Islet transplantation in diabetes is hampered by the need of life-long immunosuppression. Encapsulation provides partial immunoprotection but could possibly limit oxygen supply, a factor that may enhance hypoxia-induced beta cell death in the early posttransplantation period. Here we tested susceptibility of alginate microencapsulated human islets to experimental hypoxia (0.1–0.3% O2 for 8？h, followed by reoxygenation) on viability and functional parameters. Hypoxia reduced viability as measured by MTT by % in encapsulated and % in nonencapsulated islets ( ). Nonencapsulated islets released 37.7% (median) more HMGB1 compared to encapsulated islets after hypoxic culture conditions ( ). Glucose-induced insulin release was marginally affected by hypoxia. Basal oxygen consumption was equally reduced in encapsulated and nonencapsulated islets, by % versus %. Among 27 tested cytokines/chemokines, hypoxia increased the secretion of IL-6 and IL-8/CXCL8 in both groups of islets, whereas an increase of MCP-1/CCL2 was seen only with nonencapsulated islets. Conclusion. Alginate microencapsulation of human islets does not increase susceptibility to acute hypoxia. This is a positive finding in relation to potential use of encapsulation for islet transplantation. 1. Introduction Transplantation of pancreatic islets containing the insulin-producing beta cells could in principle cure type 1 diabetes. However, transplantation of allografts necessitates treatment with immunosuppressant drugs with ensuing side effects. Encapsulation of islets (or isolated beta cells) could potentially alleviate this problem, thus motivating previous and ongoing research on the feasibility of encapsulated islets for successful transplantation. Promising results (reversal of diabetes in animal models of diabetes) have been reported [1–4]. However, questions remain as to both the short and long term functionality of encapsulated islets or beta cells. One question pertains to the impact of hypoxia on encapsulated islets. Native pancreatic beta cells have high rates of oxidative metabolism to meet the demand of insulin production and secretion [5], and even moderately decreased levels of oxygen have been shown to inhibit insulin release [6]. Hypoxia after transplantation is a major (albeit not the only) contributor to the dramatic drop of viable beta cells (nonencapsulated) that occurs in the immediate period following transplantation [7–10]. A negative impact of the—inevitable—hypoxia during the immediate period following transplantation could possibly be worsened by encapsulation, since the
References
[1]
M. Qi, B. L. Strand, Y. M？rch, et al., “Encapsulation of human islets in novel inhomogenous alginate-Ca2+/Ba2+ microbeads: in vitro and in vivo function,” Artificial Cells, Blood Substitutes, and Immobilization Biotechnology, vol. 36, pp. 403–420, 2008.
[2]
M. Qi, Y. M？rch, I. Lacik, et al., “Survival of human islets in microbeads containing high guluronic acid alginate crosslinked with Ca2+ and Ba2+,” Xenotransplantation, vol. 19, pp. 355–364, 2012.
[3]
A. Remuzzi, R. Cornolti, R. Bianchi et al., “Regression of diabetic complications by islet transplantation in the rat,” Diabetologia, vol. 52, no. 12, pp. 2653–2661, 2009.
[4]
D. Jacobs-Tulleneers-Thevissen, M. Chintinne, Z. Ling, et al., “Sustained function of alginate-encapsulated human islet cell implants in the peritoneal cavity of mice leading to a pilot study in a type 1 diabetic patient,” Diabetologia, vol. 56, pp. 1605–1614, 2013.
[5]
C. Hellerstr？m, “Effects of carbohydrates on the oxygen consumption of isolated pancreatic islets of mice,” Endocrinology, vol. 81, pp. 105–112, 1967.
[6]
K. E. Dionne, C. K. Colton, and M. L. Yarmush, “Effect of hypoxia on insulin secretion by isolated rat and canine islets of Langerhans,” Diabetes, vol. 42, no. 1, pp. 12–21, 1993.
[7]
J. H. Juang, B. R. Hsu, C. H. Kuo, and S. W. Uengt, “Beneficial effects of hyperbaric oxygen therapy on islet transplantation,” Cell Transplantation, vol. 11, no. 2, pp. 95–101, 2002.
[8]
S. J. Hughes, S. E. Davies, S. H. Powis, and M. Press, “Hyperoxia improves the survival of intraportally transplanted syngeneic pancreatic islets,” Transplantation, vol. 75, no. 12, pp. 1954–1959, 2003.
[9]
N. Sakata, N. K. Chan, R. P. Ostrowski et al., “Hyperbaric oxygen therapy improves early posttransplant islet function,” Pediatric Diabetes, vol. 11, no. 7, pp. 471–478, 2010.
[10]
N. A. Deters, R. A. Stokes, and J. E. Gunton, “Islet transplantation: factors in short-term islet survival,” Archivum Immunologiae et Therapiae Experimentalis, vol. 59, no. 6, pp. 421–429, 2011.
[11]
J. Schrezenmeir, J. Kirchgessner, L. Ger？, L. A. Kunz, J. Beyer, and W. Mueller-Klieser, “Effect of microencapsulation on oxygen distribution in islets organs,” Transplantation, vol. 57, no. 9, pp. 1308–1314, 1994.
[12]
M. de Groot, T. A. Schuurs, and R. van Schilfgaarde, “Causes of limited survival of microencapsulated pancreatic islet grafts,” Journal of Surgical Research, vol. 121, no. 1, pp. 141–150, 2004.
[13]
A. S. Johnson, R. J. Fisher, G. C. Weir, and C. K. Colton, “Oxygen consumption and diffusion in assemblages of respiring spheres: performance enhancement of a bioartificial pancreas,” Chemical Engineering Science, vol. 64, no. 22, pp. 4470–4487, 2009.
[14]
J. P. Kitzmann, L. Law, A. Shome, et al., “Real-time assessment of encapsulated neonatal porcine islet prior to clinical xenotransplantation,” Xenotransplantation, vol. 19, pp. 333–336, 2012.
[15]
S. Vériter, N. Aouassar, P.-Y. Adnet et al., “The impact of hyperglycemia and the presence of encapsulated islets on oxygenation within a bioartificial pancreas in the presence of mesenchymal stem cells in a diabetic Wistar rat model,” Biomaterials, vol. 32, no. 26, pp. 5945–5956, 2011.
[16]
A. S. Johnson, E. O'Sullivan, L. N. D'Aoust, et al., “Quantitative assessment of islets of Langerhans encapsulated in alginate,” Tissue Engineering, vol. 17, pp. 435–449, 2011.
[17]
A. M. Rokstad, O. L. Brekke, B. Steinkjer et al., “Alginate microbeads are complement compatible, in contrast to polycation containing microcapsules, as revealed in a human whole blood model,” Acta Biomaterialia, vol. 7, no. 6, pp. 2566–2578, 2011.
[18]
A. M. Rokstad, B. I. Gustafsson, T. Espevik et al., “Microencapsulation of small intestinal neuroendocrine neoplasm cells for tumor model studies,” Cancer Science, vol. 103, no. 7, pp. 1230–1237, 2012.
[19]
M. Qi, B. Barbaro, S. Wang, Y. Wang, M. Hansen, and J. Oberholzer, “Human pancreatic islet isolation—part I: digestion and collection of pancreatic tissue,” Journal of Visualized Experiments, no. 27, Article ID e1125, 2009.
[20]
M. Qi, B. Barbaro, S. Wang, Y. Wang, M. Hansen, and J. Oberholzer, “Human pancreatic islet isolation—part II: purification and culture of human islets,” Journal of Visualized Experiments, no. 27, Article ID e1343, 2009.
[21]
R. Nano, L. Racanicchi, R. Melzi et al., “Human pancreatic islet preparation release HMGB1: (Ir)relevance for graft engrafment,” Cell Transplant, vol. 22, no. 11, pp. 2175–2186, 2013.
[22]
T. Itoh, M. Takita, J. A. SoRelle, et al., “Correlation of released HMGB1 levels with the degree of islet damage in mice and humans and with the outcomes of islet transplantation in mice,” Cell Transplant, vol. 21, pp. 1371–1381, 2012.
[23]
M. T. Lotze and K. J. Tracey, “High-mobility group box 1 protein (HMGB1): nuclear weapon in the immune arsenal,” Nature Reviews Immunology, vol. 5, no. 4, pp. 331–342, 2005.
[24]
M. T. Lotze, H. J. Zeh, A. Rubartelli et al., “The grateful dead: damage-associated molecular pattern molecules and reduction/oxidation regulate immunity,” Immunological Reviews, vol. 220, no. 1, pp. 60–81, 2007.
[25]
V. Vaithilingam, J. Oberholzer, G. J. Guillemin, and B. E. Tuch, “Beneficial effects of desferrioxamine on encapsulated human islets—in vitro and in vivo study,” The American Journal of Transplantation, vol. 10, no. 9, pp. 1961–1969, 2010.
[26]
C. Fraker, M. R. Timmins, R. D. Guarino et al., “The use of the BD oxygen biosensor system to assess isolated human islets of Langerhans: oxygen consumption as a potential measure of islet potency,” Cell Transplantation, vol. 15, no. 8-9, pp. 745–758, 2006.
[27]
K. K. Papas, C. K. Colton, R. A. Nelson et al., “Human islet oxygen consumption rate and DNA measurements predict diabetes reversal in nude mice,” The American Journal of Transplantation, vol. 7, no. 3, pp. 707–713, 2007.
[28]
A. R. Pepper, C. P. Hasilo, C. W. J. Melling, et al., “The islet size to oxygen consumption ratio reliably predicts reversal of diabetes posttransplant,” Cell Transplant, vol. 21, pp. 2797–2804, 2012.
[29]
K. Zacharovova, Z. Berkova, T. Spacek et al., “In vitro assessment of pancreatic islet vitality by oxymetry,” Transplantation Proceedings, vol. 37, no. 8, pp. 3454–3456, 2005.
[30]
E. S. O'Sullivan, A. S. Johnson, A. Omer et al., “Rat islet cell aggregates are superior to islets for transplantation in microcapsules,” Diabetologia, vol. 53, no. 5, pp. 937–945, 2010.
[31]
S. Negi, A. Jetha, R. Aikin, C. Hasilo, R. Sladek, and S. Paraskevas, “Analysis of beta-cell gene expression reveals inflammatory signaling and evidence of dedifferentiation following human islet isolation and culture,” PLoS ONE, vol. 7, no. 1, Article ID e30415, 2012.
[32]
J. Scheller, A. Chalaris, D. Schmidt-Arras, and S. Rose-John, “The pro- and anti-inflammatory properties of the cytokine interleukin-6,” Biochimica et Biophysica Acta, vol. 1813, no. 5, pp. 878–888, 2011.
[33]
C. Garbers, H. M. Hermanns, F. Schaper, et al., “Plasticity and cross-talk of interleukin 6-type cytokines,” Cytokine and Growth Factor Reviews, vol. 23, pp. 85–97, 2012.
[34]
R. J. Noelle and E. C. Nowak, “Cellular sources and immune functions of interleukin-9,” Nature Reviews Immunology, vol. 10, no. 10, pp. 683–687, 2010.
[35]
C. L. Langrish, B. S. McKenzie, N. J. Wilson, R. de Waal Malefyt, R. A. Kastelein, and D. J. Cua, “IL-12 and IL-23: master regulators of innate and adaptive immunity,” Immunological Reviews, vol. 202, pp. 96–105, 2004.
[36]
P. M. Murphy, “Neutrophil receptors for interleukin-8 and related CXC chemokines,” Seminars in Hematology, vol. 34, no. 4, pp. 311–318, 1997.
[37]
R. M. Strieter, M. D. Burdick, B. N. Gomperts, J. A. Belperio, and M. P. Keane, “CXC chemokines in angiogenesis,” Cytokine and Growth Factor Reviews, vol. 16, no. 6, pp. 593–609, 2005.
[38]
N. Ferrara and T. Davis-Smyth, “The biology of vascular endothelial growth factor,” Endocrine Reviews, vol. 18, no. 1, pp. 4–25, 1997.
[39]
N. Zhang, A. Richter, J. Suriawinata et al., “Elevated vascular endothelial growth factor production in islets improves islet graft vascularization,” Diabetes, vol. 53, no. 4, pp. 963–970, 2004.
[40]
R. Melzi, A. Mercalli, V. Sordi et al., “Role of CCL2/MCP-1 in islet transplantation,” Cell Transplantation, vol. 19, no. 8, pp. 1031–1046, 2010.
[41]
B. Vasir, L. P. Aiello, K.-H. Yoon, R. R. Quickel, S. Bonner-Weir, and G. C. Weir, “Hypoxia induces vascular endothelial growth factor gene and protein expression in cultured rat islet cells,” Diabetes, vol. 47, no. 12, pp. 1894–1903, 1998.
[42]
B. M. Schulte, K. H. Lanke, J. D. Piganelli et al., “Cytokine and chemokine production by human pancreatic islets upon enterovirus infection,” Diabetes, vol. 61, pp. 2030–2036, 2012.
