Progress,implications,and challenges in using humanized immune system mice in CAR-T therapy-Application evaluation and improvement

In recent years,humanized immune system(HIS)mice have been gradually used as models for preclinical research in pharmacotherapies and cell therapies with major breakthroughs in tumor and other fields,better mimicking the human immune system and the tumor immune microenvironment,compared to traditional immunodeficient mice.To better promote the application of HIS mice in preclinical research,we se-lectively summarize the current prevalent and breakthrough research and evaluation of chimeric antigen receptor(CAR)-T cells in various antiviral and antitumor treat-ments.By exploring its application in preclinical research,we find that it can better reflect the actual clinical patient condition,with the advantages of providing high-efficiency detection indicators,even for progressive research and development.We believe that it has better clinical patient simulation and promotion for the updated design of CAR-T cell therapy than directly transplanted immunodeficient mice.The characteristics of the main models are proposed to improve the use defects of the existing models by reducing the limitation of antihost reaction,combining multiple models,and unifying sources and organoid substitution.Strategy study of relapse and toxicity after CAR-T treatment also provides more possibilities for application and development.

Effects of P301L-TAU on post-translational modifications of microtubules in human iPSC-derived cortical neurons and TAU transgenic mice

TAU is a microtubule-associated protein that promotes microtubule assembly and stability in the axon.TAU is missorted and aggregated in an array of diseases known as tauopathies.Microtubules are essential for neuronal function and regulated via a complex set of post-translational modifications,changes of which affect microtubule stability and dynamics,microtubule interaction with other proteins and cellular structures,and mediate recruitment of microtubule-severing enzymes.As impairment of microtubule dynamics causes neuronal dysfunction,we hypothesize cognitive impairment in human disease to be impacted by impairment of microtubule dynamics.We therefore aimed to study the effects of a disease-causing mutation of TAU(P301L)on the levels and localization of microtubule post-translational modifications indicative of microtubule stability and dynamics,to assess whether P301L-TAU causes stability-changing modifications to microtubules.To investigate TAU localization,phosphorylation,and effects on tubulin post-translational modifications,we expressed wild-type or P301L-TAU in human MAPT-KO induced pluripotent stem cell-derived neurons(i Neurons)and studied TAU in neurons in the hippocampus of mice transgenic for human P301L-TAU(p R5 mice).Human neurons expressing the longest TAU isoform(2N4R)with the P301L mutation showed increased TAU phosphorylation at the AT8,but not the p-Ser-262 epitope,and increased polyglutamylation and acetylation of microtubules compared with endogenous TAU-expressing neurons.P301L-TAU showed pronounced somatodendritic presence,but also successful axonal enrichment and a similar axodendritic distribution comparable to exogenously expressed 2N4R-wildtype-TAU.P301L-TAU-expressing hippocampal neurons in transgenic mice showed prominent missorting and tauopathy-typical AT8-phosphorylation of TAU and increased polyglutamylation,but reduced acetylation,of microtubules compared with non-transgenic littermates.In sum,P301L-TAU results in changes in microtubule PTMs,suggestive of impairment of microtubule stability.This is accompanied by missorting and aggregation of TAU in mice but not in i Neurons.Microtubule PTMs/impairment may be of key importance in tauopathies.

Against all odds:The road to success in the development of human immune reconstitution mice

The mouse genome has a high degree of homology with the human genome,and its physiological,biochemical,and developmental regulation mechanisms are similar to those of humans;therefore,mice are widely used as experimental animals.However,it is undeniable that interspecies differences between humans and mice can lead to experimental errors.The differences in the immune system have become an impor-tant factor limiting current immunological research.The application of immunodefi-cient mice provides a possible solution to these problems.By transplanting human immune cells or tissues,such as peripheral blood mononuclear cells or hematopoietic stem cells,into immunodeficient mice,a human immune system can be reconstituted in the mouse body,and the engrafted immune cells can elicit human-specific immune responses.Researchers have been actively exploring the development and differen-tiation conditions of host recipient animals and grafts in order to achieve better im-mune reconstitution.Through genetic engineering methods,immunodeficient mice can be further modified to provide a favorable developmental and differentiation microenvironment for the grafts.From initially only being able to reconstruct single T lymphocyte lineages,it is now possible to reconstruct lymphoid and myeloid cells,providing important research tools for immunology-related studies.In this review,we compare the differences in immune systems of humans and mice,describe the devel-opment history of human immune reconstitution from the perspectives of immuno-deficient mice and grafts,and discuss the latest advances in enhancing the efficiency of human immune cell reconstitution,aiming to provide important references for im-munological related researches.

Characterization of genetic humanized mice with transgenic HLA DP401 or DRA but deficient in endogenous murine MHC classⅡgenes upon Staphylococcus aureus pneumonia

Background:Staphylococcus aureus can cause serious infections by secreting many superantigen exotoxins in“carrier”or“pathogenic”states.HLA DQ and HLA DR humanized mice have been used as a small animal model to study the role of two molecules during S.aureus infection.However,the contribution of HLA DP to S.aureus infection is unknown yet.Methods:In this study,we have produced HLA DP401 and HLA DRA0101 humanized mice by microinjection of C57BL/6J zygotes.Neo-floxed IAβ+/-mice were crossbred with Ella-Cre and further crossbred with HLA DP401 or HLA-DRA0101 humanized mice.After several rounds of traditional crossbreeding,we finally obtained HLA DP401-IAβ-/-and HLA DRA-IAβ-/-humanized mice,in which human DP401 or DRA0101 molecule was introduced into IAβ-/-mice deficient in endogenous murine MHC classⅡmolecules.A transnasal infection murine model of S.aureus pneumonia was induced in the humanized mice by administering 2×108CFU of S.aureus Newman dropwise into the nasal cavity.The immune responses and histopathology changes were further assessed in lungs in these infected mice.Results:We evaluated the local and systemic effects of S.aureus delivered intranasally in HLA DP401-IAβ-/-and HLA DRA-IAβ-/-transgenic mice.S.aureus Newman infection significantly increased the m RNA level of IL 12p40 in lungs in humanized mice.An increase in IFN-γand IL-6 protein was observed in HLA DRA-IAβ-/-mice.We observed a declining trend in the percentage of F4/80+macrophages in lungs in HLA DP401-IAβ-/-mice and a decreasing ratio of CD4+to CD8+T cells in lungs in IAβ-/-mice and HLA DP401-IAβ-/-mice.A decreasing ratio of Vβ3+to Vβ8+T cells was also found in the lymph node of IAβ-/-mice and HLA DP401-IAβ-/-mice.S.aureus Newman infection resulted in a weaker pathological injury in lungs in IAβ-/-genetic background mice.Conclusion:These humanized mice will be an invaluable mouse model to resolve the pathological mechanism of S.aureus pneumonia and study what role DP molecule plays in S.aureus infection.

Effect of Human Umbilical Cord Mesenchymal Stem Cells on GRP78/ATF4 Pathway in Alzheimer s Disease Model Mice

[Objectives]To study the effect of human umbilical cord mesenchymal stem cells(hUC-MSCs)on GRP78/ATF4 pathway in APP/PS1 mice.[Methods]Twelve 6-month-old female APP/PS1 mice were randomly divided into model group(MOD,n=6)and human umbilical cord mesenchymal stem cell treatment group(MSC,n=6);six 6-month-old C57BL/6N mice were used as control group(CON,n=6).The mice in each group were treated with the fourth generation of human umbilical cord mesenchymal stem cells through tail vein.Four weeks later,the mice in each group were killed.The expression of GFP78 and ATF4 in the cortex of mice in each group was detected by Western blotting and real-time fluorescence quantitative PCR.[Results]The results of immunoblotting and real-time fluorescence quantitative PCR showed that the expression of GRP78 in MOD group was lower than that in CON group and the expression of ATF4 increased.The expression of GRP78 protein in MSC group was higher than that in MOD group,but the expression of ATF4 protein was lower.The results of real-time fluorescence quantitative PCR showed that the mRNA level of GRP78 decreased and the mRNA level of ATF4 increased in MOD group compared with CON group.The mRNA level of GRP78 in MSC group was higher than that in MOD group,while the mRNA level of ATF4 in MSC group was lower than that in MOD group.[Conclusions]Human umbilical cord mesenchymal stem cells can regulate the expression of GRP78/ATF4 pathway in APP/PSI mice,which may be related to the stress level of endoplasmic reticulum in the brain of APP/PS1 mice mediated by human umbilical cord mesenchymal stem cells.

Establishment of a humanized ST6GAL1 mouse model for influenza research

Background:This study aimed to construct and characterize a humanized influenza mouse model expressing hST6GAL1.Methods:Humanized fragments,consisting of the endothelial cell-specific K18 promoter,human ST6GAL1-encoding gene,and luciferase gene,were microinjected into the fertilized eggs of mice.The manipulated embryos were transferred into the oviducts of pseudopregnant female mice.The offspring were identified using PCR.Mice exhibiting elevated expression of the hST6GAL1 gene were selectively bred for propagation,and in vivo analysis was performed for screening.Expression of the humanized gene was tested by performing immunohistochemical(IHC)analysis.Hematologic and biochemical analyses using the whole blood and serum of humanized hST6GAL1 mice were performed.Results:Successful integration of the human ST6GAL1 gene into the mouse genome led to the overexpression of human SiaT ST6GAL1.Seven mice were identified as carrying copies of the humanized gene,and the in vivo analysis indicated that hST6GAL1gene expression in positive mice mirrored influenza virus infection characteristics.The IHC results revealed that hST6GAL1 was expressed in the lungs of humanized mice.Moreover,the hematologic and biochemical parameters of the positive mice were within the normal range.Conclusion:A humanized influenza mouse model expressing the hST6GAL1 gene was successfully established and characterized.

Metastatic human hepatocellular carcinoma models in nude mice and cell line with metastatic potential

Metastatic human HCC model is needed for the studies on mechanism and intervention of metastatic recurrence. By using orthotopic implantation of histologically intact tissues of 30 surgical specimens, a patient-like metastatic model of human HCC in nude mice (LCI-D20) and a low metastatic model of human HCC in nude mice (LCI-D35) have been established. All mice with transplanted LCI-D20 tumors exhibited extremely high metastatic ability including spontaneous metastasis to liver, lungs, lymph nodes and peritoneal seeding. Remarkable difference was also found in expression of some of the invasiveness related genes and growth factors between the LCI-D20 and LCI-D35 tumors. PAI-1 increased gradually following tumor progression in LCI-D20 model, and correlated with tumor size and AFP level. Phasic expression of tissue intercellular adhesion molecule-1 in this model was also observed. Using corneal micropocket model, it was demonstrated that the vascular response induced by LCI-D20 tumor was stronger than that induced by LCI-D35 tumor. Similar report on metastatic human HCC model in nude mice and human HCC cell line with metastatic potential was rarely found in the literature. This LCI-D20 model has been widely used for the studies on intervention of metastasis, including anti-angiogenesis,antisense approach, metalloproteinase inhibitor, differentiation inducer, etc. It is concluded that the establishment of metastatic human HCC model in nude mice and human HCC cell line with metastatic potential will provide important models for the in vitro and in vitro study of HCC invasiveness, angiogenesis as well as intervention of HCC recurrence.

Effects of epidermal growth factor on the growth of human gastric cancer cell and the implanted tumor of nude mice

AIM: Epidermal growth factor (EGF) plays an important role in the regulation of gastrointestinal tissue growth and development, and it can stimulate epithelial proliferation, cell differentiation and growth. It has been established that the EGF can promote gastric cytoprotection and ulcer healing. But the potential ability of EGF to regulate the gastric cancer growth is unknown. This study is to investigate the influence of EGF on human gastric cancer cell and the implanted tumor growth of nude mice. METHODS: The cell growth rates of human gastric adenocarcinoma cell lines MKN-28, MKN-45, SGC-7901 and normal human gastric epithelial cells 3T3 were assessed when incubated with recombinant human EGF (rhEGF, 0.05, 0.1, 0.5, 1.0, 10, 50, 100 mg.L(-1)) using MTT method. The cells of MKN-28, MKN-45, SGC-7901 (gastric cancer tissue 1.5mm(3)) were implanted in the BALB/cA nude mice for 10 days.The EGF was given intraperitoneally (15, 30, 60 microg.kg(-1)) for 3 weeks. The body weights of the tumor-bearing animals and their tumor mass were measured afterwards to assess the mitogenic effect of rhEGF in the nude mice. RESULTS: Within the concentration range of 0.05-100mg.L(-1), rhEGF could increase the cell growth of normal 3T3 cells (cell growth rate 100% vs 102.8%, P【0.05), but partially restrain the gastric cancer cell growth. The latter effect was related to cell differentiation. In 15-60 microg/kg rhEGF groups, the mean implanted tumor mass of MKN-28 cell were 1.75 g, 1.91 g, 2.08 g/NS group 1.97 g (P】0.05), the mean tumor mass of SGC-7901 cell were 1.53 g, 1.07 g, 1.20 g/NS group 1.07 g (P】0.05), and for MKN-45 cell, the tumor mass were respectively 1.92 g, 1.29 g, 1.77 /NS group 1.82 g (P】0.05). So rhEGF had no obvious effect on implanted MKN-28, SGC-7901 and MKN-45 tumor growth. CONCLUSION: EGF has no stimulating effect on the human gastric cancer cell growth neither in vitro nor in vivo.

Antitumor Activities and Apoptosis-regulated Mechanisms of Fermented Wheat Germ Extract in the Transplantation Tumor Model of Human HT-29 Cells in Nude Mice

Objective A subcutaneous transplantation tumor model of human HT-29 cells in nude mice was established to evaluate anticarcinogenic activities, and the apoptosis-regulated mechanism effect of aqueous extract of fermented wheat germ with Lactobacillus plantarum dy-1 （LFWGE）. Methods The HT-29 cells were transplanted via subcutaneous injection of 1×10^7cells into the right flank of each nude mouse. Then, nude mice were treated for 30 d with LFWGE （high-dose 2 g/kg/d; low-dose 1 g/kg/d） and for 7 d with 5-fluorouracil （5-FU, 25 mg/kg/d） by gavage and intraperitoneal injection, respectively. An inhibition of tumor growth was observed. Results Tumor volume and weights decreased significantly in both groups of nude mice treated with LFWGE. In addition, the cell apoptosis rate of the LFWGE group （2 g/kg/d, 60.2%＋4.4%; 1 g/kg/d, 58.6%＋6.9%） was significantly higher than that of the control group （11.5%＋1.6%） and 5-FU group （32.1%＋3.5%） as measured by the TUNEL assay. Moreover, the real-time fluorescent quantitative PCR and Western blot method further confirmed these enhancing apoptosis and growth inhibition effects. The involvement of LFWGE in inducing apoptosis was confirmed by the expression of Bax, Bcl-2, Caspase-3, and CyclinD1. Conclusion The results showed that LFWGE could induce subcutaneous transplantation tumor apoptosis in nude mice and could be as a natural nutrient supplements or chemopreventive agent in the treatment of human colon cancer.

Effects of recombinant human growth hormone on growth of human gastric carcinoma xenograft model in nude mice

AIM： To study effects of recombinant human growth hormone （rhGH） on growth of a human gastric carcinoma cell in vivo. METHODS： Experimental mice were divided into control group, rhGH group, oxaliplatin （L-OHP） group and rhGH＋L-OHP group. Cultured human gastric carcinoma cells BGC823 were inoculated into right axilla of nude mice and carcinoma xenograft model was established successfully. Inhibitory rate of xenograft tumor growth was estimated by measuring tumor volume; expression of proliferating cell nuclear antigen （PCNA）, Bax and Bcl-2 proteins of xenograft tumor was detected using immunohistochemical S-P method. RESULTS： Tumor growth inhibitory rate, the positive expression rate of PCNA, Bax and Bcl-2 were 49.3%, 58.2%, 65.2% and 59.2% in rhGH＋L-OHP group respectively; 46.6%, 62.5%, 59.7% and 64.7% in L-OHP group; 5.0%, 82.7%, 23.2% and 82.2% in rhGH group and 0, 77.8%, 23.5% and 80.3% in control group. There was significant difference between rhGH＋L-OHP group （or L-OHP group ） and control group or rhGH group （P 〈 0.05）, whereas there were no significant differences （P 〉 0.05） between L-OHP group and rhGH＋L-OHP group and between rhGH group and control group. CONCLUSION： rhGH does not accelerate the proliferation of human gastric cancer cell in vivo.

Antitumor Activities and Apoptosis-regulated Mechanisms of Fermented Barley Extract in the Transplantation Tumor Model of Human HT-29 Cells in Nude Mice

Objective A subcutaneous transplantation tumor model of human HT-29 cells was established in nude mice to study the anticarcinogenic activities and apoptosis-regulatory mechanistic effect of aqueous extract of fermented barley with Lactobacillus plantarum dy-1 （LFBE）. Methods HT-29 cells were transplanted via subcutaneous injection of 1 × 107cells into the right flank of each nude mouse. Then, nude mice were treated for 30 days with LFBE （high-dose 2 g·kg-1·d-1; low-dose 1 g·kg-1·d-1） and for 7 days with 5-fluorouracil （5-FU, 25 g·kg-1·d-1） by gavage and intraperitoneal injection, respectively. Results Tumor volume and weight decreased significantly in both groups of nude mice treated with LFBE. In addition, the cell apoptosis rate of the LFBE group was significantly higher than that of the control group and 5-FU groups as measured by the TUNEL assay. Moreover, the real-time fluorescent quantitative PCR and Western blot methods further confirmed these apoptosis-enhancing and growth-inhibiting effects. The involvement of LFBE in inducing apoptosis was confirmed by the expression of Bax, Bcl-2, caspase-3, and cyclin D1. Conclusion The results showed that LFBE could induce subcutaneous transplantation tumor apoptosis in nude mice and could be used as a natural nutrient supplement or chemopreventive agent in the treatment of human colon cancer.

Generation and expression analysis of BAC humanized mice carrying HLA-DP401 haplotype

Background:Human leukocyte antigen(HLA)-DP is much less studied than other HLA class Ⅱ antigens,that is,HLA-DR and HLA-DQ,etc.However,the accumulating data have suggested the important roles of DP-restricted responses in the context of cancer,allergy,and infectious disease.Lack of animal models expressing these genes as authentic cis-haplotypes blocks our understanding for the role of HLA-DP haplotypes in immunity.Methods:To explore the potential cis-acting control elements involved in the tran-scriptional regulation of the HLA-DPA1/DPB1 gene,we performed the expression analysis using bacterial artificial chromosome(BAC)-based transgenic humanized mice in the C57BL/6 background,which carried the entire HLA-DP401 gene locus.We further developed a mouse model of Staphylococcus aureus pneumonia in HLA-DP401 humanized transgenic mice,and performed the analysis on the expres-sion pattern of HLA-DP401 and immunological responses in the model.Results:In this study,we screened and identified a BAC clone spanning the entire HLA-DP gene locus.DNA from this clone was analyzed for integrity by pulsed-field gel electrophoresis and then microinjected into fertilized mouse oocytes to produce transgenic founder animals.Nine sets of PCR primers for regional markers with an average distance of 15 kb between each primer were used to confirm the integrity of the transgene in the five transgenic lines carrying the HLA-DPA1/DPB1 gene.Transgene copy numbers were determined by real-time PCR analysis.HLA-DP401 gene expression was analyzed at the mRNA and protein level.Although infection with S aureus Newman did not alter the percentage of immune cells in the spleen and thymus from the HLA-DP401-H2-Aβ1 humanized mice.Increased expression of HLA-DP401 was observed in the thymus of the humanized mice infected by S aureus.Conclusions:We generated several BAC transgenic mice,and analyzed the expres-sion of HLA-DPA1/DPB1 in those mice.A model of S aureus-induced pneumonia in the HLA-DP401-H2-Aβ1^(-/-)humanized mice was further developed,and S aureus in-fection upregulated the HLA-DP401 expression in thymus of those humanized mice.These findings demonstrate the potential of those HLA-DPA1/DPB1 transgenic humanized mice for developing animal models of infectious diseases and MHC-associated immunological diseases.

Inhibitory effect of parvovirus H-1 on the formation of colonies of human hepatoma cell line in vitro and its tumors in nude mice

The inhibitory effect of parvovirus H-1 on the colonyforming ability in vitro of QGY-7703, a cultured human hepatoma cell line, and on the formation and growth of its tumors in nude mice was studied. With higher multiplicity of infection (MOI) of H-1 given, survival of the QGY-7703 cells was found to be decreased. H-1 DNA amplification level at 30 h postinfection(p.i.) was detected to be 7.4 times higher than that at 2 h by dispersed cells assay, while the cells were delayed to enter into S phase.Plaques were formed in the indicator cells (new-born human kidney cell line, NBK) by progeny H-1 virus particles released from the infected QGY-7703 cells by infectious cell center assay. The formation of tumors in nude mice by QGY-7703 cells which were injected s c at 2 h postinfection was observed to be prevented in 2 groups with given MOI 25 and 50. The tumor growth of MOI 10 group occurred at a lower exponential rate than that of control,after a 20 d latent period. It was evident that parvovirus H-1 exhibited a direct inhibitory effect on the formation and growth of human hepatoma cells in vivo as well as in vitro.

Experimental study on effect of recombinant human growth hormone combined with chemotherapy on stomach neoplasms implanted in nude mice

Objective: To investigate the effect of different doses of recombined growth hormone (rhGH) on stomach neo- plasms implanted in nude mice, and its efficacy in combining with chemotherapy (flurouracil, 5-FU). Methods: Human stom- ach neoplasms model was established in nude mice. The nude mice were divided into control group, moderate-dose of rhGH group, low-dose rhGH group, 5-FU group, moderate-dose rhGH/5-FU group, and low-dose rhGH/5-FU group. The results of each group were observed after ten days. Results: After therapy, the body mass of rhGH groups was significantly increased compared with control group (P<0.05), the body mass of rhGH/5-FU groups was significantly increased compared with 5-FU group (P<0.05), but it was no significant difference between rhGH/5-FU groups and control group (P>0.05). The average tumor mass and volume of rhGH groups were not significantly increased compared with control group (P>0.05), but they were significantly reduced in 5-FU group and rhGH/5-FU groups (P<0.05). They were no significant difference between rhGH/5- FU groups and 5-FU group (P>0.05). After treatment, the percentages of S, G0/G1 and G2/M phases and proliferation index (PI) were not significantly changed in rhGH groups compared with control group (P>0.05), and the same with rhGH/5-FU groups compared with 5-FU group (P>0.05). The difference caused by dose of rhGH was not significant. Conclusion: rhGH enhances body mass, does not stimulate tumor growth, and has no adverse effects on tumor bearing nude mice. Combined with flurouracil, rhGH does not influence the efficacy of chemotherapy, and has no effect on tumor cell cycle kinetics.

Localization and Biodistribution of Conjugate ATG－Dex－DNR in Nude Mice as Models for Human Leukemia

I-labelled anti-thymoglobuline (ATG), 131 I-labelled immunoconjugate ATG-Dex-DNR and 131 I-labelled Ts-MoAb as control antibody, respectively.were injected by intraperitoneal (i. p.) administration into nude mice used as models for human T-cell leukemia. SPECT imaging was performed from day 1 to day 8 following i. p. injection. The results showed that radioimmunoimaging of buman tumor xenografts was clearest day 3 after injection in both of ATG and ATG-Dex-DNR groups, whereas it's not the case in Ts-MoAb group. Nude mice were killed 8th day after injection with antibody or conjugate. The tumor, as well as different dissected normal organs including heart, liver, lungs, kidney, femur and intestine, were harvested, weighed precisely, and radioiodine-counted. T/NT ratios in experimental group was greater than 1. 0 (ranged from 1. 246-7. 865). and in control group they were less than 1. 0 (ranged from 0. 263-0. 757, except for tumor/femur ratio). Our results indicated that ATG and ATG-Dex-DNR had specific affinity to cell line of Tcell leukemia CEM.

Feasibility study on construction of humanized mice with antibiotics combined with fecal bacteria transplantation

Objective:To select a common method of humanized mice and verify its feasibility with the aim to provide atheoretical basis for subsequent fecal bacteria transplantation research.Methods:1.Specific Pathogen Free(SPF)mice were fed with antibiotics mixed with sterilized drinking water for 3 weeks,during which the general situation of mice was recorded.After 3 weeks,the number of microbes in mice's feces was evaluated by Gram staining.2.After antibiotic treatment,mice were transplanted fecal bacteria by gavage for a week.Then,the contents of fecal bacteria in the donor and recipient feces was determined by RT-PCR,to evaluate the colonization effect of fecal bacteria.Results:(1)Antibiotic treatment had an effect on weight,feed and drinking water consumption of mice,and the fecal bacteria in mice decreased obviously.(2)After fecal bacteria transplantation,the Firmicutes,Bacteroidetes and Firmicutes/Bacteroidetes of the mice receiving Donor1 fecal bacteria accounted for 15.4%,112%and 13.7%of the mice receiving Donor2 fecal bacteria,respectively.The Firmicutes,Bacteroidetes and Firmicutes/Bacteroidetes of Donor1 fecal bacteria accounted for 33.7%,104%and 32%of Donor2,respectively.The recipient's gut microbes had the same trend as human donors.Conclusions:These results indicate that antibiotic treatment combined with fecal bacterial transplantation is feasible and safe for humanizing SPF mice.

RESPONSE OF HUMAN RENAL CANCER TO UFT IN NUDE MICE

A primary human renal cell carcinoma was developed as a xenograft (NT-25) and maintained by serial transplantation in nude mice. The effect of UFT on this neogrowth was tested and evaluated as well its distribution in the animal tissues. The concentration of UFT was higher in tumor tissues than that in other tissues and in the animal experimentation UFT was found to be effective on human renal cell carcinoma.

ANTI-HUMAN LUNG GIANT CELL CANCER (PG) EFFECT OF HUMAN LAK CELLS IN VITRO AND IN NUDE MICE

Human LAK cells were prepared by culturing normal human peripheral blood mononuclear cells (PBMC) with or without rIL-2 and assayed for T cell surface markers as well as anti-tumor activity against PC in vitro and in nude mice. Although the percentages of T3, T4, and T8 positive cells in rIL-2-activated cells did not differ significantly from those of control cells in vitro, the former showed stronger cytotoxicity than control cells to PG tumor cells in vitro. In vivo, LAK cells completely inhibited the growth of PG tumor in nude mice, whereas PBMC control cells were to be of no effect. The anti-tumor effect of human LAK cells in nude mice may offer a useful model to study the role of human LAK cells against human tumor in vivo.

EFFECTS OF PSEUDOFYPE RETROVIRUS CONTAINING HUMAN N-RAS ANTISENSE GENE ON THE GROWTH OF HUMAN LIVER CANCER LTNM4 TRANSPLANTED IN NUDE MICE

An amphotropic pseudotype retrovirus containing human N-ras antisense gene was constructed and packaged with helper cells. It has been previously demonstrated that the virus did inhibit the growth of human hepatocarcinoma cell line PLC PRF/5 in vitro accompanied with the blockage of p21 expression. Based on these results, further study was carried on to examine the effect of these viruses on the growth of human hepatoma transplanted LTNM4 in nude mice. It has been shown that the retrovirus containing human antisense N-ras gene could inhibit the hepatoma in nude mice at a rate of 78% (P<0.05) as compared with saline control. No inhibition was observed in group treated with retrovirus which contained no N-ras sequence. These results in vivo lend further support that human N-ras antisense gene mediated by retrovirus could block the expression of the relevant oncogene and lead to the inhibition of cancer growth. It also provided the basis for further approaches of gene therapy for human cancer.