Table 1.

In vitro studies employing argon for cell and tissue preservation

Article	Cell/tissue	Model	Ar treatment	Histopathology/functionality	Biochemistry
Lemoine et al., 2017[17]	1. Cardiomyo cytes	H/R	Ar 70%	EAD: ↑	NA
			Duration: 5 min	Conduction blocks: ↑
	2. Human right atrial appendage		Reentries: ↑
			Contractile force: ↑
Mayer et al., 2016[18]	Cardiomyocytes	Hypoxia + Ar preconditioning	Ar 50%	Cell survival: ↑	HSP27: +
			Duration: 1 h		SOD2: +
					VEGF: +
					iNOS: +
					COX2: ≈
					STAT3: ≈
					HSPA4: ≈
					HIF1α: ≈
					ERK1-2 phosphorylation: ≈
					Akt: ≈
Hafner et al., 2016[19]	Airway epithelial cells	N2O2 oxidative stress + Ar preconditioning	Ar 30-50%	Apoptosis: ↑	JNK: +
			Duration: 30-180 min	Cell viability: ↑	p38: +
					ERK 1-2: +
					Akt: ≈
Ulbrich et al., 2015[20]	Human neuroblastoma cells	Drug-induced cell injury (rotenone)	Ar 25-75%	Apoptosis: ↑	TLR 2 - 4: -
			Duration: 2-4 h		IRAK 4: -
					ERK1 - 2: +
					Caspase-3: -
Rizvi et al., 2010[21]	Human tubular kidney cells	OGD + Ar preconditioning	Ar 75%	Cell viability: ≈	p-AKT: ≈
			Duration: 3 h		HIF1α: ≈
					Bcl 2: ≈
Ulbrich et al., 2016[22]	Human neuroblastoma cells	Drug-induced cell injury (rotenone)	Ar 75%	NA	Mithocondrial ΔΨ: ↑
			Duration: 2 h		ROS: -
					NF-kB: -
					STAT3: -
					IL-8: -
Spaggiari et al., 2013[23]	Human osteosarcoma cells	Drug-induced cell injury (STS, MTX, rotenone, antimycin A, menadione)	Ar 75%	NA	Caspase 3: -
			Duration: 6-16 h		Cytochrome c: -
					Mithocondrial ΔΨ: ↑
Fahlenkamp et al., 2012[24]	Neuronal, astroglial cells, and microglial cells	Selective influence of	Ar 50%	NA	Phospho-ERK 1-2: +
		Ar on ERK 1-2	Duration: 15-120 min		IL 1β: -/≈
					TNFα: ≈
					IL 6: ≈
Jawad et al., 2009[25]	Neuronal cells	OGD+hypoxia	Ar 75%	Cell viability: ↑	Cell reducing ability: ↑
			Duration: 24 h
Loetscher et al., 2009[26]	Hippocampal slices	1. OGD	Ar 25-74%	OGD and TBI tissue injury: ↑	NA
		2. TBI above CA1	Duration: 72 h
David et al., 2012[27]	Brain coronal slices	OGD	Ar 25-75%	NA	LDH release: -
			Duration: 3 h
Zhao et al., 2016[28]	Rat cortical neuronal cultures	OGD	Ar 70% + MTH	Neuronal death: ↑	HO-1: +
			Duration: 2h		p-Akt: +
Zhao et al., 2016[29]	Rat cortical neuronal cultures	OGD	Ar 70%	Cell viability: ↑	PI-3K: +
			Duration: 2 h		Erk 1/2: +
					mTOR: +
					Nrf2: +
					ROS: -
Harris et al., 2013[30]	Mouse hippocampal slices	Focal mechanical trauma	Ar 33% Duration: 30 mins-24 h	Cell injury (PI): ↑	NA
Yarin et al., 2005[31]	Rat organ of Corti cultures	1. Hypoxia	1. Ar 95%	1. Number of OHC: ↑	NA
			Duration: 30 h	Number of IHC: ↑
		2. Drug-induced cell injury (cisplatin)	2. and 3. Ar 74%	2. Number of OHC: ↑
		3. Drug-induced cell injury (gentamycin)	Duration: 48 h	Number of IHC: ≈
				3. Number of OHC: ↑ Number of IHC: ↑
David et al., 2013[32]	Enzymatic and thrombolytic efficiency of tPA	1. Catalytic efficiency:	Ar 25-75%	NA	1. Catalytic efficacy
		tPA + specific chromogenic substrate + distilled water saturated solution	Duration: 120 min		Ar 75%: +
					Ar 50: ≈
					Ar 25%: -
		2. Thrombolytic efficiency			2. Thrombolytic efficacy
		whole blood (rats) + saline + tPA saturated solution			Ar 75%: +
					Ar 50: ≈
					Ar 30%: -
Grüßer et al., 2017[33]	Hippocampal slices	TBI	Ar 50%	Cell survival≈	NA
			Duration: 2 h

↑: Treatment with Ar was significantly cell protective compared to control; ≈: Treatment with Ar was equivalent to control; +: Increased with Ar treatment compared to control; -: Decreased with Ar treatment compared to control, Ar: Argon, O₂: Oxygen, CO₂: Carbon dioxide, N₂: Nitrogen, He: Helium, Kr Krypton, Xe Xenon, Ne: Neon, NA: Not available, H/R: Hypoxia-reoxygenation, EAD: Early after depolarization, HSP: Heat shock protein, SOD: Superoxide dismutase, VEGF: Vascular endothelial growth factor, iNOS: Inducible nitric oxide synthase, COX: Cyclooxygenase, STAT: Signal transducers and activator of transcription, HIF: Hypoxia-inducible factor, ERK: Extracellular signal-regulated protein kinases, p-Akt (also known as PKB): Phospho protein kinase B, N₂O₂: Nitrogen peroxide, JNK: c-Jun N-terminal kinase, p38: Protein 38, TLR: Toll-like receptor, IRAK: IL-1 Receptor-associated kinase, Bcl: B-cell lymphoma, OGD: Oxygen-glucose deprivation, ΔΨ: Membrane potential, ROS: Reactive oxygen species, NFkB: Nuclear factor-kB, IL: Interleukin, MTX: Mitoxantrone, STS: Broad-spectrum kinase inhibitor staurosporine, LPS: Lipopolysaccharide, TNF: Tumor necrosis factor, TBI: Traumatic brain injury, LDH: Lactate dehydrogenase, MTH: Mild therapeutic hypothermia, HO-1: Heme oxygenase-1, PI-3K: Phosphatidylinositol-3-kinases, mTOR: Mechanistic target of rapamycin, Nrf2: Nuclear factor (erythroid-derived 2) factor 2, PI: Propidium iodide, OHC: Outer hair cells, IHC: Inner hair cells, tPA: Tissue plasminogen activator