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.
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.
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?
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.
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 :)
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.
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.
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?
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:
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.
Thanks!
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 :)