How did you evaluate the competitors?

The full rules are here.

The competitors sent us (the Brain Preservation Foundation) preserved brains, and then we independently verified that the brains were preserved to our standards by taking multiple random samples and analyzing them with electron microscopy. If the resulting electron micrograph images looked good (i.e. no cracks, cell damage, etc) compared to reference images of healthy brain tissue, then we had a winner. To claim the prize, a contestant had to also publish the details of their method in a reputable scientific journal. Performing our verification procedure using electron microscopy required that the brain samples were fixed, embedded in plastic, and then sliced into very thin slices.

For chemopreserved brains, most of this procedure was already done. We simply received the plastic embedded brain, and did our own slicing and analysis.

For cryopreserved brains, we observed the vitrification process to ensure that the whole brain was preserved. Then we extracted small random samples from the thawed brain and used the standard small-scale plastic embedding procedure for preparing small samples for electron microscopy. Since it is much easier to plasticize very small samples of frozen brain tissue (it’s done all the time in labs across the world), evaluating cryopreserved brains this way put cryopreservation on a more equal footing with chemopreservation for the purposes of winning the prize.