免疫隔离大鼠胰岛移植治疗小鼠药物性糖尿病的研究

目的　探讨免疫隔离的胰岛异种移植治疗小鼠药物性糖尿病的可行性。方法　新生 Wistar大鼠胰岛分离后包裹在由 THF制成的免疫隔离室内 ,移植给药物诱导的 Balb/ c糖尿病小鼠。移植后不使用免疫抑制剂 ,观察血糖变化情况。结果　免疫隔离及非隔离的胰岛均显示了良好的对葡萄糖加茶碱刺激的反应能力 ,胰岛素的释放量在 2组间无明显差异。移植后免疫隔离胰岛移植组血糖在 3d内降至正常 ,平均维持正常血糖 (72 .8± 3.1) d,多饮、多尿现象明显改善。单纯胰岛移植组血糖降低后仅维持平均 (8.1± 0 .5 ) d。对照组小鼠则持续高血糖状态。组织学检查示免疫隔离室外形成厚度不一的纤维化反应层 ,隔离室内大部分胰岛坏死 ,部分可见残存的胰岛。结论　免疫隔离胰岛异种移植能有效延长移植物的存活 ;隔离室外的纤维化反应是造成移植物丧失功能的主要原因     

Postmortem Brain: An Underutilized Substrate for Studying Severe Mental Illness

We propose that postmortem tissue is an underutilized substrate that may be used to translate genetic and/or preclinical studies, particularly for neuropsychiatric illnesses with complex etiologies. Postmortem brain tissues from subjects with schizophrenia have been extensively studied, and thus serve as a useful vehicle for illustrating the challenges associated with this biological substrate. Schizophrenia is likely caused by a combination of genetic risk and environmental factors that combine to create a disease phenotype that is typically not apparent until late adolescence. The complexity of this illness creates challenges for hypothesis testing aimed at understanding the pathophysiology of the illness, as postmortem brain tissues collected from individuals with schizophrenia reflect neuroplastic changes from a lifetime of severe mental illness, as well as treatment with antipsychotic medications. While there are significant challenges with studying postmortem brain, such as the postmortem interval, it confers a translational element that is difficult to recapitulate in animal models. On the other hand, data derived from animal models typically provide specific mechanistic and behavioral measures that cannot be generated using human subjects. Convergence of these two approaches has led to important insights for understanding molecular deficits and their causes in this illness. In this review, we discuss the problem of schizophrenia, review the common challenges related to postmortem studies, discuss the application of biochemical approaches to this substrate, and present examples of postmortem schizophrenia studies that illustrate the role of the postmortem approach for generating important new leads for understanding the pathophysiology of severe mental illness.     

Strategies for immunoisolation in islet transplantation: challenges for the twenty-first century

A number of investigations have pursued the feasibility of a bioartificial endocrine pancreas (Bio-AEP) in which pancreatic endocrine cells (PE-cells) are encapsulated within a semipermeable membrane to protect them from immunological rejection. The goal of PE-cell transplantation in human diabetes is to maintain the PE-cell graft in the recipient without the use of immunosuppression. One approach is to encapsulate the donor PE-cells in a semipermeable membrane. A type of diffusion chamber for a Bio-AEP is described. The system is based on a chamber designed to improve the diffusion of insulin secretion in response to glucose transfer across a membrane. An implantable diffusion chamber for the Bio-AEP was constructed by placing PE-cells in agarose, containing nicotinamide and a sugar-chain coated polymer, in a ring holder which was sandwiched between two nucleopore membranes (pore size 0.1 μm), for transplantation into diabetic animals. This compatible diffusion chamber prevented rejection, and maintained normoglycemia in diabetic rats when implanted intraperitoneally.     

Chitosan/gelatin hydrogel as immunoisolative matrix for injectable bioartificial pancreas

Abstract: Background: The feasibility of using chitosan/gelatin hydrogel as immunoisolative matrix to provide an additional protection to the microencapsulated islet cells was demonstrated in this study. We hope that the use of hydrogel can extend the functional longevity of microencapsulated islet cells during xenotransplantation. Methods: Chitosan/gelatin solution with glycerol 2‐phosphate disodium salt hydrate was prepared and utilized as a cell carrier. The biocompatibility of the chitosan/gelatin hydrogel was first established by using a mouse insulinoma cell line, NIT‐1. Insulinoma cells were encapsulated in agarose as microspheres and then macroencapsulated in chitosan/gelatin hydrogel. In vitro cell activity, material‐mediated cytotoxicity, cytokine‐mediated cytotoxicity assay, and insulin secreting profiles of insulinoma/agarose microspheres macroencapsulated in chitosan/gelatin hydrogel were analyzed. For in vivo study, insulinoma/agarose microspheres with chitosan/gelatin solution was applied as an injectable bioartificial pancreas (BAPs). Insulinoma/agarose microspheres suspended in phosphate‐buffered saline or in chitosan/gelatin solution was injected into the subcutaneous layer of diabetic rats. Non‐fasting blood glucose (NFBG) concentration of rat was measured perioperatively. After pre‐determined intervals, the chitosan/gelatin hydrogel containing insulinoma/agarose microspheres was retrieved for histologic examinations. Results: Insulinoma/agarose microspheres macroencapsulated in hydrogel revealed functional activity and secreted insulin continually for 60 days in vitro. Chitosan/gelatin hydrogel was not cytotoxic to islet cells, and in contrast, the hydrogel showed cytoprotective effects against cytokine‐mediated cytotoxicity. The NFBG of diabetic rats transplanted with free insulinoma/agarose microspheres was decreased to euglycemia but restored to hyperglycemia in 15 days. Contrarily, the NFBG of rats transplanted with insulinoma/agarose microspheres with hydrogel remained euglycemic for 42 days. Histologic sections revealed that the fibrous tissue envelopment and the infiltrated immune‐related cells contributed to the dysfunction of BAPs. Conclusions: This study indicates that using chitosan/gelatin hydrogel as a cell carrier is feasible and can provide an additional protection for the microencapsulated islet cells during xenotransplantation.     

用非同位素法测定抗细胞性单抗靶抗原分子量

本文报告了一种敏感、简单、重复性好、成功率高的非放射性同位素法测定抗细菌性单抗的靶抗原的分子量的技术。此法综合了生物素标记细胞表面抗原、固相免疫分离法、ＳＤＳ－ＰＡＧＥ、免疫印染法和增强的化学发光检测系统等优点，并成功测定了一组抗Ｅｗｉｎｇ氏肉瘤等单克 隆抗体相应的细胞表面靶分子的分子量。     

The influence of intraperitoneal transplantation of free and encapsulated Langerhans islets on the second set phenomenon

To protect the allografts or xenografts against transplant rejection special semipermeable membranes are applied. So far, there are only a few studies on the influence of an immunoisolated graft on the recipient immune system. Therefore, the possibility that an intraperitoneally grafted alginate/poly L-lysine/alginate (APA) coated pancreatic islets graft can effectively sensitize the recipient and provoke second set phenomenon was studied. C3H male mice and male WAG rats were used as donors of full-thickness skin and of free or encapsulated islet intraperitoneal grafts. Male BALB/c mice served as recipients. Skin grafts were performed following the method of Billingham and Medawar. The length of the second skin graft survival time served as the criterion for the sensitizing capacity of the primary graft. APA encapsulation of islets delayed but has not prevented the development of the second set phenomenon. However, the second skin graft rejection time was significantly longer after grafting of encapsulated islets than after free islets transplantation. APA microencapsulation of intraperitoneally transplanted islets delayed but did not prevent the development of the second set phenomenon. Encapsulation does not ensure complete immunoisolation, but only creates "an artificially immunoprivileged site of transplantation."     

Somatic gene therapy for a neurodegenerative disease using microencapsulated recombinant cells

Neurodegenerative diseases caused by lysosomal enzyme deficiencies are catastrophic illnesses with both peripheral organ and central nervous system abnormalities. The mucopolysaccharidosis type VII mouse with beta-glucuronidase deficiency was used to develop an alternate approach to gene therapy, in which a "universal" cell line engineered to secrete the missing enzyme is implanted directly into all recipients requiring the same enzyme replacement. The cells, though nonautologous, were rendered immunologically tolerable by protection in immunoisolating microcapsules. Since the blood-brain barrier impedes the passage of large molecules such as beta-glucuronidase, encapsulated cells producing beta-glucuronidase were introduced directly into the lateral ventricles of the brain. Based on this strategy, beta-glucuronidase was delivered throughout most of the central nervous system, reversing the histological pathology and reducing the previously elevated levels of lysosomal enzymes beta-hexosaminidase and alpha-galactosidase. The effectiveness of this approach was further demonstrated with improvements in the mutant circadian rhythm behavioral abnormalities. Compared to wild-type and heterozygous mice, the mutant mice had an unstable periodicity, fragmented activity, and a sixfold reduction in wheel running activity. After treatment, the mutant behavioral abnormalities were significantly improved with a more stable periodicity and a less fragmented pattern of activity. While the overall total activity level did not increase in the treated mutants, it did not show the deterioration observed in the sham-treated as well as in the untreated mutant mice. Hence, this alternative cell-based gene therapy demonstrates biochemical, histological, and behavioral efficacy and provides a potentially cost-effective and nonviral treatment applicable to all lysosomal storage diseases with neurological deficits.     

海藻酸钠-多聚赖氨酸-海藻酸钠微囊化胰岛细胞移植治疗糖尿病的实验研究

采用Ｓｕｎ海藻酸钠－多聚赖氨酸－海藻酸钠（ＡＰＡ）微囊制作技术,分别包裹大鼠胰岛和胰岛素分泌细胞系,移植于糖尿病小鼠腹腔。结果表明ＡＰＡ微囊化大鼠胰岛或胰岛素分泌细胞移植,均可使糖尿病小鼠血糖降低至接近正常水平达３周至１１０天;移植微囊无明显的组织学反应。证明该ＡＰＡ微囊化胰岛细胞移植具有较好的治疗效果,微囊具有较好的生物相容性和免疫隔离作用。为进一步发展生物型人工胰岛奠定了基础。