杏吧原创

Take heart: rat hearts have been stripped of their cells, repopulated with fresh ones and made to beat again.

You can engineer heart tissue in the lab but building the whole organ from scratch is tricky, due to its intricate network of blood vessels (New 杏吧原创, 1 February 2007, p 24). Whole organs have therefore been limited to thin structures, including bladders and skin.

Doris Taylor at the University of Minnesota in Minneapolis and colleagues 鈥渄ecellularised鈥� rat hearts by adding chemicals that break up cells, leaving behind just the connective tissue, which contains none of the molecules that could trigger an immune response. These scaffolds still have the heart鈥檚 complex 3D shape, including space for all the blood vessels.

The team seeded the scaffolds with blood vessel and heart muscle cells from newborn rats by flowing them through the scaffold in a soup of nutrients. The seed cells migrated through the structure and grew into muscle and blood vessels. The team also applied small electrical jolts to trigger beating. Within four days, the tissue had started to contract, and within eight days the new heart was pumping with 2 per cent of the efficiency of an adult rat鈥檚 heart (Nature Medicine, ).

鈥淚t鈥檚 really ingenious,鈥� says Julia Polak of Imperial College London鈥檚 Tissue Engineering Centre. She says that seeding could be done with a recipient鈥檚 own cells, avoiding the immune response that complicates organ transplants. 鈥淚t can be applied to any organ taken from cadavers 鈥� that opens up new possibilities for saving lives,鈥� she adds.