Human and Animal Interrelationships from Domestication to Present - Essay Example

Animals and use of them in Transpla Introduction Transplantation surgeries are one of the most important surgical techniques today. Organ transplantation surgeries help thousands of ailing people around the world get a second chance at life. However, with an increase in chronic and serious diseases and a decrease in the number of human organ donors along with illegal human organ marketing, the waiting list for patients who require an organ for a transplantation surgery increases every single day. Thousands of people need to wait anxiously for indefinite periods of time for organs to become available for surgery. The concept of xenotransplantation which means organ transfer from a non-human species to humans was always present. However, in the recent years this particular concept has come into limelight because of the sudden emerging urgency for a greater number of organs for transplantation surgeries. Some surgeons consider that using organs from suitable animals such as monkeys and pigs and believe that these could lead to a decrease in the organ shortage problem once the various problems associated with xenotransplantation surgeries are overcome. Thus, the usage of animals for transplantation may become yet another milestone in animal-human relationship. Emerging Need for Xenotransplantation The main problem in transplantation remains the odd ratio between donor and patients. Non-availability of certain organs in particular leads to an increase in death rate. In fact the waiting list of patients waiting for vital organs such as liver, heart, kidney and pancreas is increasing every single minute. Approximately about 20 people die each day in the U.S. alone waiting for a transplant. The concept of cross-species transplantation is one of the most prospective methods that have the potential to decrease this problem and result in supply of unlimited tissues and cells for surgeries. In fact, the concept of transplantation is also seen to exist in mythology defining the intimate relation that animals and humans have had since times unknown. Animals in Transplantation Several transplantation surgeries exist such as blood xenotransfusion, skin xenotransplantation, Transplantation of cornea and transplantation of vital organs such as heart. The probability of transplantation from non-human sources such as pigs, goats, sheep and monkeys are being considered now. Presently, no whole organs are used from animal donors except for valves from the pig’s heart and the cow’s heart. Presently, in cases where the human heart valves fail to function, they are replaced by valves from either the pig’s or the cow’s heart. Studies have shown that bovine pericardial valves are less durable than porcine pericardial valves (Bloomfield, 2002, p.583). Goat hematopoietic cells are also considered for xenotransplantation. Problems with Xenotransplantation When the field of transplantation surgery came into consideration some 100 years ago, surgeons first considered animals and not humans as organ donors since the availability of human organs could not be assured. However, owing to the various problems associated with xenotransplantation, animal organs could not be used in the human body system. One of the major problems of integrating animal organs inside the human body is that of immune response. The human body is designed to recognize and destruct any foreign body that enters the human body and transplantation tissues would be recognized by the human system as “foreign” leading to failure in acceptance of the organ. Each and every immune and inflammatory response of the human body system is initiated by xenotranslanation (Zhong and Platt, 2005, p.1415). Various Reponses are responsible for graft rejection. Production of anti-Gala1-3Gal antibodies initiate vascular rejection Lin et al tested the production of these antibodies in primate body grafted with pig tissue and observed that anti-Gala1-3Gal antibodies bind to the tissue and prevented it from functioning. The researchers also observed that by removing these antibodies from the blood system would reduce the chances of rejection and allow the grafted organs to function normally (Lin et al, 2000, p.1667). The problems of coagulation and thrombosis also contribute towards prevention of graft acceptance by the human body. Studies used mice to show that up regulation of certain anti-coagulating genes or deleting coagulating genes by means of genetic engineering would help in inhibit the acute graft rejection phenomena (Zhong and Platt, 2005, p1418). However, rejection of pig grafts have been associated with increase in activation of procoagulants and in spite of knocking out the dominant xenoantigen gene the problems of rejection persists and requires enhanced research. One of the more important challenges to xenotransplantation is the risk of infectious diseases associated with the grafted tissue. Some surgeons believe that xenotransplantation would enable entry of infectious and fatal non-human pathogens from non-human tissue and organs (Benova et al, 2001, p.1). This fear is vindicated since infectious diseases such as HIV1, HIV2, Marburg virus etc have entered into humans from animal sources such as chimpanzees, sooty mangebeys and African green monkeys respectively. Presently research is focused on development of specific pathogen free animals such as pigs for use in research. However owing to the complexity of the methods and infrastructure required along with the time investment remains questionable whether the same could be done for other candidates of xenotransplants as well. Genetically modified animals in Transplantation As a result of the various problems associated with the transplantation of non-human organs researchers have proposed that modification of the donor’s genes could potentially help in overcoming most of the problems associated with xenotransplantation. Pigs are considered one of the most prospective donors for organs owing to the similarity in the anatomical and physiological features of its organs. The sole barrier to such transplantations is graft rejection. However, by genetically modifying the gene of the pigs by knocking out or using RNAi technology to silence alpha-1,3-Gal epitopes, there are possibilities that these genes which are primarily responsible for triggering immune response and subsequent graft rejection would not function leading to acceptance of the grafts by the recipient’s body (Klymiuk et al, 2010,p.209). Other considered genetic medications includes down regulation of expression of human complement coagulant proteins, modulators of immune systems such as TNF alpha etc. Researchers have already successfully generated genetically modified pigs with non-fucntional GalT genes. The absence of these genes would not trigger the immune response upon grafting and aid in tissue acceptance. Conclusion The concept of xenotransplantation is undoubtedly the answer to transplantation surgeries. Even though there persists problems with donor tissue acceptance within the humans system research focussed on solving these problems through usage of pathogen free species , genetically engineered donor or usage of advanced immunosuppressant methods would help the grafted tissue function normally inside the recipient’s body. Presently researchers are heading towards solving the immunological drawbacks and introducing usage of whole animal organs for transplantation. Hence, in the future, research needs to be focused on both the donors as well as on the recipients and in-depth study of the immunological phenomena associated with transplantation surgeries. References Benova.,R.S., et al.” Infectious Disease Issues in Xenotransplantation.” Clinical Microbiology reviews, 14. 1(2000):1-14. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC88959/ on 20 october, 2014. Bloomfield,P. “Choice of heart valve prosthesis.”BMJ, 86. 6 (2002):583-589. Klymiuk,N. Et al.” Genetic modification of pigs as organ donors for xenotransplantation.” Molecular reproduction and Development, 77. 3 (2010):219-221. Lin, SS., et al. “The role of anti-Galalpha1-3Gal antibodies in acute vascular rejection and accommodation of xenografts.” Transplantataion, 70. 12 (2000):1667-1674.Print. Zhong,R. and Platt, J. “Current status of animal-to-human transplantation.” Expert opinion on Biological therapy, 5.11 (2005): 1415-1420. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1475507/ on 29 October, 2014. Read More