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Research Articles and Materials (Chemical and Materials Engineering)

This collection houses journal articles and other research material produced by the Department of Chemical and Materials Engineering.
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  1. Errata to Organ Preservation Alliance’s Organ Banking Summit abstracts as published in Cryobiology Volume 71 (1) 2015 [Download]

    Title: Errata to Organ Preservation Alliance’s Organ Banking Summit abstracts as published in Cryobiology Volume 71 (1) 2015
    Creator: Elliott, J.A.W.
    Subjects: Erratum, Error, Priority Journal, Cryopreservation, Organ Preservation
    Date Created: 2015/08/28
  2. Cryopreserved amniotic membrane as transplant allograft: viability and post-transplant outcome [Download]

    Title: Cryopreserved amniotic membrane as transplant allograft: viability and post-transplant outcome
    Creator: Perepelkin, N.M.J.
    Description: Amniotic membrane (AM) transplantation is increasingly used in ophthalmological and dermatological surgeries to promote re-epithelialization and wound healing. Biologically active cells in the epithelial and stromal layers deliver growth factors and cytokines with anti-inflammatory, anti-bacterial, anti-immunogenic and anti-fibrotic properties. In this work, confocal microscopy was used to show that our cryopreservation protocol for AM yielded viable cells in both the stromal and epithelial layers with favorable post-transplant outcome. AM was obtained from Caesarean-section placenta, processed into allograft pieces of different sizes (3 cm × 3 cm, 5 cm × 5 cm, and 10 cm × 10 cm) and cryopreserved in 10 % dimethyl sulfoxide using non-linear controlled rate freezing. Post-thaw cell viability in the entire piece of AM and in the stromal and epithelial cell layers was assessed using a dual fluorescent nuclear dye and compared to hypothermically stored AM, while surveys from surgical end-users provided information on post-transplant patient outcomes. There was no significant statistical difference in the cell viability in the entire piece, epithelial and stromal layers regardless of the size of allograft piece (p = 0.092, 0.188 and 0.581, respectively), and in the entire piece and stromal layer of hypothermically stored versus cryopreserved AM (p = 0.054 and 0.646, respectively). Surgical end-user feedback (n = 49) indicated that 16.3 % of AM allografts were excellent and 61.2 % were satisfactory. These results support the expanded clinical use of different sizes of cryopreserved AM allografts and address the issue of orientation of the AM during transplant for the treatment of dermatological defects and ocular surface disorders.
    Subjects: Amniotic membrane, Cryobiology, Cryopreservation, Dermal surgery, Epithelium, Ocular surgery, Stroma, Tissue transplantation
    Date Created: 2015/9/11
  3. Cryoprotectant agent toxicity in porcine articular chondrocytes. [Download]

    Title: Cryoprotectant agent toxicity in porcine articular chondrocytes.
    Creator: Jomha, N. M.
    Description: Large articular cartilage defects have proven difficult to treat and often result in osteoarthritis of the affected joint. Cryopreservation of articular cartilage can provide an increased supply of tissues for osteochondral allograft but cryoprotective agents are required; however, few studies have been performed on the toxicity of these agents. This study was designed to determine the order of toxicity of five commonly used cryoprotectant agents as well as interactions that occur between them. Isolated porcine articular chondrocytes were exposed to individual cryoprotectant agents and combinations of these agents at 1 M and 3 M concentrations for 5 min and 120 min. Cell viability was determined using membrane integrity dyes and a metabolic activity assay. Subsequently, a regression analysis based study was undertaken to extract the maximum amount of information from this data. Results of this study demonstrated that all 1 M solutions were minimally toxic. The 3 M solutions demonstrated varying toxicity after 120 min. Ethylene glycol and glycerol were less toxic than propylene glycol, dimethyl sulfoxide, and formamide. Combinations of cryoprotectant agents were less toxic than single cryoprotectant agents at the same concentration. This is the most comprehensive study investigating cryoprotectant agent toxicity in articular chondrocytes and has resulted in important information regarding the order of toxicity and interactions that occur between these agents.
    Subjects: statistical analysis, viability, chondrocytes, articular cartilage, cryoprotectant agents, porcine, cryopreservation
    Date Created: 2010
  4. Errata to "Permeation of several cryoprotectants in porcine articular cartilage" [Download]

    Title: Errata to "Permeation of several cryoprotectants in porcine articular cartilage"
    Creator: Jomha, N.M.
    Description: Some minor errors in our published manuscript need to be addressed
    Subjects: errata
    Date Created: 2014/10/08
  5. Corps propre or corpus corporum: Unity and Dislocation in the Theories of Embodiment of Merleau-Ponty and Jean-Luc Nancy [Download]

    Title: Corps propre or corpus corporum: Unity and Dislocation in the Theories of Embodiment of Merleau-Ponty and Jean-Luc Nancy
    Creator: Morin, Marie-Eve
    Subjects: Maurice Merleau-Ponty, Jean-Luc Nancy, Rene Descartes, Phenomenology, Body
    Date Created: 2015
  6. Permeation of several cryoprotectant agents into porcine articular cartilage [Download]

    Title: Permeation of several cryoprotectant agents into porcine articular cartilage
    Creator: Jomha, N.M.
    Description: Objective: Osteochondral allografting is an effective method to treat large osteochondral defects but difficulties in tissue preservation have significantly limited the application of this technique. Successful cryopreservation of articular cartilage (AC) could improve the clinical availability of osteochondral tissue and enhance clinical outcomes but cryopreservation of large tissues is hampered by a lack of knowledge of permeation kinetics within these tissues. This study describes the refinement and extension of a recently published technique to measure the permeation kinetics of cryoprotectant agents (CPAs) within porcine AC. Design: Dowels of porcine AC (10 mm diameter) were immersed in solutions containing 6.5 M concentrations of four commonly used CPAs [dimethyl sulfoxide (Me2SO), propylene glycol (PG), ethylene glycol (EG) and glycerol] for different times (1 second, 1, 2, 5, 10, 15, 30, 60, 120, 180 minutes, 24 hours) at three different temperatures (4, 22, and 37 C). The cartilage was isolated and the amount of CPA within the matrix was determined. Results: Diffusion coefficients (Me2SO = 2.4 - 6.2 x 10-6 cm2/s; PG = 0.8 - 2.7 x 10-6 cm2/s; EG = 1.7 - 4.2 x 10-6 cm2/s; and glycerol = 0.8 - 2.4 x 10-6 cm2/s) and activation energies (Me2SO = 4.33 kcal/mol, PG = 6.29 kcal/mol, EG = 3.77 kcal/mol, and glycerol = 5.56 kcal/mol) were determined for each CPA. Conclusion: The results of this experiment provide accurate permeation kinetics of four commonly used CPAs in porcine articular cartilage. This information will be useful for developing effective vitrification protocols for cryopreservation of AC.
    Subjects: activation energy, diffusion coefficient, cryoprotectant agents, cryopreservation, vitrification, porcine, permeation, articular cartilage
    Date Created: 2014/09/26
  7. Application of the Osmotic Virial Equation in Cryobiology [Download]

    Title: Application of the Osmotic Virial Equation in Cryobiology
    Creator: Prickett, R. C.
    Description: The multisolute osmotic virial equation is the only multisolute thermodynamic solution theory that has been derived from first principles and can make predictions of multisolute solution behaviour in the absence of multisolute solution data. Other solution theories either (i) include simplifying assumptions that do not take into account the interactions between different types of solute molecules or (ii) require fitting to multisolute data to obtain empirical parameters. The osmotic virial coefficients, which are obtained from single-solute data, can be used to make predictions of multisolute solution osmolality. The osmotic virial coefficients for a range of solutes of interest in cryobiology are provided in this paper, for use with concentration units of both molality and mole fraction, along with an explanation of the background and theory necessary to implement the multisolute osmotic virial equation.
    Subjects: phase diagram, freezing point, osmolality, thermodynamics, solution theory, multisolute solutions
    Date Created: 2010
  8. Investigating cryoinjury using simulations and experiments: 1. TF-1 cells during two-step freezing (rapid cooling interrupted with a hold time) [Download]

    Title: Investigating cryoinjury using simulations and experiments: 1. TF-1 cells during two-step freezing (rapid cooling interrupted with a hold time)
    Creator: Ross-Rodriguez, L. U.
    Description: There is significant interest in designing a cryopreservation protocol for hematopoietic stem cells (HSC) which does not rely on dimethyl sulfoxide (Me2SO) as a cryoprotectant. Computer simulations that describe cellular osmotic responses during cooling and warming can be used to optimize the viability of cryopreserved HSC; however, a better understanding of cellular osmotic parameters is required for these simulations. As a model for HSC, the erythroleukemic human cell line TF-1 was used in this study. Simulations, based on the osmotic properties of TF-1 cells and on the solution properties of the intra- and extracellular compartments, were used to interpret cryoinjury associated with a two-step cryopreservation protocol. Calculated intracellular supercooling was used as an indicator of cryoinjury related to intracellular ice formation. Simulations were applied to the two-step cooling protocol (rapid cooling interrupted with a hold time) for TF-1 cells in the absence of Me2SO or other cryoprotectants and optimized by minimizing the indicator of cryoinjury. A comparison of simulations and experimental measurements of membrane integrity supports the concept that, for two-step cooling, increasing intracellular supercooling is the primary contributor to potential freezing injury due to the increase in the likelihood of intracellular ice formation. By calculating intracellular supercooling for each step separately and comparing these calculations with cell recovery data, it was demonstrated that it is not optimal simply to limit overall supercooling during two-step freezing procedures. More aptly, appropriate limitations of supercooling differ from the first step to the second step. This study also demonstrates why high cell recovery after cryopreservation could be achieved in the absence of traditional cryoprotectants.
    Subjects: stem cells, computer modeling, cryopreservation, TF-1, simulations, intracellular ice formation
    Date Created: 2014/09/22
  9. Vitrification of intact human articular cartilage. [Download]

    Title: Vitrification of intact human articular cartilage.
    Creator: Jomha, N. M.
    Description: Articular cartilage injuries do not heal and large defects result in osteoarthritis with major personal and socioeconomic costs. Osteochondral transplantation is an effective treatment for large joint defects but its use is limited by the inability to store cartilage for long periods of time. Cryopreservation/vitrification is one method to enable banking of this tissue but decades of research have been unable to successfully preserve the tissue while maintaining cartilage on its bone base – a requirement for transplantation. To address this limitation, human knee articular cartilage from total knee arthroplasty patients and deceased donors was exposed to specified concentrations of 4 different cryoprotective agents for mathematically determined periods of time at lowering temperatures. After complete exposure, the cartilage was immersed in liquid nitrogen for up to 3 months. Cell viability was 75.4 ± 12.1% determined by membrane integrity stains and confirmed with a mitochondrial assay and pellet culture documented production of sulfated glycosaminoglycans and collagen II similar to controls. This report documents successful vitrification of intact human articular cartilage on its bone base making it possible to bank this tissue indefinitely.
    Subjects: cartilage tissue engineering, transplantation, human, arthritis, vitrification, articular cartilage
    Date Created: 2012
  10. Investigating cryoinjury using simulations and experiments: 2. TF-1 cells during graded freezing (interrupted slow cooling without hold time) [Download]

    Title: Investigating cryoinjury using simulations and experiments: 2. TF-1 cells during graded freezing (interrupted slow cooling without hold time)
    Creator: Ross-Rodriguez, L.U.
    Description: Cryopreservation plays a key role in the long-term storage of native and engineered cells and tissues for research and clinical applications. The survival of cells and tissues after freezing and thawing depends on the ability of the cells to withstand a variety of stresses imposed by the cryopreservation protocol. A better understanding of the nature and kinetics of cellular responses to temperature-induced conditions is required to minimize cryoinjury. An interrupted freezing procedure that allows dissection of cryoinjury was used to investigate the progressive damage that occurs to cells during cryopreservation using slow cooling. Simulations of cellular osmotic responses were used to provide interpretation linking states of the cell with events during the freezing procedure. Simulations of graded freezing (interrupted slow cooling without hold time) were correlated with cell recovery results of TF-1 cells. Calculated intracellular supercooling and osmolality, were used as indicators of the probability of cryoinjury due to intracellular ice formation and solution effects, providing direct links of cellular conditions to events in the freezing process. Using simulations, this study demonstrated that both intracellular supercooling and osmolality are necessary to explain graded freezing results.
    Subjects: computer modeling, solution effects injury, intracellular ice formation, TF-1, cryobiology
    Date Created: 2014/09/22