GENE THERAPY

GENE THERAPY: 

GENE THERAPY Presented By, Rinu P Jose First year M. Pharm Dept. of pharmaceutics Date:27-06-11

CONTENTS : 

CONTENTS DEFINITION BASIC TECHNIQUE IN GENE THERAPY GENE MODIFICATION GENE TRANSFER GENE TRANSFER IN SPECIFIC CELL LINES EUGENIC APPROACH APPLICATION REFERENCE 2

GENE THERAPY: 

GENE THERAPY It is the treatment of disease by the transfer and expression of genetic material in a patient cell in order to restore normal cellular function. The newly introduced genes will encode proteins and correct the deficiencies that occur in genetic diseases. 3

AN Overview OF GENE THERAPY: 

AN Overview OF GENE THERAPY 4 GENE EXPRESSION GENE DELIVERY MAKING COPIES OF CORRECTED GENE

BASIC TECHNIQUE IN GENE THERAPY: 

BASIC TECHNIQUE IN GENE THERAPY Entry of the therapeutic nucleic acid with its vector into the cell cytoplasm. Transfer of the nucleic acid into the nucleus of the recipient cell, followed by integration of the foreign genetic material into the cellular DNA. The foreign gene is expressed, resulting in the synthesis of the desired protein product. 5

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There are 4 approaches to achieve gene therapy. They are: Gene modification Gene transfer Gene transfer in specific cell lines Eugenic approach 6

GENE MODIFICATION : 

GENE MODIFICATION REPLACEMENT THERAPY - A defective gene is inserted somewhere in the genome so that its product could replace that of a defective gene. -Mainly used for recessive disorders ,that is in case of deficiency of an enzyme or other proteins. 7

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2. CORRECTIVE GENE THERAPY Replacement of a mutant gene or a part of it with a normal sequence. Suppression of a particular mutation by a transfer RNA that is introduced into a cell. 8

GENE TRANSFER: 

GENE TRANSFER PHYSICAL METHOD a. Microinjection - A fine capillary needle is used to deliver DNA into cells. - Small structures can be injected. - The amount of DNA delivered per cell is not limited. - Only one cell is targeted per injection. - Handling requires specialized skill and instrumentation. 9

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b. Gene gun - DNA can be coated onto gold particle and can be ‘shot’ into superficial cells using a “gene gun”. - The DNA is co-precipitated onto gold particles and propelled form a Mylar sheet using an electric spark or pressurized gas. - Used for targeting DNA to skin and skin tumors. 10

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c. Electroporation - An electric pulse is used to introduce DNA into cells. - By exposure to brief electric shock, the cells become temporarily permeable to DNA. - It is a convenient, simple, fast and efficient method. - It involves low cell toxicity. 11

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2. CHEMICAL METHOD Liposome - Liposome's are small artificial lipid vesicles in which large number of DNA are enclosed. - Nucleic acid entrapped in such liposome’s renders them highly tolerant to attack by nucleases. Adv: Targeting of drugs to intracellular location and reduces toxicity 12

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3. BIOLOGICAL METHOD a. Viral vectors - Vectors are the carrier particles or molecules used to deliver genes to target site Adenovirus - Large, non enveloped structures and have double stranded DNA as their genetic material. - Only a small fraction of genome is removed when constructing an adenovirus based vector. - Upon cellular infection, adenoviral DNA becomes localized in the nucleus, but does not integrate into the host cell DNA. 13

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Retroviral vectors - Enveloped virus and RNA is the genetic material. - Upon entry into sensitive cells, viral RNA is reverse transcribed and yields double stranded DNA - This subsequently integrates into host cell genome. - This contain a minimum of 3 structural genes; gag ( codes for core viral protein), pol (codes for reverse transcriptase) and env (codes for viral envelop proteins). 15

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GENE DELIVERY USING RETROVIRUS 16

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Herpes simplex virus (HSV) - It is a neurotrophic virus, useful in delivering genes to neurons of the peripheral and central nervous system. - Upon infection HSV usually remains latent in non dividing neurons with its genome remaining in an un integrated form. b. Human Artificial Chromosomes - Synthetically produced vector DNA, possessing the characteristics of human chromosome. - It can carry human genes that are too long. 17

GENE TRANSFER IN SPECIFIC CELL LINES: 

GENE TRANSFER IN SPECIFIC CELL LINES a. SOMATIC GENE THERAPY - Insertion of a fully functional and expressible gene into a target somatic cell to correct a genetic disease permanently. - These are not passed to the offspring . b. GERM CELL GENE THERAPY - This involves the introduction of DNA into germ cell is passed on to the successive generations. 18

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EUGENIC APPROACH (GENE INSERTION): 

EUGENIC APPROACH (GENE INSERTION) - This is by inserting gene to alter or improve complex traits of a person. Gene therapy are of 2 types: 1. Ex-vivo gene therapy - This involves the transfer of genes in cultured cells which are then reintroduced into the patient. 20

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2. In-vivo gene therapy This is the direct delivery of genes into the cells of a particular tissue. APPLICATIONS OF GENE THERAPY Gene therapy can be applied to a large variety of diseases such as those arising from malfunctioning of organs , cancer, and infections. 1. cystic fibrosis 2 .Familial Hypercholesterolemia 3. Atherosclerosis 4. Cancer 22

REFERENCE: 

REFERENCE U. Satyanarayana et.al, Biochemistry, third edition, Uppala , Books and Allied (P) Ltd, P:625-633. S.S. Purohit , Biotechnology Fundamentals and applications, third edition, student edition, P:153-157. Gary Walsh,Biopharmaceuticals Biochemistry and Biotechnology, P:465. Channarayappa , Molecular Biotechnology Principles and Practices, published by Universities Press, P. 608-610, 497-500. http://www.scribd.com/doc/55097706/Gene-Therapy-Ppt 23

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24 THANK YOU