Ablekaak
01-15-07, 05:48 PM
Engineered chickens produce cancer drugs
A TEAM at the British institute that cloned Dolly the sheep
has made genetically engineered chickens that produce cancer
drugs in their eggs.
The chickens produce the drugs in their egg whites, the team at
the Roslin Biocentre in Edinburgh reported.
The drugs include a monoclonal antibody - itself a lab-engineered
immune system protein - and a human immune system protein
used to treat cancer and other conditions, the researchers report
in the coming issue of Proceedings of the National Academy
of Sciences.
Cattle, sheep and goats have all been genetically engineered
to produce human proteins in their milk, including insulin and drugs
to treat cystic fibrosis, but the Roslin team thought chickens, with
their shorter life cycles and egg-laying prowess, might also be useful.
Helen Sang and colleagues at Roslin made the genetically engineered
or transgenic hens by inserting the genes for the desired proteins into
the hen's gene for ovalbumin, a protein that makes up half of egg whites.
They wanted to ensure the hens made the proteins in their egg whites
and nowhere else.
These drugs are not easy to make in the lab. The active ingredients
are usually made in industrial quantities in bio-reactors containing a
mixture of bacteria or other cells that have been modified to produce
complex proteins. The process is expensive and time-consuming.
Scientists have been trying to find good ways to turn animals into
factories instead - given that animals naturally make such proteins anyway.
While the production of pharmaceutical proteins has been demonstrated
in other genetically modified animals, until now the proteins have been
difficult to extract and the ability to produce useful proteins vanishes
after a few generations.
Researchers said that in the latest study they had bred five generations
of chickens and each one had produced good concentrations of drugs.
In theory, they added, the technique could be used with a wide range
of genes so that hens could produce many different drugs for a range
of diseases, from Parkinson's to diabetes and other types of cancer.
Professor Herbie Newell of Cancer Research UK said: "Anything that
allows us to expedite the number of novel therapeutics that we can
offer cancer patients and also potentially reduces the cost of their
manufacture must be welcomed."
The researchers have now bred several hundred chickens that can
produce the desired proteins. The chickens used are ISA browns, a
common breed that can produce up to 300 eggs a year.
The researchers created the chickens by first using a virus to infect
very early chicken embryos. The virus inserted the genetic material into
the DNA of chick embryos in newly laid eggs. The researchers hatched
these chicks and found the male chicks who had indeed incorporated
the new DNA in their semen.
These cockerels were then bred with normal hens and they screened
the resulting chicks to see which ones still carried the new genes.
Source:
http://www.smh.com.au/news/world/engineered-chickens-produce-cancer-drugs/2007/01/15/1168709679041.html
A TEAM at the British institute that cloned Dolly the sheep
has made genetically engineered chickens that produce cancer
drugs in their eggs.
The chickens produce the drugs in their egg whites, the team at
the Roslin Biocentre in Edinburgh reported.
The drugs include a monoclonal antibody - itself a lab-engineered
immune system protein - and a human immune system protein
used to treat cancer and other conditions, the researchers report
in the coming issue of Proceedings of the National Academy
of Sciences.
Cattle, sheep and goats have all been genetically engineered
to produce human proteins in their milk, including insulin and drugs
to treat cystic fibrosis, but the Roslin team thought chickens, with
their shorter life cycles and egg-laying prowess, might also be useful.
Helen Sang and colleagues at Roslin made the genetically engineered
or transgenic hens by inserting the genes for the desired proteins into
the hen's gene for ovalbumin, a protein that makes up half of egg whites.
They wanted to ensure the hens made the proteins in their egg whites
and nowhere else.
These drugs are not easy to make in the lab. The active ingredients
are usually made in industrial quantities in bio-reactors containing a
mixture of bacteria or other cells that have been modified to produce
complex proteins. The process is expensive and time-consuming.
Scientists have been trying to find good ways to turn animals into
factories instead - given that animals naturally make such proteins anyway.
While the production of pharmaceutical proteins has been demonstrated
in other genetically modified animals, until now the proteins have been
difficult to extract and the ability to produce useful proteins vanishes
after a few generations.
Researchers said that in the latest study they had bred five generations
of chickens and each one had produced good concentrations of drugs.
In theory, they added, the technique could be used with a wide range
of genes so that hens could produce many different drugs for a range
of diseases, from Parkinson's to diabetes and other types of cancer.
Professor Herbie Newell of Cancer Research UK said: "Anything that
allows us to expedite the number of novel therapeutics that we can
offer cancer patients and also potentially reduces the cost of their
manufacture must be welcomed."
The researchers have now bred several hundred chickens that can
produce the desired proteins. The chickens used are ISA browns, a
common breed that can produce up to 300 eggs a year.
The researchers created the chickens by first using a virus to infect
very early chicken embryos. The virus inserted the genetic material into
the DNA of chick embryos in newly laid eggs. The researchers hatched
these chicks and found the male chicks who had indeed incorporated
the new DNA in their semen.
These cockerels were then bred with normal hens and they screened
the resulting chicks to see which ones still carried the new genes.
Source:
http://www.smh.com.au/news/world/engineered-chickens-produce-cancer-drugs/2007/01/15/1168709679041.html