New Tissue Engineering Technique Could Lead to Growing Larger Organs in the Laboratory

Tissue engineers from the Universities of Liverpool and Bristol have invented a novel tissue “scaffold” technology that might one day enable the growth large organs in the laboratory.

According to data generated by these experiments, it is possible to combine cells with a special scaffold to produce living tissues in the laboratory. Hopefully, such organs can then be implanted into patients who need to have a diseased body part replaced. To this point, growing large organs in the laboratory has been impossible because growing larger structures in the laboratory limits the delivery of oxygen supply to the cells in the center of the organ. Therefore, growing tissues in the laboratory has been restricted to small structures that are readily served by the diffusion of oxygen.

In the experiments conducted by the University of Liverpool and Bristol teams, cartilage tissue engineering was employed as a model system for testing strategies for overcoming the oxygen limitation problem.

They manufacture a new class of artificial membrane binding proteins that attached to stem cells. Then they attached to these cell surface proteins the oxygen-carrying protein, myoglobin, before they used the cells to engineer cartilage. Since myoglobin is an oxygen-storage molecule, it will bind oxygen and provide a reservoir of oxygen for cells that cells can access when the oxygen in the scaffold drops to dangerously low levels.

Professor Anthony Hollander, Head of the University of Liverpool’s Institute of Integrative Biology, said: “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. 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.”

These results could expand the possibilities in tissue engineering, not only in cartilage, but also for other tissues such as cardiac muscle or bone. This new methodology in which a normal protein is converted into a membrane binding protein to which helpful molecules can be attached, is likely to pave the way for the development of a wide range of new biotechnologies.

Dr Adam Perriman, from the University of Bristol, added: “From our preliminary experiments, we found that we could produce these artificial membrane binding proteins and paint the cells without affecting their biological function. However, we were surprised 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.”

Previous work by Hollander’s group includes the development of a method of creating cartilage cells from stem cells. This method helped make the first successful transplant of a tissue-engineered trachea, which utilized the patient’s own stem cells, possible.

This work appeared in the paper, “Artificial membrane-binding proteins stimulate oxygenation of stem cells during engineering of large cartilage tissue,” which was published in Nature Communications.