Gene therapy

GENE THERAPY A GIFT TO MODERN MEDICINE

1. By, Ved prakash panda M.Pharm (Pharmacology)

2. Definition: Gene Therapy is a field of medicine in which the genes are introduced into the body to cure the diseases. It is the intracellular delivery of genes to generate a therapeutic effect by correcting an existing abnormality.

3. What is a gene? The chromosomes of the cell is made of coils of DNA. DNA is organised in the form of genes. Genes are bits of DNA. The entire sets of genomic material is Genome. Human genome=30000 genes. Genes are coded to produce proteins. Genetic instructions are carried out by the proteins.

4. Gene therapy involves Detection of gene Determination and its role Isolation and cloning Introducing the gene by proper way - germ line gene therapy -somatic gene therapy

5. Somatic cell gene therapy Somatic means non-productive cells of an organism These are the cells other than egg and sperm cells. Ex: Bone marrow cells , blood cells , skin cells It involves the insertion of functional and expressible gene into a target somatic cell to correct the diseases permanently.

6. Germ cell gene therapy Germ cells are reproductive cells. It involves introduction of DNA into germ cells, which is passed onto the next generations. Genetic alterations in somatic cells are not carried to next generations . Therefore somatic is preferred.

7. Approaches for gene therapy 1 . Gene modification a)Replacement Therapy b)Corrective gene Therapy 2. Gene Transfer a)Physical(gene gun , naked DNA) b)Chemical(CaPO4 transfection) c)Biological(Viral vectors) 3. Gene transfer in special cell lines

8. GENE GUN: Employs a high pressure delivery system to shoot tissue with gold or tungsten particles that are coated with DNA. MICROINJECTION: Process of using a glass micropipette to insert microscopic substances into a single living cell. Normally performed under a specialized optical microscopic setup called as micromanipulator.

9. USING DETERGENTS: Certain charged chemical compounds like calcium phosphate are mixed with functional cDNA o desired function. The mixture is introduced at the vicinity of recipient cells. The chemicals disturb the cell membrane widens the pore size and allows the cDNA to pass through the cell.

10. LIPOFECTION: It is a technique used to inject genetic material into a cell by means of liposomes . Liposomes are artificial phospholipid vesicles used to deliver a variety of molecules including DNA into the cells.

11. Gene therapy is used to treat a number of diseases such as 1.Cancer 2.HIV 3.Haemophilia 4.Severe combined Immuno deficiencies 5.Parkinson’s disease 6.Diabetes

12. TYPES OF GENE THERAPY Ex vivo gene therapy It involves transfer of genes into cultured cells which are then reintroduced into the patient. ex : bone marrow cells Technique involves following steps Isolate cells with genetic defect Grow the cells in culture Introduce therapeutic gene to correct defect Select genetically corrected genes and grow Transplant the modified cells to the patient

13. In vivo gene therapy Direct delivery of therapeutic gene into target cells of a particular tissue ex : liver , muscle ,skin , spleen. Gene delivery by viral/non viral systems By non viral systems means viral proteins induce inflammatory responses in host Depends on efficiency of uptake of genes by target cells

14. VECTORS IN GENE THERAPY To transfer the desired gene into a target cell , a carrier is required. Such vehicles of gene delivery are known as vectors. Vectors are of two classes 1.Viral vectors 2.Non-viral vectors

15. GENE THERAPY IN TREATMENT OF DIABETES Diabetes mellitus is the most common endocrine disorder. It is a chronic condition which is characterised by hyperglycaemia due to impaired insulin secretion or with or without insulin resistance. Goal of gene therapy is to maintain normoglycemia irrespective of the diet intake. Whole pancreas or islets cells transplantationbut it is difficult and complex.

16. T ype 1 DM : Results from the body failure to produce enough insulin. This is called as insulin dependent diabetes mellitus or juvenile diabetes Type 2 DM : Begins with insulin resistance , a condition in which cells fail to respond to insulin properly. As the disease progresses a lack of insulin may also develop. This is also called as non insulin de[pendent diabetes mellitus

17. Recent advancement is successful islet cell transplantation by glucocorticoid free immunosuppressive regimen. Major goal in gene therapy : To generate an unlimited source of cells exhibiting glucose responsive insulin secretion. Should be used for transplantation.

18. Gene therapy of Type 1 DM: Facilitation of Islet transplantation: Exvivo transduction of vectors encoding immunoregulatory transgenes . In vivo administration to transplantation site of vectors encoding factors for islets. Tolerance induction Invivo administration of vectors encoding putative autoantigens . Immunomodulation using vectors.

19. Gene therapy of Type 2 DM Prevention of insulin resistance: Transduction of adipose or muscle cell with vectors encoding insulin sensitizing genes and proteins or peptides. Anti obesity strategy: Transduction of adipose with vectors encoding anti lipolytic genes.

20. Genes promoting islets survival Anti apoptic genes: Manganese superoxide dismutase Dominant negative protein kinase C delta Immunoregulatory genes: Indoleamine 2,3 dioxygenase Cytokines: IL-1 receptor antagonist protein

21. References: Drug discovery and development: Rang and dale www.google.com Clinical pharmacology : D.R. Lawrence

22. THANK YOU