Researchers continue to expand the application of decellarization to engineer more types of patient-matched tissues from more types of donor organ. Here is news of a proof of concept carried out in rats, in which a donor diaphragm is decellularized and transplanted successfully:
An international collaboration between scientists has resulted in the successful engineering of new diaphragm tissue in rats using a mixture of stem cells and a 3D scaffold. When transplanted, it has regrown with the same complex mechanical properties of diaphragm muscle. The diaphragm is a sheet of muscle that has to contract and relax constantly to allow breathing. It is also important in swallowing, and acts as a barrier between the chest cavity and the abdomen. The success of this study also offers hope for the possibility of regenerating heart tissue, which undergoes similar pressure as it contracts and relaxes with every beat. "So far, attempts to grow and transplant such new tissues have been conducted in the relatively simple organs of the bladder, windpipe and esophagus. The diaphragm, with its need for constant muscle contraction and relaxation puts complex demands on any 3D scaffold; until now, no one knew whether it would be possible to engineer. This bioengineered muscle tissue is a truly exciting step in our journey towards regenerating whole and complex organs. You can see the muscle contracting and doing its job as well as any naturally-grown tissue - there can be no argument that these replacements are truly regenerated."
In the current study, the researchers took diaphragm tissue from donor rats and removed all the living cells from it using a series of chemical treatments. This process removes anything that might cause an immune response in the recipient animals, while keeping all the connective tissue - or extracellular matrix - which gives tissues their structure and mechanical properties. When tested in vitro, these diaphragm scaffolds at first appeared to have lost their important rubber-like ability to be continually stretched and contracted for long periods of time. However, once seeded with bone marrow derived alloegenic stem cells and then transplanted into the animals, the diaphragm scaffolds began to function as well as undamaged organs. The method must now be tested on larger animals before it can be tried in humans, but the hope is that tissue-engineered repairs will be at least as effective as current surgical options.