Currently, scientists are able to create some types of tissues for human transplant use. The simplest kind are flat, simple structures such as skin that consist of one cell type. Tubular structures that involve two cell types, such as blood vessels, are also possible using current techniques and technology. Most recently, scientists have been able to create hollow organs, like the stomach and bladder, that only require two cell types but have a more complex shape.
What still lies out of reach are the solid organs, such as the liver or kidneys.
"They require so many more cells per centimeter," said Atala. "And they need more blood vessels to keep the cells alive."
Despite the challenges, Atala has had some early success with the creation of solid organs. In 2010, his group was the first in the world to create a functioning liver from human cells.
So far, these livers have only been tested in an artificial lab setting. They would still need to be studied in animal models before they could ever be considered for humans. Also, Atala's livers weigh only one-fifth of an ounce. They would need to reach at least one pound to have a chance of sustaining human life -- "not an easy task," according to Atala.
But his group is not alone. Researchers around the world are working feverishly towards making lab-grown solid organs a possibility. The Boston University Center for Regenerative Medicine successfully created rat lungs in 2010. They were even able to transplant the lungs into live rats and sustain life for about six hours.
While the widespread use of regenerated body parts may still be years away, these small successes in lab and animal studies leave scientists hopeful that solid organ regeneration may someday be a reality
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