Dielectric measurements for the design of an electromagnetic rewarming system

Marsland, T.P.; Evans, Stephen D.; Pegg, D.E.

doi:10.1016/0011-2240(87)90035-6

Cited by 36 publications

(10 citation statements)

References 26 publications

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“…Pegg and coworkers showed that dielectric heating of tissues in the frequency range of 300–1000 MHz was optimal for better penetration depth and uniformity of heating and further investigated the effects of CPA concentration and sample shape on the uniformity of heating. [ 30 , 31 , 32 ] Evans and coworkers showed that dielectric rewarming results in a compromise, where either non‐uniformity in heating is accepted at higher frequencies or low rewarming rates are inevitable at lower frequencies. In addition to these issues, they describe factors that guide choice of frequency and applicator geometry in a resonant EM applicator to control “hot spots” (“thermal runaway”) and generate uniform heating.…”

Section: Discussionmentioning

confidence: 99%

“…), temperature dependence of the electrical permittivity and geometry of the sample. [ 30 , 31 , 32 , 33 , 34 ] These non‐uniformities are further accentuated as the size is scaled up to the liter volumes that would be needed for human organs. Ruggerra et al previously described the use of RF helical coils in pressurized vessels for rewarming vitrified CPA under high‐pressure conditions at an average warming rate of 20 °C min −1 /100 W per 100 mL.…”

Section: Discussionmentioning

confidence: 99%

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Vitrification and Nanowarming of Kidneys

et al. 2021

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Vitrification can dramatically increase the storage of viable biomaterials in the cryogenic state for years. Unfortunately, vitrified systems ≥3 mL like large tissues and organs, cannot currently be rewarmed sufficiently rapidly or uniformly by convective approaches to avoid ice crystallization or cracking failures. A new volumetric rewarming technology entitled "nanowarming" addresses this problem by using radiofrequency excited iron oxide nanoparticles to rewarm vitrified systems rapidly and uniformly. Here, for the first time, successful recovery of a rat kidney from the vitrified state using nanowarming, is shown. First, kidneys are perfused via the renal artery with a cryoprotective cocktail (CPA) and silica-coated iron oxide nanoparticles (sIONPs). After cooling at −40°C min −1 in a controlled rate freezer, microcomputed tomography (μCT) imaging is used to verify the distribution of the sIONPs and the vitrified state of the kidneys. By applying a radiofrequency field to excite the distributed sIONPs, the vitrified kidneys are nanowarmed at a mean rate of 63.7°C min −1 . Experiments and modeling show the avoidance of both ice crystallization and cracking during these processes. Histology and confocal imaging show that nanowarmed kidneys are dramatically better than convective rewarming controls. This work suggests that kidney nanowarming holds tremendous promise for transplantation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Vitrification and Nanowarming of Kidneys

et al. 2021

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“…A most useful result from the measurements of Marsland et al (1987) is that the dielectric properties of perfused kidney tissue are dominated by the perfusate in use and are similar to the perfusate alone (within the range of their measurements which was from −30 • C to +20 • C and from 50 MHz to 2.6 GHz). With this result in view, the measurements in this paper are restricted to four pure cryoprotectant agents (CPA) and their aqueous solutions at concentrations greater than the critical concentration C v for vitrification, such that no crystalline ice forms during slow cooling (Fahy et al 1984).…”

Section: Introduction: Electromagnetic Re-warming Of Cryopreserved Ma...mentioning

confidence: 95%

Dielectric properties of supercooled cryoprotectant agents

Michelson

Evans

1996

Phys. Med. Biol.

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The dielectric properties of glycerol, propylene glycol, ethylene glycol and dimethyl sulphoxide have been measured in various aqueous concentrations generally sufficient to allow supercooling rather than freezing. The temperature range investigated is from -80 degrees C to +20 degrees C and the frequency range is 100 MHz to 2 GHz. The aim is to find the materials and conditions most favorable for very rapid re-warming of perfused biological tissue by electromagnetic fields, avoiding thermal runaway in the bulk and local non-uniformity of temperature. Frequencies below 500 MHz are generally indicated.

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“…It is necessary that heat generation is uniform. The most well-recognized attempts at achieving uniform heat generation employed microwave rewarming [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. Unfortunately, variability in the resonance of the cavity and the geometric variability of dielectric properties within tissue samples have not yet led to uniform rapid rewarming, likely due to “hot spots” within the samples.…”

Section: Resultsmentioning

confidence: 99%

Ice Control during Cryopreservation of Heart Valves and Maintenance of Post-Warming Cell Viability

Brockbank

Bischof

Chen³

et al. 2022

Cells

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Heart valve cryopreservation was employed as a model for the development of complex tissue preservation methods based upon vitrification and nanowarming. Porcine heart valves were loaded with cryoprotectant formulations step wise and vitrified in 1–30 mL cryoprotectant formulations ± Fe nanoparticles ± 0.6 M disaccharides, cooled to −100 °C, and stored at −135 °C. Nanowarming was performed in a single ~100 s step by inductive heating within a magnetic field. Controls consisted of fresh and convection-warmed vitrified heart valves without nanoparticles. After washing, cell viability was assessed by metabolic assay. The nanowarmed leaflets were well preserved, with a viability similar to untreated fresh leaflets over several days post warming. The convection-warmed leaflet viability was not significantly different than that of the nanowarmed leaflets immediately after rewarming; however, a significantly higher nanowarmed leaflet viability (p < 0.05) was observed over time in vitro. In contrast, the associated artery and fibrous cardiac muscle were at best 75% viable, and viability decreased over time in vitro. Supplementation of lower concentration cryoprotectant formulations with disaccharides promoted viability. Thicker tissues benefited from longer-duration cryoprotectant loading steps. The best outcomes included a post-warming incubation step with α-tocopherol and an apoptosis inhibitor, Q-VD-OPH. This work demonstrates progress in the control of ice formation and cytotoxicity hurdles for the preservation of complex tissues.

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Dielectric measurements for the design of an electromagnetic rewarming system

Cited by 36 publications

References 26 publications

Vitrification and Nanowarming of Kidneys

Vitrification and Nanowarming of Kidneys

Dielectric properties of supercooled cryoprotectant agents

Ice Control during Cryopreservation of Heart Valves and Maintenance of Post-Warming Cell Viability

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