Cryo with magnetics added

post by morganism · 2016-10-01T22:27:05.573Z · score: 5 (8 votes) · LW · GW · Legacy · 11 comments

Contents

  Subzero 12-hour Nonfreezing Cryopreservation of Porcine Heart in a Variable Magnetic Field
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11 comments

This is great, by using small interlocking magnetic fields, you can keep the water in a higher vibrational state, allowing a "super-cooling" without getting crystallization and cell rupture

Subzero 12-hour Nonfreezing Cryopreservation of Porcine Heart in a Variable Magnetic Field

"invented a special refrigerator, termed as the Cells Alive System (CAS; ABI Co. Ltd., Chiba, Japan). Through the application of a combination of multiple weak energy sources, this refrigerator generates a special variable magnetic field that causes water molecules to oscillate, thus inhibiting crystallization during ice formation18 (Figure 1). Because the entire material is frozen without the movement of water molecules, cells can be maintained intact and free of membranous damage. This refrigerator has the ability to achieve a nonfreezing state even below the solidifying point."

 

http://mobile.journals.lww.com/transplantationdirect/_layouts/15/oaks.journals.mobile/articleviewer.aspx?year=2015&issue=10000&article=00005#ath

11 comments

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comment by Fluttershy · 2016-10-02T00:40:42.838Z · score: 6 (6 votes) · LW · GW

The most striking problem with this paper is how easy all of the tests of viability they used are to game. There are a bunch of simple tests you can do to check for viability, and it's fairly common for non-viable tissue to produce decent-looking results on at least a couple, if you do enough. (A couple of weeks ago, I was reading a paper by Fahy which described the presence of this effect in tissue slices.)

It may be worth pointing out that they only cooled the hearts to -3 C, as well.

comment by Fluttershy · 2016-10-02T01:09:38.064Z · score: 4 (4 votes) · LW · GW

OTOH it's plausible they don't have much compelling evidence mainly because they were resource-constrained. I'm still not expecting this to go anywhere, though.

Whole kidneys can already be stored and brought back up from liquid nitrogen temps via persufflation well enough to properly filter waste and produce urine, and possibly well enough to be transplanted (research pending), though this may or may not go anywhere, depending on the funding environment.

comment by WhySpace_duplicate0.9261692129075527 · 2016-10-03T15:42:46.029Z · score: 4 (4 votes) · LW · GW

persufflation

That was a mild pain to google, so I'm leaving what I dug up here so others don't have to duplicate the effort.

Persufflation is perfusion with gaseous oxygen. Perfusion is when fluid going to an organ passes through the lymphatic system or blood vessels to get there.

If I'm reading this correctly, there's no thermodynamic reason to pump the organ full of oxygen gas, but only a biological one. Cells need less oxygen when they're on ice for an organ transplant, but they still consume O2. If this isn't being delivered via blood flow, another source is needed.

I take it that the persufflation is to help with recovering kidneys from liquid nitrogen temperatures, and not in getting there without damage?

comment by Fluttershy · 2016-10-04T01:43:49.557Z · score: 3 (3 votes) · LW · GW

I'm sorry! Um, it probably doesn't help that much of the relevant info hasn't been published yet; this patent is the best description that will be publicly available until the inventors get more funding. From the patent:

By replacing the volume of the vasculature (from 5 to 10 percent of the volume of tissues, organs, or whole organisms) with a gas, the vasculature itself becomes a “crush space” that allows stresses to be relieved by plastic deformation at a very small scale. This reduces the domain size of fracturing...

So, pumping the organ full of cool gas (not necessarily oxygen) is done for reasons of cooling the entire tissue at the same time, as well as to prevent fracturing, rather than for biological reasons.

ETA: To answer your last question, persufflation would be done on both cooling and rewarming.

comment by WhySpace_duplicate0.9261692129075527 · 2016-10-04T20:51:45.460Z · score: 3 (3 votes) · LW · GW

Thanks!

comment by Manfred · 2016-10-02T18:20:42.665Z · score: 1 (1 votes) · LW · GW

Yeah, -3 C was exactly as intended by the authors, since they were (supposedly) suppressing the freezing of water in the experimental group - much colder and the water in their experimental organs would have stopped being liquid :)

comment by Manfred · 2016-10-02T18:14:24.130Z · score: 2 (2 votes) · LW · GW

Not relevant to cryonics. "Super-cooling" is not a neologism, it means that the water didn't freeze when they cooled the organs down to -3 degrees C. This is not extendable to lower temperatures.

comment by Luke_A_Somers · 2016-10-03T00:01:11.531Z · score: 3 (3 votes) · LW · GW

It might help, though - if you suddenly stop applying the magnetic fields, then it might freeze more abruptly than if you simply lower the temperature. That could reduce the extent of crystallization and thus damage.

comment by WhySpace_duplicate0.9261692129075527 · 2016-10-05T18:47:28.788Z · score: 1 (1 votes) · LW · GW

Precisely. Normally, vitreous H2O (glass phase of ice) is produced through 1 of 2 methods:

  1. Pouring liquid H2O on a highly conductive heatsink which is cooled to liquid nitrogen temperatures (Ie, a block or sheet of copper in contact with LN)

  2. Taking a block of ice and compressing it at low temperatures.

The first method only works for thin sheets of ice, or creates a thin vitreous layer on the outside of a larger water-filled object. The second method allows one of the normal phases of ice to form, and then converts it to vitreous ice.

However, if we could supercool large volumes of water low enough without spontaneous crystallization, it might be possible to choose which phase of ice forms by deliberately nucleating with that. If turning off the magnetic field doesn’t cause freezing fast enough to vitrify, maybe a sufficiently sharp ultrasonic pulse could disrupt the metastable liquid state fast enough? Similarly, I’d be curious whether a thermoacoustic heat pump could remove heat fast enough to vitrify the water without completely shredding everything nearby.

On a related note, I wonder if it would be possible to suppress the less dense phases of ice (which expand more, and therefore cause more damage) just by increasing the ambient pressure during freezing? Method #2 is a crystalline solid to vitreous solid phase change, but there's no reason the same thing wouldn't work for a liquid to vitreous solid phase change. It looks like it's done at 5,000-1,600 atmospheres of pressure, but that might just be to speed up the rate of transition.

The depth diving record is the equivalent to 701 meters, which works out to 68 atmospheres of pressure. However, most of the effects have to do with respiration, such as the lung's ability to remove CO2 as it builds up in the blood. Nitrogen narcosis has effects on judgment a bit like alcohol, but this might not matter for cryonics. If it does, we could always use a liquid or gas like helium, which has effectively zero lipid solubility.

Is the reason this isn’t done cost, or something else? From a material science perspective, pressure seems like the obvious solution to fight expansion during crystallization. Working with nature is much easier than messing with thermodynamically unfavorable solutions.

comment by morganism · 2016-10-02T21:18:20.602Z · score: 0 (0 votes) · LW · GW

too bad.

Might be useful for extended spaceflight though. They are looking at using heavy duty magnetic shielding to deflect some of the more energetic rays raining down. If they are in topor, and using this tech to slow down bio systems, it may be part of a "stasis" system.

comment by morganism · 2016-10-02T21:52:45.410Z · score: 0 (0 votes) · LW · GW

Not really related, but Interesting paper on DNA degradation rates in fossils. They do discuss optimal temp for storage at -5c.

"In an attempt to document a correlation between sample age and DNA preservation, we use a quantitative real-time PCR (qPCR) design to measure relative copy numbers of mitochondrial DNA (mtDNA) fragments from bones of the extinct New Zealand moa "

http://rspb.royalsocietypublishing.org/content/279/1748/4724