Search

Objective: We aim on developing a polymeric ectopic scaffold in a readily accessible site under the skin., Summary Background Data: The liver as transplantation site for pancreatic islets is associated with significant loss of islets. Several extrahepatic sites were tested in experimental animals, but many have practical limitations in the clinical setting and do not have the benefit of easy accessibility., Methods and Results: Functional survival of rat islets was tested during 7 days of culture in the presence of poly(D,L-lactide-co-ε-caprolactone) (PDLLCL), poly(ethylene oxide terephthalate)/polybutylene terephthalate (PEOT/PBT) block copolymer, and polysulfone. Tissue responses were studied in vivo after subcutaneous implantation in rats. Culture on PEOT/PBT and polysulfone profoundly disturbed function of islets, and induced severe tissue responses in vivo. Modification of their hydrophilicity did not change the suitability of the polymers. PDLLCL was the only polymer that promoted functional survival of rat islets in vitro and was associated with minor tissue reactions after 28 days. Rat islets were transplanted in the PDLLCL scaffold in a diabetic rat model. Before islet seeding, the scaffold was allowed to engraft for 28 days to allow the tissue response to dampen and to allow blood vessel growth into the device. Islet transplantation into the scaffold resulted in normoglycemia within 3 days and for the duration of the study period of 16 weeks., Conclusions: In conclusion, we found that some polymers such as PEOT/PBT and polysulfone interfere with islet function. PDLLCL is a suitable polymer to create an artificial islet transplantation site under the skin and supports islet survival.

Background: The liver as transplantation site for human pancreatic islets is a harsh microenvironment for islets and it lacks the ability to retrieve the graft. A retrievable, extrahepatic transplantation site that mimics the pancreatic environment is desired. Ideally, this transplantation site should be located subdermal for easy surgical-access but this never resulted in normoglycemia. Here, we describe the design and efficacy of a novel prevascularized, subcutaneously implanted, retrievable poly (D,L-lactide-co-ε-caprolactone) scaffold., Method: Three dosages of rat islets, that is, 400, 800, and 1200, were implanted in immune compromised mice to test the efficacy (n = 5). Islet transplantation under the kidney capsule served as control (n = 5). The efficacy was determined by nonfasting blood glucose measurements and glucose tolerance tests., Results: Transplantation of 800 (n = 5) and 1200 islets (n = 5) into the scaffold reversed diabetes in respectively 80 and 100% of the mice within 6.8 to 18.5 days posttransplant. The marginal dose of 400 islets (n = 5) induced normoglycemia in 20%. The glucose tolerance test showed major improvement of the glucose clearance in the scaffold groups compared to diabetic controls. However, the kidney capsule was slightly more efficacious because all 800 (n = 5) and 1200 islets (n = 5) recipients and 40% of the 400 islets (n = 5) recipients became normoglycemic within 8 days. Removal of the scaffolds or kidney grafts resulted in immediate return to hyperglycemia. Normoglycemia was not achieved with 1200 islets in the unmodified skin group., Conclusions: Our findings demonstrate that the prevascularized poly (D,L-lactide-co-ε-caprolactone) scaffold maintains viability and function of islets in the subcutaneous site.

Objective: To assess the distribution of cerebral white matter lesions in women who had eclampsia, preeclampsia, or normotensive pregnancies. The pathophysiology of these lesions, more often seen in formerly eclamptic and preeclamptic women, is unclear but may be related to a predisposition for vascular disease, the occurrence of the posterior reversible encephalopathy syndrome, or both while pregnant. Assessing the distribution of such lesions may give insight into their pathophysiology and possible consequences., Methods: This retrospective cohort study determined the presence, severity, and location of white matter lesions on cerebral magnetic resonance imaging scans of 64 formerly eclamptic, 74 formerly preeclamptic, and 75 parous control women., Results: Formerly preeclamptic and eclamptic women have white matter lesions more often (34.4% [n=47] compared with 21.3% [n=16]; P<.05) and more severely (0.07 compared with 0.02 mL; P<.05) than parous women in a control group. In all women, the majority of lesions was located in the frontal lobes followed by the parietal, insular, and temporal lobes., Conclusion: White matter lesions are more common in women with prior pregnancies complicated by preeclampsia or eclampsia compared with parous women in a control group. In no group does regional white matter lesion distribution correspond to the occipitoparietal edema distribution seen in posterior reversible encephalopathy syndrome.

Objectives: Human cytomegalovirus (HCMV) infection has been suggested to be a causal factor in the development of type 1 diabetes, posttransplantation diabetes, and the failure of islet allografts. This effect of CMV has been interpreted as an indirect effect on the immune system rather than direct infection-induced cell death. In the present study, we investigated (i) the susceptibility of β cells to HCMV infection, (ii) regulation of immune cell-activating ligands, (iii) release of proinflammatory cytokines, and (iv) the effects on peripheral blood mononuclear cell (PBMC) activation., Methods: CM insulinoma cells and primary β cells were HCMV-infected in vitro using a laboratory and a clinical HCMV strain. The susceptibility to infection was measured by the expression of viral genes and proteins. Furthermore, expression levels of Major Histocompatibility Complex I, Intracellular Adhesion Molecule-1, and Lymphocyte Function Associated Antigen-3 and the release of proinflammatory cytokines were determined. In addition, PBMC activation to HCMV-infected β cells was determined., Results: β Cells were susceptible to HCMV infection. Moreover, the infection increased the cellular immunogenicity, as demonstrated by an increased MHC I and ICAM-1 expression and an increased proinflammatory cytokine release. Human cytomegalovirus-infected CM cells potently activated PBMCs. The infection-induced effects were dependent on both viral "sensing" and viral replication., Conclusions: In vivo β-cell HCMV infection and infection-enhanced cellular immunogenicity may have important consequences for native or transplanted β-cell survival.

Objectives: Cytomegalovirus (CMV) infection has been suggested to accelerate beta-cell destruction and thereby to contribute to new-onset diabetes and failure of islet allografts in both humans and rodents. Surprisingly, direct CMV infection of beta cells has received only minor attention. Therefore, we investigated the susceptibility of rat beta cells for rat CMV (RCMV) infection and the direct effects on the regulation of immune cell-activating ligands., Methods: Primary rat beta cells, the rat beta-cell line Rin-m5F, and fibroblasts were RCMV-infected in vitro. The viral gene and protein expression levels were determined as a measure for RCMV susceptibility. Gene expression levels of intracellular adhesion molecule 1, lymphocyte function associated antigen 3, rat major histocompatibility complex region A, rat major histocompatibility complex region E, toll like receptor 2, and clustered domain 14 were determined as a measure for cellular immunogenicity., Results: We demonstrate that beta cells are susceptible for RCMV infection but allow only low levels of viral gene expression. In contrast, infected fibroblasts demonstrated productive viral infection and formation of viral progeny. After RCMV infection, beta-cell immunogenicity was markedly increased, as demonstrated by the increased cellular expression of immune cell-activating ligands., Conclusions: Direct beta-cell infection by RCMV and subsequent low-grade viral gene expression may lead to increased immunogenicity of native or transplanted beta cells in vivo. An infection-induced enhanced beta-cell recognizability may have important consequences for beta-cell survival and the development of diabetes or rejection of islet grafts.

Yields and function of isolated islets vary considerably in spite of the introduction of new or improved methods for isolation. In most studies, these variations have been attributed to inadequacies of the applied collagenase preparations. However, when we retrospectively analyzed our rat islet isolations, we found large variations in yield and function in spite of application of identical collagenase sources. Therefore, in the present study, we determined the effect of rat donor strain, the source of inhibition of proteolytic activity (by bovine serum albumin), and the culture conditions on yield and function. AO rats showed a twofold higher islet yield than Wistar and Lewis rats. However, a higher yield was not associated with a higher response on glucose load since this response was more pronounced with Lewis islets than with Wistar and AO islets. Rats with a higher weight donate more islets but have a lower insulin secretory capacity. Islet yield and function also vary with application of different sources of bovine serum albumin during digestion. Moreover, the culture conditions influence the functional survival of isolated rat islets. CMRL1066 preserves the insulin secretory capacity of rat islets better than RPMI1640. Finally, the number of islets surviving the culture is higher when 4 instead of 12 and 24 islets were applied per square centimeter. Our observations indicate that strain and weight of the rat donor, the source of bovine serum albumin, and the culture conditions of islets are pertinent factors in efficacious isolation of islets.