Unexpected Immunoresponse to Gal and APA Antigens in Diabetic Type 1 Patients Receiving Neonatal Pig Islets After 6 Years

Cotransplantation of porcine islets and Sertoli cells into preimplanted subcutaneous devices improve metabolic control in type 1 diabetic patients, and survive grafted for more than 4 years. We report here, further assessment of the endocrine and porcine nature of the surviving cells and the immune responses elicited toward Gal α(1,3)-Gal β(1,4)-GlcNAc (Gal) antigen in patients who received a second and third transplants. No immunosuppressive drugs were administered. We were able to immunostain insulin- and glucagon-positive cells in all biopsies of patients and Sertoli cell markers in 60.9% of biopsies. Additionally, all biopsies tested, amplified the porcine COII gene. Patients demonstrated an increase in antipig antibodies in response to the first transplant with a decreasing response toward the second and third transplants. In all transplants, the IgG levels promptly returned to basal values after 3–4 months. The long-term survival of porcine cells and the reduced humoral immune response to multiple transplants indicate a form of tolerance. We have not been able to find CD25-positive cells, indicating that it is probably an immune accommodation of the graft.     

Assessment of the potential risk of infection associated with Clostridium difficile from porcine xenografts

Bakri MM, Sutherland AD, Brown DJ, Vesely P, Crossan C, Scobie L. Assessment of the potential risk of infection associated with Clostridium difficile from porcine xenografts.
Xenotransplantation 2009; 16: 472–476. © 2009 John Wiley & Sons A/S. Abstract: There are numerous concerns over the potential for transfer of pathogens between species during clinical xenotransplantation, and although current clinical application is limited, porcine xenografts have been previously used to treat patients with severe burns. Donor animals providing the xenografts are sourced from a healthy commercial herd, however, as pigs are a known source of zoonotic agents, a number of diseases are required to be excluded from pigs used for xenotransplantation purposes. Many studies have indicated the relevance of viral zoonoses, however, little has been done with regard to the potential for transfer of pathogens related to health care associated infections. Clostridium difficile is a major cause of neonatal enteritis in pigs and an important feature of this organism is that pigs can be asymptomatic carriers. This study has examined the incidence of C. difficile PCR ribotypes present in healthy donor pigs to determine if pig faeces, and in particular, contamination of skin with faecal matter, is a potential route for the transfer of C. difficile. Animals were found to have human ribotype 017 present in the faecal matter, however, no C. difficile was isolated from skin samples taken from the same animals. In addition, due to the risk factors associated with C. difficile infection, the antimicrobial susceptibility of the C. difficile isolates has been determined.     

Role of CD4+ T cells in the rat to mouse cardiac xenotransplantation

Abstract T cell subsets involved in rejection of xenografts were analyzed using a rat to mouse cardiac xenotransplant model. Proliferating response and interleulin-2 (IL-2) production in recipients' spleen cells were almost completely abrogated by elimination of L3T4⁺ T cells, but not by elimination of Lyt2.1⁺ T cells. Cytotoxic T lymphocyte (CTL) activities were mediated by both L3T4⁺ and Lyt2.1⁺ T cells with the help of IL-2-producing L3T4⁺ T cells. Administration of anti-L3T4 monoclonal antibody (mAb) into recipient mice resulted in a significant prolongation of graft survival (mean graft survival was 29.2 days). Moreover, anti-L3T4 mAb treatment plus thymectomy led to indefinite graft survival. Anti-rat endothelial cell (EC) antibody production in the grafted mice was remarkably suppressed by anti-L3T4 mAb treatment. In contrast, Lyt2.1 mAb treatment did not prolong the graft survival and did not suppress anti-EC antibody production. These results indicated the absolute requirement of L3T4⁺ T cells in the rejection of rat to mouse cardiac xenografts.     

Engraftment of NOD/SCID/gammac(null) mice with multilineage neoplastic cells from patients with juvenile myelomonocytic leukaemia

Several lines of evidence indicate the clonal nature of juvenile myelomonocytic leukaemia (JMML), involving myeloid, erythroid, megakaryocyte and B-lymphoid lineages. However, it is unclear whether the T-lymphocyte lineage is involved. We demonstrated that cells from six patients with JMML repopulated in non-obese diabetic/severe combined immunodeficient/gammac(null) mice and differentiated into granulocytes, monocytes, erythrocytes, B lymphocytes, T lymphocytes and natural killer cells. The percentage of human CD45 antigen-positive cells ranged from 41% to 73% in the murine bone marrow 12 weeks after transplantation. To examine the involvement of lymphocyte subpopulations, we purified human CD3(+), CD19(+) and CD56(+) cells from murine bone marrow cells transplanted from a patient with monosomy 7. Fluorescence in situ hybridization (FISH) showed the clonal marker in 96-100% of purified CD3(+), CD19(+) and CD56(+) subpopulations. These findings support the concept that JMML originates in transplantable multilineage haematopoietic stem cells. This novel murine xenotransplant model should be useful for investigating the nature of stem cells and testing new therapies for patients with JMML.     

Human prostate cancer heterotransplants： a review on this experimental model

A common model used for preclinical research was in vitro human tumor cell culture. An alternative model was the direct implantation of a unique patient＇s tumor biopsy specimens into immunodeficient host mice. Published data from PubMed （http：//www.ncbi.nlm.nih.gov） and Current Contents Connect databases （http：//thomsonreuters.com/ products_services/science/science_roducts/a-z/current_contents_connect） were reviewed. Prostate cancer （PCa） heterotransplantation was evaluated using histopathology, morphology, cell differentiation, DNA content, tumor marker expression, metastases, tumor kinetics, tumor take rate and tumor vasculature in the first tumor heterotransplant. The heterotransplanted tumor retained the biological properties of the original tumor, such as morphology, degree of differentiation, pathology, secretory activity, expression of tumor markers and human vasculature. Human PCa heterotransplants have considerable experimental advantages over cell culture following xenotransplantation.     

前列腺的小细胞神经内分泌癌：异种移植是一个更好的实验模型吗？

前列腺小细胞神经内分泌癌（SCNCP）是一种罕见的前列腺癌,临床恶性程度高,预后差,对其研究在临床上具有重大意义。目前,研究SCNCP的方法有人工肿瘤细胞系培养法,还有将从患者身上直接获得的新鲜肿瘤组织切片植入免疫缺陷宿主小鼠体内的方法。本综述的目的是整合20多年在前列腺小细胞神经内分泌癌的异种移植的研究数据。异种移植提供的有关数据包括组织病理学、核型、DNA含量、细胞周期频率、肿瘤标志物、雄激素受体表达、转移和成功率。我们尽可能的比较了患者体内获得的原始原位切片和宿主小鼠异种移植组织,发现小细胞神经内分泌前列腺癌异种移植与培养细胞异源移植相比各有千秋。总体而言,肿瘤异种移植均优于传统的异源移植,主要表现在保持肿瘤形态、病理、分泌活动和病人原始样本肿瘤标记物的表达等方面。此外,异种移植组织保留了前列腺肿瘤的三维结构,以保持其关键的基质上皮细胞相互作用。     

CTLA-4Ig in Combination with Anti-CD40L Prolongs Xenograft Survival and Inhibits Anti-Gal Ab Production in GT-Ko Mice

The generation of GT-Ko mice has provided unique opportunities to study allograft and xenograft rejection in the context of anti-alpha1,3-Gal antibody (anti-Gal Ab) responses. In this study we used the allotransplantation model of C3H hearts into galactosyltransferase-deficient (GT-Ko) mice and the xenotransplantation model of baby Lewis rat hearts into GT-Ko mice to investigate the ability of CTLA-41g in combination with anti-CD40L mAb to control graft rejection and anti-Gal Ab production. Murine CTLA-41g or anti-CD40L monotherapy prolonged allograft survival, and the combination of these reagents was most immunosuppressive. However short-term treatment with murine cytotoxic T lymphocyte associated antigen-4 (muCTLA-41g) and/or CD40 ligand (CD154) monoclonal antibodies (anti-CD40L mAbs) was unable to induce indefinite allograft survival. CTLA-4-immunoglobulin fusion protein (CTLA-41g) or anti-CD40L monotherapy only marginally prolonged xenograft survival; the combination of human CTLA-41g and anti-CD40L significantly prolonged xenograft survival (74days), while the combination of murine CTLA-41g and anti-CD40L resulted in graft survival of >120days. CTLA-41g or anti-CD40L monotherapy or the combination of these agents inhibited the production of alloAbs, including anti-Gal Abs. CTLA-41g or anti-CD40L monotherapy partially controlled xenoAb and anti-Gal Ab production, while the combination was more effective. These observations corroborate our previous observations that humoral, including anti-Gal Ab, responses and rejection following allograft or concordant xenograft transplantation in GT-Ko mice are T-cell dependent and can be controlled by costimulation blockade.     

骨髓增生异常综合征小鼠模型研究进展

骨髓增生异常综合征(MDS)是一组造血干、祖细胞发生突变造成以外周血细胞减少、骨髓病态造血为特征的恶性血液病。近年来,为了建立确切的MDS小鼠模型来研究该病,全世界的研究者们做了大量的努力。建立MDS小鼠模型大致可以归纳为3种途径:转致病基因、异种移植人MDS细胞、基因工程改造小鼠的造血细胞。本综述描述几种MDS小鼠模型,以阐述恶性克隆造成的致病机制和骨髓微环境的改变,同时,阐述异种移植人MDS细胞小鼠模型的进展和尚待解决的问题。     

Acute myeloid leukemia does not deplete normal hematopoietic stem cells but induces cytopenias by impeding their differentiation

Acute myeloid leukemia (AML) induces bone marrow (BM) failure in patients, predisposing them to life-threatening infections and bleeding. The mechanism by which AML mediates this complication is unknown but one widely accepted explanation is that AML depletes the BM of hematopoietic stem cells (HSCs) through displacement. We sought to investigate how AML affects hematopoiesis by quantifying residual normal hematopoietic subpopulations in the BM of immunodeficient mice transplanted with human AML cells with a range of genetic lesions. The numbers of normal mouse HSCs were preserved whereas normal progenitors and other downstream hematopoietic cells were reduced following transplantation of primary AMLs, findings consistent with a differentiation block at the HSC–progenitor transition, rather than displacement. Once removed from the leukemic environment, residual normal hematopoietic cells differentiated normally and outcompeted steady-state hematopoietic cells, indicating that this effect is reversible. We confirmed the clinical significance of this by ex vivo analysis of normal hematopoietic subpopulations from BM of 16 patients with AML. This analysis demonstrated that the numbers of normal CD34⁺CD38⁻ stem-progenitor cells were similar in the BM of AML patients and controls, whereas normal CD34⁺CD38⁺ progenitors were reduced. Residual normal CD34⁺ cells from patients with AML were enriched in long-term culture, initiating cells and repopulating cells compared with controls. In conclusion the data do not support the idea that BM failure in AML is due to HSC depletion. Rather, AML inhibits production of downstream hematopoietic cells by impeding differentiation at the HSC–progenitor transition.