Encapsulating insulin producing cells in tiny seaweed bubbles and injecting them into people with type 1 diabetes could one day remove the need for daily insulin injections
- From: "Pro-Humanist FREELOVER" <prohumanist@xxxxxxxxxxxxx>
- Date: 22 Feb 2006 20:46:14 -0800
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by Judy Skatssoon
ABC Science Online
February 21, 2006
http://www.abc.net.au/science/news/stories/s1573640.htm
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Complete article:
Encapsulating insulin producing cells in tiny seaweed
bubbles and injecting them into people with type 1
diabetes could one day remove the need for daily
insulin injections, an Australian researcher says.
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Researchers have put insulin producing cells like this
into tiny capsules as a treatment for type 1 diabetes
(Image: NIH)
http://www.abc.net.au/science/news/img/health/islet230805.jpg
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Professor Bernie Tuch of the University of New South
Wales launched a trial of the technology this week,
using capsules made from the seaweed derivative
alginate and measuring just 300 micrometres across.
Tuch says if the trial works, it will mean that insulin
producing cells, or islets, can be transplanted, effec-
tively reversing type 1 diabetes, without the need for
immunosuppressive drugs.
This is because the capsules protect the transplanted
cells from being sought out and destroyed by the body's
immune system.
The capsules also contain tiny holes that let the insulin
flow out while allowing oxygen and nutrients in.
"The concept of the seaweed is that it forms a coating
around the islets ... with holes that are small enough to
prevent immune cells entering," Tuch says.
The trial, involving a 51-year woman who was diag-
nosed with type 1 diabetes 40 years ago, is the first of
its kind in Australia.
Tuch's team at the Diabetes Transplant Unit at Syd-
ney's Prince of Wales Hospital has previously tested
the method in animals.
An Italian group began a similar human trial two years
ago but is using capsules made from a different material.
About 75,000 capsules
During Monday's half-hour procedure the woman was
injected with 75,000 capsules containing a total of around
200,000 islet cells.
The islets had been isolated from a cadaver and put into
the capsules in a procedure Tuch compares to blowing
soap bubbles.
"There's the alginate, there's your cells and there's air,"
he says.
"You blow the air and the alginate and the cells together
and it's like blowing soap bubbles; they come out with
the cells inside the capsules."
The capsules were injected into the patient's abdomen
where it's hoped they will start producing insulin within
24 hours, allowing her to slowly begin reducing her
insulin injections.
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Microcapsules containing insulin producing cells
(Image: DTU)
http://www.abc.net.au/science/news/img/health/islet200206.jpg
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Tuch says one injection could potentially last a lifetime
although it's not yet known whether the current patient
will need extra injections.
What could go wrong?
Immunologist Dr Bronwyn O'Brien, who is working with
a team from the University of Technology Sydney to
genetically engineer liver cells so they produce insulin,
says Tuch's method is promising but may have com-
plications.
"In practice one of the big problems is that ... often
islets that are in the centre of the capsule become
hypoxic, they're not getting oxygen, and they die," she
says.
"The implications would be the cells would break up into
possibly small enough pieces that could leave the cap-
sule."
There's also a chance that immune cells could grow
around the outside of the capsules, blocking the flow
of insulin, she says.
And while the pores in the capsules are big enough to
keep T cells and antibodies out, there's still a chance
that cytokines, the so-called messengers of the im-
mune system, will slip through and produce an inflam-
matory response.
Tuch acknowledges this risk and says the patient re-
ceived anti-inflammatory drugs as a precaution.
"We don't anticipate there is going to be a major in-
flammatory response but if they do get in then the
islets may be destroyed," he says.
Not just for diabetes
The concept of microencapsulation as a means of
avoiding rejection drugs could apply to any transplant
involving cells, Tuch says, and in particular stem cell
therapies.
"The concept of using capsules is certainly some-
thing that is reaching its clinical testing and time will
tell what it has to offer," he says.
- - - end of article - - -
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