Heparin crisis rekindles concern about disease from pig transplants

From ANIMAL PEOPLE, March 2008:
DEERFIELD, Ill.; chang-zhau–Concern
about the possibility of pig diseases crossing
into humans through medical procedures using pig
byproducts rose worldwide after the drug maker
Baxter International on February 25, 2008
suspended sales of the blood-thinning product
heparin.
Baxter International, of Deerfield,
Illinois, reportedly distributes more than a
million doses of heparin annually, amounting to
about half of the U.S. supply.

The U.S. Food & Drug Administration
linked four human deaths and as many as 400
complications of illnesses to bad reactions to
heparin in the weeks preceding the recall.
“Investigators are trying to determine
whether the raw material for the drug, made from
pig intestines, became contaminated on the
journey that begins in the slaughterhouses of
China,” reported David Barboza and Walt
Bogdanich of the New York Times.
Baxter International buys crude heparin
for processing into the pharmaceutical product
from Scientific Protein Laboratories, a U.S.
firm that obtains the material from a subsidiary,
Changzhou SPL, located in Changzhou, China. On
February 16, 2008, Bogdanich and Jake Hooker of
the New York Times revealed that Changzhou SPL
was not inspected as a pharmaceutical maker by
either Chinese regulators or the FDA. Instead,
like the Chinese source of pet food contaminated
by the coal byproduct melamine that may have
caused thousands of animal deaths worldwide
during the winter of 2006-2007, Changzhou SPL
was known to the Chinese government as a maker of
industrial chemicals.
“One of the wholesalers named by
Scientific Protein Laboratories, Ruihua
Biochemical in Hangzhou, said it provided a mix
of crude heparin that it manufactured and some
that it bought ‘from small factories nearby in
several villages,'” Barboza and Bogdanich
revealed on February 28, 2008.
“Some experts say as much as 70 percent
of China’s crude heparin-for domestic use and for
export-comes from small factories in poor
villages,” Barboza and Bogdanich continued.
Citing “interviews with dozens of heparin
producers and traders in several Chinese
provinces,” Barboza and Bogdanich explained that
“The Chinese heparin market has become
increasingly unsettledŠAfter an outbreak of blue
ear pig disease swept through 25 of China’s 31
provinces and regions last year, prices soared.”
The blue ear epidemic, Shandong
University School of Medicine heparin expert Cui
Huifei told the New York Times, “made biotech
companies inevitably purchase from the
family-style plants, for cheaper prices.”
The risk of pig diseases crossing into
humans via medical procedures has concerned
public health officials for decades, but heparin
had not been seen as a likely vector. First
isolated from canine liver cells in 1916,
heparin debuted as a pharmaceutical product in
1933, and was first marketed in 1937.
Pharmaceutical heparin was initially
extracted from the remains of slaughtered cattle,
but most heparin today is derived from the small
intestinal submucosa of pigs–the same source as
SIS, a patching material first used in the U.S.
in 1988. In February 2000 the FDA approved SIS
for treatment of almost any sort of soft-tissue
wound–even eye injuries and some types of
stomach ulcer.
Other pharmaceutical products made from
pig tissues are also now widely used,
stimulating research into genetically modifying
pigs to produce ready-to-transplant replacements
for human organs. The pork production
conglomerates Hormel and Smithfield have
reportedly invested millions of dollars in the
effort, with partners including Baxter
Healthcare and the Mayo Clinic.
But in August 2000 the Roslin Institute
of Scotland and Geron Bio-Med of California
dropped efforts to produce transplantable organs
for humans in pigs, citing concern about the
risk of accidentally transmitting pig endogenous
retroviruses into humans. Called PERVs for
short, pig endogenous retroviruses do not harm
pigs, and may not harm people, but British
virologist Robin A. Weiss demonstrated in 1997
that cross-species infection can occur.
Because PERV invades cells in much the
same manner as HIV, integrating itself into the
genetic program of the host, the Roslin
Institute and Geron Bio-Med preferred to avoid
the potential liability if a PERV strain ever
attacks humans.