The rate of research on xenotransplantation has increased, according to World Health Organization record more than ten patients die each day while on the waiting list to receive lifesaving vital organ transplants. Moreover, recent evidence has suggested that transplantation of cells and tissues may be therapeutic for certain diseases such as neurodegenerative disorders and diabetes, where human materials are not readily available.
What Then Is Xenotransplantation?
Xenotransplantation is a medical procedure that involves the transplantation and implantation of solid organs, tissues or clusters of specialized cells from an animal example pig into a human. Xenotransplantation can also involve the infusion or transplantation of body fluids, tissues or cells that have been in contact with the tissues or cells of another species outside the recipient’s body. For example, a person might be treated for liver failure by having their blood passed through an artificial device containing pig liver cells. Some nonliving animal devices, such as pig heart valves have been used in humans for many years. Xenotransplants differ from these devices in that they are alive and can perform the same functions as the organ, tissue or cells that they replace.
Moreover, the development of Xenotransplantation is in fact driven by the demand for human organs for clinical transplantation which highly exceeds the supply. Although the potential benefits are considerable, it risks cannot be over emphasized, the use of xenotransplantation raises concerns regarding the potential infection of recipients with both recognized and unrecognized infectious agents and the possible subsequent transmission to their close contacts and into the general human population. In regard to this public health concern is on the potential for cross-species infection by retroviruses, which may be latent and lead to disease years after infection. Moreover, new infectious agents may not be readily identifiable with current techniques.
Why Is Xenotransplantation Being Considered?
The development of xenotransplantation is in fact, driven by the fact that the demand for human organs for clinical transplantation far exceeds the supply. Transplantation between members of the same species is known as Allotransplantation, and in humans this is a very successful way to treat a variety of illnesses. However, very few human tissues and organs are available for transplantation, so that many patients who could benefit from a transplant wait in vain for a suitable donor. Transplant specialists are therefore considering animals as a possible source of organs and tissues for human transplantation. The greatest benefit of xenotransplantation would be a potentially unlimited supply of cells, tissues and organs for use in humans.
Advancement in science and technology have increased the possibility of successful xenotransplantation and stimulated research in this area. For example, genetic engineering has allowed human genes to be inserted into pigs so that their cells, tissues and organs are less likely to be rejected when transplanted into humans. Xenotransplantation has the potential to treat a wide range of life-threatening or debilitating conditions. For example, it is possible that isolated cells could be transplanted to treat diseases such as diabetes, strokes etc. Another possibility is that xenotransplantation could be used while potential transplant patients wait for a suitable donor. Xenotransplantation is really not that easy but considering the options surrounding its need more research has to be carried out in animal to animal studies (preclinical studies) in which proposed xenotransplantation procedures are tested on animals example pig – chimpanzee kidney transplant and animal to human trials (clinical trials) in which animal products are used for xenotransplantation procedures on human beings example pig to human brain cell transplants.
Why Are Pigs Considered The Most Suitable Specie For Source Of Material For Xenotransplantation?
From the various recent research that have been carried Pigs are considered the most suitable species as a source of material for xenotransplantation because their reproduction rate is high and their off-springs are larger in size like that of the human; some of their organs are similar in size to those of humans; they are easy to rear in conditions free of particular pathogens (disease-causing organisms); they can be genetically manipulated to reduce the risk of rejection. But nonetheless some risks have been associated with xenotransplantation, researchers says,
“The main risk to the recipient of a transplant is rejection due to the patient’s immune response. In human to human transplantation (Allotransplantation), rejection has been largely overcome by tissue matching of donors and recipients, and by giving the recipient drugs that suppress their immune response”.
Also, they stated that the risk of rejection in xenotransplantation is more severe because the differences between the donor and the recipient are much greater. The most promising approach at this stage is to genetically modify the source animals so that they do not cause such a strong immune response. Scientists have already produced several genetically modified strains of pig that show promising results. Xenotransplantation carries some risks for the wider community, the major concern for public health is that xenotransplantation might transmit an infectious agent (such as a virus) from animals to humans. Retroviruses are the chief concern, because there are many examples of such viruses moving from one species to become infectious in another. However, retroviruses do not always cause obvious signs of disease initially. If a retrovirus present in a xenotransplant were to infect the recipient of the transplant, it may spread to close contacts and even the general population before it became obvious that an infection had occurred.
Reducing The Risk Of Xenotransplantation On Recipients
Considering the level of risk in xenotransplantation researchers have actually found out some methods that can be used to reduce it, it was stated that the pig endogenous retrovirus that is of concern as a possible infectious agent in humans, at least one strain of ‘mini-pigs’ does not. Researchers are therefore investigating the use of this strain and breeding others for xenotransplantation in order to reduce the risk of infection in the recipient. Also, most importantly animal to human transplant trials will not be approved unless there is an appropriate infection control policy in the hospital where the transplant is taking place, to prevent transmission of infections from the xenotransplant recipient to hospital contacts.
In addition, because the long-term consequences of xenotransplantation will not be fully understood for some years, anyone transplanted with cells, tissues or organs from another species will need to be carefully monitored. Therefore, anyone receiving a transplant would be informed about the potential infectious disease risks to themselves and their close contacts and asked to support such long-term monitoring.