The authors of the idea of transplanting a human head onto a donor body, Italian neurosurgeon Sergio Canavero and his Chinese colleague Xiaoping Ren, stated that in an experiment on dogs they were able to significantly restore the functions of the severed spinal cord by treating the section with polyethylene glycol - a substance that they intend to use to "fusion" the spinal cord during a future head transplant. An article about the results of the experiment was published in the journal Surgical Neurology International, where both Canavero and Ren are Associate Editors for Head and Spinal Cord Transplantation.
Canavero published an article describing the operation to transplant the head of a paralyzed person to a healthy body back in 2013. The key to solving this problem, in his opinion, is polyethylene glycol, which in laboratory conditions has demonstrated the ability to "glue" damaged cell membranes. It was this substance that was supposed to help restore the severed spinal cord. In 2016, the HEAVEN / GEMINI collaboration created by Canavero reported on the success of experiments to restore the functions of the damaged spinal cord in animals. The authors published videos of mice, rats and dogs in different stages of recovery. In November 2017, the same group performed a head transplant rehearsal on human cadavers at Harbin Medical University.
The scientific community is ambivalent about the experiments of Sergio Canavero. Some experts refuse to comment on the publications of the Italian neurosurgeon, while others criticize the gaps in the description of the experiments, which makes it impossible to assess the credibility of the work. In particular, the scientists spoke about the absence of tomographic or histological evidence that the spinal cord of the animals was actually crossed to the declared depth.
In a new article, Canavero, Ren and their colleagues reported on an experiment on 12 beagle dogs. All animals had their spinal cords cut at the level of the 10th thoracic vertebra, while seven dogs were immediately injected with a syringe into the incision area with two milliliters of polyethylene glycol, and five (control group) - the same amount of 0.5% salt solution. After two and four weeks, as well as after 180 days, all animals were subjected to magnetic resonance imaging and diffusion tensor imaging (with its help, nerve fibers are visualized). Six months after the operation, all animals (except two from the control group) were sacrificed. A fragment of the spinal cord was excised from each of them - two centimeters above and two centimeters below the incision - for histological examination.
Table with data on the condition of dogs before and after surgery.
Before and after surgery, the condition of the animals was assessed using a 20-point BBB mobility scale. Before surgery, all dogs had the highest score on this scale - 19. Six months later, two dogs from the control group and one from the experimental group died. In the control group, the three remaining animals had two "fours" and one "five" on this scale. In the experimental group, two dogs recovered almost to the previous level (18 points), one had 12, two had 10, and another had 7. According to the authors, tomography showed recovery of the spinal cord in the experimental group of animals, in contrast to the control group. where the cut is preserved. A "dramatic difference" between the two groups was also shown by histological studies, where signs of axonal degeneration were seen in the controls, and in the experimental group, nerve fibers crossed the incision.
The authors argue that both histological and tomographic studies confirm the positive effects of polyethylene glycol on cells and its effect on the restoration of nerve fibers.
Sergey Kuznetsov
Promotional video: