大学精品课件：生物工程制药课件：lec14 Gene Therapy.ppt

1、nlec14 Gene TherapynLec15 Stem cellsnLec16 patent applicationGene TherapyFirst Human Gene Therapy TrialnConducted in 1990 in EuropenPatient was a young girl with SCIDnSevere Combined ImmunoDefeciencynSingle gene defectnAdenosine deaminaseTwo setbacks in gene therapyn1.In 1999,gene therapy suffered a

2、 major setback with the death of 18-year-old Jesse Gelsinger.Jesse was participating in a gene therapy trial for ornithine transcarbamylase deficiency(OTCD).n2.In 2000,two children participated in a gene therapy for X-linked severe combined immunodeficiency disease(X-SCID)developed leukemia-like con

3、dition.The first commercial gene therapy(2003)nIn 2003,China s State Food and Drug Administration granted approval to the Shenzhen SiBiono GenTech for the worlds first commercial gene therapy product,Genedicine.The drug,which was developed for$9.6 million dollars in addition to government research g

4、rants,uses an adenoviral vector to deliver genes to head and neck squamous cell carcinoma(HNSCC,鳞状细胞癌)patients,of which there are 250,000 new cases in China every year,according to Nature Biotech.DefinitionnTreatment of a disease caused by a faulty gene,by Stably transducing or transfecting the malf

5、unctioning cells of the diseased organism with a normal gene.Gene therapy strategiesn1.In vivo gene therapyn2.Ex vivo gene therapyRetrovirus life cyclenInfection of target cellnRNA genome converted to dsDNA copynDNA transported to nucleusnIntegration of DNA into chromosomenTranscription of viral DNA

6、 to yield mRNAnTranslation of mRNA to yield gag,pol,envnCapsid forms,mRNAs/RTase packagednViral particles shed from infected cellsProblems caused by retroviral vector gene therapynInsertional mutagenesis:n(1).Bone marrow cells transduced with retroviral vector induced leukaemia in micen(2).Bone marr

7、ow cells transduced with retroviral vector during the severe combined immunodeficiency trials had developed leukaemia-like disorder,as a result of the vector genome integration in,or near,the oncogene LMO2.Adenovirus life cyclenInfection of target cellnViral dsDNA released to cytoplasmnViral dsDNA t

8、ransported to nucleus and made an episomenViral DNA replicatednEarly genes activated to produce enzymes for DNA replicationnLate genes activated to synthesize capsid proteinsnViral DNA packagednViral particles shed from infected cellProblems caused by adenovirus vector gene therapynLack of adenoviru

9、s specificity:nLack of adenovirus specificity was directly linked to the Induction of the massive systemic immune response that caused the death of Jesse Gelsinger in 1999Solutions to adenovirus vector gene therapy Place the therapeutic gene under the control of a cell-type specific promoter.The vir

10、al particles infect many different cell types,but the transgene is not actively expressed in cell types that do not express the transcription factors that are necessary to drive the expression from the cell-type-specific promoter.Adeno-retroviral chimeric vectorn(1)Incorporate the favorable attribut

11、es of different vectors.n(2)Combine the wide range of target cells and high transduction efficiency of adenovirus vectors with the integrative capacities derived from retrovirus vectorsLiposomesnSpherical vesicles composed of synthetic lipid bilayers that mimic the structure of biological membranesn

12、The transgene is packaged in vitro with liposomes and used directly for delivering the DNA to a suitable target tissue in vivonThe lipid coating protects the DNA in vivo and binds to cellsnThe packaged DNA enters into cells by endocytosisnThe efficiency of transfer is low and the introduced DNA does not integrate into chromosomal DNA.