Pathology of Aging in NOD scid gamma Female Mice.

In the past decade, NOD.Cg- Prkdcscid Il2rgtm1Wjl/SzJ (NSG, NOD scid gamma) mice have become a model of choice in several areas of biomedical research; however, comprehensive data on their spontaneous age-related pathology are not currently available in the literature. The prevalence of spontaneous morbidity affecting aged NSG female breeders enrolled in a parasitology study was documented with classification of neoplastic and non-neoplastic (inflammatory, metabolic, degenerative) lesions. Malignant mammary neoplasms were most commonly diagnosed, often accompanied by pulmonary metastases, while a low frequency of lymphoma and histiocytic sarcoma was documented. The major inflammatory conditions were suppurative pleuropneumonia and bronchopneumonia with abscess formation, from which Pasteurella pneumotropica was commonly isolated, followed by otitis media. Both inflammatory and degenerative lesions of the genital tract were identified, along with neoplasms such as endometrial yolk sac carcinomas and granulosa cell tumors. Novel conditions identified included renal tubular degeneration and necrosis associated with 2 concurrent types of intranuclear inclusions, focal or multifocal hyperostosis of the skull, and neuroendocrine tumors of the mesometrium. The majority of degenerative lesions that affected the genital tract, endocrine, and skeletal systems did not represent the actual underlying cause of death but rather were considered incidental findings. This study indicates that both inflammatory and neoplastic conditions contribute to morbidity and mortality in experimentally manipulated aged female NSG mice.

Stevens-Johnson syndrome/toxic epidermal necrolysis mouse model generated by using PBMCs and the skin of patients.

BACKGROUND: Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening cutaneous reactions caused by drugs or infections and exhibiting widespread epidermal necrosis. Currently, there is no animal model that reproduces SJS/TEN symptoms. OBJECTIVE: We sought to develop a novel mouse model of SJS/TEN by using PBMCs and skin from patients who had recovered from SJS/TEN. METHODS: For our mouse model, patients' PBMCs were injected intravenously into immunocompromised NOD/Shi-scid, IL-2Rγ(null) (NOG) mice, followed by oral administration of a causative drug. Subsequently, to replace human skin, unaffected skin specimens obtained from patients who had recovered from SJS/TEN were grafted onto NOG mice, after which patient-derived PBMCs and the causative drug were applied. RESULTS: Mice injected with PBMCs from patients with SJS/TEN and given the causative drug showed marked conjunctival congestion and numerous cell death of conjunctival epithelium, whereas there were no symptoms in mice injected with PBMCs from patients with ordinary drug skin reactions. CD8(+) T lymphocyte-depleted PBMCs from patients with SJS/TEN did not elicit these symptoms. In addition, skin-grafted mice showed darkening of the skin-grafted areas. Cleaved caspase-3 staining showed that dead keratinocytes were more numerous in the skin-grafted mice than in the healthy control animals. CONCLUSION: We have established a novel human-oriented SJS/TEN mouse model and proved the importance of CD8(+) T lymphocytes in SJS/TEN pathogenesis. The mouse model promises to promote diagnostic and therapeutic approaches.

Comparison of different fabrication techniques for human adipose tissue engineering in severe combined immunodeficient mice.

Adipose tissue engineering has been advocated for soft-tissue augmentation and for the treatment of soft tissue defects. The efficacy in terms of persistence of the engineered fat is, however, not yet understood and could depend on the nature of fabrication and application. The high metabolic demand of adipose tissue also points to the problem of vascularization. Endothelial cell (EC) cotransplantation could be a solution. Human adipose tissue-derived stromal cells were seeded on collagen microcarriers and submitted to adipogenic differentiation ("microparticles"). In a first run of experiments, these microparticles were implanted under the skin of severe combined immunodeficient (SCID) mice (n = 45) with and without the addition of human umbilical vein ECs (HUVECs). A group of carriers without any cells served as control. In a second run, adipose tissue constructs were fabricated by embedding microparticles in fibrin matrix with and without the addition of HUVEC, and were also implanted in SCID mice (n = 30). The mice were sacrificed after 12 days, 4 weeks, and 4 months. Mature adipose tissue, fibrous tissue, and acellular regions were quantified on whole-specimen histological sections. The implantation of microparticles showed a better sustainment of tissue volume and a higher degree of mature adipose tissue compared with adipose tissue constructs. Immunohistology proved obviously perfused human tissue-engineered vessels. There was a limited but not significant advantage in EC cotransplantation after 4 weeks in terms of tissue volume. In groups with EC cotransplantation, there were significantly fewer acellular/necrotic areas after 4 weeks and 4 months. In conclusion, the size of the implanted tissue equivalents is a crucial parameter, affecting volume maintenance and the gain of mature adipose tissue. EC cotransplantation leads to functional stable vascular networks connecting in part to the host vasculature and contributing to tissue perfusion; however, the long-term benefit depends on additional basic conditions that need further research.

Comparison of biological features between severely immuno-deficient NOD/Shi-scid Il2rgnull and NOD/LtSz-scid Il2rgnull mice.

Biological background data up to 11 weeks of age and tumorigenic susceptibility to xenotransplantation with HeLa cells were compared between severely immuno-deficient NOG and NSG mice. The body weight was lower in NOG mice than in NSG mice. Severe depletion of peripheral blood lymphocytes and lymphoid hypoplasia that are well-known characteristics of these mice were equally observed. No lymphoproliferative lesions developed in any mouse of either strain. The occurrence of ectopic exocrine gland and cyst was a common finding in the thymus of both strains. In addition, minimal spongiotic change was observed in the medulla oblongata and spinal cord in both strains, and its incidence in female NOG mice was a little higher than that in NSG mice. In the adrenal, subcapsular cell hyperplasia that is known as an age-related change in non-genetically modified mice developed earlier and its incidence was higher in NSG mice than in NOG mice. The development of female genital organs of NOG mice was slightly retarded in comparison with that of NSG mice. To evaluate tumorigenic susceptibility to xenotransplantation, female mice were implanted in the dorsal subcutis with 1×103 to 1×106 cells/head of HeLa cells, and were checked up to 16 weeks after implantation. As a result, there was no significant strain difference on tumor formation rate and tumor volume. In conclusion, the present study clearly demonstrated that NOG and NSG mice showed no distinct strain differences in either biological features or biological disadvantages.

Humanized Mice Are Instrumental to the Study of Plasmodium falciparum Infection.

Research using humanized mice has advanced our knowledge and understanding of human haematopoiesis, non-adaptive and adaptive immunity, autoimmunity, infectious disease, cancer biology, and regenerative medicine. Challenges posed by the human-malaria parasite Plasmodium falciparum include its complex life cycle, the evolution of drug resistance against anti-malarials, poor diagnosis, and a lack of effective vaccines. Advancements in genetically engineered and immunodeficient mouse strains, have allowed for studies of the asexual blood stage, exoerythrocytic stage and the transition from liver-to-blood stage infection, in a single vertebrate host. This review discusses the process of "humanization" of various immunodeficient/transgenic strains and their contribution to translational biomedical research. Our work reviews the strategies employed to overcome the remaining-limitations of the developed human-mouse chimera(s).

Human hematolymphoid cells in SCID mice.

The severe combined immunodeficient C.B.-17 scid/scid (SCID) mouse has been widely used to study the normal processes of murine lymphoid differentiation. To create an in vivo model of the human hematolymphoid system, this mouse strain has been engrafted with human organ systems (the SCID-hu mouse) or with human peripheral blood mononuclear cells (the hu-PBL-SCID mouse). These mouse models have now been characterized and used to analyze human infectious diseases, hematopoiesis, malignancies and vaccines.

Background data on NOD/Shi-scid IL-2Rγnull mice (NOG mice).

To obtain background data of NOD/Shi-scid IL-2Rγnull (NOG) mice, severely immunedeficient mice, a total of 120 animals were examined at 7, 26 and 52 weeks-old (20 mice/sex/group). The survival rate at 52 weeks-old was 95% (19/20) in both sexes. Clinically, circling behavior in one direction along the cage wall was observed in males after 8 weeks and females after 47 weeks-old, and hunchback position was found in males after 32 weeks-old. Hematologically, lymphocyte count markedly decreased at all ages, while white blood cell count increased in several mice at 52 weeks-old. Blood chemistry results revealed high values of aspartate aminotransferase, lactate dehydrogenase and creatine phosphokinase in some females at 26 weeks-old, without any related histological change. Histologically, lymphoid hypoplasia characterized by severe lymphocyte depletion with poorly developed tissue architectures was observed. In addition, spongiotic change in the nerve tissue was observed in both sexes at 7 and 26 weeks-old, and intracytoplasmic materials known as tubular aggregates in the skeletal muscles were found in males terminated at 26 and 52 weeks-old and in females at 52 weeks-old. Malignant lymphoma was found in one female euthanized at 20 weeks-old. Further, small intestinal adenoma, hepatocellular adenoma, leukemia, cerebral lipomatous hamartoma, Harderian gland adenoma and uterine polyp were also observed, and their incidences were low except for that of uterine polyp. This study provided detailed background data on NOG mice up to 52 weeks-old and provided information on appropriate use of NOG mice in the various research fields.

Impact of stromal sensitivity on radiation response of tumors.

BACKGROUND: Irradiation of tumors causes the death of both parenchymal tumor cells as well as normal tissue stromal cells (e.g., endothelium, connective tissue). However, it has been difficult to distinguish the contributions to overall tumor response after irradiation from the two compartments. The development of the severe combined immunodeficient (SCID) mouse provides a model in which the contribution of stromal cell responses to ionizing radiation to overall tumor response can be defined, because its normal tissue cells are extremely radiosensitive. Therefore, the results of irradiation of tumors in radiation-sensitive (SCID) and radiation-resistant hosts can be compared, and the contribution of the normal tissue stroma clarified. PURPOSE: Our purpose was to investigate the effects of radiation-induced stromal cell damage on tumor cell death, using tumor growth delay (GD) and local control (complete and permanent regression of the irradiated tumor) as end points. METHODS: Tumor GD and local control experiments were performed in SCID, athymic, and C3H mice. Sixty SCID and 60 nude mice for each of three human tumor cell lines (HGL9, HSTS26, HCT15) and for each of five murine cell lines (FSC1, FSC2, FSM1, FSM2, E01) and 60 SCID and 60 C3H mice for the FSa2 spontaneous C3H sarcoma were studied. Neoplasms were produced by injection of 10(6) cells from in vitro tissue cultures into the flanks of donor mice; after tumors had grown, experimental neoplasms were produced by transplanting 2- to 3-mm fragments into recipient mice. Animals were randomly assigned to various groups when tumors reached average volumes of 120 mm3. Graded, single-dose x irradiations (15-115 Gy, dose rate about 7 Gy/min) were given under acutely hypoxic conditions. Tumors were scored one to two times per week until recurrence. RESULTS: The x-ray doses needed to achieve local control in 50% of the animals (tumor control doses, TCD50) ranged from 45.1 to 58.0 Gy for human tumors and from 36.3 to 114.0 Gy for murine tumors. On average, the TCD50 values in SCID mice were only about 3.5% lower than values in nude or C3H mice. The amount of GD defined at 66% of the TCD50 for the various groups was, however, 27% longer in the SCID mice (P = .004). CONCLUSIONS: While the three-fold higher radiation sensitivity of the normal tissue stromal cells in the SCID mice did not alter the percentage of tumors controlled by x irradiation in the SCID mouse hosts as compared with other hosts, there appear to be significant differences in GD. Radiation-induced stromal cell damage does not significantly contribute to tumor cell death; however, it can prolong the interval of tumor regression.

Tumors arising in SCID mice share enhanced radiation sensitivity of SCID normal tissues.

We addressed the question of whether cancers arising in an abnormally radiation sensitive normal tissue are also abnormally sensitive to ionizing irradiation. Germ line mutation-carrying mice with an enhanced radiation sensitivity of the normal tissue, the severe combined immunodeficient (SCID), and normally radiation sensitive mice (C3H) were used to study the sensitivity of normal and tumor tissues in vivo and in vitro. The lethal dose for 50% of the irradiated animals after single dose whole body irradiation was 2.6-fold higher in C3H compared to SCID mice. The dose for an isoeffective acute skin reaction after single dose irradiation was end point dependent 1.7 to 3.7 times higher in C3H than in SCID mice. Embryonic fibroblast and methylcholanthrene induced soft tissue sarcomas derived from C3H and SCID mice were established in vitro and colony-forming assays after single dose irradiation were carried out. Choosing mean inactivation dose as the end point, SCID fibroblast lines were 3.0-fold and SCID tumor cell lines 2.7-fold more radiation sensitive than C3H fibroblast lines and C3H tumor cell lines. Tumor control and growth delay assays for 110-mm3 tumors were used to compare the radiation sensitivity of SCID and C3H tumors in vivo. The doses for 50% local tumor control and a growth delay of 40 days were 2.6 times higher in C3H tumors compared to SCID tumors. Tumors arising in an abnormally radiation sensitive normal tissue are also sensitive to irradiation. The difference in radiation sensitivity of normal tissues predicted the difference in tumor tissues in these two murine systems.

Absolute requirement of macrophages for the development and activation of beta-cell cytotoxic CD8+ T-cells in T-cell receptor transgenic NOD mice.

The development of autoimmune diabetes in NOD mice results from selective destruction of beta-cells by a T-cell-dependent autoimmune process. However, the mechanisms that control the generation of beta-cell cytotoxic T-cells in vivo are poorly understood. We recently established 8.3-T-cell receptor (TCR)-beta transgenic NOD mice that show a selective acceleration of the recruitment of CD8+ T-cells into the islets of prediabetic animals, resulting in rapid beta-cell destruction and early onset of diabetes. This study was initiated to determine the role of macrophages in the development and activation of diabetogenic CD8+ T-cells in 8.3-TCR-beta transgenic NOD mice. Inactivation of macrophages in these transgenic mice resulted in the complete prevention of diabetes. When splenic T-cells from macrophage-depleted 8.3-TCR-beta transgenic NOD mice were transfused into severe combined immunodeficiency disease (NOD.scid) mice, none of the recipients developed diabetes up to 10 weeks after transfer, while most of the recipients of T-cells from age-matched control 8.3-TCR-beta transgenic NOD mice became diabetic. When intact NOD islets were transplanted under the renal capsule of macrophage-depleted 8.3-TCR-beta transgenic NOD mice, the majority of the grafted islets remained intact, while most of the islets grafted into age-matched, control 8.3-TCR-beta transgenic NOD mice were destroyed within 3 weeks after transplantation. The depletion of macrophages in these mice resulted in a decrease in the Th1 immune response along with an increase in the Th2 immune response because of significant decreases in the expression of macrophage-derived cytokines, particularly interleukin-12, and a decrease in beta-cell-specific T-cell activation, as shown by significant decreases in the expression of Fas ligand (FasL), CD40 ligand (CD40L), and perforin, as compared with control mice. We conclude that macrophages are absolutely required for the development and activation of beta-cell cytotoxic CD8+ T-cells in 8.3-TCR-beta transgenic NOD mice.

Primary tumour growth in an orthotopic osteosarcoma mouse model is not influenced by analgesic treatment with buprenorphine and meloxicam.

Little is known about the treatment of bone pain in animal models of bone cancer. In the present study, the orthotopic 143-B human osteosarcoma xenotransplantation model was used to address the following questions: (1) Can repetitive analgesic treatment extend the experimental period by prolonging the time to reach humane endpoints and (2) Does repetitive analgesic treatment affect bone tumour development and metastasis? The analgesics, buprenorphine and meloxicam, were either applied individually or in combination at 12 h intervals as soon as the animals began to avoid using the tumour cell injected leg. While control mice treated with NaCl showed continuous body weight loss, the major criterion previously for terminating the experiments, animals treated with analgesic substances did not. The control mice had to be sacrificed 26 days after tumour cell injection, whereas the groups of animals with the different pain treatments were euthanized after an additional eight days. Importantly, primary intratibial tumour growth was not affected in any of the experimental groups by any of the pain treatment procedures. Between days 26 and 34 after tumour cell injection an increase of about 100% of the number of lung metastases was found for the groups treated with buprenorphine alone or together with meloxicam, but not for the group treated with meloxicam alone. In summary, the results indicated that both buprenorphine and meloxicam are suitable analgesics for prolonging the experimental periods in an experimental intratibial osteosarcoma mouse model.

Skin as a potential organ for ectopic monoclonal antibody production.

The therapeutic potential of monoclonal antibodies for treating a variety of severe or life-threatening diseases is high. Although intravenous infusion appears the simplest and most obvious mode of administration, it is not applicable to many long-term treatments. It might be advantageously replaced by gene/cell therapies, however, rendering treatments cost-effective and eliminating the short- and long-term side-effects associated with injection of massive doses of antibodies. We have tested whether skin can potentially be used as an organ for production and systemic delivery of ectopic antibodies. Normal human primary keratinocytes were shown to be capable of synthesis and secretion of a model monoclonal antibody directed against human thyroglobulin upon retroviral gene transduction in vitro. Neo- epidermis reconstructed in vitro, either in cell culture inserts or on dermal substrates, from such modified keratinocytes also produced the monoclonal antibody. Interestingly, the latter could cross the epidermis basal layer and be released in culture fluids. Finally, grafting of epidermis reconstituted in vitro on dermal substrates to SCID mice permitted sustained monoclonal antibody delivery into the bloodstream to be achieved. Our data thus show that genetically engineered keratinocytes can potentially be used for genetic antibody-based immunotherapies. They also indicate that proteins as big as 150 kDa, after release by engineered keratinocytes into skin intercellular spaces, can migrate to the general circulation, which is potentially important for a number of other gene-based therapies.

Recessive dystrophic epidermolysis bullosa phenotype is preserved in xenografts using SCID mice: development of an experimental in vivo model.

Recessive dystrophic epidermolysis bullosa (RDEB) is a subgroup of hereditary blistering diseases characterized by repetitive wounding and healing with subsequent extensive scarring. The purpose of this study was to establish a xenograft model that retains the RDEB phenotype and thus might be used as an experimental in vivo model to explore the molecular and biochemical mechanisms of the chronically wounded phenotype of RDEB. Full-thickness, tumor-free RDEB skin tissues were grafted onto the dorsum of severe combined immunodeficiency (SCID) mice. At 4, 8, 12, and 24 weeks after grafting, the xenografts were removed for examination. Immunofluorescence studies were performed using species-specific antibodies to human class I antigen, mouse class I antigen, human type IV and VII collagens and with cross-reacting antibody against bullous pemphigoid antigen (BPA). Staining with the antibody to human class I antigen, W6/32, and with the antibody to mouse class I antigen, 20.8.4s, confirmed the species-specific results obtained with the type IV and type VII collagen and laminin antibodies. The RDEB grafts showed essentially no staining with the type VII collagen antibody. Antibodies against laminin and BPA showed normal staining patterns in RDEB grafts. There was an overall paucity of anchoring fibrils in the grafts when examined with electron microscopy. Blisters could be induced in these grafts with minor trauma and showed a sublamina densa separation by immunomapping and electron microscopy. As late as 24 weeks post-transplantation, the RDEB grafts remain human, are not significantly replaced by mouse cells, and retain the RDEB disease phenotype.

Histologic and cell kinetic studies of hair loss and subsequent recovery process of human scalp hair follicles grafted onto severe combined immunodeficient mice.

To establish a model for studying human scalp hair, individually isolated hair follicles were grafted onto back skin of severe combined immunodeficient mice. Histologic changes and cell kinetics in the hair loss and subsequent recovery process were investigated. In the dystrophic stage (from day 7 to 30), all the hair shafts became dystrophic and were shed. Thickening and corrugation of vitreous membrane, apoptosis, and regression of the lower part were observed in the grafted hair follicles. 5-bromo-2'-deoxy-uridine-labeled cells were not detected in the lower end of the follicles, and keratin 19-positive cells appeared there. At the end of this stage their lower part was maximally retracted, secondary germ remained beneath the bulge, and the vitreous membrane disappeared. In the regeneration stage (from day 30 to 50), the same histologic findings as those at the end of the dystrophic stage were observed. The keratin 19-positive cells in the secondary germ, however, were replaced with keratin 19-negative and 5-bromo-2'-deoxy-uridine-labeled cells. Then, differentiation into an inner root sheath and a hair shaft began, and apoptosis was terminated. In the stable growth stage (from day 40 to at least 150), the grafted follicles were immunohistochemically and light microscopically identical with the normal anagen hair follicles except for the presence of melanin incontinence. These findings suggest that the grafted hair follicles entered into dystrophic catagen, subsequently dystrophic telogen, then returned to normal anagen follicles, and that stem cells or their close progeny in the secondary germ play an important part in the recovery process.

Bcl-2 antisense oligonucleotides (G3139) inhibit Merkel cell carcinoma growth in SCID mice.

Merkel cell carcinoma was first described in 1972 by Toker and is an aggressive neuroendocrine skin tumor with a high metastatic potential. Merkel cell carcinoma is thought to derive from the neuroendocrine (Merkel) cells of the skin, although in contrast to fetal and especially adult Merkel cells, Merkel cell carcinomas express high levels of the Bcl-2 oncoprotein. Bcl-2 is capable of blocking programmed cell death and has been shown to play an important role in normal cell turnover, tumor biology, and chemoresistance. High Bcl-2 expression leading to prolonged survival of cells may therefore be of importance in the biological and clinical characteristics of Merkel cell carcinoma. In a SCID mouse xenotransplantation model for human Merkel cell carcinoma, we investigated the influence of the bcl-2 antisense oligonucleotide G3139 (Genta) on tumor growth in comparison with control oligonucleotides or cisplatin. Bcl-2 antisense treatment, targeting the first six codons of the bcl-2 mRNA, resulted in either a dramatic reduction of tumor growth or complete remission, whereas reverse sequence and two-base mismatch control oligonucleotides or cisplatin had no significant antitumor effects compared with saline-treated controls. Apoptosis was enhanced 2.4-fold in the bcl-2 antisense treated tumors compared with the saline-treated group, and no other treatment showed a comparable increase in apoptosis. Our findings suggest that bcl-2 antisense treatment may be a novel approach to improve treatment outcome of human Merkel cell carcinoma.

Preservation of functioning human thyroid "organoids" in the scid mouse. IV. In vivo selection of an intrathyroidal T cell receptor repertoire.

To study the in vivo influence of thyroid cells on the T cell receptor repertoire in human autoimmune thyroid disease, we mixed lymphocyte-free thyrocytes (approximately 1.2 x 10[6]) from patients with Graves' disease with autologous peripheral blood mononuclear cells (PBMC; approximately 1.5 x 10[6]) and transplanted this mixture sc into scid mice while suspended in a basement membrane gel (approximately 0.4 ml). Controls included mice that received either thyrocytes only or PBMC only. The resulting artificial mixed cell thyroid organoids were explanted after 5 weeks, and their T cell receptor repertoire was examined. Of a total of 63 organoids constructed, 60 were recovered (95.2%). Total RNA was extracted and then analyzed by reverse transcription-PCR primarily for human T cell receptor (hTcR) Vbeta gene expression using 21 hTcR Vbeta amplimers. A restricted pattern of hTcR Vbeta gene expression was found, with 6 Vbeta genes (Vbeta5, 6, 7, 8, 13.1, and 18) predominantly expressed [P < 0.05, by ANOVA on ranks and Student-Newman-Keul's (SNK) test]. PBMC and control organoids showed no preferential selection of particular hTcR V gene-expressing T cells. This reductionist, mixed cell, thyroid model reflected earlier observations in human and murine autoimmune thyroid diseases in which a bias in hTcR V gene family expression had been observed. The model permitted in vivo T cell selection and/or enrichment of potentially disease relevant human T cells.

B-cell reconstitution and xenoreactive anti-pig natural antibody production in severe combined immunodeficient mice reconstituted with immunocompetent B cells from varying sources.

BACKGROUND: Little is known about the B-cell subsets that produce xenoreactive natural antibodies (NAb). This study was undertaken to investigate the potential role of varying B-cell populations in anti-pig NAb production in mice. METHODS: Severe combined immunodeficient (scid) mice were reconstituted with bone marrow or splenic or peritoneal B cells from immunocompetent mice. B-cell reconstitution and anti-pig NAb were evaluated by flow cytometric analysis. RESULTS: Adult marrow failed to reconstitute normal numbers of CD5+ B1a cells, but fully reconstituted CD5- Mac1- B2 and CD5- Mac1+ B1b cell populations in scid mice. Recipients of peritoneal B cells showed poor reconstitution of B2 cells, and an overshoot of B1 cells in the peritoneal cavity. Although B2 cells predominate in the adult spleen, splenic B cells from immunocompetent mice preferentially reconstituted B cells, including B1 cells, in the peritoneal cavity, but did not reconstitute splenic B2 cells. Therefore, neither adult marrow, splenocytes nor peritoneal cells can fully reconstitute scid mice with all B-cell subpopulations. Nevertheless, serum anti-pig NAb in marrow-reconstituted mice recovered to normal levels by 3 weeks, and were maintained for at least 30 weeks. Serum NAb in scid mice receiving peritoneal B cells reached normal levels by 4-7 weeks after transfer. However, NAb in sera of scid mice receiving splenic B cells took longer (>25 weeks) to reach normal levels. CONCLUSIONS: These results indicate that adult marrow-derived B cells can efficiently produce anti-pig NAb, and that peritoneal B cells have greater NAb-producing ability than splenic B cells or their immediate progeny.

The usefulness of severe combined immunodeficiency (SCID) mice to study human carcinogenesis.

In the present study, we engrafted normal colonic epithelial and histologically diagnosed colonic adenomas from a familial adenomatous polyposis (FAP) patient into severe combined immunodeficient (SCID) mice and subsequently examined them histologically and molecular biologically. Successful engraftment and metastasis was observed. The facts that human normal colonic epithelium and adenomatous polyps can take in SCID mice indicates the possibility that this human SCID mouse system will be useful for investigating the dynamics of human carcinogenesis in various tissues.

Simultaneous xenotransplantation of human Graves' thyroid tissue and autologous bone marrow cells in severe combined immunodeficient mice: successful reconstitution of human Graves' hyperthyroidism.

Human thyroid xenografts and the autologous bone marrow (BM) cells from five patients with Graves' disease (GD) were simultaneously xenografted into severe combined immunodeficient (SCID) mice to study the role of BM cells for the perpetuation of human GD autoimmunity and hyperthyroidism. All SCID mice engrafted with thyroid tissue (TH) alone, TH + autologous peripheral blood mononuclear cells, and TH + autologous BM cells produced similar amounts of human IgG; however, the production in TH + BM-engrafted mice peaked later than that of mice without BM. Production of thyroperoxidase antibody and thyroglobulin antibody in TH + BM-bearing SCID mice peaked in later weeks after xenografting than in those without BM. Moreover, human Graves' hyperthyroidism was actually reconstituted in TH + BM-transplanted mice; this was confirmed by (A) significantly higher levels and longer periods of secreting thyroid-stimulating antibody than those in mice without BM engraftment. (B) persistent hyperthyroxinemia up to the end of the experiment. (C) extremely high radioidine uptake of the xenografted thyroid tissue, and (D) histological findings of the maintenance of hyperplastic change of the xenografted thyroid epithelial cells. Human BM stem cells (CD34) were identified only in mice with TH + BM xenografts when analyzed by immunohistochemistry. In conclusion, (A) we have developed an animal model for human hyperthyroid GD by simultaneous xenotransplantation of GD thyroid tissue plus autologous BM cells into SCID mice, and (B) BM cells have a crucial role for perpetuating human GD autoimmunity and hyperthyroidism in this system.

Translocation of bacteria from the gastrointestinal tract in immunodeficient mice.

Host defence mechanisms associated with the inhibition of translocation of bacteria from the gastrointestinal (GI) tract were investigated in SCID and beige mice after decontamination with oral antibiotics and colonization with Escherichia coli C25. SCID mice, which have impaired T and B cell function, tended to have a greater incidence of bacterial translocation from the GI tract up to 7 days after inoculation compared with controls. However, after 7 days both SCID and controls cleared the E. coli C25 from the liver, spleen, blood and peritoneal cavity. Beige mice, with impaired NK cell and polymorphonuclear leukocyte function, were not able to clear the inoculated bacteria from their liver by 14 days after inoculation although the controls were cleared by 7 days. Numbers of bacteria in the mesenteric lymph nodes (MLN) of beige mice did not decrease significantly by 14 days after inoculation, whereas numbers in SCID mice decreased markedly within 7 days. These results suggest that defence mechanisms other than T and B cell function are important in the inhibition of systemic infection from the GI tract.