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The SCID mouse: an experimental model for endometriosis.

The purpose of this study was to validate the suitability of the severe combined immunodeficient (SCID) mouse as an experimental model for endometriosis, by defining the morphological and histological features of induced endometrial implants, and characterizing specific biochemical properties of these implants. Human secretory endometrial tissues were injected into the peritoneal cavity of SCID/SCID CB17 mature female mice. Successful peritoneal implantation was observed in 55 of 57 (96.5%) SCID mice and consisted of circumscribed elevated nodules. Haematoxylin-eosin staining of implanting lesions demonstrated the presence of endometrial glandular tissue in a mixed background of stromal and inflammatory cells. When progesterone was administered to mice, epithelial glands underwent well-defined secretory changes. Immunohistochemical analysis using polyclonal human pan-cytokeratin antibodies demonstrated selective positive staining in the glandular epithelium of the human implants with none in the surrounding stroma. In-situ hybridization analysis using complement component 3 cDNA radiolabelled riboprobes yielded significantly more intense signals in glands compared to stroma. As human endometrial implants in SCID mice were shown to retain specific histological, functional and biochemical properties, we conclude that the SCID mouse is an attractive animal model for the study of endometriosis.

Animals↗

The SCID mouse reaction to human peripheral blood mononuclear leukocyte engraftment. Neutrophil recruitment induced expression of a wide spectrum of murine cytokines and mouse leukopoiesis, including thymic differentiation.

In this study, we describe the kinetics of host immune reactions occurring in mice with severe combined immunodeficiency (SCID) at different times after the intraperitoneal injection of human peripheral blood mononuclear leukocytes (huPBL). At 24 hr, a massive neutrophil recruitment and an induced expression of a wide spectrum of murine cytokine mRNA (i.e., interleukin [IL]-1 beta, IL-4, IL-6, IL-10, IL-12, tumor necrosis factor [TNF]-alpha and interferon [IFN]-gamma) occurred in the huPBL-SCID mouse peritoneal cavity. By using ELISAs specific for mouse cytokines, large amounts of IL-1-alpha, TNF-alpha, IL-6, and IFN-gamma were detected in the peritoneal washings of huPBL-SCID mice 1 day after intraperitoneal injection. IL-6 and IFN-gamma production persisted for up to 2 weeks after PBL transplantation. Medullary and extramedullary expansion of the SCID mouse hematopoietic cells also occurred in the chimeras as early as 1 week after injection, together with a marked thymic differentiation (murine CD4+/CD8+ cells) at 10-12 weeks after transplantation. On the whole, these results indicate that, after huPBL injection, SCID mice mount a complex multistage immune response. These host reactions should be taken into consideration for any accurate interpretation of results obtained using the huPBL-SCID model. The control of responses (by means of specific antibodies to murine cytokines and to granulocytes or through the use of anti-inflammatory drugs) may be helpful in improving the engraftment of huPBL in SCID mice and in furthering our knowledge of the T and B cell-independent natural immune reactions.

Animals↗

The SCID mouse as a model for multiple myeloma.

The SCID mouse was investigated as a potential animal model for human multiple myeloma (MM). Duplicate samples of bone marrow mononuclear cells (BMMC) and/or peripheral blood mononuclear cells (PBMC) of six MM patients in different clinical phases and one patient with monoclonal gammapathy of undetermined significance (MGUS) were injected intraperitoneally into SCID mice. Human immunoglobulins (Ig) in the SCID sera were quantified with a light-chain isotype-specific ELISA, and their monoclonality biochemically characterized, using a sensitive immunoblotting technique after agar gel electrophoresis. Successful transplantation of bone marrow derived-tumour cells in SCID mice was obtained with BMCC of two MM patients with progressive disease. Human plasma cells were detected in the mesenteric fat tissue around the pancreas and the spleen. This model in SCID mice may facilitate studies on processes involved in tumour progression and provides a new tool for therapeutic approaches in MM.

Adult↗

Human recombinant interleukin-4 (HurIL-4) improves SCID mouse reconstitution with human peripheral blood lymphocytes.

The application of human-scid mouse chimera (hu-scid) technology has some limitations, because of the variable amounts and functional heterogeneity of human cells recovered from engrafted mice. Attempts to optimize the construction of hu-scid chimeras with human peripheral blood mononuclear cells (Hu-PBMC) by using in vivo anti-asialo GM1 antibody treatment in mice in order to eliminate natural killer cells have been published by other authors with interesting results. In this study, Hu-PBMC were incubated in vitro with human recombinant interleukin-4 (HurIL-4) or human recombinant interleukin-2 (HurIL-2) for two hours and were intraperitoneally transferred into scid mice. Total human IgM and IgG levels in hu-scid sera, human cell markers in the thymus and in the spleen of grafted mice were considered as parameters of successful engraftment. HurIL-4 significantly enhanced human immunoglobulin production while HurIL-2 did not show any obvious effect. Human cell markers (CD2 and CD19) were significantly higher in the group of HurIL-4 treated Hu-PBMC than in the other groups, despite the high variability in human cell proliferation in the recipients. Thus, HurIL-4 can be used as an adjuvant growth factor which improves successful engraftment of human peripheral blood lymphocytes in scid mice.

Animals↗

Induction of tumors in the colon and liver of the immunodeficient (SCID) mouse by 2-amino-3-methylimidazo[4,5-f ]quinoline (IQ)-modulation by long-chain fatty acids.

We have recently shown that immunodeficient (SCID) mice, which lack functional T and B cells, are highly susceptible to low dose site specific induction of colon aberrant crypt foci (ACF), surrogates for colon tumors, by 2-amino-3-methylimidazo[4,5-f ]quinoline (IQ). To test whether long-term exposure to a high dose in the diet might prove carcinogenic to the SCID mouse colon, in contrast to other mice strains tested to date, the compound was administered at 300 p.p.m. in the diet to female 6-7-week-old SCID mice for 32 weeks. IQ induced high numbers of ACF, hyperplastic polyps, dysplasia, and colon adenomas, as well as hepatocellular altered foci and liver adenomas. Induction of colon tumors did not correlate with the main sites where ACF developed, the proximal colon, however, being seen mainly in the mid and distal colon. Induction of colon tumors correlated significantly with the incidence of dysplasia, crypt height, the mitotic index, cell proliferation and numbers of 8-hydroxydeoxyguanosine (8-OHdG)-positive cells in the colon crypt, particularly in mid and distal colon. Administration of 20% omega-6 polyunsaturated fatty acids (corn oil), omega-3 polyunsaturated fatty acids (perilla oil), or monounsaturated fatty acids (olive oil) simultaneously with IQ in the diet resulted in: (i) inhibition of colon and liver tumor induction by corn and perilla oil, whereas olive oil showed no effects; (ii) no reduction in total numbers of ACF by corn oil or perilla oil but significant suppression in the olive oil treated group; (iii) inhibition of tumor development particularly by omega-3 polyunsaturated fatty acids in perilla oil, correlating significantly with decreased cell proliferation in both colon and liver and a marked decrease in crypt heights and mitotic indices. Selective reduction in the numbers of 8-OHdG-positive nuclei, mainly in the middle and distal colon crypts, was also found to correlate with tumor inhibition. Thus, the results indicate carcinogenicity of IQ in the colon of the SCID mouse and preventive effects of polyunsaturated fatty acids.

8-Hydroxy-2'-Deoxyguanosine↗

Orthotopic SCID mouse model with two newly established human lung squamous carcinoma cell lines.

The objective of this study was to present an orthotopic SCID mouse model using two newly established human cell lines derived from squamous cell carcinomas of the lung. GO-LCC1 cells (1 x 10(6)) and GO-LCC2 cells (3 x 10(6)) were implanted orthotopically into the right lungs of 10 C.B. 17 scid/scid mice. In both groups, aggressive tumor growth with partial infiltration of the thoracic wall, heart and diaphragm was observed. In only one case distant metastases in the contralateral lung were detected, while all animals developed tumors at the site of inoculation. Xenografted GO-LCC1 cells showed enhanced tumor propagation compared to GO-LCC2 cells. Our data underscore the usefulness of the SCID mouse model to study the biological behaviour of cultuved human tumor cells and furthemore demonstrate the clinical applicability of xenograft techniques using human tumor cell lines derived from pneumonectomy specimens of squamous lung carcinomas.

Animals↗

The human HIV/peripheral blood lymphocyte (PBL)-SCID mouse. A modified human PBL-SCID model for the study of HIV pathogenesis and therapy.

PBL from HIV-infected patients were engrafted into CB-17 SCID mice to develop a novel small animal model for the study of HIV pathogenesis and therapy. Engraftment was achieved in 84% of mice, with human Ig (hu-Ig) levels and total human mononuclear cell recovery by peritoneal wash similar to those in control hu-PBL-SCID mice engrafted with uninfected donor cells. The hu-Ig produced by hu-HIV/PBL-SCID mice had broad reactivity against HIV. Virus could be detected in 98% of mice by polymerase chain reaction and/or viral coculture. Viremia was first detected by quantitative polymerase chain reaction on day 7 (approximately 10,000 copies of viral RNA/ml of plasma) and persisted through day 17. Quasispecies analysis of amplified, cloned, proviral DNA of the V3 region of the env gene showed that nucleotide sequences from hu-HIV/PBL-SCID mouse peritoneal wash cells on day 17 were not significantly changed from those derived from donor PBL at the time of injection. Relative to human CD4+ T cell recovery by peritoneal wash in control hu-PBL-SCID mice (CD4 = 19 +/- 2%; n = 40), severe CD4+ lymphocyte depletion (CD4 = 5 +/- 0.5%; n = 59; p < 0.001) was observed in untreated hu-HIV/PBL-SCID mice 18 to 25 days after engraftment. Treatment with 2'-beta-fluoro-2',3'-dideoxyadenosine, a nucleoside analogue, significantly reduced CD4+ T cell depletion (CD4 = 13 +/- 1; n = 59; p < 0.001) and the frequency of virus isolation (70%; p = 0.015) in the hu-HIV/PBL-SCID model. Boosting hu-Ig levels in the mice by injection of purified donor Ig with neutralizing activity did not affect the frequency of CD4+ lymphocyte recovery or virus isolation. The administration of a mAb to TNF had minimal effects. These studies demonstrate that PBL from HIV-infected donors can engraft SCID mice; that HIV can be detected in the spleen, peritoneal wash cells, and blood of these mice; that HIV infection within the model results in rapid CD4+ T cell depletion; and that anti-retroviral therapy is effective in improving CD4+ T cell recovery and reducing the frequency of virus isolation. The hu-HIV/PBL-SCID mouse model thus represents a potentially useful model in which to study HIV pathogenesis and therapy.

Amino Acid Sequence↗

Severe combined immunodeficiency (SCID) mouse modeling of P-glycoprotein chemosensitization in multidrug-resistant human myeloma xenografts.

We have established a reproducible in vivo model of human multiple myeloma in the severe combined immunodeficiency (SCID) mouse using both the drug-sensitive 8226/S human myeloma cell line and the P-glycoprotein-expressing multidrug-resistant 8226/C1N subline. As demonstrated previously, the SCID mouse is well suited as a model for myeloma because: (a) human SCID xenografts are readily attained; (b) human myeloma xenografts are readily detected by their immunoglobulin secretion; and (c) differential therapy effects in drug-sensitive versus drug-resistant cell lines are readily demonstrable by monitoring mouse urinary human immunoglobulin output. In the current study, we have utilized this model to evaluate the in vivo efficacy of chemomodulators of P-glycoprotein-related multidrug resistance. In our initial experiments, doxorubicin alone was effective in treating the 8226/S human myeloma xenografts but had no effect on the drug-resistant 8226/C1N xenografts, in the absence of the chemosensitizing agent verapamil. In subsequent experiments, the combination of verapamil and doxorubicin resulted in both a decrease in human lambda light chain urinary excretion and an increase in survival of those animals bearing the 8226/C1N tumor. The median survival time of animals injected with 8226/C1N cells and subsequently treated with doxorubicin was 48.6 +/- 7 days, which compared to a survival of 89.6 +/- 18 days in animals receiving the 8226/S cell line and treated with doxorubicin alone (P < 0.001). When verapamil was added to the treatment regimen of those animals bearing the 8226/C1N xenografts, there was a 179% increase in their life span (P < 0.001), which corresponded with the observed decreased light chain in the urine. In animals receiving multiple courses of chemotherapy, an attenuated response to verapamil and doxorubicin was observed, in a manner analogous to the clinical setting of human drug-resistant myeloma escape from chemosensitivity. The SCID human myeloma xenograft model thus offers a means of evaluating the in vivo efficacy and potential toxicities of new therapeutic approaches directed against P-glycoprotein in multidrug-resistant human myeloma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

[Inhibitory effects of integrin av beta3 monoclonal antibody on implanted lesions of endometriosis model of SCID mouse].

OBJECTIVE: To explore the potential use of integrin av beta3 (Lm609) monoclonal antibody against ectopic lesion and microvessel angiogenesis of human endometriosis xenografts in SCID mice. METHODS: The endometrial tissues from endometriosis patients were inoculated subcutaneously into SCID mouse, which were treated with Lm609, an inhibitor of angiogenesis, twice a week, for 3 weeks. The mice were sacrificed and immunohistochemical staining was employed to determine the microvessel density (MVD) and expression of integrin av beta3 in the lesion tissues. RESULTS: Lm609 inhibited the growth of the ectopic lesion. The lesion weighted 0.82+/-0.09 g in the treated group versus 0.51+/-0.93 g in the control group (P<0.05). The MVDs of the treated and control groups were 31.2+/-4.4 and 14.4+/-1.8 respectively (P<0.05). CONCLUSION: Lm609 can inhibit the growth of ectopic lesion by reducing angiogenesis in SCID mouse.

Animals↗

Establishment of patient-like SCID mouse model by orthotopically implanting primary cultured cells from surgically-resected lung cancer tissues.

In our previous studies, we established a lymphogenous metastatic SCID mouse model using orthotopic implantation of human lung cancer cell lines. However, the lymphogenous metastatic potential of each cell line in our models does not reflect that of a primary tumor. In this study, we made orthotopic implanted models using primary cultured cells from surgically-resected lung cancer tissues. Tissues of 5 patients with non-small cell lung cancer (NSCLC) were applied to a primary culture method using a collagen gel coated flask. Suspensions of 2.0x10(4) cancer cells were injected into the left lung of SCID mice. We could maintain primary culture cells from 2 (FM205 and FT821 cells) of 5 lung cancers, and made orthotopically implanted SCID mouse models. The size of both tumors in implanted sites of the lung increased with time. The FM205 cells microscopically were metastasized to the mediastinum by 4 weeks after implantation and macroscopically metastasized by 16 weeks. The FT821 cells were microscopically metastasized to the mediastinum by 4 weeks after implantation and macroscopically metastasized by 6 weeks. The lymphogenous metastatic potential of these primary culture cells was similar to that of clinical tumors. As the lymphogenous metastatic potential of this model reflects that of the clinical tumor, it is useful for elucidating the mechanism of lymphogenous metastasis and selecting anticancer drugs suitable for an individual patients.

Animals↗

Dominance of a single Epstein-Barr virus strain in SCID-mouse tumors induced by injection of peripheral blood mononuclear cells from healthy human donors.

Severe Combined Immune Deficiency mouse tumors, induced by inoculating peripheral blood mononuclear cells from 11 healthy human donors (hu-PBMC-SCID tumors), were used to analyse Epstein-Barr virus (EBV) type and strain variations. PCR analysis of EBNA 2- and EBNA 3C-specific sequences showed that EBV type A was present in SCID-mouse tumors induced by PBMC from all donors but one, while, using amplimers for a highly polymorphic region within the latent membrane protein (LMP) coding sequence, 5 different strains could be detected among the samples examined. The same LMP fragment was present in different tumors arising in the same animal, as well as in different mice injected with PBMC from any donor. Compared to B95.8 and AG876 prototype viruses, sequence analysis of LMP variants disclosed a higher homology to the latter, with 33 bp additional repetitions and a few point mutations in specific sites. This study confirms and extends previous data on the presence of a single EBV type and strain in the peripheral blood of most normal healthy subjects using the SCID-mouse system.

Amino Acid Sequence↗

Preservation of functioning human thyroid organoids in the scid mouse: 1. System characterization.

We have characterized a system for preserving reconstituted human thyroid follicles in vivo by transplanting human thyrocytes into mice with severe combined immunodeficiency (scid mice). Human thyroid organoids were constructed from thyroid monolayer cells derived from both normal and abnormal thyroid tissue, and embedded within a basement membrane preparation which was then transferred sc to scid mice. As early as 4 weeks, and as late as 3 months post transplantation, histological examination of human thyroid organoids demonstrated widespread neofollicle formation and colloid accumulation which stained positive for human thyroglobulin (hTg). Although there were no changes in murine serum T4 levels; the transplanted thyroid epithelial cells secreted hTg into the scid mouse circulation (with an average level of 29 micrograms/L). In addition, hTg release was stimulated in vivo by ip administration of recombinant human TSH (0.1-1.0 IU/mouse) achieving greater than 20-fold increases in scid mouse serum hTg levels. In situ immunohistochemistry showed that thyroid organoids derived from patients with Graves' disease retained scattered lymphocytes in peripolesis with the thyroid epithelial cells; those lymphocytes were identified as human T cells of the memory (CD45RO +), rather than naive, type. These data demonstrate that functioning human thyroid organoids establish in scid mice and remain responsive to TSH stimulation. The system offers a unique opportunity to examine human thyroid-lymphocyte interaction within the confines of a predictable animal model.

Animals↗

Propagation of human blastic myeloid leukemias in the SCID mouse.

Existing in vitro culture technology does not permit the routine propagation of most human myeloid leukemias. Previous work has shown the usefulness of mice with severe combined immunodeficiency (SCID) for the growth of human lymphoblastic leukemia. We show here that human myeloid cell lines and bone marrow samples from patients with acute myeloid leukemia (AML) and blast crisis of chronic myeloid leukemia (CML) also grow in SCID mice. Human AML or CML cell lines (three of three lines tested) grew in the bone marrow and peripheral blood of the mice after intravenous (IV) inoculation in a pattern closely resembling human AML. To define the best conditions for the growth of primary human myeloid leukemia cells, samples were transplanted into mice at several alternative sites. Using flow cytometry and Southern analysis, mice were analyzed at defined intervals up to 36 weeks after transplantation for the presence of human cells in various tissues. For four of four patients with AML and two of two patients with blast crisis of CML, myeloblasts grew locally at the site of implantation and were detected in the murine hematopoietic tissues. In contrast, marrow implants from patients in the chronic phase of CML (six patients) showed infrequent and limited myeloid growth in the mice. These findings demonstrate that the SCID mouse is a reproducible system for the propagation of blastic human myeloid leukemias. The differential growth of early- versus late-phase CML suggests that the SCID mouse may be a useful assay for identifying biologically aggressive leukemias early in their clinical presentation.

Acute Disease↗

The SCID mouse: relevance as an animal model system for studying human disease.

The simultaneous description some 5 years ago of two methods for the partial reconstitution of a human immune system in severe combined immune-deficient (SCID) mice (collectively, human:SCID mice) was met with great enthusiasm. At the time, it was hoped that human:SCID mice would provide experimental animal model systems for studying human disease and the human immune system. Many of these hopes have been borne out. Importantly, the experimental results obtained from these chimeric human/animal studies appear to be relevant to human disease and immune function. In spite of these glowing achievements, the SCID mouse may not represent the optimal experimental system with which to address these questions. The incomplete penetrance ("leakiness") of the scid mutation and the recent discovery that the mutation is not lymphoid specific, but rather affects a general DNA repair pathway, will only serve to complicate the interpretation of already complex biological interactions. Recently other immune-deficient mice have been described that appear to overcome one or both of these problems and thus these mice could represent improved hosts for the adaptive transfer of a human immune system. The current status of the SCID mouse in light of these new findings is discussed.

Animals↗

Development of a severe combined immunodeficiency (SCID) mouse model consisting of highly disseminated human B-cell leukemia/lymphoma, cure of the tumors by systemic administration of immunotoxin, and development/application of a clonotype-specific polymerase chain reaction-based assay.

A new severe combined immunodeficiency (SCID) mouse model consisting of highly disseminated human B-cell leukemia/lymphoma was developed by i.v. inoculation of BALL-1a, an in vivo adapted malignant B-cell line. A 100% transplantability was achieved in nonpreconditioned SCID mice using various BALL-1a doses between 2.5 x 10(4) and 6 x 10(6) cells. Hind-leg paralysis preceded the death of the mice. Utility of the developed tumor model for the therapeutic studies was investigated by i.v. administration of an anti-B-cell monoclonal antibody SN7 (IgG1) and its conjugate with deglycosylated ricin A chain (dgRA). The therapy was initiated 2, 4, or 6 days after tumor inoculation using 4 x 24 microg of SN7-dgRA or 4 x 20 microg of SN7; the total dose (96 microg) of SN7-dgRA corresponded to 14% of the LD50 dose. SN7-dgRA showed a strong antitumor efficacy in all groups of treated mice. All of the day-2 group mice (n = 7) and six (66.7%) of the day-4 group mice (n = 9) survived healthily for as long as followed (240 days), whereas four (57.1%) of the day-6 group mice (n = 7) survived healthily for as long as followed (200 days). Unconjugated SN7 showed a significant antitumor efficacy but was less effective than SN7-dgRA. A PCR-based assay specific for the clonogenic BALL-1a tumor was developed and applied to determine tumors in various organs of BALL-1a-bearing SCID mice. The assay was highly sensitive in screening for trace quantities of residual tumors in various organs of SCID mice, and it could detect 1 malignant cell/2.5 x 10(5) tissue cells. The PCR-based assay was shown to be much more powerful than the conventional histological analysis in detecting residual tumors. Furthermore, we could estimate quantities of the detected tumors by the PCR-based assay. It is remarkable to find that all examined organs of some of the SN7-dgRA-treated mice were tumor-free as determined by the clonotype-specific PCR-based assay. The present results show the usefulness of the newly developed SCID mouse model, SN7-dgRA, and the clonotype-specific PCR-based molecular assay for the study of therapy of human B-cell leukemia/lymphoma.

Animals↗

OSI-211, a novel liposomal topoisomerase I inhibitor, is active in SCID mouse models of human AML and ALL.

OSI-211 (liposomal lurtotecan), was evaluated using several different dose schedules (1mg/kg, d1-5, 1.75 mg/kg d1, 3, 5 and 6 mg/kg d1, 8) in severe combined immunodeficient (SCID) mouse models of acute myelogenous leukemia (AML) and acute lymphocytic leukemia (ALL) with early treatment (ET, days 6-8) or late treatment (LT, days 15-19), examining early and advanced disease, respectively. Due to the aggressive nature of the Molt-4 model, the ET and LT were accelerated to day 3 or 4 and day 8 post-implant, respectively. For each model, 2 x 10(7) (KBM-3B) or 1 x 10(7) (Molt-4, HL-60 and CEM) leukemia cells were injected intravenously into the tail vein. Each control and test group consisted of eight animals. All three schedules (1mg/kg qd1-5, 1.75 mg/kg d1, 3, 5 and 6 mg/kg d1, 8) increased the life span of OSI-211 treated animals in each model, with a tendency toward improved efficacy with the 6 mg/kg d1, 8 schedule. As a result, the activity of the 6 mg/kg d1, 8 schedule is detailed for each model. ET significantly (P<0.005) increased survival in the KBM-3B model with 86% long-term survivors (LTS). Using PRC analysis, human beta-globin gene sequences in one or several tissues were amplified in all but 3 LTS, suggesting minimal residual disease in 26 of the 29 LTS. LT also significantly (P<0.005) improved average life span in the KBM-3B model, with an average ILS=196+/-11% and one LTS. Treatment of HL-60 leukemia animals significantly (P<0.005) increased life span, with an ILS=213+/-9% and two LTS for ET, and with an ILS=219+/-4% and no LTS for LT. Treatment of Molt-4 animals, the most aggressive leukemia model tested, significantly (P<0.005) increased life span, with an average ILS=181+/-3% and no LTS for ET and an average ILS=172+/-1% with no LTS for LT. In the CEM model, ET resulted in a significantly (P<0.005) improved ILS=244+/-24% with one LTS. In comparison to OSI-211, treatment with DaunoXome, the liposomal formulation of daunorubicin, a drug with clinical efficacy in AML and ALL, had no effect on survival in the KBM-3B, nor Molt-4 A4 leukemia models when administered at its maximum or near maximum tolerated doses of 3mg/kg d1, 8. These data demonstrate that OSI-211 has potent antileukemia activity in preclinical SCID mouse AML and ALL leukemia models, supporting the clinical investigation of OSI-211 for hematological malignancies.

Animals↗

Theileria sergenti infection in the Bo-RBC-SCID mouse model.

We have previously developed the Bo-RBC-SCID mouse model for Theileria sergenti infection. In the present study, this model was further examined to delineate the models of parasite infection. The Bo-RBC-SCID mice were prepared by periodically transfusing uninfected bovine erythrocytes (Bo-RBCs) into splenectomized SCID mice via the intraperitoneal (i.p.) route. The mice, separated into three groups, were inoculated i.p., intravenously (i.v.), or subcutaneously (s.c.) with T. sergenti-infected Bo-RBCs. Examination of samples of peripheral blood demonstrated that the parasite infected mice inoculated via any one of the three routes. The mice inoculated i.v., however, developed parasitemia earlier than those inoculated i.p. or s.c. When Bo-RBC-SCID mice prepared without splenectomy were infected with T. sergenti, a high-level parasitemia appeared only once. After that, not only the level of parasitemia but also the number of Bo-RBCs in the peripheral blood rapidly decreased despite the continuation of Bo-RBC transfusions. The results suggest that T. sergenti proliferates primarily in the circulating blood in Bo-RBC-SCID mice and that in response to the parasites growth, the spleen may play an important role in the removal of both parasitized and unparasitized Bo-RBCs from the blood circulation.

Animals↗

p27Kip1 and cyclin D1 are necessary for focal adhesion kinase regulation of cell cycle progression in glioblastoma cells propagated in vitro and in vivo in the scid mouse brain.

We have reported previously that the expression of focal adhesion kinase (FAK) is elevated in glioblastomas and that expression of FAK promotes the proliferation of glioblastoma cells propagated in either soft agar or in the C.B.17 severe combined immunodeficiency (scid) mouse brain. We therefore determined the effect of FAK on cell cycle progression in these cells. We found that overexpression of wild-type FAK promoted exit from G(1) in monolayer cultures of glioblastoma cells, enhanced the expression of cyclins D1 and E while reducing the expression of p27(Kip1) and p21(Waf1), and enhanced the kinase activity of the cyclin D1-cyclin-dependent kinase-4 (cdk4) complex. Transfection of the monolayers with a FAK molecule in which the autophosphorylation site is mutated (FAK397F) inhibited exit from G(1) and reduced the expression of cyclins D1 and E while enhancing the expression of p27(Kip1) and p21(Waf1). Small interfering RNA (siRNA)-mediated down-regulation of cyclin D1 inhibited the enhancement of cell cycle progression observed on expression of wild-type FAK, whereas siRNA-mediated down-regulation of cyclin E had no effect. siRNA-mediated down-regulation of p27(Kip1) overcame the inhibition of cell cycle progression observed on expression of FAK397F, whereas down-regulation of p21(Waf1) had no effect. These results were confirmed in vivo in the scid mouse brain xenograft model in which propagation of glioblastoma cells expressing FAK397F resulted in a 50% inhibition of tumor growth and inhibited exit from G(1). Taken together, our results indicate that FAK promotes proliferation of glioblastoma cells by enhancing exit from G(1) through a mechanism that involves cyclin D1 and p27(Kip1).

Animals↗