The first vitrification agent in cryonics: B2C
In 2001 the Alcor Life Extension Foundation licensed its first vitrification agent from the cryobiology research company 21st Century Medicine (21CM) to be used for its neuropatients. The composition of this agent, called B2C, has now been made public on Alcor’s website. The published composition is:
Dimethyl sulfoxide 24.765% w/v
Ethylene glycol 17.401%
Polyvinyl pyrrolidone K12 2%
Polyvinyl pyrrolidone K30 2%
X-1000 ice blocker 1%
Z-1000 ice blocker 1%
B2C was formulated as a “hyperstable” variant of 21CM’s VM3 to virtually eliminate the risk of ice formation. B2C differs from VM3 in two important ways. It has increased concentrations of DMSO, formamide, and ethylene glycol and contains two different molecular weights of the non-penetrating polymer polyvinyl pyrrolidone (PVP). Where VM3 includes 7% w/v of PVP K12, B2C includes 2% PVP K12 and 2% PVP K30.
Like VM3, B2C reflects the technical advances in 21CM-based vitrification solutions: neutralization of the toxicity of formamide by DMSO, reduced toxicity by substitution of ethylene glycol for propylene glycol, and addition of non-penetrating polymers and “ice-blockers.” Because the primary objective of B2C was to protect the brain against ice formation, not maintain viability, the concentrations of DMSO, formamide and ethylene glycol are higher than in the older 21CM solutions in addition to the advantages of the non-penetrating polymers and “ice-blockers” of the newer solutions.
In 2005, the state of the art at Alcor and 21CM converged when the vitrification agent M22 was introduced for cryopreservation of both neuro and whole body patients. As can be seen in the electron micrographs on the Alcor website, perfusion and vitrification with M22 produces better ultrastructural results than B2C. Perhaps the only advantage of B2C over M22 is that such a highly concentrated vitrification agent (9.93 Molar for the penetrating cryoprotectants) is more suitable for remote vitrification and transport on dry ice.
Because B2C was not available to Alcor’s whole body patients, from 2001 until 2005 Alcor offered a temporary combination option in which a patient’s brain would be perfused with B2C and the rest of the body with higher molarity glycerol. Currently all Alcor patients who have made whole body arrangements are perfused with M22. Although whole body patients could still benefit from separate treatment of the body and the brain, Alcor currently does not offer the option of whole body cryopreservation with preferential treatment of the brain.