Xenotransplantion is the use of animal cells, tissues or organs for treatment of human diseases. This is indeed not a new technology since it had been practiced by the medical scientists of the past (i.e. Ancient Physicians of the East). A still surviving xenotransplantation technique utilized in the far reaches of our country is the use of animal bones to bridge fractured human bones.
The current revival of this technology stems out from the need to find alternative treatment for terminal organ failure patients. Patients who had to spend their life hooked on machines that could only partially replace the function of the diseased organs. Human organ transplantation had met with much drawbacks due to shortage of supply and the immunological implications which had made the recipient suffer subsequently.
The fact that xenotransplantation has met with some success is testimony of its workability. Of course there are some ruffles that need to be ironed out but that does not mean that we should convict it and hang it completely. We have looked at the crumpled piece of material in the eyes of western society and have tried our very best to get around these problems. Not to satisfy them but rather to ensure that what we produce would be safe and effective for the people in need of this alternative form of treatment. Xeno-transplantation cannot guarantee longevity, but rather its success would provide better quality life for these individuals.
Fetal live cell therapy is the ultimate in cell therapy utilizing animal cells to treat human diseases.
Live Cell Therapy
Stem cells have generated tremendous public and professional interest in recent times. The therapy is becoming more accepted by societies of the world as a form of treatment for conditions like acute leukaemia. As we advance in the study of stem cells we now recognize its potentials in treatment of numerous other diseases and injuries.
Stem cells are defined as cells that are able to turn into many different cell types, while retaining the ability to replenish their own numbers. Essential characteristics of a stem cell include the ability to:
- Retain the potential for self-renewal
- Sustain the population of at least one functional, differentiated cell type
Based on their capability to differentiate stem cells are categorized as follows:
- Totipotent – capable of giving rise to all of the body’s cells
- Pluripotent – capable of giving rise to a limited range of cells
- Multipotent – capable of giving rise to a few cell types
- Unipotent – capable of giving rise to only one cell type
Numerous sources of stem cells exist and amongst them are cells originating from animals. The west today is slowly acknowledging the fact that stems cells of animal origin are usable in the treatment of various diseases. The first successful xenotransplantation using baboon bone marrow cells done in the west and reported in the journal Transplantation 2004 Dec. 15; 78(11):1582-9. Michaels et al found that a 38 year old male with advance AIDS and resistant to anti-retroviral therapy survived 8 years with clinical improvement and no adverse events following transplantation of Baboon bone marrow cells in 1995.
Stem cells from Animal Source
Xenotherapy essentially means the use of animals, animal parts and animal products to treat human disease. This is not a new technology but rather as ancient as the human beings. Ancient scientists had recognized the capabilities of animal parts to treat human diseases and to help maintain the integrity of the human body. The Indian and Chinese scientist-physicians like Sushruta and Bian Que had incorporated various animal parts in their treatment of ailments like impotency, infertility and even the terminally ill with some success.
They preceded even Banting in the use of animal parts to treat diabetes. While the west are still bogged down by social rights and ethical issues of xenotherapy, countries like Russia, China and Eastern European bloc forge ahead in research to come up with improvements in the field of xeno-cell therapy. Today they are leaders in xeno-cell-therapy using implantations of stem cells of animal origins with close relationship to humans phylogenetically.
Fears in Xenotransplantation
A. Zoonoses is the transmission of infectious agents from animals to humans much like Avian Flu, Swine Flu, Mad Cow Disease and the likes. Such fears could be eliminated if such procedures could be performed before and after xeno-cell therapy:
- Screen source animals for presence of organism
- Development of specific pathogen-free animals for purposes of xeno-cell therapy
- Lifetime continuous surveillance of transplant patients and periodic surveillance of their contacts for evidence of infectious zoonoses
- Establishment of a national and local registry of patients receiving xeno-cell therapy
B. Immunological Reaction or rejection poses a serious problem especially with whole organ transplantation. This is believed to be due to exposure of the body’s immune system to the inner lining cells of the donor organ. Immediate severe rejections has been reported frequently which necessitate the use of immune-suppressants (drugs to reduce the body defence system) to reduce this.
To overcome such adverse reactions the following should be taken into consideration
- Choice of animal source – animals closer to humans phylogenetically would be a better choice that those further in the phylogenetic tree.
- The use of tissues and cells is better than whole organs. Cells are the most appropriate especially foetal cells because they lack the immune system recognition markers and they are separate from the organ vasculature which elicits a strong immune response.