Banner by Daniel Walsh
New Era of Organ Transplants
by Maura Sackett
Twenty transplant patients die every day (UNOS, 2018). The total number of patients who need transplants is 114,638; however, this need far exceeds the number of organs available from active donors (UNOS, 2018). Doctors struggle to find matches for patients in order to reduce the risk of complications such as rejection and/or death. Though improved since its inception, there are still a plethora of innovations to be made in the realm of organ transplantation.
Matching donors and patients is quite a complicated process as the UNOS transplant list is about eleven times as long as the donor list. To be considered a viable transplant option, donor organs must share the same or compatible blood type, as the recipient. Donors also need to undergo several other tests such as CT scans, tissue typing and/or physical exams in order to be considered for donation (Tests You Need Before Surgery, 2009).
The lack of donor-recipient matches gave rise to what is now known as the “Organ Transplant Crisis” (Abouna, 2008). Researchers find ways to combat this issue by thinking of potential future innovations. Many of these designs include the concept of synthetically made organs that perfectly match the donor. New developments in transplant research potentially serve to eliminate the need for human, or animal, donors; therefore, erasing the transplant crisis.
To understand the direction in which transplants are going, one must first look to the beginnings. Doctor Joseph Murray conducted the first successful organ transplant in the 1950s by utilizing a twin’s kidney. After this development, many other success stories arose; however, most cases reported something similar – patients rejected the newly introduced organ. Such an event arises when the body’s immune system identifies the new organ as foreign and thus attacks the organ. Because of this, doctors began introducing immunosuppressants as a vital part of the transplant process (“History of Organ and Tissue Transplant”, 2017). This does not eliminate the overall possibility of rejecting the organ; therefore, doctors strive to produce new methods that reduce the risk of infection, rejection, and/or death (“Immunosuppressants”, 2017).
Stem cells have been thought to be the solution to the transplant crisis; however, Jeffery Platt and Marilia Cascalho state that this might not be realistic. In their article, “New and Old Technologies for Organ Replacement” that, while stem cells can reduce the use of immunosuppressants, the cost of the procedure will still be significantly higher than normal transplants. This is because the stem cells need introduced to a xenogeneic fetus and allowed to grow first. Xenogeneic refers to the idea that the fetus belongs to a different species, such as a pig. Then, once the organ or group of cells is large enough, the product will be removed and implanted into the recipient.
Doctor Denise Faustman supports furthering xenogeneic research because she believes the process will provide every transplant patient with the organ(s) they need. As she stated in a conference presentation, “Removing the barriers to xenogeneic (cross-species) transplantation could open the way to organ banks with an unlimited supply of replacement cells and organs” (Institute of Medicine (US) Conference Committee on Fetal Research and Applications, 1994). Furthering this type of research potentially saves the thousands of lives otherwise lost due to the lack of donor organs.
Doctor Megan Sykes also believes in the power of xenografts; however, she is coupling that technique with immunosuppressants. Reducing immune response to new organs is also something that researchers use to close the organ-patient gap. While this concept is not new by any standard, Sykes plans on utilizing a different approach to suppress the body’s response: bone marrow. Sykes believes that this method can make the patient tolerant to foreign bodies and, when coupled with antibodies, makes the recipient’s body less susceptible to rejection (King, 2018). The goal of combining both xenogeneic research and inhibitory methods is to decrease organ rejection rates; therefore, giving patients a better chance of living and a better quality of life after the transplant.
One of the well-known ideas concerning organ transplants, is the concept of “ready-made” organs or “bioartificial” organs. This idea completely forgoes donors, both animal and human, and instead uses plastic scaffolds and recipient stem cells as the basis of the new organ. Using the recipient’s own stem cells is something quite remarkable as the chance of rejecting the introduced organ reduces, if not eliminates (Fountain, 2012).
“Bioartificial” research is especially intriguing and important because it hints that donors will no longer be needed. If someone needs a transplant, doctors can procure stem cells and then make the patient a completely new organ. They have already done this type of procedure with windpipes and bladders and are currently researching how to apply similar techniques to produce livers, kidneys and blood vessels (Fountain, 2012). Researchers plan to create other structures and produce organs without the plastic scaffolds. Instead, they want to use drugs to signal the body to make its own natural scaffold by sending cells to the area of interest. This leads researchers into further research on regenerative medicine – patients growing their own organs – but, for now, that thought is very distant.
Scaffolds, the basic structure of the organ, can also be created using donor organs. Such a process includes, obviously, a donor organ and, less obviously, detergent. Once the detergent strips the organ of the donor’s cells, the natural scaffold is basically marinated in the cells of the recipient. Using a donor organ is not as reliable as the previous method, plastic scaffolding, because there is currently a low supply of donors. Researchers look towards plastic scaffolds and regeneration because of this (Fountain, 2012).
Perhaps the most unconventional of the advancements mentioned so far, is using cotton candy machines to produce fiber strands smaller than a human hair – about thirty-five microns (Aguiar, n.d.). Doctor Leon Bellon, the first to apply the mechanics of cotton candy machines to his preliminary research, created thin, fibrous stands similar to capillaries in size and shape. The strands formed are then suspended within a hydrogel and human cell mixture to produce a three-dimensional version of capillaries. However, the fiber strands placed in the hydrogel must be both soluble and insoluble in water so that they can, first, make the mold and, second, dissolve to create this capillary network. For this reason, Bellon and his team use poly(N-isopropylacrylamide) or PNIPAM (spun on a machine similar to a cotton candy machine) because the compound is soluble only below thirty-two degrees Celsius. Using this method, Bellon plans to create three-dimensional vascular systems for artificial organs ( “Cotton Candy Machines May Hold Key for Making Artificial Organs”).
The future of organ transplantation is quite vast. Research ideas range from tissue engineering to regeneration - leaving a lot of room for new innovations. Scaffolds, both plastic and natural, seem the most likely beginnings for future experimentation and/or implementation. What remains clear is that xenogeneic and bioartificial research influence future transplant methods. No matter what technique becomes popular, there will always be researchers striving to further the field of transplants in order to reduce rejection rates and combat a lack of donor organs.