Encapsulated Cells for the Treatment of Diabetes: Danger of Acute Hypoglycemia Following Injury?

Transplants comprised of encapsulated islets have shown promise in treating insulin-dependent diabetes. A question raised in the scientific and clinical communities is whether the insulin released from an implanted encapsulation device damaged in an accident could cause a serious hypoglycemic event. In this commentary, we consider the different types of damage that a device can sustain, including the encapsulation membrane and the islets within, and the amount of insulin released in each case. We conclude that the probability that device damage would cause an adverse hypoglycemic event is indeed very low.

Oxygenation strategies for encapsulated islet and beta cell transplants.

Human allogeneic islet transplantation (ITx) is emerging as a promising treatment option for qualified patients with type 1 diabetes. However, widespread clinical application of allogeneic ITx is hindered by two critical barriers: the need for systemic immunosuppression and the limited supply of human islet tissue. Biocompatible, retrievable immunoisolation devices containing glucose-responsive insulin-secreting tissue may address both critical barriers by enabling the more effective and efficient use of allogeneic islets without immunosuppression in the near-term, and ultimately the use of a cell source with a virtually unlimited supply, such as human stem cell-derived ß-cells or xenogeneic (porcine) islets with minimal or no immunosuppression. However, even though encapsulation methods have been developed and immunoprotection has been successfully tested in small and large animal models and to a limited extent in proof-of-concept clinical studies, the effective use of encapsulation approaches to convincingly and consistently treat diabetes in humans has yet to be demonstrated. There is increasing consensus that inadequate oxygen supply is a major factor limiting their clinical translation and routine implementation. Poor oxygenation negatively affects cell viability and ß-cell function, and the problem is exacerbated with the high-density seeding required for reasonably-sized clinical encapsulation devices. Approaches for enhanced oxygen delivery to encapsulated tissues in implantable devices are therefore being actively developed and tested. This review summarizes fundamental aspects of islet microarchitecture and ß-cell physiology as well as encapsulation approaches highlighting the need for adequate oxygenation; it also evaluates existing and emerging approaches for enhanced oxygen delivery to encapsulation devices, particularly with the advent of ß-cell sources from stem cells that may enable the large-scale application of this approach.

Update on cellular encapsulation.

There is currently a significant disparity between the number of patients who need lifesaving transplants and the number of donated human organs. Xenotransplantation is a way to address this disparity and attempts to enable the use of xenogeneic tissues have persisted for centuries. While immunologic incompatibilities have presented a persistent impediment to their use, encapsulation may represent a way forward for the use of cell-based xenogeneic therapeutics without the need for immunosuppression. In conjunction with modern innovations such as the use of bioprinting, incorporation of immune modulating molecules into capsule membranes, and genetic engineering, the application of xenogeneic cells to treat disorders ranging from pain to liver failure is becoming increasingly realistic. The present review discusses encapsulation in the context of xenotransplantation, focusing on the current status of clinical trials, persistent issues such as antigen shedding, oxygen availability, and donor selection, and recent developments that may address these limitations.

A Synopsis of the "Influence of Epigenetics, Genetics, and Immunology" Session Part A at the 35th Annual Society of Toxicologic Pathology Symposium.

The overarching theme of the 2016 Society of Toxicology Pathology's Annual Symposium was "The Basis and Relevance of Variation in Toxicologic Responses." Session 4 focused on genetic variation as a potential source for variability in toxicologic responses within nonclinical toxicity studies and further explored how knowledge of genetic traits might enable targeted prospective and retrospective studies in drug development and human health risk assessment. In this session, the influence of both genetic sequence variation and epigenetic modifications on toxicologic responses and their implications for understanding risk were explored. In this overview, the presentations in this session will be summarized, with a goal of exploring the ramifications of genetic and epigenetic variability within and across species for toxicity studies and disseminating information regarding novel tools to harness this variability to advance understanding of toxicologic responses across populations.

Extraparenchymal Bile/Pancreatic Ducts and Duodenal Papillae: Pathologic Evaluation in Nonclinical Species--A Brief Review.

This review focuses on the anatomy, histologic preparation, and pathologic evaluation of extraparenchymal bile and pancreatic ducts (BPDs) and their openings at the duodenal papillae in the cynomolgus macaque (Macaca fascicularis), the Beagle dog (Canis familiaris), the Wistar Hanover rat (Rattus norvegicus), and the CD1 mouse (Mus musculus). In nonclinical safety assessment, intraparenchymal BPDs (with sections of liver and pancreas, respectively) are evaluated routinely. However, detailed evaluation of the extraparenchymal BPDs or the duodenal papillae is not included. In the context of nonclinical safety assessment studies, this review describes situations in which evaluation of extraparenchymal ductal structures and duodenal papillae may be useful in characterizing test article-related changes; elucidates anatomic similarities between human, macaque, and dog and notable differences in rats and mice; and consolidates the information required for the histopathologic evaluation of these tissues.

Post-infection activities of fungicides against Cercospora arachidicola of peanut (Arachis hypogaea).

BACKGROUND: Despite strong indirect evidence of post-infection activity by a selection of systemic fungicides against Cercospora arachidicola, the causal organism of early leaf spot of peanut, direct post-infection activities in this pathosystem have yet to be reported in detail. This study was conducted to describe the activities of pyraclostrobin, penthiopyrad and prothioconazole on early leaf spot when each fungicide was applied after pathogen penetration began and throughout the incubation period. RESULTS: Most C. arachidicola penetration events occurred between 3 and 5 days after inoculation (dai), and the mean incubation period was 11.8 dai. Post-infection activities of the systemic fungicides were similar for all dependent variables measured. Systemic fungicides reduced lesion density compared with the non-treated control when applied at 3, 5 and 7 dai, and disease severity was >60% less for leaves treated with a systemic fungicide at all application dates (3, 5, 7, 9, 11 and 13 dai). CONCLUSIONS: Pyraclostrobin, penthiopyrad and prothioconazole showed similar systemic mobility within peanut leaves and activities against C. arachidicola, and appear to completely arrest the development of the pathogen at least 2 days post penetration, and limit pathogen colonization even when applications occur after symptom onset.

Drug-induced hemolytic anemia and thrombocytopenia associated with alterations of cell membrane lipids and acanthocyte formation.

CXCR3 is a chemokine receptor, upregulated upon activation of T cells and expressed on nearly 100% of T cells in sites of inflammation. SCH 900875 is a selective CXCR3 receptor antagonist. Thrombocytopenia and severe hemolytic anemia with acanthocytosis occurred in rats at doses of 75, 100, and 150 mg/kg/day. Massively enlarged spleens corresponded histologically to extramedullary hematopoiesis, macrophages, and hemosiderin pigment and sinus congestion. Phagocytosed erythrocytes and platelets were within splenic macrophages. IgG and/or IgM were not detected on erythrocyte and platelet membranes. Ex vivo increased osmotic fragility of RBCs was observed. Lipid analysis of the RBC membrane revealed modifications in phosphatidylcholine, overall cholesterol, and/or sphingomyelin. Platelets exhibited slender filiform processes on their plasma membranes, analogous to those of acanthocytes. The presence of similar morphological abnormalities in acanthocytes and platelets suggests that possibly similar alterations in the lipid composition of the plasma membrane have taken place in both cell types. This phenotype correlated with alterations in plasma lipids (hypercholesterolemia and low triglycerides) that occurred after SCH 900875 administration, although other factors cannot be excluded. The increased cell destruction was considered triggered by alterations in the lipid profile of the plasma membranes of erythrocytes and platelets, as reflected morphologically.

Chromosomal changes in high- and low-invasive mouse lung adenocarcinoma cell strains derived from early passage mouse lung adenocarcinoma cell strains.

The incidence of adenocarcinoma of the lung is increasing in the United States, however, the difficulties in obtaining lung cancer families and representative samples of early to late stages of the disease have lead to the study of mouse models for lung cancer. We used Spectral Karyotyping (SKY), mapping with fluorescently labeled genomic clones (FISH), comparative genomic hybridization (CGH) arrays, gene expression arrays, Western immunoblot and real time polymerase chain reaction (PCR) to analyze nine pairs of high-invasive and low-invasive tumor cell strains derived from early passage mouse lung adenocarcinoma cells to detect molecular changes associated with tumor invasion. The duplication of chromosomes 1 and 15 and deletion of chromosome 8 were significantly associated with a high-invasive phenotype. The duplication of chromosome 1 at band C4 and E1/2-H1 were the most significant chromosomal changes in the high-invasive cell strains. Mapping with FISH and CGH array further narrowed the minimum region of duplication of chromosome 1 to 71-82 centimorgans (cM). Expression array analysis and confirmation by real time PCR demonstrated increased expression of COX-2, Translin (TB-RBP), DYRK3, NUCKS and Tubulin-alpha4 genes in the high-invasive cell strains. Elevated expression and copy number of these genes, which are involved in inflammation, cell movement, proliferation, inhibition of apoptosis and telomere elongation, were associated with an invasive phenotype. Similar linkage groups are altered in invasive human lung adenocarcinoma, implying that the mouse is a valid genetic model for the study of the progression of human lung adenocarcinoma.

Suicidal and homicidal soldiers in deployment environments.

Suicidal and homicidal soldiers present one of the most frequent and challenging scenarios for deployed mental health providers. A chart review of 425 deployed soldiers seen for mental health reasons found that 127 (nearly 30%) had considered killing themselves and 67 (nearly 16%) had considered killing someone else (not the enemy) within the past month. Of these, 75 cases were considered severe enough to require immediate intervention. Interventions included unit watch, comprehensive treatment, and medical evacuation. Of the 75 dangerous soldiers, 5 were evacuated out of theater. The rest were returned to duty. Evacuation to a hospital in the rear is often the quickest and most risk-free option but is seldom the best choice for maintaining the fighting force. This article presents several case examples and describes methods for dealing with suicidal and homicidal soldiers during deployment.

Incidental mononuclear cell infiltrate in the uvea of cynomolgus monkeys.

Mononuclear cell infiltrate (MCI) in the uvea was observed in naïve, untreated (control group) cynomolgus monkeys in approximately 25% of drug safety evaluation studies. The total incidence of MCI in the choroid and the ciliary body was 29% of 342 males and 25% of 306 female monkeys. In the studies in which MCI was present in the ciliary body or choroid, the incidence was as high as 75%. There were no other ocular histopathologic findings in these monkeys. All monkeys were clinically healthy and the eyes were not remarkable when examined ophthalmoscopically.

Increased gene copy number of the transcription factor E2F1 in malignant melanoma.

Translocations and unique chromosome break points in melanoma will aid in the identification of the genes that are important in the neoplastic process. We have previously shown a unique translocation in malignant melanoma cells der(12)t(12;20). The transcription factor E2F1 maps to 20q11. Increased expression of E2F has been associated with the autonomous growth of melanoma cells, however, the molecular basis has not yet been elucidated. To this end, we investigated E2F1 gene copy number and structure in human melanoma cell lines and metastatic melanoma cases. Fluorescent in situ hybridization (FISH) analysis using a specific E2F1 probe indicated increased E2F1 gene copies in melanoma cell lines compared to normal melanocytes. We also observed increased copies of the E2F1 gene in lymph node metastases of melanoma. In addition, Western blot analysis demonstrated increased E2F1 protein levels in 8 out of 9 melanoma cell lines relative to normal melanocytes. Inhibition of E2F1 expression with RNAi also reduced melanoma cell growth. Our results suggest that the release of E2F activity by elevated E2F1 gene copy numbers may play a functional role in melanoma growth.

Genomic Alterations in Gastrointestinal Stromal Tumors as Revealed by Conventional and Array-based Comparative Genomic Hybridization.

Gastrointestinal stromal tumor (GIST) is the most commonly occurring mesenchymal neoplasm of the gastrointestinal tract, accounting for 80 percent of these tumors. GIST is highly unresponsive to standard chemotherapy, particularly in patients with advanced or metastatic disease. Recent molecular studies have shown that activating c-kit (KIT) mutations are detectable in a large proportion (>75%) of tumors, between 78% (1) and 89% (2). Approximately 30% of tumors without an identifiable KIT mutation exhibit PDGFRA mutations (3). Furthermore, the KIT mutations are heterogeneous, some being known to confer a relatively better prognosis than others (1). Gross cytogenetic abnormalities associated with GIST appear to be similar regardless of whether a KIT mutation is identified. The molecular genetic alterations associated with multistep GIST tumorigenesis, particularly those which confer intrinsic or acquired resistance to both standard as well as targeted therapeutic approaches, however, are not fully recognized. As an initial approach to identify chromosomal sites of candidate gene(s), which may predict overall clinical and biologic behavior of GISTs, as they relate to response to the specific therapeutic drug Gleevec, we analyzed six GIST samples using both conventional as well as array-based Comparative Genomic Hybridization (CGH). The common abnormalities detected by CGH in low and high grade tumors included loss of all or part of chromosome 14; an entire chromosome 14 was lost in four tumor samples, with the remaining two samples exhibiting loss of the 14q22-q32.3 region. Other recurrent abnormalities included loss of the 1p chromosomal region (four tumor samples), loss of part or entire chromosome 9 (only in metastatic tumors), loss of chromosomes 15 and 22, and a gain of the chromosome 3q region in three samples each. Array- based CGH performed using human BAC arrays (1400V11 Spectral Genomics Chip™) on the other hand, not only detected recurrent abnormalities of the chromosomes and chromosomal sites mentioned above, but also identified losses of additional chromosomal sites on chromosomes 6q and 13q. Array-based CGH further delineated the regions of loss or gain to specific chromosome bands or sub bands based on location of chromosomal site-specific BACs. The specific regions of losses are located at 1p36.2-36.3,6q12,9p13-ter,13q33.33-q34, and gain or amplification of chromosomal DNA at bands 3q26-27. It is interesting to note that some of the chromosomal sites of losses and gains also harbor gene(s) such as AFAR, RIZ1, p73(1p35-36), Akt-1(14q32), p14 and p16(9p21), NF2(22q12), ZASCI, p63 and PIK3CA oncogenes (3q26-27), all of which are known to play a major role in solid tumor pathogenesis. The role of these genes in GIST, however, remains to be seen. Thus, the results of our current study demonstrate that such a combined approach to detect global genomic alterations in GIST is significant in providing information related to chromosomal sites of potential tumor suppressor genes associated with multistep tumorigenesis; some of which also may be predictive of prognosis and clinical outcome following specific targeted therapy, which is the focus of future studies.