Download to read offline
More Related Content
Similar to 3.4 Nucleic acid based Bio Product .pptx
![Gene rx [autosaved]](https://cdn.slidesharecdn.com/ss_thumbnails/generxautosaved-190320072736-thumbnail.jpg?width=640&height=640&fit=bounds)
3.4 Nucleic acid based Bio Product .pptx
- 1. 1 HARAR HEALTH SCIENSECOLLEGE Department of Pharmacy Course Title: Immunological and Biological Products 3. Immunological products and biological products 3.3 Nucleic acid based biological products For 3rd Year B.pharm Student By:-MENBERE DEBELE (BSc.in C/Nurse & B.Pharm)
- 2. 2 Out lines Genetherapy Antisense therapy Aptamer technology Nucleic acid based biological products
- 3. 3 Learning objectives:- Atthe end of this unit, you will be able to Describe the concepts, types and therapeutic applications of Nucleic acid based biological products (Gene therapy, Antisense therapy & Aptamer technology )
- 4. 4 Nucleic acid basedbiological products Current developments in nucleic-acid-based therapeutics center around gene therapy, as well as antisense and aptamer technology. These technologies have the potential to revolutionize medical practice.
- 5. 5 Gene based products Genetherapy Gene therapy is the unique technique that uses gene to prevent or recover any diseases. Approaches to gene therapy, includes: i) replacing a mutated gene that causes disease with a healthy gene; ii) ‘knocking out’ or inactivating, a mutated gene that is functioning improperly; and iii) introducing new genes into the cells to protect from any diseases.
- 6. 6 Cont. . . The principle stable introduction of a gene into the genetic complement of a cell, such that subsequent expression of the gene achieves a therapeutic goal. The potential of gene therapy as a curative approach for inborn errors of metabolism and other conditions induced by the presence of a defective copy of a specific gene (or genes) is understandable.
- 7. 7 Cont. . . Table:Some diseases for which gene-based therapeutic approaches are currently being appraised in clinical trials
- 8. 8 Cont. . . Indeed two-thirds of all gene therapy trials conducted to date aim to treat cancer. The first such trial was initiated in the USA in 1989. Moreover, gene therapy, like all other medical interventions, is not without associated risk, serious adverse effects including some fatalities. As a result, regulation and monitoring of gene therapy trials has been increased.
- 9. 9 Cont. . . Basicapproach to gene therapy The desired gene must usually be packaged into a vector system capable of delivering it safely inside the intended recipient cells. A variety of vectors can be used to effect gene transfer.
- 10. 10 These includeboth viruses (particularly retroviruses and adenoviruses) and non-viral carriers, such as plasmid-containing liposomes/ lipoplexes. Once integrated by the cell, the exogenous nucleic acid must now travel/be delivered to the nucleus.
- 11. 11 Cont. . . Gene therapy protocols may need one of three different strategies. A. In vitro gene therapy entails removal of target cells from the body followed by their incubation with nucleic acid-containing vector. - After the vector delivers the nucleic acid into the human cells, they are placed back in the body.
- 12. 12 Cont. . . B,In situ gene therapy entails direct injection of the vector immediately adjacent to the body target cells. C, In vivo gene therapy involves IV administration of the vector. • The vector has been designed such that it will only recognize and bind the intended target cells. • In this way, the nucleic acid is delivered exclusively to those cells.
- 13. 13 Figure: The variouspractical approaches that may be pursued when undertaking gene therapy.
- 14. 14 Cont. . . The in vitro approach entails initial removal of the target cells from the body. then cultured in vitro and incubated with vector containing the nucleic acid to be delivered. genetically altered cells are then reintroduced into the patient’s body. the most commonly adopted protocol to date.
- 15. 15 In orderto be successful, the target cells must be relatively easy to remove from the body, and reintroduce into the body. Such in vitro approaches have successfully been undertaken utilizing various body cell types, including blood cells, stem cells, epithelial cells, muscle cells and hepatocytes.
- 16. 16 Cont. . . A second approach involves direct injection/administration of the nucleic- acid-containing vector to the target cell, in situ in the body. Examples of this approach have included the direct injection of vectors into a tumour mass, as well as aerosol administration of vectors (e.g. containing the cystic fibrosis gene) to respiratory tract epithelial cells.
- 17. 17 Although lesscomplicated than the in vitro approach, direct in situ injection of vector into the immediate vicinity of target cells is not always feasible. This would be true, for example, if the target cells are not localized to one specific area of the body (e.g. blood cells).
- 18. 18 Cont. . . An alternative (in vivo) approach entails the development of vectors capable of recognizing and binding only to specific, predefined cell types. Such vectors could then be administered easily by, for example, i.v. injection.
- 19. 19 Cont. . . Vectorsused in gene therapy Vectors are conveniently categorized as being viral-based or non-viral-based systems.
- 20. 20 Gene therapy. .. Gene therapy represents a seemingly straightforward therapeutic option that could correct genetic-based diseases. This would be achieved simply by facilitating insertion of a ‘healthy’ copy of the gene in question into appropriate cells of the subject. Although simple in concept, the application of gene therapy to treat/cure genetic diseases has, thus far, made little impact in practice.
- 21. 21 Cont. . . To date, the majority of gene therapy trials undertaken aim to cure not inherited genetic defects, but cancer. Initial gene therapy trials aimed at treating/curing cancer began in 1991. Various strategic approaches have since been developed in this regard. Numerous trials aimed at assessing the application of gene therapy for the treatment of a wide variety of cancer types are now underway.
- 22. 22 Cont. . . Table: Some specific cancer types for which human gene therapy trials have been initiated
- 23. 23 Antisense technology Differentdisease states are associated with the inappropriate production/overproduction of gene products. Examples include: the expression of oncogenes, leading to the transformed state; the overexpression of cytokines during some disease states with associated worsening of disease symptoms; The overproduction of angiotensinogen, - which ultimately results in hypertension.
- 24. 24 Cont. . . An additional example includes the intracellular transcription and translation of virally encode genes during intracellular viral replication. In all such instances, the medical consequences of such inappropriate gene (over)expression could be prevented if this expression could be downregulated. A nucleic-acid-based approach to achieve just this is termed ‘antisense technology’.
- 25. 25 Cont. . . The antisense approach is based upon the generation of short, single-stranded stretches of nucleic acids (which can be DNA- or RNA-based) displaying a specific nucleotide sequence. These are generally termed ‘antisense oligonucleotides’. are capable of binding to DNA (at specific gene sites) or, more commonly, to mRNA derived from specific genes.
- 26. 26 This binding occursvia nucleotide base pair complementarity. Binding prevents expression of the gene product by preventing either the transcription or translation process. The end goal is the prevention of expression of a particular gene product (invariably a protein) by either blocking the transcription or translation of that gene
- 27. 27 Cont. . Figure: Overviewof the concept of the antisense approach:
- 28. 28 Cont. . . Antisenseoligonucleotides The nucleotide sequence of an mRNA molecule contains the encoded blueprint that dictates the amino acid sequence of a protein. Because of this, the mRNA sequence is said to make ‘sense’. This mRNA, therefore, is complementary to an ‘antisense’ DNA strand, i.e. it is the antisense strand of DNA in a given gene that serves as template for the mRNA synthesis.
- 29. 29 Cont. . . As long as at least part of the nucleotide sequences of any mRNA is known, it becomes potentially possible to synthesize chemically an oligonucleotide, either a ribo- or deoxyribo-nucleotide, whose base sequence is complementary to at least a section of the mRNA sequence. Binding results in the blocking of translation of the mRNA and, hence, prevents synthesis of the mature gene’s protein product.
- 30. 30 Cont. . . The prevention of mRNA translation by duplex formation with antisense oligonucleotides appears to be underpinned by various mechanisms, including: A. the oligonucleotides act as steric blockers, i.e. prevent proteins involved in translation, or other aspects of mRNA processing, from binding to appropriate sequences in the mRNA;
- 31. 31 B . thegeneration of duplexes also likely allows targeting by intracellular Ribonuclease (RNases). This enzyme is capable of binding to RNA– DNA duplexes and degrading the RNA portion of the duplex (most synthetic antisense oligonucleotides are DNA based).
- 32. 32 Uses, Advantages anddisadvantages of ‘oligos’ Uses Antisense oligonucleotides (oligos) are being assessed in preclinical and clinical studies as therapeutic agents in the treatment of cancer, as well as a variety of viral diseases e.g. HIV, hepatitis B, herpes and papillomavirus infections, rheumatoid arthritis and allergic disorders. Cancer, however, remains the most common target indication.
- 33. 33 Cont. . . Advantages specificity. Relatively low toxicity The requirement for only low levels of the oligo to be present inside the cell, as target mRNA is, itself, usually present only in nanomolar concentrations. The ability to manufacture oligos of specified nucleotide sequence is relatively straightforward using automated synthesizers.
- 34. 34 Cont. . . Disadvantages sensitivity to nucleases; very low serum half lives; poor rate of cellular uptake; orally inactive
- 35. 35 Aptamer technology Aptamersare single-stranded DNA or RNA-based sequences that fold up to adopt a unique three dimensional structure, allowing them to bind a specific target molecule. Binding displays high specificity, and aptamers capable of distinguishing between closely related isoforms or different conformational states of the same protein have been generated. Binding affinity is also high.
- 36. 36 Cont. . . It is in the low nanomolar to picomolar range, which is comparable to the binding affinity of an antibody for the antigen against which it was raised. Aptamer technology was first developed in 1990. It entails the initial generation of a large aptamer library, with subsequent identification of individual aptamers binding a target ligand via an appropriate selection strategy.
- 37. 37 Cont. . . Identification of specific aptamers binding the target molecule is most easily undertaken by an automated in vitro selection approach known as systematic evolution of ligands by exponential enrichment (SELEX). Most libraries contain up to 1015 species.
- 38. 38 Because oftheir high binding specificity and affinity, aptamers (like antibodies) are/may prove useful for affinity-based purification, target validation and drug discovery, diagnostics and therapeutics.
- 39. 39 Cont. . . One such product (Macugen) has been approved for general medical use to date. A modest number of additional aptamers are in clinical trials, aimed at treating conditions including infectious diseases, cancer and haemophilia.
- 40. 40 Cont. . . Aptamers appear to display low immunogenicity; but, when administered systemically, they are quickly excreted via size-mediated renal clearance. In order to prevent renal removal, such aptamers are usually conjugated to PEG.
- 41. 41 PEG may alsohelp further protect the aptamers from degradation by serum nucleases; native aptamers are prone to nuclease attack, but their half-lives can most effectively be extended via chemical modification.
- 42.