'Spare part heart' beats in lab
Pastor Dale Morgan
'Spare part heart' beats in lab*
A new heart was grown on a basic tissue scaffold
The stripped-out shell of a heart has been made to work again - using
brand new cells planted inside it.
Scientists removed all the muscle cells in a rat heart, leaving just a
"scaffold" of other tissues such as blood vessels and valves.
When the University of Minnesota team added heart cells, they quickly
grew and produced a pumping action.
It is hoped the Nature Medicine study will ultimately mean human or
animal hearts can be crafted for transplant.
It opens a door to this notion that you can make any organ: kidney,
liver, lung, pancreas - you name it and we hope we can make it-Dr Doris
Taylor-University of Minnesota
Experts believe that failing organs in humans could in theory be
replaced by new versions grown using stem cells.
These are the body's master cells, which have the potential to be
transformed into any cell type in the body.
Any organ constructed in this way would have a significant advantage
over donor organs for transplantation because they could be made to
match the patient, and face a much smaller risk of rejection by the
immune system.
However, one of the biggest obstacles to developing three-dimensional
organs is finding a way to persuade cells to form the complex structures
needed.
The Minnesota researchers decided that the best template would be
another heart.
They took an adult rat heart, bathed it in detergents which removed all
the cardiac cells, leaving a "frame" of other heart tissues forming the
basic shape of the organ.
This frame was then "seeded" with cardiac cells taken from a newborn
rat, and kept in lab conditions designed to simulate the growing heart.
'Speechless'
In just four days, the cells had multiplied and spread to such an extent
that the researchers could see contractions in the new muscle tissue.
By the eight day, the home-grown hearts were capable of pumping, albeit
at only 2% of the power of a normal rat heart.
This isn't something that we will see in man for at least a decade, I
believe
Dr Peter Weissberg
British Heart Foundation
Dr Doris Taylor, who led the experiment, suggested that it might change
the way scientists think about producing artificial organs.
"It opens a door to this notion that you can make any organ: kidney,
liver, lung, pancreas - you name it and we hope we can make it."
Another researcher, Dr Harald Ott, said: "When we saw the first
contractions we were speechless."
Pig transplant
Professor Sian Harding, from Imperial College London, who is working on
ways to repair failing human hearts with new heart cell "patches",
described the technique as "potentially a real advance".
She said that it might be possible in the future to remove the cells
from a pig heart - which is very similar in scale and function to a
human heart. Human stem cells could then be seeded to produce an organ
capable of being transplanted into humans.
She said: "Heart muscle cells need so much oxygen, that each of them has
to be virtually touching a blood vessel, and achieving that kind of
level of blood supply is a challenge.
"If you could use the existing blood vessel structure from another
heart, that would be really useful."
Dr Peter Weissberg of the British Heart Foundation said that the
research was "important", but cautioned that it would be some time
before the technique could be use for human transplant organs.
"This isn't something that we will see in man for at least a decade, I
believe," he said.
"First we have to find a way of getting hold of the patient's own stem
cells so that the new heart is not rejected."
Dr Jon Frampton Wellcome Trust Senior Fellow at the University of
Birmingham said: "Although this is only a first step requiring
considerable follow-up development, the study nevertheless represents an
exciting breakthrough that will eventually make the prospect of
repairing damaged hearts a reality and will also be an approach that can
be extended to other organs."