Microencapsulation may allow for immunosuppression-free islet transplantation. Herein we investigated whether human islets can be shipped safely to a remote encapsulation core facility and maintain in vitro and in vivo functionality. In non-encapsulated islets before and encapsulated islets after shipment, viability was 88.3+/-2.5 and 87.5+/-2.7% (n=6, p=0.30). Stimulation index after static glucose incubation was 5.4+/-0.5 and 6.3+/-0.4 (n=6, p=0.18), respectively. After intraperitoneal transplantation, long-term normoglycemia was consistently achieved with 3,000, 5,000, and 10,000 IEQ encapsulated human islets. When transplanting 1,000 IEQ, mice returned to hyperglycemia after 30-55 (n=4/7) and 160 days (n=3/7). Transplanted mice showed human oral glucose tolerance with lower glucose levels than non-diabetic control mice. Capsules retrieved after transplantation were intact, with only minimal overgrowth. This study shows that human islets maintained the viability and in vitro function after encapsulation and the inhomogeneous alginate-Ca(2+)/Ba(2+) microbeads allow for long-term in vivo human islet graft function, despite long-distance shipment.

Human islet isolation outcomes were compared between two purification methods; 32 pancreases were processed by conventional Biocoll purification method (SM, standard method) and 132 pancreases by a refined University of Illinois at Chicago UW/Biocoll method (UIC-UB). There was no difference in donor characteristics between the two study groups. The prepurification equivalent islet number was similar between the groups (359,425+/-40,794 equivalent islet number in SM vs. 370,682+/-17,579 in UIC-UB). SM purified islets were mostly collected in only 2 of 12 fractions (68.9% and 36.3% purity). With the UIC-UB, highly purified islets were collected in 6 of 12 separate fractions (fractions 3-8 with purity of 84.8%, 82.5%, 72.0%, 59.3%, 46.8%, and 36.2%). UIC-UB yielded significantly greater islet yield compared with SM (368,419+/-18,245 vs. 260,908+/-37,835, P=0.017). Islet recovery rate was superior in UIC-UB (84.9% vs. 64.5%, P=0.04). Our study demonstrates a superior recovery of highly pure human pancreatic islets after purification using the refined method of UIC-UB gradient.

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A low-Mach, unstructured, large-eddy-simulation-based, unsteady flamelet approach with a generalized heat loss combustion methodology (including soot generation and consumption mechanisms) is deployed to support a large-scale, quiescent, 5-m JP-8 pool fire validation study. The quiescent pool fire validation study deploys solution sensitivity procedures, i.e., the effect of mesh and time step refinement on capturing key fire dynamics such as fingering and puffing, as mesh resolutions approach O(1) cm. A novel design-order, discrete-ordinate-method discretization methodology is established by use of an analytical thermal/participating media radiation solution on both low-order hexahedral and tetrahedral mesh topologies in addition to quadratic hexahedral elements. The coupling between heat losses and the flamelet thermochemical state is achieved by augmenting the unsteady flamelet equation set with a heat loss source term. Soot and radiation source terms are determined using flamelet approaches for the full range of heat losses experienced in fire applications including radiative extinction. The proposed modeling and simulation paradigm are validated using pool surface radiative heat flux, maximum centerline temperature location, and puffing frequency data, all of which are predicted within 10% accuracy. Simulations demonstrate that under-resolved meshes predict an overly conservative radiative heat flux magnitude with improved comparisons as compared to a previously deployed hybrid Reynolds-averaged Navier–Stokes/eddy dissipation concept-based methodology.

Oxidative stress during islet isolation induces a cascade of events injuring islets and hampering islet engraftment. This study evaluated islet isolation and transplantation outcomes after intra-ductal glutamine administration. Human pancreata deemed unsuitable for pancreas or islet transplantation were treated with either a 5 mM solution of L-glutamine (n = 6) or collagenase enzyme alone (n = 6) through the main pancreatic duct. Islet yield, viability, in vitro function; markers of oxidative stress [malondialdehyde (MDA) and Glutathione (GSH)] and apoptosis were assessed. Islet yields were significantly increased in the glutamine group compared to controls (318, 559 ± 25, 800 vs. 165, 582 ± 39, 944 mean ± SEM, p < 0.01). The amount of apoptotic cells per islet was smaller in the glutamine group than the control. The percentage of nude mice rendered normoglycemic with glutamine-treated islets was higher than the controls (83% n = 10/12 vs. 26% n = 6/23; p < 0.01), and the time to reach normoglycemia was decreased in the glutamine group (1.83 ± 0.4 vs. 7.3 ± 3 days; p < 0.01). Glutamine administration increased GSH levels (7.6 ± 1.7 nmol/mg protein vs. 4.03 ± 0.5 in control, p < 0.05) and reduced lipid-peroxidation (MDA 2.45 ± 0.7 nmol/mg of protein vs. 6.54 ± 1.7 in control; p < 0.05). We conclude that intra-ductal administration of glutamine reduces oxidative injury and apoptosis and improves islet yield and islet graft function after transplantation.