Biomedical subjects

Nicole Kirchhof

Publications and source records attributed to Nicole Kirchhof.

At least 19 recordsLinked to original sources

PubMed2006

A murine Mll-AF4 knock-in model results in lymphoid and myeloid deregulation and hematologic malignancy.

The 2 most frequent human MLL hematopoietic malignancies involve either AF4 or AF9 as fusion partners; each has distinct biology but the role of the fusion partner is not clear. We produced Mll-AF4 knock-in (KI) mice by homologous recombination in embryonic stem cells and compared them with Mll-AF9 KI mice. Young Mll-AF4 mice had lymphoid and myeloid deregulation manifest by increased lymphoid and myeloid cells in hematopoietic organs. In vitro, bone marrow cells from young mice formed unique mixed pro-B lymphoid (B220(+)CD19(+)CD43(+)sIgM(-), PAX5(+), TdT(+), IgH rearranged)/myeloid (CD11b/Mac1(+), c-fms(+), lysozyme(+)) colonies when grown in IL-7- and Flt3 ligand-containing media. Mixed lymphoid/myeloid hyperplasia and hematologic malignancies (most frequently B-cell lymphomas) developed in Mll-AF4 mice after prolonged latency; long latency to malignancy indicates that Mll-AF4-induced lymphoid/myeloid deregulation alone is insufficient to produce malignancy. In contrast, young Mll-AF9 mice had predominately myeloid deregulation in vivo and in vitro and developed myeloid malignancies. The early onset of distinct mixed lymphoid/myeloid lineage deregulation in Mll-AF4 mice shows evidence for both "instructive" and "noninstructive" roles for AF4 and AF9 as partners in MLL fusion genes. The molecular basis for "instruction" and secondary cooperating mutations can now be studied in our Mll-AF4 model.

Animals↗

PubMed2006

Prolonged diabetes reversal after intraportal xenotransplantation of wild-type porcine islets in immunosuppressed nonhuman primates.

Cell-based diabetes therapy requires an abundant cell source. Here, we report reversal of diabetes for more than 100 d in cynomolgus macaques after intraportal transplantation of cultured islets from genetically unmodified pigs without Gal-specific antibody manipulation. Immunotherapy with CD25-specific and CD154-specific monoclonal antibodies, FTY720 (or tacrolimus), everolimus and leflunomide suppressed indirect activation of T cells, elicitation of non-Gal pig-specific IgG antibody, intragraft expression of proinflammatory cytokines and invasion of infiltrating mononuclear cells into islets.

Animals↗

PubMed2006

Gene expression array analyses predict increased proto-oncogene expression in MMTV induced mammary tumors.

Exogenous infection by milk-borne mouse mammary tumor viruses (MMTV) typically induce mouse mammary tumors in genetically susceptible mice at a rate of 90-95% by 1 year of age. In contrast to other transforming retroviruses, MMTV acts as an insertional mutagen and under the influence of steroid hormones induces oncogenic transformation after insertion into the host genome. As these events correspond with increases in adjacent proto-oncogene transcription, we used expression array profiling to determine which commonly associated MMTV insertion site proto-oncogenes were transcriptionally active in MMTV induced mouse mammary tumors. To verify our gene expression array results we developed real-time quantitative RT-PCR assays for the common MMTV insertion site genes found in RIII/Sa mice (int-1/wnt-1, int-2/fgf-3, int-3/Notch 4, and fgf8/AIGF) as well as two genes that were consistently up regulated (CCND1, and MAT-8) and two genes that were consistently down regulated (FN1 and MAT-8) in the MMTV induced tumors as compared to normal mammary gland. Finally, each tumor was also examined histopathologically. Our expression array findings support a model whereby just one or a few common MMTV insertions into the host genome sets up a dominant cascade of events that leave a characteristic molecular signature.

Animals↗

PubMed2005

Somatic integration of an oncogene-harboring Sleeping Beauty transposon models liver tumor development in the mouse.

The Sleeping Beauty (SB) transposon system can integrate foreign sequences of DNA in the genome of mouse somatic cells eliciting long-term expression in vivo. This technology holds great promise for human gene therapy as a nonviral technology to deliver therapeutic genes. SB also provides a means to study the effects of defined genetic elements, such as oncogenes, on somatic cells in mice. Here, we test the ability of the SB transposon system to facilitate somatic integration of a transposon containing an activated NRAS oncogene in mouse hepatocytes to elicit tumor formation. NRAS oncogene-driven tumors developed when such vectors were delivered to the livers of p19Arf-null or heterozygous mice. Delivery of the NRAS transposon cooperates with Arf loss to cause carcinomas of hepatocellular or biliary origin. These tumors allowed characterization of transposon integration and expression at the single-cell level, revealing robust NRAS expression and both transposase-mediated and random insertion of delivered vectors. Random integration and expression of the SB transposase plasmid was also observed in one instance. In addition, studies using effector loop mutants of activated NRAS provide evidence that mitogen-activated protein kinase activation alone cannot efficiently induce liver carcinomas. This system can be used to rapidly model tumors caused by defined genetic changes.

Animals↗

PubMed2005

Cyclosporine toxicity in immunosuppressed streptozotocin-diabetic nonhuman primates.

Streptozotocin (STZ) is widely applied in animal models of insulin-dependent diabetes mellitus. Adverse effects of STZ mainly concern liver and kidney. In nonhuman primates a single 100-150 mg/kg dose invariably induces diabetes with only rare adverse effects. We report one animal with renal failure necessitating sacrifice. Body weight (age) might be a confounding factor, i.e. older animals might be more vulnerable to STZ-related toxicity. We therefore recommended to administer STZ on a mg/m2 basis and not on a mg/kg basis. In our islet transplantation program nonhuman primates with STZ-induced diabetes received transplants under chronic immunosuppression including calcineurin inhibitors (cyclosporine, tacrolimus), drugs in the rapamycin class affecting growth factor-induced cell proliferation, and the sphingosine 1-phosphate receptor antagonist FTY720. Four animals developed renal failure and had to be sacrificed, most likely caused by cyclosporine. Kidney histology was typical for cyclosporine toxicity including thrombotic microangiopathy in glomeruli and fibrinoid necrosis of arteries, and for STZ toxicity including acute tubular necrosis and accumulations of erythroid precursors. This adverse effect was observed at a pharmacologically active cyclosporine exposure. Additionally, six diabetic animals without major adverse effects during cyclosporine or tacrolimus treatment are presented. We conclude that cyclosporine facilitates renal dysfunction in animals with STZ-induced diabetes, presumably related to an increased vulnerability to a toxic insult after STZ administration.

Animals↗

PubMed2005

In vivo haematopoietic activity is induced in neurosphere cells by chromatin-modifying agents.

Modifications of DNA and chromatin are fundamental for the establishment and maintenance of cell type-specific gene expression patterns that constitute cellular identities. To test whether the developmental potential of fetal brain-derived cells that form floating sphere colonies (neurospheres) can be modified by destabilizing their epigenotype, neurosphere cells were treated with chemical compounds that alter the acetylation and methylation patterns of chromatin and DNA. Intravenous infusion of bulk or clonally derived neurosphere cells treated with a combination of trichostatin A (TSA) plus 5-aza-2'-deoxycytidine (AzaC) (TSA/AzaC neurosphere cells) yielded long-term, multilineage and transplantable neurosphere-derived haematopoietic repopulation. Untreated neurosphere cells exhibited no haematopoietic repopulation activity. The neurosphere-derived haematopoietic cells showed a diploid karyotype, indicating that they are unlikely to be products of cell fusion events, a conclusion strengthened by multicolour fluorescence in situ hybridization. Our results indicate that altering the epigenotype of neurosphere cells followed by transplantation enables the generation of neurosphere-derived haematopoietic cells.

Animals↗

PubMed2005

Post-transplant upregulation of chemokine messenger RNA in non-human primate recipients of intraportal pig islet xenografts.

BACKGROUND: We have previously shown that pig-to-primate intraportal islet xenografts reverse diabetes, escape hyperacute rejection, and undergo acute cellular rejection in non-immunosuppressed recipients. To gain a better understanding of mechanisms contributing to xenoislet rejection in non-human primates we examined gene expression in livers bearing islet xenografts in the first 72 h after transplantation. METHODS: Liver specimens were collected at sacrifice from seven non-immunosuppressed rhesus macaques at 12, 24, 48 and 72 h after intraportal porcine islet transplantation. Following total RNA extraction, mRNA was quantified using SYBR green real-time reverse transcription polymerase chain reaction (RT-PCR) for species-specific immune response genes. Data were analyzed using comparative cycle threshold (Ct) analysis, adjusted for specific primer-efficiencies and normalized to cyclophilin expression. RESULTS: Porcine insulin mRNA was detected in all liver samples. Cluster analysis revealed differential gene expression patterns at 12 and 24 h (early) compared with at 48 and 72 h (late) post-transplant. Gene expression patterns were associated with histological findings of predominantly neutrophils and only a few lymphocytes at 12 and 24 h and an increasing number of lymphocytes and macrophages at 48 and 72 h. Transcript levels of CXCR3 and its ligands, interferon-inducible protein 10 (IP-10) and monokine induced by IFN-gamma (Mig), significantly increased between early and late time points together with expression of MIP-1alpha, regulated on activation normal T expressed and secreted protein (RANTES) and MCP-1. CCR5 showed only a marginal, non-significant increase. Fas ligand, perforin and granzyme B transcripts were all elevated at 48 and 72 h post-transplant. CONCLUSIONS: Our data suggest that CXCR3, with ligands IP-10 and Mig, is involved in T cell recruitment in acute islet xenograft rejection in non-human primates. Upregulation of RANTES and MIP-1alpha transcripts in the absence of a significant CCR5 increase suggests a possible involvement of other chemokine receptors. MCP-1 expression is associated with T cell and macrophage infiltration. Elevated cytotoxic effector molecule expression (Fas ligand, perforin, granzyme B) indicates T-cell mediated graft destruction by cytotoxic and cytolytic mechanisms within 48 to 72 h after transplantation. These results identify the CXCR3-mediated chemoattractant pathway as an immunosuppressive target in pig-to-primate islet xenotransplantation.

Animals↗

PubMed2005

Isolation of Cokeromyces recurvatus, initially misidentified as Coccidioides immitis, from peritoneal fluid in a cat with jejunal perforation.

Cokeromyces recurvatus, a zygomycete, was isolated by fungal culture from the peritoneal fluid of a cat with jejunal perforation secondary to intestinal lymphosarcoma. This organism has not been recovered previously from a veterinary patient. The tissue form of C. recurvatus is morphologically similar to those of Coccidioides immitis and Paracoccidioides brasiliensis and may be misdiagnosed as 1 of these organisms on the basis of cytologic or histopathologic specimens, particularly in geographic regions where these organisms are not endemic.

Animals↗

PubMed2005

Comparison of gross and histologic tissue responses of skin incisions closed by use of absorbable subcuticular staples, cutaneous metal staples, and polyglactin 910 suture in pigs.

OBJECTIVE: To assess gross and histologic tissue responses of skin incisions closed by use of absorbable subcuticular staples, cutaneous metal staples, and polyglactin 910 suture in pigs. ANIMALS: 8 purpose-bred disease-free pigs. PROCEDURE: Pigs were randomly allocated to 1 of 4 groups from which tissues were collected after death on postoperative days (PODs) 7, 14, 21, or 42. In each pig, 4 incisions were made; 1 was closed subcuticularly with 3-0 polyglactin 910 suture, 1 was closed with metal staples, and 2 were closed with absorbable subcuticular staples. Incision sites were grossly evaluated every 3 days after closure. At necropsy, incision sites and surrounding tissues were examined histologically; a histopathologic scoring system was used to quantitate healing and tissue response directed against the closure material. RESULTS: Postoperatively, the metal staples induced a severe inflammatory response, compared with minimal inflammation associated with the suture or absorbable subcuticular staples. Histologic evaluation of incisions on PODs 7, 14, and 21 revealed less severe inflammation associated with absorbable subcuticular staples than that associated with the other materials. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that absorbable subcuticular staples induced a less severe inflammatory response in the early stages of healing in pigs, compared with other commonly used methods of wound closure. Use of absorbable staples potentially combines the benefits of subcuticular closure with the speed and precision of staple placement.

Animals↗

PubMed2004

ABL-MYC retroviral infection elicits bone marrow plasma cell tumors in Bcl-X(L) transgenic mice.

Multiple myeloma is characterized by the accumulation of malignant plasma cells in the bone marrow. While there have been many attempts to genetically recapitulate this disease in animal models, few reports describe plasma cell tumors that exhibit bone marrow involvement. We recently described a Bcl-X(L) transgenic mouse that developed polyclonal non-malignant B-cell expansions in the bone marrow and lymphoid organs. In this report, we describe induction of plasma cell tumors in littermate control and Bcl-X(L) transgenic mice with a retrovirus expressing v-Abl and c-Myc. Nearly 100% of the ABL-MYC-infected littermate control and Bcl-X(L) mice developed plasma cell tumors. There was no difference in tumor latency in young mice infected; however, following ABL-MYC infection, aged Bcl-X(L) mice demonstrated a median survival of 9 weeks, while littermate control mice demonstrated a median survival of 19 weeks. Interestingly, while both littermate control and Bcl-X(L) mice infected with the ABL-MYC retrovirus developed extramedullary plasma cell tumors, only the ABL-MYC-infected Bcl-X(L) mice, but not the ABL-MYC-infected littermate control mice, developed bone marrow plasma cell tumors with characteristic radiolucent bone lesions. Tumor cell populations were clonally related, and analysis of tumor immunoglobulin genes demonstrated evidence consistent with somatic hypermutation. This report implicates an unidentified role of Bcl-X(L) in bone marrow plasma cell tumor formation, as ABL-MYC retroviral infection only elicits bone marrow plasma cell tumors in mice that ectopically express Bcl-X(L) in their B- and plasma cells.

Aging↗

PubMed2004

Islet allograft survival in nonhuman primates immunosuppressed with basiliximab, RAD, and FTY720.

OBJECTIVE: In a preclinical, nonhuman primate islet allotransplant model, the authors evaluated a novel immunosuppressive combination of basiliximab for induction and of RAD and FTY720 for maintenance. METHODS: Five ABO-compatible and mixed lymphocyte reactivity-mismatched streptozotocin-induced diabetic juvenile cynomolgus monkeys underwent transplantation intraportally with 48-hr cultured 10,000 islet equivalents per kilogram. Induction immunosuppression was with intravenous basiliximab (10 mg on postoperative days 0 and 4). Maintenance immunosuppression was with RAD (everolimus) (0.075 mg/kg per day administered subcutaneously) and FTY720 (0.3 mg/kg per day administered orally), both administered on day -2 through day 180 posttransplant. RESULTS: All five recipients tolerated their transplants and immunosuppressive therapy well, without adverse events or infectious complications. Insulin requirements pretransplant were 2.6 to 4.0 U/kg per day. All recipients became normoglycemic and insulin-independent posttransplant. Posttransplant serum C-peptide levels averaged 2.7 ng/mL (range, 0.6-6.2 ng/mL). Morning blood glucose levels ranged from less than 100 mg/dL to 150 mg/dL. Posttransplant acute C-peptide response to intravenous arginine averaged 1.3 ng/mL (range, 0.23-2.72 ng/mL). In one recipient with subtherapeutic RAD blood levels on day 7 posttransplant, exogenous insulin was resumed 100 days posttransplant; basal C-peptide levels remained positive in this recipient and averaged 2.6 ng/mL. The other four recipients remained insulin-independent for more than 6 months. CONCLUSIONS: This study provides preliminary evidence of the safety and efficacy of corticosteroid- and calcineurin inhibitor-free immunosuppression in a relevant preclinical transplant model. These findings provide a strong rationale for evaluating this nondiabetogenic regimen in a clinical trial of islet transplants in type 1 diabetic recipients.

Animals↗

PubMed2004

Erythroid-like cells from neural stem cells injected into blastocysts.

OBJECTIVE: In contrast to embryonic stem (ES) cells, which are able to give rise to all cell types of the body, somatic stem cells have been thought to be more limited in their differentiation potential in that they are committed to generate only cells of their tissue of origin. Unexpectedly, some recent data suggest that somatic stem cells isolated from one tissue can also generate cells of heterologous tissues and organs, implying that somatic stem cells have a greater potential for differentiation. METHODS: To explore further the developmental potential of murine neural stem cells (NSCs) we injected cultured NSCs as neurospheres into preimplantation blastocysts and determined the seeding by donor cells in tissues of developing chimeric fetal and adult animals. RESULTS: We frequently detected progeny of injected NSCs both in embryos and in adult animals. In embryos we observed transient seeding of donor cells to hematopoietic tissues and generation of NSC-derived cells that express globin genes and an erythroid-specific cell-surface marker. In adults progeny of NSCs were mostly detected in neural tissues. The observed low level of chimerism of wild-type NSCs was increased if we injected stem cells expressing a bcl-2 transgene, without changing the seeding pattern. CONCLUSION: These results suggest that cultured NSCs, following their injection into blastocysts, generate at mid-gestation erythroid-like cells but later, in adult chimeric mice, engraftment mainly persisted in neural tissues.

Animals↗

PubMed2004

Caspase-3 inhibitor prevents apoptosis of human islets immediately after isolation and improves islet graft function.

OBJECTIVES: Apoptosis appears in islets after isolation, and it has a detrimental effect on the islet function. To improve the outcome of clinical islet transplantation, it is crucial to protect islets from apoptosis. The aim of this study was to determine whether a caspase-3 inhibitor (Z-DEVD-FMK) added to culture media protects islets from apoptosis and to compare the effects of fetal bovine serum (FBS) with human serum albumin (HSA) as a protein supplement in culture. METHODS: Isolated human islets were cultured under 4 different conditions: 0.5% HSA (control), 0.5% HSA + 25 micromol/L Z-DEVD-FMK, 0.5% HSA + 100 micromol/L Z-DEVD-FMK and 10% FBS for 2 days. Next, 1000 IEQ islets precultured with 0.5% HSA and with or without 100 micromol/L Z-DEVD-FMK were transplanted to diabetic nude mice. RESULTS: The islet yields were higher in Z-DEVD-FMK-treated groups, and the inhibitor prevented apoptosis dose dependently. The yield and insulin release were higher in FBS-treated group than in the control group, but FBS did not affect apoptosis. All 6 mice transplanted with islets pretreated with Z-DEVD-FMK, and 3 of 8 mice with control islets became normoglycemic posttransplantation. CONCLUSION: Z-DEVD-FMK prevented apoptosis of isolated human islets and improved its function. FBS (10%) improved the islet yield and insulin secretion more than 0.5% HSA.

Adult↗

PubMed2004

Reversal of diabetes in non-immunosuppressed rhesus macaques by intraportal porcine islet xenografts precedes acute cellular rejection.

BACKGROUND: The functional response and immunobiology of primarily non-vascularized islet cell xenografts remain poorly defined in non-human primates. METHODS: We transplanted 20,000 adult porcine islet equivalents/kg (purified and cultured for 48-h) intraportally into six streptozotocin-diabetic and two non-diabetic rhesus macaques. Two recipients were killed at various intervals post-transplant for histologic examination of livers bearing xenografts. RESULTS: Plasma glucose levels in diabetic recipients averaged 94 mg/dl at 12 h, 92 mg/dl at 24 h, 147 mg/dl at 48 h, and 157 mg/dl at 72 h post-transplant. Serum porcine C-peptide was present in eight of eight recipients at 12 h, in five of six at 24 h, in four of four at 48 h, and in one of two at 72 h post-transplant. C3a and SC5b-9 plasma levels increased at 12 h post-transplant and returned to pre-transplant levels by 24 h. IgG, IgM anti-pig and anti-Gal IgG serum antibody levels did not increase post-transplant. Rejection was initiated by IgM and complement deposition on islets. Neutrophils dominated the cellular infiltrate at 12 h; CD4+ and CD8+ T cells were the main infiltrating cells at 24, 48, and 72 h; and macrophages increasingly infiltrated xenografts starting at 24 h post-transplant. Numerous xenoislets were present at all time points; their proportion without intraislet infiltrates decreased from 65% at 24 h to 17% at 72 h post-transplant. CONCLUSIONS: Pig-to-primate intraportal islet xenografts reverse diabetes and the majority of intraportally transplanted xenogeneic islets are not subject to hyperacute rejection. They undergo acute cellular rejection mediated by CD4+- and CD8+ T cells and macrophages.

Acute Disease↗

PubMed2004

Comparison of tolerated and rejected islet grafts: a gene expression study.

Recently we showed that donor-specific tolerance to MHC-matched islet allografts in diabetic NOD mice could be induced by simultaneous islet and bone marrow transplantation. Mononuclear cell infiltration surrounding the islets was also found in tolerated grafts. In this study, we compared gene expression in the tolerated and rejected islet grafts by using Affymetrix Murine U74A oligonucleotide arrays. To confirm the results of microarray analysis, we performed real-time PCR and RNase protection assay on selected genes. Of over 12,000 genes studied, 57 genes were expressed at consistently higher levels in tolerated islet grafts, and 524 genes in rejected islet grafts. Genes from a variety of functional clusters were found to be different between rejected and tolerated grafts. In the rejected islet grafts, a number of T-cell surface markers and of cytotoxicity-related genes were highly expressed. Also in the rejected grafts, a number of cytokines and chemokines and their receptors were highly expressed. The differential expression of selected genes found by microarray analysis was also confirmed by real-time PCR and RNase protection assay. Our results indicated that gene microarray analysis can help us to detect gene expression differences representative of the biologic mechanisms of tolerance and rejection.

Animals↗

PubMed2003

Targeted overexpression of Bcl-XL in B-lymphoid cells results in lymphoproliferative disease and plasma cell malignancies.

Multiple myeloma is an incurable malignancy, and there is currently no mouse model that fully recapitulates the development and progression of the disease. We now describe a transgenic mouse that expresses a Bcl-XL transgene under the control of the 3'kappa immunoglobulin light chain enhancer, which is most active in murine B cells in late developmental stages. These mice developed nonmalignant plasma cell foci in the bone marrow and soft tissues and hyaline tubular casts in the kidneys. Median survival of the 3'KE/Bcl-XL mice was similar to littermate controls. When the 3'KE/Bcl-XL mouse was crossed to an Emu/c-Myc transgenic mouse, median survival of double transgenic progeny was 5.5 weeks. Peripheral blood and soft tissues were infiltrated with immature/mature B cells, and plasma cell lesions were identified in the bone marrow of all mice coexpressing Bcl-XL and c-Myc. These B- and plasma cell lesions demonstrated features consistent with malignancy. These results indicate that the 3'kappa immunoglobulin light chain enhancer can effectively target expression of Bcl-XL to B cells in late developmental stages, and they provide direct evidence that Bcl-XL can contribute to plasmacytomagenesis. Furthermore, this murine model serves as an important step in developing a novel genetically induced mouse model of plasma cell malignancies exhibiting bone marrow involvement.

Animals↗

PubMed2003

Overexpression of murine TSLP impairs lymphopoiesis and myelopoiesis.

The role of thymic stromal cell-derived lymphopoietin (TSLP) in regulating hematopoiesis is poorly characterized, so we investigated its regulatory effects in vivo using TSLP transgenic mice. Overexpression of TSLP disrupted hematopoietic homeostasis by causing imbalances in lymphopoiesis and myelopoiesis. Mice harboring a TSLP transgene had 5- to 700-fold fewer B and T precursors and no detectable pre-B lymphocyte colonyforming activity in the marrow or spleen. Conversely, TSLP transgenic mice possessed 15 to 20 times more splenic myeloid precursors than their littermates, and progenitor activity of the granulocyteerythrocyte-macrophage-megakaryocyte colony-forming units was significantly elevated. The arrest in lymphopoiesis and the expansion of myeloid progenitor cells in TSLP transgenic mice suggest that TSLP has negative and positive regulatory effects on lymphoid and myeloid development, respectively.

Animals↗

PubMed2003

Improved islet yield and function with ductal injection of University of Wisconsin solution before pancreas preservation.

BACKGROUND: Ensuring sufficient islet yield from preserved pancreases is a critical step in clinical islet transplantation. The aim of this study was to investigate whether pancreatic ductal injection, performed at procurement, using a small volume of preservation solution before cold storage (ductal preservation method) would improve islet yield and function from rat pancreases preserved for 6 and 24 hr. MATERIALS AND METHODS: Islets were isolated from Lewis rats. Pancreases were classified into five groups: fresh (group 1); preserved for 6 hr in University of Wisconsin solution without and with ductal preservation (groups 2 and 3); and preserved for 24 hr in University of Wisconsin solution without and with ductal preservation (groups 4 and 5). We assessed islet yield, function, and viability of pancreatic ductal cells. RESULTS: Islet yields per pancreas in groups 1 to 5 were 2010+/-774, 674+/-450, 1418+/-528, 527+/-263, and 1655+/-618 (islet equivalent) (+/-SD), respectively. Stimulation indices in groups 1 to 5 were 11.97+/-3.17, 6.48+/-4.04, 12.44+/-5.65, 2.56+/-2.03, and 5.55+/-2.71. Functional success rates in groups 1 to 5 were 100%, 0%, 100%, 0%, and 66.7%. Percentages of nonviable pancreatic duct cells in groups 1 to 5 were 3.8+/-2.7%, 59.7+/-4.4%, 19.5+/-7.3%, 64.7+/-4.5%, and 17.2+/-2.6%. In all experiments, the differences were significant between the groups without versus the groups with ductal preservation (P<0.05, group 2 vs. group 3 and group 4 vs. group 5). CONCLUSIONS: Ductal preservation improved islet yield and function after 6 and 24 hr of preservation. Well-preserved pancreatic ducts maintained good distribution of collagenase solution.

Adenosine↗