In recent years, the science of regenerative medicine has made impressive strides in developing tissue capable of repairing hearts, muscles, and even vocal cords. While these innovations have the potential to revolutionize how we treat disease and injury, they also raise an important question: are there any limits to how far regenerative medicine can go? Can synthetic tissue ever be used to replace entire limbs, or heal major internal organs like the liver or pancreas? Combining knowledge of chemistry, physics, biology, and engineering, scientists from McGill University develop a biomaterial tough enough to repair the heart, muscles, and vocal cords, representing a major advance in regenerative medicine.
The history of synthetic tissue
Until recently, synthetic tissue was typically used as a way to support weak or damaged organs during transplantation. For example, if someone had a heart attack and was on the organ-donor waiting list, surgeons might place synthetic tissue into their heart to try to improve its function until an organ became available. Other applications for these grafts include lab-grown blood vessels and tracheas (windpipes). But now researchers are creating tissues that may actually replace failing organs for good.
Last year, Anthony Atala of Wake Forest University Medical Center in Winston-Salem, North Carolina, showed that engineered bladders grown from patients’ own cells were able to safely store urine just like normal bladders. And scientists at Massachusetts General Hospital have been implanting living vocal cords made from synthetic tissue inside of patients’ throats since 2011—some patients have even regained their singing voices thanks to these implants. Over time, doctors may be able to make replacements for other internal organs as well.
The science behind growing synthetic organs?
Human body parts made from plastic? It might sound like science fiction, but scientists at Wake Forest Baptist Medical Center have created a method for printing human tissue—in particular, heart valves and vocal cords. The advance could one day be used to repair ailing hearts and vocal cords that no longer work properly due to disease or injury. And it could eventually lead to many other applications, including growing replacement tissue and organs inside of patients, who would not need anti-rejection drugs after surgery. The process is similar to 3D printing, which has been in use since 1985; however, most 3D printers build solid objects layer by layer out of plastic or metal.
Because living cells are much more fragile than these materials, Wake Forest’s custom bioprinter creates organ structures out of hydrogel, an extremely pliable material made primarily of water. The hydrogel is built in layers just 20 microns thick (for comparison, a strand of hair measures about 100 microns across), with each new layer slightly overlapping with its predecessor so as to maintain structural integrity. After an object is printed, researchers place it in a chemical solution that causes it to stiffen into a gel-like state. Over time, cells will grow into and around these tiny synthetic structures until they become fully functional organs. A three-dimensional model of a heart valve was developed using Wake Forest’s printing technique.
Imagine if your doctor was able to help you heal faster by replacing damaged cartilage in your knee joint with cartilage grown from your own stem cells, grown right there in your body!
Where the research is today
Scientists have been working to develop synthetic tissue for decades, but advances in synthetic biology—the engineering of life-like materials and cells—have made it a much more realistic prospect. The first human trials of bioengineered blood vessels are already underway. Other researchers are developing replacement tissues for heart disease, and some scientists even believe they’ll be able to restore muscle function with synthetics like an artificial trachea. Researchers hope that these technologies will have major implications for aging populations and people suffering from degenerative diseases.