It's not possible to simply grow an entire heart from cells. Organs require a scaffold to give the cells a shape. In the normal course of things, this scaffold, known as an extracellular matrix, is created from proteins secreted by the cells.

"These include providing a structural scaffold that is able to support cardiac function, a supply of specialised cardiac cells, and a supportive environment in which cells can repopulate the scaffold to form mature tissue capable of handling complex cardiac functions."

Rather than grow these extracellular matrices, which would take time, the team used 73 donor hearts from the New England Organ Bank. These hearts had been determined unsuitable for transplantation.

To prepare the hearts, the team stripped them down to the extracellular matrix with a detergent solution. This removes all the living cells and leaves behind a neutral scaffold for the new cellular material.

To seed the matrices with cells, the team used a newer method that uses messenger RNA to revert the skin cells to stem cells, a more efficient technique than the older genetic manipulation. These pluripotent stem cells were then induced to grow into cardiac muscle cells.

Today I learned that:

1. Specific cells can be reverted to stem cells!

2. Complex organs such as hearts cannot be grown just from cells with current technology. They need scaffolding for shape!

Wow, the medical advances lately have been astonishing.