A new biomaterial may help surgeons rebuild the delicate soft structures of the human face (like the cheeks) after a disease or injury has caused disfigurement. The material, which is half synthetic and half biological, can be injected under the skin as a liquid, massaged into shape, and then permanently "locked" by exposure to light. A new liquid polymer that can be injected under the skin, molded and sculpted, then set in place with a LED array is being tested. Alexander Hillel and his colleagues at Johns Hopkins University have created a new type of transplant material that addresses these problems. It is a blend of hyaluronic acid - a biological material already used as a soft-tissue implant and polyethylene glycol- a synthetic material. The blend is a liquid polymer that can be injected, thus avoiding the need for surgery. Once injected, the material can be sculpted into the necessary shape. When exposed to light of specific wavelengths, the messy tangle of polymer chains in the liquid implant rearrange into a stable, crosshatched form, stiffening the implant. It only takes a few minutes in front of the LED light array before the material sets, and the procedure is generally pain-free once finished. Use of LED lights is important because visible light is much safer than UV light, which can have a number of adverse effects, primarily DNA damage and cell death. To set the implants, the researchers devised a green-light LED array that can penetrate up to 4 millimeters of skin. It only takes two minutes of exposure before the implant fully sets, and there were no painful side effects. The researchers staged a pilot clinical study in Canada by injecting small implants in the stomachs of three patients scheduled to undergo "tummy tucks." The implants lasted about 12 weeks, with the only problem being inflammation around the implant, that is relatively easy to overcome. The inflammation could be a result of irritation caused by the rigidity of the implants, a reaction to the chemicals in the implant, or a by-product of the fat tissue surrounding the implant site. The next step is a full-scale clinical trial.
A cancerous windpipe was removed and replaced by the world's first artificial trachea, made of the patient’s own stem cells grown on a man-made plastic matrix, as per USA today. This is the first permanent artificial organ ever," says Paolo Macchiarini, professor of regenerative surgery at the Karolinksa Institute in Stockholm, who led an international team of researchers. Just as remarkable as the man-made windpipe, is how quickly it was produced. Collaborators in Sweden, London and USA created the trachea from scratch in just two days for a 36 year old man whose cancer was so far advanced that only emergency surgery offered him any chance of survival. Rejection is unlikely because the new trachea was made of a special plastic polymer and the patient's own cells. It started with removal of the patient's bone marrow and filtering out of certain cells, called mononucleocytes. These cells, when treated with growth factors and other substances, morph into the cells that form the rings on the trachea. Then a team led by Alexander Seifalian at the University College of London worked round-the-clock to produce a Y-shaped matrix that would replace the cancerous portion of the patient's windpipe and connect with his lungs. David Green's team at Harvard Biosciences traveled to Stockholm and placed the matrix and the solution of cells into a custom-made device called a bioreactor. The bioreactor keeps the body temperature constant at 98.6 degrees and rotates the matrix once per minute just as a rotisserie turns a chicken. With every revolution, the lower part of the matrix dips into the cell broth, coating it and at the same time exposing the living cells to oxygen. Within 48 hours, the man-made windpipe was ready for implantation. Doctors not only replaced the windpipe, they gave it a blood supply by sliding a section of tissue from his stomach up through his diaphragm, which is a standard technique.
Researchers at MIT and MGH have developed a polymer gel that mimics the vibrations of human vocal cords. A team led by Langer and Zeitels (professor of laryngeal surgery at Harvard Medical School) has developed a polymer gel that they hope to start testing in a small clinical trial next year. The gel, which mimics key traits of human vocal cords, could help millions of people with voice disorder. About 6% of the U.S. population has some kind of voice disorder, and the majority of those cases involve scarring of the vocal cords, says Sandeep Karajanagi, a former MIT researcher who developed the gel while working as a postdoc in the Langer lab. Many of those are children whose cords are scarred from intubation during surgery, while others are victims of laryngeal cancer. Other people who could benefit are those with voices strained from overuse, such as teachers. The team decided to pursue a synthetic material because it would likely take less time to reach patients. The team chose polyethylene glycol (PEG) as its starting material, in part because it is already used in many FDA-approved drugs and medical devices. By altering the structure and linkage of PEG molecules, the researchers can control the material’s viscoelasticity. In this case, they wanted to make a substance with the same viscoelasticity as human vocal cords. Viscoelasticity is critical to voice production because it allows the vocal cords to vibrate when air is expelled through the lungs. For use in vocal cords, the researchers created and screened many variations of PEG and selected one with the right viscoelasticity, which they called PEG30. In laboratory tests, they showed that the vibration that results from blowing air on a vocal-fold model of PEG30 is very similar to that seen in human vocal folds. Also, tests showed that PEG30 can restore vibration to stiff, non-vibrating vocal folds such as those seen in human patients suffering from vocal-fold scarring. Under FDA guidelines, the gel would be classified as an injectable medical device, rather than a drug. The researchers, who have published more than a dozen papers on their voice-restoration efforts, have applied for a patent on the material and are working toward FDA approval. If approved for human use, the gel would likely have to be injected at least once every six months, because it eventually breaks down.
Researchers have created a biologically based spinal implant they say could someday provide relief for the millions of people suffering lower back and neck pain. Instead of removing damaged spinal discs - a surgery known as a discectomy - and fusing the vertebrate bones to stabilize the spine in patients diagnosed with severe degenerative disc disease, or herniated discs, the artificial discs could be used to replace damaged discs, performing better than current implants that are made from a combination of metal and plastic. Although discectomies prevent pain, the often limit mobility. Human discs look something like a tire, with the outer part, called the annulus, made of a stiff material, and the inner circle, the nucleus, made of a gel-like substance that gets pressurized and bears weight. To mimic this structure, engineers at Cornell University in Ithaca and doctors at the Weill Cornell Medical College in New York City engineered artificial discs out of two polymers - collagen, which wraps around the outside, and a hydrogel called alginate in the middle. They seeded the implants with cells that repopulate the structures with new tissue. Compared to artificial implants that degrade over time, the researchers found that the new implants get better as they mature in the body, due to the growth of the cells. A surgical procedure approved by the FDA in 2005 for treating the degeneration of the intervertebral disc involves removing the damaged disc completely and replacing it with an implant made from a combination of metal and plastic, with the aim of mimicking the normal movement of the lumbar and the spine. Because the new discs integrate and mature with the vertebrae they would have a huge advantage over traditional implants. This major surgery would also become less invasive, safer and come with fewer long-term side effects.