X-Message-Number: 33097
Date: Fri, 3 Dec 2010 09:28:32 -0800 (PST)
From:
Subject: could argon/xenon improve vitrification solutions?
[Argon and xenon, offer powerful neuroprotectation, and act as novel
cryoprotectants. Could argon/xenon reduce the toxicity of vitrification
solutions? By preforming an intracellular clathrate, cell dehydration and
membrane rupture are largely avoided during both freezing and
rewarming. Clathrate would also presumably reduce vitrification solution
toxicity, by limiting intracellular egress of toxic solvents like DMSO,
and ethylene glycol.
IMHO, there are enough unused novel technologies around such as
directional freezing, variable magnetic field freezing, flavonoid
additives, and here clathrate formation for cryonics to develop fully
reversible whole body cryopreservation protocols within 5 years. As far as
I am aware, the only limiting factor here preventing this is a lack of
vision, and more importantly alas a lack of money. It is hard to say how
to get around the funding desert that surrounds both cryonics, and organ
cryopreservation. A vastly more effective sales strategy is here
indicated than I have seen to date. Perhaps "paper" research into novel
technologies, and development of a shared library of all the
relevant research papers published on these novel technologies would be a
start. Perhaps a think tank with input from both professional salesman and
skeptical scientists could then be used to develop an effective sales
campaign. Otherwise it could easily take over 50 years before the
technologies available now are finally used to engineer fully reversible
whole organ (and whole body) cryopreservation.]
J Huazhong Univ Sci Technolog Med Sci. 2007 Aug;27(4):426-8.
Experimental study on the cryopreservation of LLC-PK1 epithelial cells with
hypoxic UW solution.
Wan C, Wang C, Liu T, Wang H, Yang Z. Department of General Surgery, Union
Hospital, Tongji Medical College, Huazhong University of Science and Technology,
Wuhan 430030, China.
Abstract
The effects of oxygen partial pressure on cryopreservation of the cells with
organ preservation solution were explored. Hypoxic UW solution was made by
purging the UW solution with argon. The pig proximal tubule epithelial cells
(LLC-PK1 cells) were cryopreserved in hypoxic UW solution (Ar-UW group) or
standard UW solution (UW group) at 4 degrees C for 48 h. Trypan blue
staining and LDH detection were performed to evaluate the injury of the
cells. The results showed that the oxygen partial pressure in Ar-UW group
was significantly declined from 242+/-6 mmHg to 83+/-10 mmHg. After
cryopreservation at 4 degrees C for 48 h, LDH leakage rate and Trypan
blue-stained rate in Ar-UW group were (11.3+/-3.4)% and (10.5+/-4.7)%,
respectively, which were significantly lower than in UW group [(49.5+/-6.9)%
and (47.6+/-9.3)% respectively, both P<0.01]. It was concluded that lower
oxygen partial pressure of UW solution was more beneficial to the
cryopreservation of LLC.
PMID: 17828502
[Here xenon forms an intracellular clathrate at above freezing
temperatures, and thereby prevents most cell dehydration during water ice
formation at sub-zero temperatures. This proved to be highly
effective at preserving cell viability by preventing membrane
rupture by large ice crystals, particularly during rewarming. Unlike
pure water ice, the xenon/water clathrate itself is apparently
non-damaging.]
Int J Clin Exp Pathol. 2008 Jan 1;1(5):440-7.
Cardiac mitochondrial membrane stability after deep hypothermia using a xenon
clathrate cryostasis protocol - an electron microscopy study.
Sheleg S, Hixon H, Cohen B, Lowry D, Nedzved M. Innovative Biological
Preservation Technologies LLC Scottsdale, AZ, USA. Sergey.
Abstract
We investigated a new cryopreservation method using xenon, a
clathrate-forming gas, under medium pressure (100psi). The objective of the
study was to determine whether this cryostasis protocol could protect
cardiac mitochondria at cryogenic temperatures (below 100 degrees
Celsius).We analyzed transmission electron microscopy images to obtain
information about changes in mitochondrial morphology induced by
cryopreservation of the hearts. Our data showed absence of mitochondrial
swelling, rupture of inner and outer membranes, and leakage of mitochondrial
matrix into the cytoplasm after applying this cryostasis protocol. The
electron microscopy results provided the first evidence that a cryostasis
protocol using xenon as a clathrate-forming gas under pressure may have
protective effects on intracellular membranes. This cryostasis technology
may find applications in developing new approaches for long-term
cryopreservation protocols.
PMID: 18787624
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2480575/pdf/ijcep0001-0440.pdf
Ann Neurol. 2010 Mar 8. [Epub ahead of print]
Xenon enhances hypothermic neuroprotection in asphyxiated newborn pigs.
Chakkarapani E, Dingley J, Liu X, Hoque N, Aquilina K, Porter H, Thoresen M.
Department of Clinical Sciences at South Bristol, University of Bristol,
Bristol, United Kingdom.
Abstract
OBJECTIVE: To investigate whether inhaling 50% xenon during hypothermia (HT)
offers better neuroprotection than xenon or HT alone. METHODS: Ninety-eight
newborn pigs underwent a 45-minute global hypoxic-ischemic insult severe enough
to cause permanent brain injury, and 12 pigs underwent sham protocol. Pigs then
received intravenous anesthesia and were randomized to 6 treatment groups: (1)
normothermia (NT; rectal temperature 38.5 degrees C, n = 18); (2) 18 hours 50%
xenon with NT (n = 12); (3) 12 hours HT (rectal temperature 33.5 degrees C, n =
18); (4) 24 hours HT (rectal temperature 33.5 degrees C, n = 17); (5) 18 hours
50% xenon with 12 hours HT (n = 18); and (6) 18 hours 50% xenon with 24 hours HT
(n = 17). Fifty percent xenon was administered via a closed circle with 30%
oxygen and 20% nitrogen. After 10 hours rewarming, cooled pigs remained
normothermic until terminal perfusion fixation at 72 hours. Global and regional
brain neuropathology and clinical neurological scores were performed. RESULTS:
Xenon (p = 0.011) and 12 or 24 hours HT (p = 0.003) treatments offered
significant histological global, and regional neuroprotection. Combining xenon
with HT yielded an additive neuroprotective effect, as there was no interaction
effect (p = 0.54). Combining Xenon with 24 hours HT offered 75% global
histological neuroprotection with similarly improved regional neuroprotection:
thalamus (100%), brainstem (100%), white matter (86%), basal ganglia (76%),
cortical gray matter (74%), cerebellum (73%), and hippocampus (72%). Neurology
scores improved in the 24-hour HT and combined xenon HT groups at 72 hours.
INTERPRETATION: Combining xenon with HT is a promising therapy for severely
encephalopathic infants, doubling the neuroprotection offered by HT alone. ANN
NEUROL 2010.
PMID: 20658563 [PubMed - as supplied by publisher]
Stroke. 2008 Apr;39(4):1307-13. Epub 2008 Feb 28.
Xenon and hypothermia combine additively, offering long-term functional and
histopathologic neuroprotection after neonatal hypoxia/ischemia.
Hobbs C, Thoresen M, Tucker A, Aquilina K, Chakkarapani E, Dingley J. Department
of Clinical Sciences at South Bristol, University of Bristol, Bristol, UK.
Abstract
BACKGROUND AND PURPOSE: Hypoxic/ischemic (HI) brain injury affects 1 to 6
per 1000 live human births, with a mortality of 15% to 20%. A quarter of
survivors have permanent disabilities. Hypothermia is the only intervention
that improves outcome; however, further improvements might be obtained by
combining hypothermia with additional treatments. Xenon is a noble
anesthetic gas with an excellent safety profile, showing great promise in
vitro and in vivo as a neuroprotectant. We investigated combinations of 50%
xenon (Xe(50%)) and hypothermia of 32 degrees C (HT(32 degrees C)) as a
post-HI therapy. METHODS: An established neonatal rat HI model was used.
Serial functional neurologic testing into adulthood 10 weeks after injury
was performed, followed by global and regional brain histopathology
evaluation. RESULTS: In the combination Xe(50%)HT(32 degrees C) group,
complete restoration of long-term functional outcomes was seen. Hypothermia
produced improvement on short- (P<0.001) and long- (P<0.001) term functional
testing, whereas Xe(50%) alone predominantly improved long-term function
(P<0.05), suggesting that short-term testing does not always predict
eventual outcome. Similarly, the Xe(50%)HT(32 degrees C) combination
produced the greatest (71%) improvement in global histopathology scores, a
pattern mirrored in the regional scores, whereas Xe(50%) and HT(32 degrees
C) individually produced smaller improvements (P<0.05 and P<0.001,
respectively). The interaction between the 2 treatments was additive.
CONCLUSIONS: The xenon/hypothermia combination additively confers greater
protection after HI than either treatment alone. The functional improvement
is almost complete, is sustained long term, and is accompanied by greatly
improved histopathology. The unique safety profile differentiates xenon as
an attractive combination therapy with hypothermia to improve the otherwise
bleak outcome from neonatal HI.
PMID: 18309163
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http://stroke.ahajournals.org/cgi/reprint/39/4/1307
Crit Care. 2009;13(6):R206. Epub 2009 Dec 17.
Argon: neuroprotection in in vitro models of cerebral ischemia and traumatic
brain injury.
Loetscher PD, Rossaint J, Rossaint R, Weis J, Fries M, Fahlenkamp A, Ryang YM,
Grottke O, Coburn M. Department of Anesthesiology, University Hospital of the
RWTH Aachen, Aachen, Germany.
Comment in: Crit Care. 2010;14(1):117.
Abstract
INTRODUCTION: Recently, it has been shown in several experimental settings
that the noble gases xenon and helium have neuroprotective properties. In
this study we tested the hypothesis that the noble gas argon has a
neuroprotective potential as well. Since traumatic brain injury and stroke
are widespread and generate an enormous economic and social burden, we
investigated the possible neuroprotective effect in in vitro models of
traumatic brain injury and cerebral ischemia. METHODS: Organotypic
hippocampal slice cultures from mice pups were subjected to either
oxygen-glucose deprivation or to a focal mechanical trauma and subsequently
treated with three different concentrations (25, 50 and 74%) of argon
immediately after trauma or with a two-or-three-hour delay. After 72 hours
of incubation tissue injury assessment was performed using propidium iodide,
a staining agent that becomes fluorescent when it diffuses into damaged
cells via disintegrated cell membranes. RESULTS: We could show argon's
neuroprotective effects at different concentrations when applied directly
after oxygen-glucose deprivation or trauma. Even three hours after
application, argon was still neuroprotective. CONCLUSIONS: Argon showed a
neuroprotective effect in both in vitro models of oxygen-glucose deprivation
and traumatic brain injury. Our promising results justify further in vivo
animal research.
PMID: 20017934
Free text>
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2811924/pdf/cc8214.pdf
Neurosci Lett. 2009 Sep 4;460(3):232-6. Epub 2009 Jun 7.
Neuroprotection (and lack of neuroprotection) afforded by a series of noble
gases in an in vitro model of neuronal injury.
Jawad N, Rizvi M, Gu J, Adeyi O, Tao G, Maze M, Ma D. Department of
Anaesthetics, Pain Medicine and Intensive Care, Imperial College London, Chelsea
and Westminster Hospital, 369 Fulham Road, London SW10 9NH, United Kingdom.
Abstract
Xenon-induced neuroprotection has been well studied both in vivo and in
vitro. In this study, the neuroprotective properties of the other noble
gases, namely, krypton, argon, neon and helium, were explored in an in vitro
model of neuronal injury. Pure neuronal cultures, derived from foetal
BALB/c mice cortices, were provoked into injury by oxygen and glucose
deprivation (OGD). Cultures were exposed to either nitrogen hypoxia or noble
gas hypoxia in balanced salt solution devoid of glucose for 90min. The
cultures were allowed to recover in normal culture medium for a further 24h
in nitrogen or noble gas. The effect of noble gases on cell reducing ability
in the absence of OGD was also investigated. Cell reducing ability was
quantified via an MTT assay and expressed as a ratio of the control. The OGD
caused a reduction in cell reducing ability to 0.56+/-0.04 of the control
in the absence of noble gas (p<0.001). Like xenon (0.92+/-0.10; p<0.001),
neuroprotection was afforded by argon (0.71+/-0.05; p<0.01). Neon and
krypton did not have a protective effect under our experimental conditions.
Helium had a detrimental effect on the cells. In the absence of OGD, krypton
reduced the reducing ability of uninjured cells to 0.84+/-0.09 (p<0.01),
but argon showed an improvement in reducing ability to 1.15+/-0.11 (p<0.05).
Our data suggest that the cheap and widely available noble gas argon may
have potential as a neuroprotectant for the future.
PMID: 19500647
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