Objective : To construct myeloid specific Spi1 gene knockout mice and analyze their genotypes , so as to provide animal model basis for the study of pathological mechanism of diseases and drug targets . Methods : According to the principle of CRISPR/Cas9 technology and C re/LoxP system , sgRNA and Donor vectors were de signed and constructed . The transcript of Exon 2 ( Exon 2) was used as the knockout region , and Loxp elements were placed on both sides of Exon 2 . Cas9 protein , sgRNA and Donor vector were mixed and microinj ected into the fertilized eggs of C57BL/6J mice , the fertilized eggs were transplanted into the uterus of C57BL/6J pregnant female mice , and F0 generation was obtained after 19 ~ 20 days . Positive F0 mice were mated with C57BL/6J mice to ob tain stable F1 Spi1 flox/ + mice . Spi1 flox/ + mice of F1 generation were selfed to obtain Spi1 flox/flox mice . Spi1 flox/flox mated with Lyz2-Cre + mice to obtain Spi1 flox/ + /Lyz2-Cre + mice , and then mated with Spi1 flox/flox , the Spi1 flox/flox/Lyz2-Cre + mice were myeloid specific Spi1 gene knockout ( KO) mice . Spi1 flox/flox/Lyz2-cre - mice were used as wild type (WT) mice . DNA of WT and KO mice was extracted , and the genotypes were identified by agarose gel electro phoresis after PCR amplification . Western blot was used to detect the expression of spleen focus forming virus proviral integration oncogene , Spi - 1 /purine rich box - 1(PU . 1) in immune cells of WT and KO mice . Results: The results of PCR identification showed that the genotype of mice with only 220 bp amplified by flox primer was Spi1 flox/flox homozygote , and the genotype of mice with 700 bp amplified by Lyz2-Cre primer was Lyz2-Cre + . Western blot showed that compared with WT group , the protein PU . 1 was not expressed in bone marrow derived macropha ges (BMDMs ) and peritoneal macrophages (PM) in KO group (P < 0.01) . There was no significant difference of statistics in the expression level of PU . 1 in T cells between KO mice and WT mice . The results of PCR and West ern blot showed that myeloid specific Spi1 KO mice were successfully constructed . Conclusion The myeloid spe cific Spi1 gene KO mice are successfully constructed and identified , which provides animal model basis for further revealing the potential mechanism of PU . 1 inimmune regulation .

Objective : To construct Csf1r-CreERT2 R26REYFP reporter gene mice and assess the efficacy of Csf1r- CreERT2 -mediated enhancement of CSF1R in CD45 + cells labeled with yellow fluorescein protein EYFP． Methods: Csf1r-CreERT2 mice were crossbred with R26REYFP homozygous mice，and Csf1r-CreERT2 R26REYFP mice were identified through PCR and Western Blot analyses．Flow cytometry was employed to evaluate CSF1R tag-efficiency in CD45 + cells across different mouse tissues following tamoxifen induction. Results : Csf1r-CreERT2 R26REYFP reporter gene mice were acquired．In addition，it was found that Csf1r-CreERT2 -mediated EYFP could effectively mark CSF1R in various tissues of mice and CD45 + cells in different locations．Compared to the R26REYFP group，the highest labeling efficiency was observed in the brain tissue (P＜0. 001) ，the lowest in the thymus tissue (P＜0. 05) ，and no sig- nificant difference was observed in the spleen tissue． Conclusion Adult Csf1r-CreERT2 mice and R26REYFP mice are effective ways to obtain Csf1r-CreERT2 R26REYFP induced conditional fluorescence mice．Csf1r-CreERT2 can mediate EYFP to effectively trace CSF1R in CD45 + cells in different parts of mice.

Objective : To breed and identify the T lymphocyte-conditional Spi1 knockout mice for the further in- vestgation of the specific role of Spi1-encoded protein PU. 1 . Methods : The Lck-Cre mice were mated with Spi1 flox/flox mice to obtain Lck-Cre ×Spi1 flox/flox mice (T lymphocyte-specific Spi1 knockout mice) , and the genotype was determined by polymerase chain reaction (PCR) and agarose gel electrophoresis . Magnetic beads were used to sort out the splenic T lymphocytes , and the knockdown efficiency of PU. 1 in T cells was detected by Western blot , quantitative real-time PCR ( qPCR) and flow cytometry. Results : The Lck-Cre ×Spi1 flox/flox mouse genotype was stably inherited . Compared with Spi1 flox/flox mice , the expression level of PU. 1 was significantly reduced in splenic T cells of Lck-Cre ×Spi1 flox/flox mice . Conclusion In this study , the T lymphocyte-specific Spi1 knockout mice was successfully constructed by applying Cre/LoxP system and CRISPR/Cas9 technology , which provided a reliable an- imal model for the subsequent experiments of the specific role of PU. 1 in T cell-related diseases .

Objective: To obtain chimeric antigen receptor macrophages ( CAR-M) targeting HER2 stably transfected． Methods : CAR lentivirus vector targeting HER2 was constructed and infected with human monocytic leukemia cell line (THP-1) ．CAR THP-1 cells with green fluorescent labeling were selected by sorting flow cytometry and continued to be cultured in vitro．The CAR THP-1 cells targeting HER2 were co-cultured with the endometrial cancer cell line Ishikawa with negative and positive HER2 expression，and their targeted phagocytosis of CAR-M to HER2 positive tumor cells was detected by imaging flow cytometry ，and the targeted phagocytosis efficiency of CAR-M to HER2 positive tumor cells was detected by flow cytometry. Results : CAR lentivirus infection with THP- 1 cells was less efficient ; After co-culture with cancer cells，flow cytometry and imaging flow cytometry showed that CAR THP-1 cells had enhanced phagocytosis of HER2 positive Ishikawa cells compared with the empty body group (P＜0. 01) ． Conclusion In this experiment，CAR THP-1 cell line targeting HER2 was established by constructing CAR lentivirus vector and transfecting THP-1 cells ，and it was proved that CAR THP-1 could phagocytize HER2 positive Ishikawa cells through specific targeting.