XENOTRANSPLANTATION: DISEASED ORGAN RESCUE?

Chike I, Patrick Anibeze PhD, FRSB (Lond)

Department of Anatomy, Faculty of Basic Medical Sciences, ESUT College of Medicine, Enugu.

The increasing life expectancy of humans has led to growing number of people with diseased organs. This is imposing a burden on bio-genetic engineering research to provide solutions for diseased organs. Although the third millennium is burgeoning greatly with significant advances in the realms of bio-genetic research, solutions to diseased organ replacement is still a subject of research with minimal target outcomes.

Such processes as xenotransplantation is receiving significant attention among scientists albeit with serious ethical issues. Xenotransplantation is any procedure that involves the use of live cells, tissues or organs from a nonhuman source for transplantation, implantation or infusion into a human recipient.

Recently in 2021, scientists at NYU Langone Health in the United States attached a genetically engineered edited breed of pig's kidney to a cadaver and watched it begin to work. The pig had been genetically edited to avoid the human intolerable sugar and immune system attack.For this procedure, the researchers had kept a diseased woman's body on a ventilator after her family had agreed to the experiment. The success of this research marks a significant step to the quest for the use of animal organs for live-saving transplants.

Pigs appear to have offered the best option for research success in xenotransplantation, but the hurdles are still numerous. For instance, some sugar in pig cells foreign to the human body is reported to cause immediate organ rejection. Although scientists have had to use a gene-edited pig, engineered to eliminate the immune system attacking sugar.

Xenotransplantation is not a new concept. The dream of transferring bodily organs from animals to humans goes back to antiquity, as articulated in the myth of Daedalus and Icarus in Greek mythology. By the 17th century the possibility of transferring animal organs to humans came into practice with stumbling attempts to use animal blood for transfusions. Xenotransfusion of blood from lambs to humans were recorded as far back as 1667 (Aristizabal et al 2017). Similarly, clinical use of animal organs such as the transplantation of a rabbit kidney to humans was documented in 1905 (Nagarian 2003).

Advancing to the 20th century researchers were already attempting transplants of organs from baboons to humans. Of particular interest is the story of the Baby Fae, a dying infant, who lived 21 days with a transplanted baboon heart.

The recent giant steps made in the field of xenotransplantation at the NYU Langone Health offers significant hope for solving organ ailments. This is more so when the recent transplant of a pair of large blood vessels outside the body of a diseased recipient for two days had the kidney adequately filter the waste and produced urine without triggering any immune rejection. This feat performed has been described by notable scientists as a significant step in the right direction.

Pigs have been the animal of choice for research in xenotransplantation for several reasons. The animal is produced mainly for food, so using them for organ supply raises fewer ethical concerns. Pigs have large litters, short gestation periods and organs comparable to humans. Pig heart valves have been used successfully for decades in humans. The blood thinner heparin is derived from pig intestines. Pig skin grafts are used on burns and may provide sufficient xenografts (Takayuki Yamamoto et al 2018). Chinese surgeons'search for allotransplants have yielded successful results in the use of genetically engineered pig corneas to restore sight (Chang Ho Yoon et al 2021).

Despite the scientific advances in xenotransplantation, the process still suffers from several ethical backlash. Similar situation has plagued the stem cell cloning technology. It will be recalled that in 1998, a British embryologist became the first living proof to show that an adult cell can revert to embryonic stage and produce a full new being. From a cell in adult ewe's mammary gland, Wilmot and his colleagues managed to create a frisky lamb named Dolly, scoring an advance in reproductive technology as unsettling as it was startling (Anibeze 2007).Unlike offspring produced in the usual fashion, Dolly does not merely take after her biological mother, she is indeed a carbon copy, a laboratory counterfeit so exact that she is indeed her mother/s identical twin.

This exotic biological engineering seems to have opened a vista of possibilities both for propagating endangered species and producing replacement organs for transplant patients. However, the myriad of possibilities from this research outcome have raised critical ethical issues militating against its advancement.

Rollin (2018) observed that xenotransplantation is largely condemned because of people's extremely primitive views of biology and the mind. This provides the basis for rejecting life-saving biotechnology. Thus, creating a scientifically literate public is essential for societal acceptance of feats in genetic engineering.Research have showed that moral considerations regarding biotechnology are putatively of greater concern to society than even issues of safety.

Literature cited

Anibeze Chike (2017). Who am I? Exploring the Anatomical Underpinning of the Science of Life. 26th Inaugural Lecture of Enugu State University of Science and Technology, 29th June 2017. DOI: 10.13140/RG.2.2.11815.29603.

Aristizabal AM, Caicedo LA, Martinez JM, Moreno MGJE. (2017). Clinical Xenotransplantation, a closer reality: literature review. Cir Esp 95:62-72. DOI: 10.1016/j.cireng.2017.03.007

Chang Ho Yoon, HyukJin Choi, Mee Kum Kim (2021). Corneal xenotransplantation: Where are we standing? Progress in Retinal Eye Research 80 January 2021 100876 www.elsevier.com/locate/preteyeres

Najarian JS. (2003) Experimental xenotransplantation: a personal history. Xenotransplantation DOI: 10.1034/J.1399- 3089.2003.01082.x

Rollin BE (2020) Ethical and Societal Issues Occasioned by Xenotransplantation. Animals – an Open Access Journal (Basel) Sep; 10(9): 1695. doi: 10.3390/ani10091695

Takayuki Yamamoto, Hayato Iwase, Timothy W King, Hidetaka Hara, David K C Cooper (2018). Skin xenotransplantation: Historical review and clinical potential. Burns DOI: 10. 1016/j.burns2018.02.029

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