Biochip A help in gene therapy

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Biochip: A help in gene therapy

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Presentation on Biochip : A help in gene therapy -Madhuri Andhale

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Gene ??... These are carried on chromosome & are the basic physical & functional unit of heredity. (Chromosomes?)

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Genetic disease : Human beings suffer from more then 5000 different disease cause by single gene mutation. ex - sickle cell anemia , hemophilia, cancer, hypertension ,mental illness...etc. Genetic diseases??... (mutation?)

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It is a technique for correcting defective genes responsible for disease development . The approaches are:- (1)A normal gene may be inserted into a nonspecific location within the genome to replace a functional gene. (2) An abnormal gene could be repaired through selectively reverse mutation, which return the gene to its normal function. Gene Therapy ??...

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Law & ethics related to gene therapy... Every person could not use these ,the candidate for gene therapy are selected on the basis of the following criteria- -The disease should be life threatening. -The gene responsible for the disease has been cloned. - A suitable delivery system should be available. (cloned?)

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First approved gene therapy - On sept.14.1990 at the US National institutes of health. W.F. Anderson & his collages, performed the first approved gene therapy procedure on four year old Ashanthi desilva, born with a rare genetic disease called severe combined immunodeficiency (SCID) also known as bubble baby syndrome. What did they do? In Ashanthi gene therapy procedure doctors removed white blood cells from the child body let the cells grow in the laboratory, inserted the genetically modified blood cells back into the patient blood stream.& success, as of early 2007,she was still in good health & she was attending college.

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How does gene therapy work?... In gene therapy a normal gene is inserted into the genome to replace an abnormal disease causing gene. A carrier molecule called a vector must be used to deliver the therapeutic gene to the patient’s target cells. Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. Viruses have evolved a way of encapsulating & delivering their genes to human cells in pathogenic manner. Scientists have tried to take advantage of this capability & manipulate the genome to removed disease causing genes & insert therapeutic genes. (Genome?)

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Vectors for gene therapy- Some different type of viruses used as gene therapy vector: -Retro viruses: A class of viruses that can create stranded DNA copies of their RNA genomes. these copies of its genome can be integrated into the chromosome of host cells. -Adenoviruses , Adeno-associated viruses, herpes simplex viruses, are also used as vector.

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Some non virus mediated gene delivery system- The simplest method in the direct introduction of therapeutic DNA into target cells, like microinjection & gene gun method. -Introduction of the foreign DNA into cell by use liposome is known as lipofection. -Introduction of DNA into cell by exposing a very brief period of high voltage electric pulses is called electrophoration.

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Types of gene therapy- Gene therapy mainly classified into 2 types:- -germ line gene therapy - somatic cell gene therapy. -Method of germ line gene therapy-In vitro fertilization of egg. Insertion of normal gene to the embryo through retrovirus or microinjection. Integration of the normal gene & show its character. -method of somatic cell gene therapy- Identification of defective gene which is responsible for disease causing Synthesis of normal gene. Isolation of particular cell in which the integration of normal gene take place. Integration of normal DNA to the defective tissue.

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Gene therapy uses in cancer treatment- Gene therapy can be used to selectively target & destroy cells by Insertion of a copy of wild type p53 gene. Antisence gene insertion which disable the over expression of oncogene. (Oncogene?)

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Problems need to be solved in gene therapy- Short lived nature of gene therapy-The rapidly dividing nature of cells prevent gene therapy from achieving any long-term benefits. patients will have to undergo multiple rounds of gene therapy. Immune response- Anytime a foreign object is introduced into human tissue, the immune system is designed to attack the invader. Problem with viral vector... There is always fear that viral vector once inside the patient may recover its ability to cause disease.

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Use of gene therapy- Though gene therapy is still in its initial stage & is associated with many unsolved problems but, still it has many uses like- - Replace missing or defective gene. -Deliver bacterial or viral gene as a form of vaccination. -Provide genes that promote the growth of new tissue. -Deliver gene that stimulate the healing of damaged tissue. Large verity of genes are now being tested for use in gene therapy, Example= gene CFTR~for cystic fibrosis, Gene EIA &p53 ~for cancer, gene AC6~for heart failure, etc...

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-Fundamentally, biochips are computer-chiplook-alikes intended to speedily, reliably, and inexpensively perform biochemical procedures that together constitute a medical test. Through their miniaturization and automation of laboratory procedures, they replace far slower, more cumbersome, more expensive laboratory equipment. ---Their current applications lie chiefly in the analysis of genes for defects or sequence variations. They may soon facilitate screening of molecules for potential usefulness as drugs. The immediate goal is to enable them to serve point-of-care diagnosis. Biochip??...

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Biochip, its Parts and Working- The current, in use, biochip implant system is actually a fairly simple device . Biochip implant is basically a small (micro) computer chip, inserted under the skin, for identification purposes.-The biochip implant system consists of two components; A transponder-A reader or scanner- The transponder is the actual biochip implant. TYPES- passive & active transponders… -Passive= no battery , long life , no maintenance ,its inactive until the reader activates it by sending it a low power electrical charge. -Active = would provides its own energy source, normally a small battery . The reader reads or scans the implanted biochip and receives back data from the chip. The communication between the biochip & the data is via low frequency radio-signal.

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Parts of transponders- The biochip-transponder consists of four parts;computer microchip, antenna coil, capacitor and the glass capsule.

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The microchip stores a unique identification number from 10 to 15 digits long. The storage capacity of the current microchips is limited, capable of storing only a single ID number.The unique ID number is "etched" or encoded via a laser onto thesurface of the microchip before assembly. Once the number is encoded it is impossible to alter. The microchip also contains the electronic circuitry necessary to transmit the ID number to the "reader". Computer microchip: The capacitor stores the small electrical charge (less than 1/1000 of a watt) sent by the reader or scanner, which activates the transponder. This "activation" allows the transponder to send back the ID number encoded in the chip. Because "radio waves" are same frequency as the reader. computer Tuning capacitor:

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This is normally a simple coil of copper wire around a ferrite or iron core. This tiny, primitive, radio antenna "receives and sends" signals from the reader or scanner. Antenna coil: The glass capsule "houses" the microchip, antenna coil and capacitor . The capsule is made of biocompatible material such as soda lime glass. After assembly, the capsule is hermetically is very smooth and susceptible to movement, a material such as a polypropylene polymer sheath is attached to one end of the capsule. This sheath provides a compatible surface which the bodily tissue fibers bond or interconnect, resulting in a permanent placement of the biochip. Glass capsule:

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The reader consists of an "exciter" coil which creates an electromagnetic field that, via radio signals, provides the necessary energy (less than 1/1000 of a watt) to "excite" or "activate" the implanted biochip. The reader also carries a receiving coil that receives the transmitted code or ID number sent back from the "activated" implanted biochip. This all takes place very fast, in milliseconds. The reader also contains the software and components to decode the received code and display the result in an LCD display. The reader can include a RS-232 port to attach a computer. The reader and biochip can communicate through most materials, except metal. The Reader: Types of chips: -Plate based DNA arrays -gel based DNA arrays -micro fluidic chips:

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Applications of biochips- -Genomics -Biodiagnostics and (Nano) Biosensors -Data acquisition -Implantable microchips for drug delivery -Color-Coded Clustered Image Maps (CIMs) for Gene Expression Fingerprinting and Cancer Drug Discovery

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The different approaches of visual prosthesis do have some advantages and disadvantages. With retinal implants, only those diseases where the optic nerve and the central visual pathways are intact are treatable. Cortical implants will cover a larger range of diseases to treat. Epi- and sub-retinal approaches both have their pros and cons. Subretinal implants may have the problem of an interruption between the pigment epithelium- choriocapillaris complex and the retina itself. They need a complex connection to the energy-and-data system. Epiretinal implants are difficult to fixate. Currently, retinal tacks are applied, possibly causing epiretinal gliosis in the tack area. Epiretinal stimulators could, however, build much larger than sub retinal implants, allowing for a larger retinal area to be stimulated. Subretinal implants may use the pre-existing neuronal network for data processing, although this network is heavily reorganized, whereas epiretinal stimulators are closer to intact ganglion cells and do not have to overcome the high resistance of the pathologic Muller cell seal in the external limiting membrane, as seen in advanced cases of RP. The external data processing in epiretinal implants may allow for a modified-stimulation algorithm, possibly more efficient than converting light to currents, as done by microphotodiodes in subretinal approaches. These questions could only be answered by comparative studies, which are not yet available. Adv. & Disadvantages: