1. Rat limb
Recently, researchers at Massachusetts General Hospital grew an entire rat arm in a dish (above). The forelimb was created with a technique called “decellularization,” which uses living donor cells to regrow organ tissue. The bioengineered rat forelimb contained bone, cartilage, blood vessels, tendons, ligaments, and nerves, and could pave the way for entire limb transplants for amputees. The research is published in the August issue of Biomaterials.
2. Miniature brain
In 2013, scientists from the Institute of Molecular Biotechnology in Vienna, Austria announced they had successfully created a miniature brain in the lab. Using stem cells, they grew a model of a developing brain that was about the size of an embryonic human brain at nine weeks old. The cerebral organoid didn’t look exactly like a real brain, but it had active neurons and had much the same organizational structure.
3. Breast tissue
Breast epithelial cells in a gel that encourages mammary gland growth.
Researchers from the Helmholtz Center for Health and Environmental Research in Germany recently grew miniature mammary glands in an effort to study the development of breast cancer. Healthy tissue taken from women undergoing breast reduction surgery was turned into a gel that allowed the cells to divide and spread much like the mammary gland would during puberty.
4. Beating heart
Scientists from the University of Pittsburgh used human skin cells to create primitive heart cells. These cells developed into heart muscle, and once exposed to a blood supply, the miniature heart (grown on a mouse heart that had had all its cells removed) began to contract spontaneously. One day, similar tissue could be used to replace heart tissue damaged by a heart attack. Heart tissue regeneration has already proven successful in monkey transplants.
For people missing an ear, the reconstruction process is slow and painful, involving harvesting cartilage from the patient’s ribs. However, new techniques might make it easier. Physicians at Cornell University managed to 3D print a realistic ear using living cells from cows and collagen from rat tails. Others have grown ears from cow and sheep cells in the lab using a flexible wire frame.
The ear was then transplanted onto a rat to make sure it retained its shape and flexibility, as seen in the video above.
Before they were growing legs, researchers at Massachusetts General Hospital created new kidneys. Using the same decellularization process, they grew rat kidneys in a lab. Once transplanted into a rat, the kidneys were able to produce urine just like a normal organ. Scientists have also produced mini-kidneys in the lab, though those have not been transplantable yet.
7. Tear Gland
A project spearheaded by the Tokyo University of Science bioengineered the glands that produce tears and saliva in research that could help people with chronically dry eyes and mouths. The lab-grown glands were implanted in mice in 2013. The new salivary and lacrimal glands connected to nerves and ducts and were able to successfully secrete tears and saliva.