Researchers say they have developed a new tissue scaffold technology that could one day enable the engineering of large organs. The team led by the Universities of Bristol and Liverpool has shown that it is possible to combine cells with a special scaffold to produce living tissue in the laboratory. It is hoped this can then be implanted into patients as a way of replacing diseased parts of the body.

Until now, the approach has generally been limited to growing small pieces of tissue, as larger dimensions reduce the oxygen supply to the cells in the center.

The scientists used cartilage tissue engineering as a model system for testing a new method of overcoming the oxygen limitation problem. They synthesized a new class of artificial membrane binding proteins that can be attached to stems cells. By attaching an oxygen-carrying protein, myoglobin, to the stem cells before they are used to engineer cartilage, they ensure that each cell has its own oxygen reservoir that it can access when the oxygen in the scaffold drops to dangerously low levels.

“From our preliminary experiments, we found that we could produce these artificial membrane binding proteins and paint the cells without affecting their biological function,” said Adam Perriman, Ph.D., from the University of Bristol’s school of cellular and molecular medicine. “However, we were surprised and delighted to discover that we could deliver the necessary quantity to the cells to supplement their oxygen requirements. It's like supplying each cell with its own scuba tank, which it can use to breathe from when there is not enough oxygen in the local environment.”

The team's study (“Artificial membrane-binding proteins stimulate oxygenation of stem cells during engineering of large cartilage tissue”), published in Nature Communications, could expand the possibilities in tissue engineering, not only in cartilage, but also for other tissue such as cardiac muscle or bone, according to the University of Liverpool’s Anthony Hollander, Ph.D., head of integrative biology.

“We have already shown that stem cells can help create parts of the body that can be successfully transplanted into patients, but we have now found a way of making their success even better,” he explained. “Growing large organs remains a huge challenge but with this technology we have overcome one of the major hurdles. Creating larger pieces of cartilage gives us a possible way of repairing some of the worst damage to human joint tissue, such as the debilitating changes seen in hip or knee osteoarthritis or the severe injuries caused by major trauma, for example in road traffic accidents or war injuries.”

Dr. Hollander's pioneering work includes the development of a method of creating cartilage cells from stem cells, which helped to make possible the first successful transplant of a tissue-engineered trachea, utilizing the patient's own stem cells.