Fusive Neurosurgery: How Paralyzed Pigs Are Walking Again – Could Humans Be Next?

Currently, over 15 million individuals worldwide suffer from spinal cord injuries, with limited treatment options available. A new study explores exciting advancements in regenerative medicine, revealing how pigs with complete spinal cord severance regained mobility. Read the latest research here.

This groundbreaking work was spearheaded by Michael Levenstein-Gumowski at the Skrifosovsky Institute of Emergency Medicine, Russia. Notably, the study includes insights from neurosurgeon Sergio Canavero, who previously claimed that human head transplants might be possible within two years. His involvement further fuels interest, especially as Russia aims to add spinal cords to its list of transplantable tissues this year.

So, what methods did Levenstein-Gumowski and his research team employ? Initially, they anesthetized the pigs, removed the bony arch of the spinal column, cooled the region, and made a clean cut through the spinal cord. This procedure simulated one of the most severe spinal cord injuries.

Subsequently, the team stabilized the spine around the lesioned area and positioned the severed spinal ends close together. Three pigs were administered a fusogenic compound, composed of polyethylene glycol—used in cosmetics and pharmaceuticals—and chitosan, a biopolymer derived from crustacean shells. This mixture was injected both at the injury site and into the bloodstream, while two pigs served as control subjects without fusogen.

All animals received anti-inflammatory medications and were given electrical stimulation to the limbs for 20 minutes, twice daily. One week post-surgery, the experimental group also received an additional injection of the fusion-promoting agent.

Immediately following surgery, all pigs exhibited motor and sensory paralysis in their hind limbs and pelves, symptoms that persisted in control animals. Remarkably, within 48 hours, one treated pig began to move its hind limbs. By the end of the week, one displayed attempts to stand.

Throughout the 60-day observation period, all three treated pigs achieved the ability to walk, albeit unsteadily. They also regained pelvic control and some sensory function. Examination of the injury site showed reduced degeneration and a significant presence of twisted, thickened axons, creating what the authors termed an “axonal bridge” across the damaged area.

The researchers hypothesize that polyethylene glycol helps to seal injured nerves, limiting degeneration and fostering axon fusion across the injury. Chitosan may additionally aid in sealing neural membranes and providing structural support.

This innovative approach is akin to connecting two wires end-to-end, allowing for the potential continuity of electrical signals across the lesion.

However, the anatomy of the spinal cord presents significant challenges. Unlike simple electrical cables, the spinal cord comprises a complex network of axons, immune cells, blood vessels, and supporting tissues. Injury to the spinal cord triggers inflammation and scarring, complicating the healing process. Previous studies in mice indicated that functional recovery hinges on returning axons to their intended targets, highlighting the limitations of randomized nerve regrowth.

The research team provided New Scientist with a video demonstrating their technique and voiced confidence in their findings due to the controlled nature of their surgical procedure. Yet, Levenstein-Gumowski confirms plans to integrate electrophysiological evaluations in future studies.

“The outcomes of this research were unexpected, as treated subjects regained some sensory and motor functions,” remarks Melissa Andrews from the University of Southampton, UK. “This includes the ability to stand and respond to stimuli in previously affected limbs, functionalities typically lost in human spinal cord injury cases.”

Nonetheless, she points out that the spinal cord was cooled before severance, which may not accurately reflect typical injury scenarios. Regardless, Andrews notes, “the results thus far appear promising.”

Are Human Head Transplants Next?

Upon inquiry, Levenstein-Gumowski emphasized that their primary objective revolves around innovating strategies to restore functionality and structure to injured spinal cords in humans. Yet, with Canavero’s involvement, the potential intersection with head or brain transplants looms large.

While not explicitly stated as the immediate aim of the pig study, Levenstein-Gumowski conceded that it exists within the broader paradigm of ‘fusion neurosurgery.’ This novel approach marries bioengineering, membrane fusion, and neuroplasticity. Simultaneously, the team is investigating potential applications for “transplant neurosurgery.”

Looking forward, the researchers plan to replicate this experiment with larger animal cohorts, ideally involving independent teams across various nations. “I aim to avoid making unsubstantiated promises and will thoroughly vet this methodology before any clinical application,” he asserts.

Future directions include the exploration of human clinical trials, as similar techniques have been initially tested on cadavers. However, applying them in living subjects remains a complex challenge.

Practical concerns are also paramount. Real-life spinal injuries typically incite significant inflammation, degradation, and scarring, rendering repair efforts much more arduous than in controlled research environments. Levenstein-Gumowski acknowledges the undeniable difficulty of “introducing a potent fusion agent into an unprepared spinal cord, akin to placing a quantum computer in a rustic cabin.” The technology is present, but the necessary systems for effective application are not yet in place.

Consequently, the team is exploring ways to ensure timely access to appropriate preoperative care for individuals suffering new injuries. However, this approach holds limited promise for those with chronic injuries. For these cases, techniques involving donor spinal cord segments are being developed to bridge the damaged regions.

Legal considerations are also critical. Starting September 1, a new law will classify “nerves, spinal cords, and their fragments” as approved transplant materials in Russia. While no other country currently includes spinal cords on such a list, places like Israel and the United States permit the harvesting of stem cells from patients for spinal cord transplant applications.

We may be on the cusp of realizing the feasibility of whole head and brain transplants. Canavero insists that this perspective is grounded in reality. He states, “This is another pivotal step toward human brain transplants.” Notably, he alleges that the inaugural surgery employing the spinal fusion protocol on paraplegics is scheduled for later this year, although further details remain undisclosed.

This area of research encompasses a rich history that extends from Robert White’s monkey head transplant trials in the 1970s—where spinal connectivity was never established—to today’s conversations among life extension advocates who aspire to transplant a consciousness into a younger, brainless clone. For millions wheelchair-bound, it often appears that the transformative benefits of such advances remain distant.

Within this field, extraordinary claims can overshadow tangible evidence. When it comes to human applications of fusion neurosurgery, independent validation, stringent oversight, transparent data sharing, and meticulous regulation will be imperative. Furthermore, distinguishing between spinal cord repair as a viable treatment for paralysis and the ethically sensitive aims of brain transplants will be essential. Lacking these measures, promising therapies for paralysis might encounter unwarranted obstacles.