July 03, 2013

Full Body Donation Can be Ethical and Head Transplanting can have ethical and valid clinical uses

The need for organ donors has never been greater. Presently, there are more than 110,000 people on the national waiting list who need a life-saving organ transplant.

Organ donations in the USA are made after a donor has been declared brain dead.

Recently a proposed procedure seems to make the possibility of human body transplants (head transplants) a near term possibility.

There has been strong reaction around the internet and in other news sources.

I do not see the argument that donating all of the body of a brain dead person to another recipient is unethical. It seems that careful policy would make it as ethical as organ donation from someone deceased.

Experiments on animals for body transplant also seems ethical as it would be work to lead to clinical treatment.

Data on the number of US organ transplants in each year.

The number of organ donors ranges from about 6 to 34 donors per million people depending upon country. There are plans to get up to 40 donors per million people. The number of organ transplants is higher because one donor could provide organs for multiple transplants.

There has been work to make genetically modified pigs as a source for human heart transplants.

Xenotransplantation is the transplantation of living cells, tissues or organs from one species to another. There have been a few dozen xenotransplantations into humans.

So how far could an ethical boundary go ?

Could genetically modified pigs be used for body donation to keep someone's head alive for extended periods of years ?

Could you transplant someones head, arms and legs to the genetically modified pig ?

Could genetically modified chimps or gorillas be mass produced for whole body donation ? The immune system would be modified for compatibility but other aspects would remain to prevent it becoming too human as a source.

There has been research on giving mammals improved regeneration and self-healing capabilities like those that exist in salamanders. Regeneration and healing genetic enhancement has been done mainly in mice. It could be adapted to chimps, gorillas and pigs. It would be immune and healing steps to enhance the level of recovery of the spinal cord and acceptance of the transplant.

The case that Body transplants would be successful

The technical hurdles have now been cleared thanks to cell engineering. As described in a paper, the keystone to successful spinal cord linkage is the possibility to fuse the severed axons in the cord by exploiting the power of membrane fusogens/sealants. Agents exist that can reconstitute the membranes of a cut axon and animal data have accrued since 1999 that restoration of axonal function is possible. One such molecule is poly-ethylene glycol (PEG), a widely used molecule with many applications from industrial manufacturing to medicine, including as an excipient in many pharmaceutical products. Another is chitosan, a polysaccharide used in medicine and other fields.

Surgical Neurological International - HEAVEN: The head anastomosis venture Project outline for the first human head transplantation with spinal linkage (GEMINI)

* In 2000, guinea pigs had spinal cords surgically cut and then protected with PEG chemical (like what is proposed here) and they had over 90% of spinal nerve transmission restored with a lot of mobility and function restored
* a head of a monkey was transplanted in the 1970s but the spinal cord could not be repaired at the time
* Spinal cords have been regrown in rats.

* Effective repair of traumatically injured spinal cord by nanoscale block copolymer micelles (Nature Nanotechnology, 2009) These experiments treated the damage after about ten minutes and were able to get a lot of movement back in most cases. The damage was a crushing of the spinal cord, so the transplant procedure would have better results because it would be a careful separation of the spinal cord under cold conditions with immediate application of the protectant chemicals.

Spinal cord injury results in immediate disruption of neuronal membranes, followed by extensive secondary
neurodegenerative processes. A key approach for repairing injured spinal cord is to seal the damaged membranes at an early stage. Here, we show that axonal membranes injured by compression can be effectively repaired using self-assembled monomethoxy poly(ethylene glycol)-poly(D,L-lactic acid) di-block copolymer micelles. Injured spinal tissue incubated with micelles (60 nm diameter) showed rapid restoration of compound action potential and reduced calcium influx into axons for micelle concentrations much lower than the concentrations of polyethylene glycol, a known sealing agent for early-stage spinal cord injury. Intravenously injected micelles effectively recovered locomotor function and reduced the volume and inflammatory response of the lesion in injured rats, without any adverse effects. Our results show that copolymer micelles can interrupt the spread of primary spinal cord injury damage with minimal toxicity.

Improvement in the locomotor function in the micelle-treated group was evident by a more rapid increase of BBB scores in the first 14 days and continuation of improvement over the following two weeks. Specifically, at 28 days post-injury, the BBB scores were 12.5 + or minus 3.1. From a clinical perspective, an animal with a BBB score equal to or less than 11 lacks hindlimb and forelimb coordination, whereas a score of 12 to 13 corresponds to occasional to frequent forelimb and hindlimb coordination. Reaching a BBB score of 12 is significant in that it is a sign of axonal transduction through the lesion site

Illustration of the monkey head transplant from the 1970s.

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