stem cells.”
Stem cells are the mother cells of every tissue in the human body, and they are found in many different kinds of tissues, including muscle, brain and blood. Initially scientists thought stem cells could only recreate the kind of tissue from which they were taken, but that turns out not to be the case.
When treated with the right growth factors and hormones, stem cells can be coaxed to become many different kinds of tissue, as Dr. Guilak discovered in 2001, when he became the first scientist to turn stem cells from fat into cartilage.
He then implanted human cartilage into mice to make sure that once fat cells were turned into cartilage that they wouldn’t revert back to their original state.
In the lab, Dr. Guilak said that his team has been able to get “really good cartilage” to grow on a scaffold in about three weeks. If it works in dogs, Dr. Guilak hopes to try the procedure in human patients in about four years.
Currently, doctors replace about 750,000 knees and hips in the United States each year, and that number is expected to climb as the population ages. Dr. Guilak says a biological joint replacement like the one he is working on could help younger patients conserve bone and could cut down on the number of revisions.
Milestones in Stem Cell Research
1981 – Discovery of ways to derive embryonic stem cells from early mouse embryos
1988 – Discovery of ways to derive human embryonic stem cells and grow them in the laboratory.
2006 – Discovery of ways to reprogram specialized adult cells to assume a stem cell-like state.
Read the other articles in the July/August issue of Research Update: