Tricking Cells into Accepting a Foreign Transplant
Written by Tanishq Vaidya
Edited by Pooja Dandekar
Jan 31, 2021
Edited by Pooja Dandekar
Jan 31, 2021
As reported by Donate Life America, over 8000 people die each year due to the rampant organ shortage in today’s medical industry. In the USA, while the number of people that require organ donation is continually rising, there is still a huge disparity between the number donated versus the number needed. As such, scientists are intently searching for an alternate means of procuring the organs needed. One particularly interesting solution is xenotransplantation, or the transplantation of organs between species (for example, between pigs and humans). However, there are challenges in such procedures since each animal has specialized markers on its cells that make it recognizable to its own immune system. The risk of organ rejection is extremely high in the application of xenotransplantation, because the human recipient’s immune system immediately recognizes that the organ is a foreign body that lacks its own specialized markers and launches an attack on the donated organ. This means that the donated organ starts to degrade and harmful inflammation associated with the process can put the recipient's life at risk. Luckily, scientists from the Columbia Center for Translational Immunology have found a critical mechanism of self recognition that they say could be used to prevent the body from attacking the organ.
The mechanism in question is called the CD47-SirpA cell surface glycoprotein mechanism. This mechanism allows our white blood cells to interact with other cells in the body to initiate an anti phagocytosis signal. CD47 is a crucial part of this system, as it is a biomarker expressed on all cells in the body that lets the immune cells know that no attack is needed. SirpAis expressed only on immune cells and is the complement to the CD47. Through an interaction similar to a lock and key, an individual’s unique CD47 matches with its unique SirpA. Once the match is made, a process known as phosphorylation deactivates the immune cell and prevents it from destroying the healthy cells. The scientists propose that through genetic engineering it would be possible to breed pigs that express an individual’s particular CD47, so that the SirpA in the recipient’s body would correctly match with the new organ. This would prevent rejection because the correct lock and key mechanism would occur and the organ would not be detected as foreign. Early experimentation has already shown that pig cells that express human CD47 have safer reactions when exposed to human immune cells.
While the current state of organ translation in the US cannot meet the demands placed upon it, through better understanding of the organ rejection mechanism, we can find innovative solutions to assist in this crisis. Hopefully, in the near future organ shortages will no longer be the reason for patient death.
Works Cited
Navarro-Alvarez, Nalu, and Yong-Guang Yang. “CD47: A New Player in Phagocytosis and Xenograft Rejection.” Cellular & Molecular Immunology, vol. 8, no. 4, 4, Nature Publishing Group, July 2011, pp. 285–88. www.nature.com, doi:10.1038/cmi.2010.83.
“Organ Donation Statistics.” Donate Life America, https://www.donatelife.net/statistics/. Accessed 31 Oct. 2020.