Tag: Xenotransplantation

Mayo Clinic Researchers Observe Fusing of Human, Non-Human Cells in Living Body

The Mayo Clinic announced on January 8 that its genomics researchers demonstrated for the first time that human and non-human cells could naturally mix their genetic material in a living body. According to a press release from the Mayo Clinic announcing the discovery,

In the research reported today, Mayo Clinic investigators implanted human blood stem cells into fetal pigs. The pigs look and behave like normal pigs. But cellular analysis shows they have some human blood cells, as well as some cells that are hybrid — part human, part pig — in their blood, and in some of their organs. Molecular examination shows the hybrid cells have one nucleus with genetic materials from both the human and the pig. Importantly, the hybrid cells were found to have the porcine endogenous retrovirus, a distant cousin of HIV, and to be able to transmit that virus to uninfected human cells.

Jeffrey Platt, director of the Mayo Clinic Transplantation Biology Program, said the surprising results may help explain how some viruses can jump so quickly between humans and non-humans. In a press release statement, Platt said,

What we found was completely unexpected. This observation helps explain how a retrovirus can jump from one species to another — and that may speed discovery about the origin of diseases such as AIDS and SARS. The discovery may also help explain how cells in the circulation may become part of the solid tissue.

The Mayo Clinic findings will be published in March in the online Express edition of the Federation of American Societies for Experimental Biology Journal.

Source:

Mayo researchers observe genetic fusion of human, animal cells — may help explain origins of AIDS. Press Release, Mayo Clinic, January 8, 2004.

Woman's Diseased Heart Rebuilt Using Human and Cow Tissue

A 46-year-old woman suffering from a rare hereditary disorder successfully had her heart removed and parts of it rebuilt using tissue from cows.

Sandra Lanier of Ware, Mass., is one of only about 400 people known worldwide to suffer from “Carney Complex” — a hereditary disorder that causes recurring non-cancerous tumors. In Lanier’s case, it caused tumors to repeatedly grow in her left atrium, and she had endured three open heart surgeries before her most recent operation.

Dr. James Gammie and Dr. Bartley Griffith of the University of Maryland Medical Center removed her heart as part of a 12-hour operation and rebuilt the left and right atrium with human and cow tissue. According to the Associated Press,

During the operation, Gammie took out the remaining atrial tissue and used cow tissue to replace the back portion of the atria and line up the pulmonary veins so they could be reattached to the heart.

Meanwhile, Griffith rebuilt Lanier’s atria with a combination of animal and human tissue. Griffith said the animal and human tissue knitted together nicely with the remaining half of her own heart.

Griffith performed a similar surgery in 2000.

Source:

Surgeons use animal and human tissue on woman’s heart to remove tumor. Brian White, Associated Press, August 29, 2003.

Researchers Keep Diabetic Monkeys Alive for 70 Days Using Pancreatic Cells from Pigs

A University of Minnesota researcher presented the results of his successful xenotransplant of islet cells from pigs into monkeys at the American Transplant Congress in June.

In research sponsored by Immerge BioTherapeutics, Dr. Bernhard Hering transplanted pancreatic tissue from pigs into monkeys who were not capable of producing their own insulin. Drugs were used to prevent the monkeys’ immune systems from rejecting the pig cells.

That is not news — cross-species transplanting of islet cells has been performed before. What was new was that as of June the monkeys in Dr. Hering’s experiment had kept producing insulin from the pig islet cells for more than 70 days,

We have been able to reverse diabetes in past islet studies, but we had only seen two or three-week survival times before the graft was lost due to the overwhelming rejection response. The survival times we are reporting on today should only increase as we further optimize the immunosuppressive regimes.

Which, of course, gets us one step closer to the possibility of one day transplanting non-human islet cells into human beings to treat diabetes.

Source:

Pig-to-monkey transplants may herald cure for diabetes. Steve Connor, The Independent (London), June 4, 2003.

Treating Congestive Heart Failure by Transplanting Cow Tissue

The Associated Press ran a story in April highlighting how animal tissue is being implanted in human beings today to prolong the lives of people suffering from certain types of congestive heart failure.

Congestive heart failure occurs when the heart is unable to pump enough blood to supply the body with oxygen and other nutrients. The heart tries to compensate by enlarging which, however, makes it even less efficient. About 250,000 people die every year in the United States from congestive heart failure.

A new procedure called surgical ventricular restoration uses an implant made of cow heart muscle to repair the heart’s ventricles. As the heart expands, the ventricles go from a healthy football-like shape to a more rounded, basketball-like shape.

Implanting the cow heart tissue allows surgeons to reshape the ventricle into the correct shape and restore much of its functionality. The Associated Press and the surgeons at Oregon Health & Science University touted the story of Jerry Westling, 56, who was among the first people to benefit from the new procedure.

Thanks to his congestive heart failure, Westling used to have difficulty climbing up a flight of stairs, but after the implantation of the cow heart tissue, much of his heart function was restored. “I feel tremendously blessed and have a new lease on life,” Westling said in an OHSU press release.

(Of course we all know this can’t possibly be true, since animal-based medical science is nonsense and, besides, who does this guy think he is to put his life above the suffering of a cow?)

Sources:

Surgery gives cow muscle to humans. Associated Press, April 6, 2003.

New treatment available in northwest for patients with congestive heart failure. Oregon Health & Science University, Press Release, April 3, 2003.

Infigen Announces Pig Cloning Advance

Wisconsin-based biotech company Infigen announced in February that it had cloned a litter of pigs that bring the possibility of xenotransplantation one step closer. Researchers at Infigen genetically modified the pigs to turn off two sets of genes that would result in rapid rejection of tissues by the human immune system. Researchers at University of Missouri-Columbia announced earlier in January that they had produced double knockout pigs.

Pigs possess two copies of a gene that results in the sugar molecule alpha-1-galactose being added to the surface of cells. The human immune system would spot the alpha-1-galactose molecules and launch a quick response.

Infigen researchers not only knocked out both copies of this gene, but they did so in a species of pig that was genetically modified to avoid passing on porcine endogenous retrovirus to human beings. Xenotransplantation opponents have used the risk of the exchange of retroviruses like PERV between pigs and humans to argue that such transplants are simply too risky.

Sources:

Pig-Organ Transplants for Humans One Step Closer. TheBostonChannel.Com, February 28, 2003.

DeForest firm achieves litter of cloned pigs. John Fauber, Milwaukee Journal-Sentinel, February 27, 2003.

Infigen Announces the Birth of Genetically Modified Miniature Swine for Potential Use as Organ Donors for Humans. Infigen, Press Release, February 27, 2003.

Infigen Clones Litter of Pigs for Organ Donor Use. Wisconsin Ag Connection, February 28, 2003.

Immerge BioTherapeutics Identify Swine That Do Not Produce PERV

In February 2002 biotech company Immerge BioTherapetucis announced that
it had identified miniature swine that do not produce porcine endogenous
retrovirus (PERV). In laboratory tests, PERV has been shown capable of
infecting human cells, raising concerns over the safety of potential
xenotransplantation of pig tissues and organs to human beings.

PERV is difficult to eradicate in pigs, however, because the virus is
actually coded into the genome of pigs.

Immerge’s Dr. Clive Patience was able to identify strains of miniature
swine that did not produce of three sub-classes of PERV.

Immerge has already shown that it can knock out a gene in this species of
swine that would cause transplants to be rejected by human
beings.

Julian Greenstein, CEO and President of Immerge, said in a press
release,

These two studies show that animals within this herd of miniature
swine have the potential to be an ideal source for xenotransplantation.
While there is still much work to be done, we are very excited that we
have moved the science of xenotransplantation forward several steps
toward clinical application.

Source:

Immerge
biotherapeutics identifies miniature swine that do not transmit pig
retrovirus to humans.
Immerge BioTherapeutics, Press Release, February 25, 2002.