Written By: Ashley Koca

It’s been nearly a year since news outlets were flooded with stories about “partly-alive,” or even “zombie,” pig brains revived post-mortem. April 17, 2019, Yale scientists shook the world with their “Restoration of brain circulation and cellular functions hours post-mortem,” revealing it is possible to reanimate certain brain functions and structures even an astonishing four hours after death. 

Coined “BrainEx,” the researchers have devised a type of dialysis machine that supplies the brain with oxygen and re-establishes circulation. Though the mammalian brain may be highly oxygen-dependent, it is believed that cell death can be halted minutes to even hours post-mortem — the same going for mitochondrial functionality. These lasting systems are what allow the researcher’s method of reperfusion to be the success that it is. 

Using leftover USDA-regulated pig specimens, the researchers designed an acellular perfusion system consisting of echogenic particles to allow for ultrasound analysis. In addition to both the system and perfusate itself, the Yale team developed a surgical procedure aimed to isolate the brain above the medulla oblongata along with the associated vascular system. At approximately four hours post-mortem the BrainEx device was connected and ran for another six hours — adding to a total of ten hours post-mortem (Vrselja et al. 2019).

The results of this reperfusion system yielded spontaneous synaptic activity, reduced cell death, preservation of the cellular structure, re-establishment of vascular dilatory along with glial inflammatory responses, and continued metabolism event after the loss of electric activity within the brain (Vrselja et al. 2019).  Although the brain showed continued life-like responses, there was no evidence of neurological activity associated with consciousness remaining (Younger et al. 2019). The purpose of the study was not to revive the mind of the animal, but rather to restore any type of physiological or cellular function hours after death — all in hope that this research could be applied to developing therapies for brain injuries due to lack of oxygen. 

A bittersweet of the application of this reperfusion system is that it could potentially perpetuate strain on the U.S. organ donor list but also allow those pronounced brain dead a second chance. The United Network for Organ Sharing (UNOS)  transplant list is one that many could spend days to even years on, awaiting an essential organ for which each recipient is ranked based on necessity. Roughly twenty people die each day awaiting an organ (American Transplant Foundation) and a new patient is added to the list every ten minutes (UNOS). With the employment of the BrainEx system, so-called “brain dead” patients could become eligible for brain resuscitation as opposed to organ donation (Younger et al. 2019). 

Alternatively, in previous human cases, reperfusion has proven to not be all sunshine and roses thus far. The technique is most commonly employed in cardiac medicine for ischemic and hypoxic myocardia, it should, theoretically, recover cell and organ function through restored blood flow.  Unfortunately, this recovery oftentimes not the case — leading to side effects coined “reperfusion injuries.” Reperfusion Injuries (IRI) are the result of inflammation and oxidation damage due to oxidative stress post-ischemic period, the unanticipated after-effects that were intended to be tissue function restoration. “Paradoxical” in nature, IRIs inflict damage through reactive oxygen species, inflammation-signaling cytokines, and neutrophil-secreted proteases (Crowled et al. 2011). Given this technique’s track record, further refinement must be made if it is to be used in human cases of brain hypoxia and ischemia. 

 While the BrainEx system is, undeniably, a very attractive possibility with promises of a change of fate for many cases of clinically brain dead patients, for the time being, it remains just that, a possibility.

Work Cited

Cowled, P., Fitridge, R., Fitridge, R., & Thompson, M. (n.d.). Pathophysiology of reperfusion injury. Mechanisms of Vascular Disease, 331–350. doi: 10.1017/upo9781922064004.019

Facts and Myths about Transplant. (n.d.). Retrieved from https://www.americantransplantfoundation.org/about-transplant/facts-and-myths/

Organ Transplant: US Organ Donation System. (n.d.). Retrieved from https://unos.org/transplant/?gclid=EAIaIQobChMI-JjkopW95wIVgsDACh20eg7_EAAYASAAEgKiQPD_BwE

Vrselja, Z., Daniele, S. G., Silbereis, J., Talpo, F., Morozov, Y. M., Sousa, A. M. M., … Sestan, N. (2019). Restoration of brain circulation and cellular functions hours post-mortem. Nature, 568(7752), 336–343. doi: 10.1038/s41586-019-1099-1

Youngner, S., & Hyun, I. (2019). Pig experiment challenges assumptions around brain damage in people. Nature, 568(7752), 302–304. doi: 10.1038/d41586-019-01169-8