Rapid MR Imaging of Cryoprotectant Permeation in an Engineered Dermal Replacement

Bidault, N.; Hammer, Bruce E.; Hubel, Allison

doi:10.1006/cryo.1999.2216

Cited by 21 publications

(7 citation statements)

References 14 publications

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“…There are a number of non-invasive techniques, which have been used to assess chemical loading as this is important for protecting cells and tissues from ice formation during freezing. The most promising techniques have focused on the use of non-invasive MR imaging 2,17 or NMR spectroscopy. 7,37 Of these techniques, the most recent work has focused on rapid acquisition times (30 s) in order to visualize the relatively fast permeation of 50% v/v Dimethyl Sulfoxide (DMSO) in tissue constructs.…”

Section: Introductionmentioning

confidence: 99%

“…For example, for a longer acquisition time (2 min) the lowest bulk concentrations were found to be 10, 20 and 30% v/v for DMSO, glycerol and propylene glycol, respectively. 2 The pixel size was 80x80 lm 2 in-plane, while the slice thickness was 2 mm. At comparable acquisition times, CT usually allows larger pixel matrix sizes to be imaged, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…38 There is also ''image contamination'' in MR imaging and spectroscopy due to bound water (water closely associated with surface layers of other molecules thereby having dampened response in MR) which can complicate the accurate measurement of concentration of chemicals loaded into tissues as previously discussed. 2 Since CT is essentially a density measurement method, it does not suffer from these artifacts. In general, CT is cheaper (in investment and operating costs) and simpler (in accessibility and material restrictions like ferromagnetic metals) than MR. Further work to improve CT data analysis specific to cryogenic applications might allow equal or better acquisition times and accuracy for concentration measurements than MR.…”

Section: Introductionmentioning

confidence: 99%

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Use of X-ray Tomography to Map Crystalline and Amorphous Phases in Frozen Biomaterials

et al. 2006

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The outcome of both cryopreservation and cryosurgical freezing applications is influenced by the concentration and type of the cryoprotective agent (CPA) or the cryodestructive agent (i.e., the chemical adjuvants referred to here as CDA) added prior to freezing. It also depends on the amount and type of crystalline, amorphous and/or eutectic phases formed during freezing which can differentially affect viability. This work describes the use of X-ray computer tomography (CT) for non-invasive, indirect determination of the phase, solute concentration and temperature within biomaterials (CPA, CDA loaded solutions and tissues) by X-ray attenuation before and after freezing. Specifically, this work focuses on establishing the feasibility of CT (100-420 kV acceleration voltage) to accurately measure the concentration of glycerol or salt as model CPA and CDAs in unfrozen solutions and tissues at 20 degrees C, or the phase in frozen solutions and tissue systems at -78.5 and -196 degrees C. The solutions are composed of water with physiological concentrations of NaCl (0.88% wt/wt) and DMEM (Dulbecco's Modified Eagle's Medium) with added glycerol (0-8 M). The tissue system is chosen as 3 mm thick porcine liver slices as well as 2 cm diameter cores which were either imaged fresh (3-4 h cold ischemia) or after loading with DMEM based glycerol solutions (0-8 M) for times ranging from hours to 7 days at 4 degrees C. The X-ray attenuation is reported in Hounsfield units (HU), a clinical measurement which normalizes X-ray attenuation values by the difference between those of water and air. NaCl solutions from 0 to 23.3% wt/wt (i.e. water to eutectic concentration) were found to linearly correspond to HU in a range from 0 to 155. At -196 degrees C the variation was from -80 to 95 HU while at -78.5 degrees C all readings were roughly 10 HU lower. At 20 degrees C NaCl and DMEM solutions with 0-8 M glycerol loading show a linear variation from 0 to 145 HU. After freezing to -78.5 degrees C the variation of the NaCl and DMEM solutions is more than twice as large between -90 and +190 HU and was distinctly non-linear above 6 M. After freezing to -196 degrees C the variation of the NaCl and DMEM solutions increased even further to -80 to +225 HU and was distinctly non-linear above 4 M, which after modeling the phase change and crystallization process is shown to correlate with an amorphous phase. In all tissue systems the HU readings were similar to solutions but higher by roughly 30 HU, as well as showing some deviations at 0 M after storage, probably due to tissue swelling. The standard deviations in all measurements were roughly 5 HU or below in all samples. In addition, two practical examples for CT use were demonstrated including: (1) glycerol loading and freezing of tissue cores and, (2) a mock cryosurgical procedure. In the loading experiment CT was able to measure the permeation of the glycerol into the sample at 20 degrees C, as well as the evolution of distinct amorphous vs. crystalline phases after freezing to -196 degrees C....

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Use of X-ray Tomography to Map Crystalline and Amorphous Phases in Frozen Biomaterials

et al. 2006

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“…In this application, the membrane permeability parameter would be altered due to a decrease in the permeability of red blood cells to glycerol (B = 0.5 s −1 for red blood cells [20]). In addition, the size of the glycerol molecule is larger and, therefore, the diffusion coefficient, D, would be smaller (D = 220–520 μm 2 /s for glycerol [21]). These changes suggest that diffusion across cell membranes may play a much more important role in determining the device length as compared to the case study for DMSO.…”

Section: Discussionmentioning

confidence: 99%

Optimization of a microfluidic device for diffusion-based extraction of DMSO from a cell suspension

Glass

Longmire

Hubel

2008

International Journal of Heat and Mass Transfer

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This study considers the use of a two-stream microfluidic device for extraction of dimethyl sulphoxide (DMSO) from a cryopreserved cell suspension. The DMSO diffuses from a cell suspension stream into a neighboring wash stream flowing in parallel. The model of Fleming et al.[14] is employed to determine and discuss optimal geometry and operating conditions for a case requiring removal of 95% DMSO from suspension streams with volumetric flow rates up to 2.5 ml/ min. The effects of Peclet number, flow rate fraction, and cell volume fraction are analyzed, and expansion of the analysis to other applications is discussed.

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“…For example, Fuller et al [6] and Walcerz et al [24] used an MR spectroscopic technique to obtain averaged CPA concentration over the entire volume of the tissues, and their procedure was improved by the chemical shift-specific slice selection (C4S) technique [23] to obtain the distribution of CPA concentration. Combining both the chemical shift selection (CHESS) and fast low angel shot (FLASH), the image quality was further improved with an enhanced signal-to-noise ratio [1,2,9]. However, to date there has been no attempts to apply these MRI techniques to organs, due to the complicated mass transfer process inside organs and the lack of simple physical models.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the apparent diffusivity of ethylene glycol in mouse ovaries through rapid MRI and theoretical investigation of cryoprotectant perfusion procedures

Han¹,

Ma²,

Benson³

et al. 2009

Cryobiology

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Successful organ cryopreservation will significantly benefit human health and biomedical research. One of the major challenges to this accomplishment is the need for optimization of cryoprotectant agent (CPA) perfusion procedures that involve highly complicated mass transfer processes in organs. The diffusivity of CPA is of critical importance for designing perfusion procedures to minimize the associated toxicity and osmotic damage. However, to date there have been no attempts to measure the CPA diffusivity in organs. In this study, we established a simple CPA diffusion model for relatively small organs, e.g. mouse ovaries, defined the apparent diffusivity (D) of CPA for these organs (please see Table 1 for symbol definitions), and established a practical approach to measure the value of D̄ through magnetic resonant imaging (MRI). Using rapid MRI techniques and water saturation analyses, the distribution of ethylene glycol (EG) concentration in the centric cross-section of mouse ovaries was measured at a series of time points during perfusion, and these data were fit to the integral form of the mass transfer equation in the established model. These fits resulted in a value of D̄ for EG in mouse ovaries of 6.1 ± 1.4×10 -7 cm 2 /s (mean ± SD). Based on these results, we proposed a modified perfusion procedure that may improve the survival of small organs or thin tissues during equilibrium cooling processes and assessed its efficiency through theoretical analyses.

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Rapid MR Imaging of Cryoprotectant Permeation in an Engineered Dermal Replacement

Cited by 21 publications

References 14 publications

Use of X-ray Tomography to Map Crystalline and Amorphous Phases in Frozen Biomaterials

Use of X-ray Tomography to Map Crystalline and Amorphous Phases in Frozen Biomaterials

Optimization of a microfluidic device for diffusion-based extraction of DMSO from a cell suspension

Measurement of the apparent diffusivity of ethylene glycol in mouse ovaries through rapid MRI and theoretical investigation of cryoprotectant perfusion procedures

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