Perfluorocarbon Emulsions Prevent Hypoxia of Pancreatic β-Cells

Abstract

As oxygen carriers, perfluorocarbon emulsions might be useful to decrease hypoxia of pancreatic islets before transplantation. However, their hydrophobicity prevents their homogenisation in culture medium. To increase the surface of contact between islets and Perfluorooctyl bromide (PFOB), and consequently oxygen delivery, we tested effect of a PFOB emulsion in culture medium on β-cell lines and rat pancreatic islets. RINm5F β-cell line or pancreatic rat islets were incubated for 3 days in the presence of PFOB emulsion in media (3.5% w/v). Preoxygenation of the medium was performed before culture. Cell viability was assessed by apoptotic markers (Bax and Bcl-2) and by staining (fluoresceine diacetate and propidium iodide). β-Cell functionality was determined by insulin release during a glucose stimulation test and. Hypoxia markers, HIF-1α and VEGF, were studied at days 1 and 3 using RT-PCR, Western blotting, and ELISA. PFOB emulsions preserved viability and functionality of RINm5F cells with a decrease of HIF-1α and VEGF expression. Islets viability was preserved during 3 days of culture. Secretion of VEGF was higher in untreated control (0.09 ± 0.041 μg VEGF/mg total protein) than in PFOB emulsion incubated islets (0.02 ± 0.19 μg VEGF/mg total protein, n = 4, p < 0.05) at day 1. At day 3, VEGF secretion was increased as compared to day 1 in control (0.23 ± 0.04 μg VEGF/mg total protein) but it was imbalance by the presence of PFOB emulsion (0.09 ± 0.03 μg VEGF/mg total protein, n = 5, p < 0.05). While insulin secretion was maintained in response to a glucose stimulation test until day 3 when islets were incubated in the presence of PFOB emulsion preoxygenated (0.81 ± 0.16 at day 1 vs. 0.75 ± 0.24 at day 3), the ability to secrete insulin in the presence of high glucose concentration was lost in islets controls (0.51 ± 0.18 at day 1 vs. 0.21 ± 0.13 at day 3). Atmospheric oxygen delivery by PFOB emulsion might be sufficient to decrease islets hypoxia. However, to improve islets functionality, overoxygenation is needed. Finally, maintenance of islet viability and functionality for several days after isolation could improve the outcome of islets transplantation.

Perfluoroalkyl substances and beta cell deficient diabetes

“…In rat psuedoislets cultured with perfluoroctyl bromide, insulin levels and insulin stimulation index were preserved three days after stimulation with buffer containing glucose. [14] While insulin levels and insulin stimulation index were similar in controls and in cells cultured with perfluoroctyl bromide on day 1, levels on day 3 in control cells were reduced compared to day 1, but remained similar to day 1 in treated cells. Markers of hypoxia, hypoxia inducible factor-alpha and VEGF mRNA levels significantly increased after three days in the control cells but remained similar throughout the experiment in cells cultured with perfluroctyl bromide.…”

“…Markers of hypoxia, hypoxia inducible factor-alpha and VEGF mRNA levels significantly increased after three days in the control cells but remained similar throughout the experiment in cells cultured with perfluroctyl bromide. [14] Ramachandran et al showed that in human donor pancreata, islet cells from pancreas preserved in perfluorocarbon solution demonstrated decreased expression of the proapoptotic genes bad, bax, caspases, TRAF5, and TNF-β/LTB compared to control cells after prolonged cold storage. [30] In contrast, there was an increased expression of the anti-apoptotic genes IAP2 and survivin in these islets isolated from pancreata stored in perfluorocarbon solution.…”

“…[13] They have also been shown to increase insulin mRNA expression[13] and to reduce pancreatic islet cell hypoxia and apoptosis. [14]…”

Covalent Organic Polymers Based on Fluorinated Porphyrin as Oxygen Nanoshuttles for Tumor Hypoxia Relief and Enhanced Photodynamic Therapy

“…In addition, in situ production of O 2 from the decomposition of endogenous H 2 O 2 inside tumors with catalase or manganese dioxides containing nanostructures has also been evidenced to be effective for tumor hypoxia attenuation and favorable for the subsequent cancer treatment . Moreover, several different oxygen nanoshuttles have been developed to enable direct tumor‐targeted delivery of oxygen for tumor hypoxia relief . In particular, nanodroplets of perfluorocarbon (PFC) with great biocompatibility and high solubility of oxygen have been found to be extremely useful as oxygen delivery carriers to allow effective tumor oxygenation and enhanced cancer PDT, as demonstrated by our and others' recent reports …”

THERAPY OF ENDOCRINE DISEASE: Islet transplantation for type 1 diabetes: so close and yet so far away

“…Perfluorocarbons are biologically inert and non-polar substances where all hydrogens are substituted by fluorine in the hydrocarbon chains without any reaction with proteins or enzymes in the biological environment (139). O 2 , CO 2 and N 2 can be physically dissolved in PFCs which lead to more rapid oxygen release from this structure compared to oxyhemoglobin (140,141). Perflurorcarbons have been applied to oxygenate islets in culture, in addition to fibrin matrix as an oxygen diffusion enhancing medium to hinder hypoxia induced by islet encapsulation (142).…”