- HEAVEN-GEMINI International Collaborative Group, Turin, Italy and Nanning, China.
DOI:10.25259/SNI_495_2019Copyright: © 2019 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Canavero S, Ren X. Advancing the technology for head transplants: From immunology to peripheral nerve fusion. Surg Neurol Int 06-Dec-2019;10:240
How to cite this URL: Canavero S, Ren X. Advancing the technology for head transplants: From immunology to peripheral nerve fusion. Surg Neurol Int 06-Dec-2019;10:240. Available from: http://surgicalneurologyint.com/surgicalint-articles/9783/
In this editorial, we hash out the details of two major aspects of the technology behind head transplants (HEAVEN), one having to do with immunosuppression (IS), the other on the reconnection of peripheral nerves at neck level.
In the context of HEAVEN,[
In the 21st century, tolerance induction through chimerism (full or partial) is a clinical reality. Tolerance to HLA matched and mismatched living donor kidney transplants with complete withdrawal of IS drugs without subsequent rejection for up to 14 years of observation has been achieved in more than 50 patients enrolled in trials in four medical centers after the establishment of transient or persistent chimerism (with nonmyeloablative conditioning regimens employing thymoglobulin, belatacept, and bone marrow transplantation plus rituximab). Complete drug withdrawal without chimerism was reported in a prospective trial of liver transplantation combined with injection of regulatory T cells. IS drug minimization without rejection was reported in recipients of living donor kidney transplants after injection of recipient regulatory T cells or injection of donor regulatory monocytes or dendritic cells.[
Apoptotic cell-based therapies represent a novel option that may improve graft survival and also be effective for the treatment of GVHD.[
As illustrated in a previous paper,[
The question arises whether other fusion protocols exist that might complement the PEG approach. In the 20th century, Luis De Medinaceli contributed one such approach, which is of particular interest (unfortunately he died in a car crash in 1996). He started observing how errors in the direction of peripheral nerve regenerating sprouts (mismatching) lead to suboptimal results and failures. He also noted how even guillotine-like devices used to make “clean” nerve sections cannot eliminate the crushing, twisting, and tearing injury that is inflicted by even the sharpest blade (lasers do not, but coagulate the tissue and are thus of no use in this context). He thus froze the stumps, resulting in smooth surfaces of transection with minimal crush injury and avoided the cell damage stemming from freezing-thawing (due to intracellular icicle formation) by bathing the nerve in appropriate fluids, carefully avoiding supercooling and keeping duration and depth of cooling to a minimum (e.g., –180°C for 30 s or –5°C for 5 min are both harmful to the nerve cells and axons). The two fluids he developed included chlorpromazine (1 mM) and polyvinyl alcohol (PVA) 15% w/v (plus NaCl 140 mM and KCl 4 mM) for first stage protection (fluid 1) and chlorpromazine and PVA as per fluid 1 plus NaCl (10 mM), KH2PO4 (120 mM), NaCO3H (5 mM), imidazole (40 mM), and potassium hydroxide to adjust pH to 6.8 (fluid 2).[
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