Gene therapy.pptx

Gene therapy

1. Gene Therapy in Periodontics Presented By DR ASIF K DEPARTMENT OF PERIODONTICS

2. Contents INTRODUCTION HISTORY FUNDAMENTALS TYPES OF GENE THERAPY GENE DELIVERY IMPLICATIONS TISSUE ENGINEERING APPLICATIONS LIMITATIONS CONCLUSION

3. Intro d uction Genes are carried on chromosomes and are the basic physical and functional units of heredity.

4. Why genetic disorders When genes are altered so that the encoded proteins are unable to carry out their normal functions, genetic disorders can result .

5. What we inherit from parents Most of us do not suffer any harmful effect s fro m o u r d efectiv e g e n e s b eca u se we carry two copies of nearly all genes, one derived from our mother and the other from our father.

6. What is Gene Therapy Gene therapy is a technique for correcting defective genes responsible for disease development.

7. It involves the transfer of a therapeutic or working gene copy into specific cells of an individual in order to repair a faulty gene copy, which is to cure or to favourably modify the clinical course of a condition. It has a promising era in the field of periodontics. Periodontal diseases, have a broad spectrum of inflammatory and destructive responses, and are thought to be multifactorial in origin.

8. How it works A vector delivers the therapeutic gene into a proteins patient target cell The target cells become infected with the viral vector The vector‟s genetic material is inserted into the target cell Functional proteins are created from the therapeutic gene causing the cell to return to a normal state

9. What Gene therapy can achieve Replacing a mutated gene that causes disease with a healthy copy of the gene. Inactivating, or “knocking out,” a mutated gene that is functioning improperly. Introducing a new gene into the body to help fight a disease.

10. History In the mid 1980s, the focus of gene therapy was entirely on treating diseases caused by single gene defects. The first gene therapy trials on humans began in 1990 on patients with Severe Combined Immunodeficiency (SCID). In 2000, the first gene therapy "success" resulted in SCID patients with a functional immune system.

11. Fundamental There are different methods to replace or repair the genes targeted in gene therapy. A normal gene may be inserted into a nonspecific location within the genome to replace a nonfunctional gene. This approach is most common.

12. An abnormal gene could be swapped for a normal gene through homologous recombination. The abnormal gene could be repaired through selective reverse mutation, which returns the gene to its normal function.

13. The regulation (the degree to which a gene is turned on or off) of a particular gene could be altered. The Spindle transfer is used to replace entire mitochondria that carry defective mitochondrial DNA.

14. Step in gene therapy

15. Manipulation corrects the defective Gene

16. Type Of Gene Therapy Classified into two types GERM LINE GENE THERAPY: Germ cells, i.e., sperm or eggs are modified by the introduction of functional genes, which are ordinarily integrated into their genomes. Heritable SOMATIC GENE THERAPY: The therapeutic genes a r e transferr e d into t h e somatic c e lls. Inheritable

17. Gene Delivery Gene delivery is done by using Viral vectors and Non viral vectors Direct delivery/viral vectors: Retroviruses Adenoviruses Adeno-associated viruses Herpes simplex viruses Vaccina viruses Pox viruses Lenti viruses

18. Non viral/cell based delivery: Micro seeding gene therapy Cationic liposomes Macromolecular conjugate Gene activated matrices(GAMS)

19. IN VIVO: Gene therapy is done by targeting the gene delivery system to the desired cell type in the patient using either physical means such as Tissue injection (brain tumor) or Biolistics (dermal DNA vaccination), Systemic infusion of cell-specific receptor-mediated DNA carriers (reconstructed liposome’s or viruses)

20. EX VIVO : E x -vi v o g e ne t h e r a p y is per f orm e d b y t r ans f e c t ing or infecting patient-derived cells in culture with vector DNA a n d t h e n r e im p l a nti n g the t r a n s f e c t e d c e lls into t h e gene therapies un d e r pat i e n t . Two t y p es o f ex- vi v o development are those dir e c t ed at f i broblas t s a n d hematopoietic stem cells .

21. Implication in Periodontitis Approaches for regenerating tooth-supporting structures Guided tissue regeneration uses a cell occlusive barrier membrane to restore periodontal tissues. Alternatively, an example of gene therapy uses vector encoding growth factors aimed at stimulating the regeneration of host cells derived from the periodontium.

22. Gene enhanced Tissue Engineering

23. There are three approach of tissue engineering in periodontics: Protein based approach : Growth and differentiation factors are used for regeneration of periodontal tissues like TGF-β, BMP-2,6,7,12, bFGF, VEGF and PDGF. Cell based approach: Using mesenchymal stem cells.

24. Gene delivery approach Gene vectors can be introduced directly to the target site (in vivo technique) or selected cells can be harvested, expanded,genetically transduced, and then reimplanted (ex vivo technique).

25. Application in Periodo n tology Gene therapeutics-periodontal vaccination Using plasmid DNA encoding the Porphyromonas gingivalis fimbrial gene resulted in the subsequent production of specific salivary IgA and or IgG, antibodies and serum IgG antibodies . This secreted IgA could neutralize P. gingivalis and limit its ability to participate in plaque formation. With genetically engineered Strepto-cocci gordoni vectors expressing P. gingivalis fimbrial antigen can be used as vaccine against P. gingivalis associated periodontitis.Protection against P. gingivalis induced bone loss.

26. Genetic approach to biofilm antibiotic resistance : Bacteria growing in biofilms become up to 1,000 fold more resistant to antibiotics as compared to a planktonic counterpart making them hard to control. Gene ndvB encoding for glycosyltransferase is required for the synthesis of periplasmic glucans in wild form of Pseudomonas aeuroginosa RA14 strain.

27. Isolation of ndvB mutan t of Pseudomonas aeuroginosa was still capable of forming biofilm but lacked the characteristic of periplasmic glucans there by rendering microbial communities in biofilm more susceptible to conventional antibiotic therapy.

28. An In-vivo gene transfer by Electroporation for Alveolar Remodeling LacZ gene encoding for remodeling molecules

29. Antimicrobial gene therapy to control disease progression One way to enhance host defense mechanism against infection is by transfecting host cells with an antimicrobial peptide/protein- encoding gene. When host cells were infected in vivo with β defensin-2 (HBD-2) gene via retroviral vector;there was a potent antimicrobial activity which enhanced host antimicrobial defenses.

30. Designer drug therapy in treating periodontal disease: If genes necessary for normal development are known, then "designer drug therapies" aimed at one area of the gene or the other can be developed. Safer than today′s medicines because they would only affect the defect in a gene clearly identified through genetic research.

31. Future prospettive of gene therapy Tig h t Ad h e r ence Gene for t he Co n t r ol of Pe r iod o ntal Disease Progression. Gene Therapy to Grow New Teeth.

32. Limitations of gene therapy Short-lived nature of gene therapy. Immune response of the patient. Problems with viral vectors like patient toxicity, immune and inflammatory responses, and gene control and targeting issues. Limitation of sufficient quantity of the engineered gene that can be delivered. Extreme cost. Ethical restrictions.

33. Ethical Consideration What is normal and what is a disability or disorder , and who decides? Are disabilities diseases? Do they need to be cured or prevented ? Does searching for a cure demean the lives of individuals presently affected by disabilities?

34. Conclusion Gene therapy has a promising role in the field of periodontics but it does encompass serious ethical issue to be dealt with. Since gene transfer tools are in their infancy, it is not likely gene transfer approaches will be used for routine periodontal care on humans. There are still lots of research and details of mechanisms to be understood to include these practically in day to day treatment modalities.

35. References Kinane DF, Shiba H, Hart TC. The genetic basis of periodontitis. Periodontol 2000 2005;39:91-117. Friedmann T. The maturation of human gene therapy. Acta Paediatr 1996;85:1261-5. Baum BJ, Kok M, Tran SD, Yamano S. The impact of gene therapy on dentistry: A revisiting after six years. J Am Dent Assoc 2002;133:35-44.

36. Sharma A, Honma K, Evans TR, Hruby DE. Oral immunization with recombinant Streptococcus gordonii expressing Porphyromonas gingivalis Fim A Domains. Infect Immun 2001;69:2928-34. Katz J, Black KP, Michalek MS. Host response to recombinant hemagglutinin B of Porphyromonas gingivalis in an experiment rat model. Infect Immun 1999;67:4352-59. Mah TF, Pitts B, Pellock B, Walker GC, Stewart PS, O’Toole GA. A genetic basis for Pseudomonas aeruginosa bio lm antibiotic resistance. Nature 2003;426:306-10.

37. B.V.kathikeyan,A.R.Pradeep Gene therapy in periodontology:A Review and future implicationsThe Journal of contemporary dental practice,volume 7,No.3,july1,2006

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