Chinese scientists find a new way to treat AIDS and leukemia!

Recently, in a research report published in the international journal the New England Journal of medicine, researchers from Deng Hongkui research group of Peking University Tsinghua University Life Science Joint Center, Chen Hu research group of the fifth medical center of PLA General Hospital and Wu Hao research group of Beijing You'an Hospital Affiliated to Capital Medical University published "CRISPR edited" through joint research Stem Cells in a Patient with HIV and Acute Lymphocytic Leukemia "(the long-term reconstruction of adult hematopoietic stem cells in patients with AIDS and acute lymphoblastic leukemia by CRISPR gene editing) research paper, this research result marks the first case in the world to treat AIDS and leukemia patients by gene editing stem cells successfully completed by Chinese scientists! Transplantation of CCR5 modified HSPCs Photo source: Lei Xu et al N Engl J Med 2019 doi: 10.1056/nejmoa1817426 As we all know, crispr-cas9 gene editing tool has been widely used to edit the genome of mammalian cells This technology has shown a potential clinical application prospect At present, researchers have begun to use this technology to explore the safety and feasibility of CRISPR based therapy for human diseases CCR5 is a protective target of HIV-1 infection The blood cells lacking CCR5 often have great resistance to HIV-1 infection Some studies have shown that when the hematopoietic stem cells and progenitor cells (HSPCs, hematopoietic stem and progenitor cells, hematopoietic stem cells) carrying natural CCR5 mutations are allogeneic Because CCR5 is the key co receptor for HIV to enter the body, these cases may increase the possibility of transplanting cells that artificially destroy CCR5 or can be used as a new method to make HIV-1 infection resistant cells In the previous study, the researchers established a virus-free editing system of CRISPR gene, which can produce human HSPCs with CCR5 destroyed, with an efficiency of 27%; in the animal model, these CCR5 modified HSPCs can produce a strong immune system that is resistant to HIV-1 infection; in this study, the researchers transferred the removed hematopoietic stem cells (HSPCs) edited by CRISPR In patients with HIV-1 infection and acute lymphoblastic leukemia (all), the researchers found that all could be completely relieved (full donor chimerism), and the donor cells with CCR5 removed could survive in the patients for more than 19 months, while the patients did not show adverse reactions related to gene editing During the interruption of antiretroviral therapy, the proportion of CD4 + T cells with CCR5 removed increased slightly Although the researchers have achieved the success and long-term transplantation of HSPCs edited by CRISPR, the proportion of CCR5 destroyed in lymphocytes is only about 5%, which needs further research later In 2017, Deng Hongkui's research group optimized the technical system and committed to the clinical application of the technology At present, it has passed the examination and approval of the ethics committee of the 307th Hospital of the former PLA and has registered the clinical research on the website of clinical trials.gov (nct03164135) The patients in this study were diagnosed as HIV-AIDS and all (T cell type) 16 times on May 14 and May 16, 2016 respectively The viral load in the patients was 8.5 * 106 copies / ml, and the CD4 + cell count was 528 * 106 / L the patients were randomly treated with antiretroviral drugs, i.e 300 mg lamivudine and 300 mg lamivudine per day Mg tenofovir and twice a day lotonavir ritonavir (400mg and 100mg) After one year of treatment, the HIV-1 infection in the patients can be effectively controlled, and the presence of viral RNA in the serum can not be detected (i.e less than 40 copies / ml); the patients also received six courses of all standard chemotherapy, which made the symptoms of the patients completely relieved, After detection by flow cytometry, the minimal residual disease was 3.10% and 0.04% before the 5th and 6th course of chemotherapy, respectively After the 6th course of chemotherapy, the minimal residual disease was not detected (less than 0.01%) The donor is a 33 year old male donor from the Chinese bone marrow donation program He carries an unmodified cccr5 gene and has a HLA (histocompatibility antigen) that matches the receptor perfectly September 2017 The patient received allogeneic hematopoietic stem cell transplantation In this study, the researchers reported that HSPCs with CCR5 mutation edited by crispr-cas9 gene were successfully transplanted to HIV-1 patients with all The donor cells were completely chimeric After HSPCs transplantation, all of the patients could maintain complete remission within 19 months During this period, the modified CCR5 gene could continue to exist, CCR5 in bone marrow cells The mutation range is 5.20% - 8.28% The results show that the researchers can achieve long-term transplantation of HSPCs edited by CRISPR However, the response efficiency of recipients after transplantation may not be enough to achieve the goal of curing HIV-1 infection In the 19 month follow-up observation, they found that CRISPR mediated CCR5 removal efficiency was 5.20% - 8.28% in bone marrow samples At the same time, CRISPR mediated CCR5 removal was observed in multiple hematopoietic lineage cells, which indicated that CCR5 knockout / mutant HSPCs could be transplanted to patients for a long time and play a corresponding role In particular, the CD4 + T cells and CCR5 mutants in the patient's body can continuously produce and release into the patient's peripheral blood, and the number of CD4 + T cells in the peripheral blood will gradually return to normal level within 6 months after transplantation At the same time, the treatment of HIV-1 infection can provide opportunistic protection for the patient The important point of this study is that researchers can evaluate the clinical safety of crispr-cas9-mediated gene therapy Previously, HSPC based gene therapy was not so effective, because exogenous DNA would be randomly integrated into the host genome, sometimes even lead to acute immune response or tumor occurrence In this study, the researchers introduced cas9 ribonucleoprotein through non viral transfection, which can effectively avoid the introduction of exogenous DNA and the long-term presence of cas9 in the target cells, which may be the potential factors leading to unexpected Miss target mutations Using the high-throughput whole genome sequencing method, the researchers analyzed the samples of patients before transplantation and 15, 12 and 19 months after transplantation The results showed that no single nucleotide mutation, large fragment deletion and chromosome rearrangement related to CRISPR modification were detected In addition, the researchers did not observe any negative events related to gene editing The clinical adverse events caused by gene editing and miss targeting often provide preliminary support for the safety of gene editing methods However, at present, the low efficiency of targeting CCR5 may limit the depth of Miss gene editing analysis Therefore, it is necessary for researchers to further analyze the safety and efficacy of CCR5 mutation in crispr-cas9-mediated HSPCs under the higher gene targeting effect Rate Anti retroviral therapy was interrupted 7 months after HSPCs transplantation, and the researchers observed an increase in the rate of CCR5 deletion in patients after two weeks of interruption; the decrease in gene editing efficiency in patients may be due to the competitive transplantation of CD34 deficient cells co fused with HSPCs and the persistence of donor T cells, in order to further clarify the efficacy of CCR5 mutant HSPCs against HIV-1 Therefore, it is necessary for researchers to increase the efficiency of crispr-cas9 gene editing system and improve the transplantation scheme Recent studies have shown that the homozygosity of CCR5 - Δ 32 mutations is often related to the decline of life expectancy of patients, which may highlight the potential harmful effects of CCR5 mutations at the individual level; however, unlike other gene editing strategies to control HIV infection, the elimination / mutation of CCR5 in the hematopoietic system of HIV infected patients does not change gene expression in non hematopoietic tissues All in all, this latest study by Chinese scientists describes the long-term transplantation of CD34 + cells edited by CCR5 CRISPR gene after allogeneic stem cell transplantation, with less than 8% gene interference rate to the genome of circulating bone marrow cells, and there is no gene editing Miss target effect This long-term work has initially confirmed the feasibility and safety of gene editing hematopoietic stem cells in clinical application, and will promote and promote the clinical application of this technology in the future In the future, researchers will continue to study various methods to optimize the gene editing hematopoietic stem cell transplantation scheme, so as to reduce the miss rate and achieve 100% CCR5 knockout efficiency.