Barium-gelled alginate microcapsules do not exhibit sodium-induced isotropic swelling noted with calcium-gelled microcapsules

Event Abstract Back to Event Barium-gelled alginate microcapsules do not exhibit sodium-induced isotropic swelling noted with calcium-gelled microcapsules Rahul Krishnan1, Ariel Dalisay1, Antonio Flores1, Ka-Hei Chan1, Michael Alexander1, Elliot Botvinick2 and Jonathan Lakey1, 2 1 University of California Irvine, Surgery, United States 2 University of California Irvine, Biomedical Engineering, United States Introduction: Encapsulation within alginate microcapsules is being actively developed for use in islet transplantation due to its advantages of safety, easy delivery and elimination of immunosuppressive therapy requirements. It is believed that alginate microcapsules exhibit isotropic shrinking at high culture temperatures and isotropic swelling in the presence of sodium ions. In this study, we evaluated various gelling ions and alginates to study their responses at specific temperatures and at physiological sodium ion concentrations to develop strategies to mitigate sodium ion-induced isotropic swelling of the alginate capsules. Materials and Methods: Aqueous solutions of ultra-pure low viscosity mannuronate (UP LVM, NovaMatrix® PRONOVA™) and ultra-pure low viscosity gluronate (UP LVG) at 2.5% w/v were used to generate alginate microcapsules using a compressed air-driven electrostatic encapsulator (Nisco Engineering AG). Standard settings of 4-5 psi (pressure), 80 rpm (agitator speed), 30 mm (needle height) and 25G (needle height) were used. Three different divalent ion solutions were compared: 20mM BaCl2, 50mM BaCl2, and 120mM CaCl2 (n=3, performed in triplicate). After each experiment, a minimum 100 microcapsules were imaged using an inverted bright field microscope after 15 min of crosslinking. Microcapsules were then stored in a buffered solution containing proteins and ions at physiological concentrations or in a 5mM buffer of CaCl2 or BaCl2 depending on the ion used for polymerization. The microcapsules were then either stored at either 3oC or 37oC. After 24 hrs, 72 hrs, 7 days, 11 days and 14 days of incubation, groups of 100 microcapsules were quantified for isotropic changes in diameter. Alginate capsules were then transferred to the following solutions: Images obtained as described were processed using a batch-processing algorithm on Image J (NIH). Microcapsule size was analyzed and compared. All results are expressed as Mean±SEM. A Mann-Whitney Test was performed to analyze whether the change in microcapsule size was statistically significant (p<0.05). Results: At the end of the study period, both UP LVG and UP LVM alginate microcapsules exhibited significant isotropic shrinking at 37oC (-4.2±0.2%, UP LVG; -6.1±0.1%, UP LVM) compared to those incubated at 3oC (p=0.04, ANOVA). Barium-gelled alginate microcapsules demonstrated isotropic shrinking regardless of alginate type, gelling ion and incubation conditions (-6.1±0.2%, UP LVG; -6.6±0.1%, UP LVM). Calcium-gelled UP LVM microcapsules demonstrated significant isotropic swelling when incubated in the physiological solution (+5.5±0.2%) compared to all other groups (p<0.01, ANOVA). Conclusions: The effects of alginate type, and choice of gelling ion directly influence microcapsule size during in vitro incubation in physiological solutions. Since microcapsules are being evaluated for use in transplantation studies, it would be pertinent to develop strategies to further evaluate barium-gelled alginate UP LVM and UP LVG microcapsules with in vivo studies to evaluate their safety and biocompatibility for islet and stem cell transplantation. Keywords: Hydrogel, material design Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Combinatorial approaches to biomaterial design Citation: Krishnan R, Dalisay A, Flores A, Chan K, Alexander M, Botvinick E and Lakey J (2016). Barium-gelled alginate microcapsules do not exhibit sodium-induced isotropic swelling noted with calcium-gelled microcapsules. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.03053 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Rahul Krishnan Ariel Dalisay Antonio Flores Ka-Hei Chan Michael Alexander Elliot Botvinick Jonathan Lakey Google Rahul Krishnan Ariel Dalisay Antonio Flores Ka-Hei Chan Michael Alexander Elliot Botvinick Jonathan Lakey Google Scholar Rahul Krishnan Ariel Dalisay Antonio Flores Ka-Hei Chan Michael Alexander Elliot Botvinick Jonathan Lakey PubMed Rahul Krishnan Ariel Dalisay Antonio Flores Ka-Hei Chan Michael Alexander Elliot Botvinick Jonathan Lakey Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.