- 1 Branches of Biotechnology – Exploring the Different Fields
- 1.1 Microbial Biotechnology
- 1.2 Production of Human Insulin in E.coli
- 1.3 Applications of Biotechnology in Agriculture
- 1.4 Bt Crops
- 1.5 Hazards of Transgenic Plants
- 1.6 Applications of Biotechnology in Animals
- 1.7 Applications of Aquatic Biotechnology
- 1.8 Applications of Biotechnology in Medicine
- 1.9 Vaccines
- 1.10 Types of Vaccines
- 1.11 Production of Vaccines by Modern Biotechnology
- 1.12 Gene Therapy
- 1.13 Gene Therapy in the Treatment of Disease
- 1.14 Example of Human Gene Therapy
Environmental biology is one of the critical Biology Topics that involves understanding how humans impact the environment and how to address environmental issues.
Branches of Biotechnology – Exploring the Different Fields
Biotechnology is the development of techniques for the application of biological processes to the production of materials of use in medicine and industry. Biotechnology is a science mostly used in human welfare. The biotechnological advancements have resulted in the production of many bio-pharmaceuticals and vaccines, the generation of sophisticated and specific ways to diagnose diseases, increase of the productivity, and the introduction of quality traits in agricultural crops using genetically modified crops.
A biofuel is a product of biological organisms that can substitute or enhance existing fuels. The production of biofuels using biotechnology has the potential to provide an alternative energy source and reduce global warming resulting from the burning of fossil fuels. Diagnosis and/or treatment of a variety of human diseases and disorders including acquired immunodeficiency syndrome (AIDS), stroke, diabetes, and cancer make up the bulk of biotechnology products on the market. The contribution of the knowledge of biotechnology may be realized from the discussion of its contribution to agriculture and human health.
The use of yeast for making beer and wine is one of the oldest applications of biotechnology. By manipulating microorganisms such as bacteria and yeast, microbial biotechnology has created better enzymes and organisms for making many foods, simplifying manufacturing and production processes, and making decontamination processes for the removal of industrial waste products more efficient. Microbes are used to make vaccines and to clone and produce batch amounts of important proteins used in human medicine, including insulin and growth hormone.
The most successful and widespread application of recombinant DNA technology has been the production by the biotechnology industry of recombinant proteins as biopharmaceutical products particularly, therapeutic proteins to treat diseases. Prior to the recombinant DNA era, biopharmaceutical proteins such as insulin, clotting factors, or growth hormones were purified from tissues such as the pancreas, blood, or pituitary glands. Clearly, these sources were in limited supply, and the purification processes were expensive.
In addition, products derived from these natural sources could be contaminated by disease agents such as viruses. Now that human genes encoding important therapeutic proteins can be cloned and expressed in a number of nonhuman host-cell types, we have more abundant, safer, and less expensive sources of biopharmaceuticals. Biopharming is a commonly used term to describe the production of valuable proteins in genetically modified (GM) animals and plants.
Insulin Production in Bacteria:
Many therapeutic proteins have been produced by introducing human genes into bacteria. In most cases, the human gene is cloned into a plasmid, and the recombinant vector is introduced into the bacterial host. Large quantities of the transformed bacteria are grown, and the recombinant human protein is recovered and purified from bacterial extracts.
Production of Human Insulin in E.coli
Insulin is a protein hormone secreted from islets of Langerhans present in the pancreas. This hormone regulates the amount of glucose in the blood of man. Healthy normal adult contains 80-120 mg of glucose/dl of blood. When the amount of glucose increases in the blood, humans suffer from diabetes. Excess glucose in the blood may be stored in muscles and the liver under the influence of insulin. But in the case of insulin deficiency, the amount of glucose increases in the blood producing symptoms of diabetes. As a result fatal conditions develop in humans. As treatment of diabetes, the affected person is provided with insulin from outside. Nowadays, human insulin is being produced by using transgenic E. coli. For this reason, treatment of the disease is not so difficult at the present time.
Effective insulin in man contains two polypeptide chains namely A chain and B chain. Two polypeptide chains together produce the effective insulin. At the initial stage of insulin production, a large polypeptide chain is produced and this chain contains all amino acids of A chain, B chain, and the amino acids of another chain called C-polypeptide (containing 33 amino acids). One mRNA molecule produces a single polypeptide chain containing 109 amino acids which is known as proinsulin. Within proinsulin, A, B, and C segments are present in the order A-C-B. A processing of proinsulin cleaves the C-chain leaving A and B polypeptide chains. Two chains then remain associated together with the formation of disulphide bonds between the amino acids of the two chains. It is to be pointed out that A polypeptide contains 21 amino acids and B polypeptide contains 30 amino acids. The A and B polypeptide chains form the effective insulin in the cell.
Humulin, a recombinant form of human insulin, was the first therapeutic protein produced by recombinant DNA technology to be approved for use in humans. Synthetic genes that encode the A and B subunits were inserted into a separate vector, adjacent to the lacZ gene encoding the bacterial form of the enzyme beta-galactosidase. When transferred to a bacterial host, the lacZ gene and the adjacent synthetic oligonucleotide were transcribed and translated as a unit.
The product is a fusion protein that is, a hybrid protein consisting of the amino acid sequence for beta-galactosidase attached to the amino acid sequence for one of the insulin subunits. The fusion proteins were purified from bacterial extracts and treated with cyanogen bromide, a chemical that cleaves the fusion protein from the beta-galactosidase. When the fusion products were mixed, the two insulin subunits spontaneously united, & forming an intact, active insulin molecule. The purified injectable insulin was then packaged for use by diabetics.
Applications of Biotechnology in Agriculture
Agricultural biotechnology aims to introduce sustainable agricultural practices with the best yield potential and minimal adverse effects on the environment. Plants, bacteria, fungi, and animals whose genes have been altered by human manipulation using genetic engineering are called Genetically Modified Organisms (GMOs).
Agricultural biotechnology has contributed to generating genetically engineered, pest-resistant, high-yielding plants that do not need to be sprayed with pesticides, foods with higher protein or vitamin content, and drugs developed and grown as plant products. Genetically modified plants have genes inserted to protect them from insects, thus increasing the crop yield while decreasing the amount of insecticides used. Agricultural biotechnology provides solutions for today’s farmers in the form of plants that are more environmentally friendly while yielding more per acre, resisting diseases and insect pests, and reducing farmers’ production costs. Biopharming is a commonly used term to describe the production of valuable proteins in genetically modified (GM) animals and plants.
GM crops (mainly soybean, maize, tomato, and cotton) are cultivated by 20.7 million farmers in 38 countries, with the United States, Brazil, and Argentina as major cultivators. Over 50 different transgenic crop varieties are available, including alfalfa, corn, rice, potatoes, tomatoes, tobacco, wheat, and cranberries.
Utilities of Genetic Engineering in Agriculture:
- Made crops more tolerant to abiotic stresses and adverse environments (cold, drought, salt, heat).
- Made pest and virus-resistant plants (insect-resistant crops) reducing reliance on chemical pesticides and thus resulting in lower costs for farmers and reduction of post-harvest losses.
- Increased efficiency of mineral usage by plants leads to the prevention of early exhaustion of fertility of soil by the crops.
- Enhanced nutritional value of food with higher vitamins, protein, and mineral content, e.g., golden rice, i.e., Vitamin ‘A’ enriched rice.
|Plants/Animals||Improvements made by using Biotechnology|
|1. Tomato with high longevity||With the help of antisense technology, a variety of tomatoes could be produced which is named Flavr Savr in which poly galactokinase is not produced which softens the ripe tomatoes. The gene for synthesis of this enzyme is prevented in this tomato plant. Due to this ripe tomatoes appear to be tasty and long lasting. Besides this another tomato variety could be produced which is named as British Genetra.|
|2. Resistant Crop (Pest)||By introducing the toxin gene of Bacillus thuringiensis in plants like maize, rice, and potato. Transgenic plants could be produced. These plants without having insecticides can prevent attack of insect pests.|
|3. Virus Resistant Crops||In some cases by introducing capsid proteins of harmful viruses into crop plants such as tomatoes, potatoes, and tobacco immunity to the viral infection could be developed.|
|4. Weed Resistant Crops||Bacteria belonging to the Streptomyces group contain a gene that destroys the weed named Basta. This gene of Streptomyces could be introduced into crops like tomato, potato, maize, and wheat. With this, the plant appears resistant to destructive weed Basta.|
|5. Pest Resistant Leguminous Plants||A toxic chemical-producing gene of Bacillus could be isolated and this gene could be introduced into Rhizobium a bacterium that produces root nodules in leguminous plants. The leguminous plants that get the transgenic Rhizobium can prevent the attack of destructive weevils on these plants.|
|6. Increment of the Quality of Crops||In most of the cases, the cereals cannot produce essential amino acids. Efforts are being made to improve the crop plants by genetic modification so that they can produce essential amino acids.|
|7. Mastitis Resistant Cow||Due to a lack of lactofer in all mastitis appears in the teats of cows when milk production is greatly affected. However, the gene for lactose may be introduced in the bull, and the transgenic bull may be produced. The progeny cow of such a transgenic bull inherits the gene for lactofer and such a cow may be resistant to mastitis.|
|8. Sheep with Rapid Growth||Introducing the growth hormone gene of man-transgenic sheep has been produced, such transgenic sheep show a high growth rate.|
|9. Fish with High Growth||By introducing genes from sea fishes into carp, and salmon, transgenic fishes of high growth have been developed. In the case of salmon, it has been found that a transgenic fish shows about 30 times increase in growth than its normal counterpart.|
Bt Some of the most well-described and controversial GM crops are the so-called Bt crops, designed to be resistant to insects. The bacterium Bacillus thuringiensis (Bt) produces a crystalline, or Cry protein, a protein that when ingested by insects and larvae will crystallize in the gut, killing pests such as corn-borer larvae that are responsible for millions of dollars of crop damage worldwide, the Bt toxin protein exist as inactive protoxins but once an insect ingest the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which breaks down and releases the Bt toxin. This toxin binds to the intestinal lining of the insect and generates holes, which cripple the digestive system, and the insect dies. Different species of Bacillus produce a family of related Cry proteins that exhibit toxicity toward various groups of insects.
Initially, applications of Bt involved spraying these bacteria on crops. However recombinant DNA technology has enabled scientists to produce Bt transgenic crops with built-in insecticide protection. The cry genes that encode the Bt crystalline protein have been effectively introduced into a number of different crops, including corn, cotton, tomatoes, and tobacco. Bt crops have been hailed as one of the greatest success stories of agricultural biotechnology.
There are two primary advantages to using Bt transgenic crops, such as cotton and corn. First, the toxin does not have to be sprayed, which reduces both the amount of work necessary and the potential for contaminating nearby fields. Second, planting Bt crops has resulted in a dramatic reduction in the amount of insecticides required.
I. Creation of Herbicide Resistant Plants
Herbicides cost the world’s farmers more than $14 billion each year. Despite this massive investment, around 10% of crops is lost due to weeds. One problem is that many of the herbicides used do not discriminate between crops and weeds. One solution is to make the crops resistant to the herbicide by genetic engineering. Therefore, when the herbicide is sprayed on the weeds and crop, only the crop will survive. One of the best herbicides on the market is glyphosate. Glyphosate is environmentally friendly because it quickly breaks down into nontoxic compounds in the soil. The glyphosate molecule is a phosphate derivative of the amino acid glycine.
Glyphosate kills plants by blocking the synthetic pathway for the aromatic amino acids phenylalanine, tyrosine, check, and tryptophan by inhibiting one particular enzyme, EPSPS (5-enolpyruvyl- shikimate-3-phosphate-synthase), which is the product of the aroA gene and is localized the chloroplast. This target enzyme is found naturally in all plants, fungi, and bacteria, but not in animals. Aromatic amino acids are therefore essential to the diets of all animals, including humans, because those organisms cannot produce them. When glyphosate is sprayed onto plants, the herbicide penetrates the chloroplasts and binds to EPSPS, blocking the pathway for aromatic amino acids. The plant essentially starves to death.
To produce a glyphosate-resistant crop plant, researchers began by isolating and cloning an EPSP synthase gene from a glyphosate-resistant strain of E. coli. Next, they cloned the EPSP gene into a Ti plasmid between promoter sequences derived from a plant virus and transcription termination sequences derived from a plant gene. This recombinant vector was then transformed into Agrobacterium tumefaciens. The Ti plasmid-carrying bacteria were then used to infect plant cells derived from plant leaves.
The clumps of cells (calluses) that formed after infection with Agrobacterium tumefaciens were tested for their ability to grow in the presence of glyphosate. Glyphosate-resistant calluses were grown into transgenic plants and sprayed with glyphosate at concentrations four times higher than that needed to kill wild-type plants. Transgenic plants that expressed EPSP synthase grew and developed, while the control plants withered and died.
II. Saving Crops from Disease and Drought
In the 1990s, the papaya industry was severely threatened by the papaya ringspot virus (PRSV), which is spread between plants by aphids. Farms in Brazil, Taiwan, and Hawaii were infected. To counter the infection, scientists utilized a phenomenon known as parasite-derived resistance, in which the expression of a gene from a parasite confers resistance to that same parasite. In this case, transgenic papaya was created that expressed the coat protein from PRSV. The scheme worked, and the transgenic papaya helped rescue the industry from decimation.
III. Boosting Nutrients and Reducing Toxins
In many areas of the world, particularly Africa and Southeast Asia, rice is a staple of the diet. Unfortunately, rice does not contain vitamin A. People who have few other alternative sources of nutrition are susceptible to vitamin A deficiency, a disease that the World Health Organization claims causes blindness in 250,000 to 500,000 children annually, half of whom die within one year. “Golden Rice” expresses the biosynthetic pathway for a vitamin A precursor called β-carotene, and a humanitarian effort to provide the developing world with this transgenic crop is slowly underway. Other researchers have fortified rice with extra zinc and iron. Soybean and canola crops, modified to produce omega-3 fatty acids have also been created.
IV. Manufacturing Pharmaceuticals
In 2012, the FDA approved the first-ever plant-made pharmaceutical intended for human use. Patients suffering from Gaucher disease, a rare lysosomal storage disease, are deficient in the enzyme glucocerebrosidase (Gcase). A company called Protalix Biotherapeutics engineered carrot cells to synthesize a replacement enzyme, taliglucerase alfa (trade name Elelyso). The enzyme is targeted to the plant cell vacuole. Inside, the protein undergoes post-translational modification and is protected from degradation. To extract the enzyme, scientists solubilize plant cells in detergent and purify the enzyme using chromatography.
V. Improving the Environment
Using plants to clean up the environment, for instance, by sequestering soil or water contamination, is known as phytoremediation. There are five ways to do this. In the first scenario, phytostabilization, plants provide ground cover for a contaminated site by protecting against erosion due to wind and water. Although unmodified plants can perform phytostabilization, the use of transgenics could increase the root system or enhance tolerance to the contaminant. In the second method, phytodegradation, the plant breaks down the pollutant, while in the third method, phytostimulation, the plant stimulates microbes to degrade it. In the fourth, called phytoextraction, a plant assimilates the contaminant into its tissues, after which it is harvested and disposed of properly. In the fifth method, phytovolatilization, pollutants are absorbed from the soil and released into the atmosphere, usually after being converted to a less toxic form.
Arabidopsis, tobacco, and poplar trees that have had the merB and merA genes from bacteria added to their genome, can convert the highly toxic form of methylmercury into Hg(II), which is less bioavailable. MerB converts methyl mercury [CH3Hg]+ and a proton to Hg(II). MerA converts Hg(II) to Hg(0), which is a less reactive elemental form.
Hazards of Transgenic Plants
The hazards of Bt crops and other transgenic plants may be indicated in the following manner.
- Genetic pollution: Transgenic plants are being produced without an image of their impact on the environment in the future. It could be realized that the transgenes may spread in the population of living organisms via the food chain. Therefore, it destroys the genetic equilibrium of nature. Hence, transgenesis leads to some kind of genetic pollution.
- Allergy: Sometimes the product of the transgene becomes allergic to the human body.
- Toxicity: Transgene may produce toxicity in the animal body including man.
- Resistance to antibiotics: Some pathogenic bacteria of the human body under the influence of transgenic GM crops may become resistant to antibiotics. Such bacteria may be dangerous and fatal to human life.
- Pesticide-resistant insects: Bt crop-consuming insect pests may be resistant to pesticides and they may hardly be controlled by spraying insecticides.
- Destruction of beneficial insects: With the consumption of Bt crops, the Cry protein of the crop causes the destruction of many beneficial insects. This is antagonistic to natural equilibrium in the environment.
- Over-destruction of insects: If the cry gene is transferred from Bt crops to the other plants, it may destroy many kinds of insects which may prevent production from natural crop plants.
- Destruction of varieties in nature: Because of the introduction of Bt crops people become indifferent to cultivating natural varieties of crops. This leads to the abolition of natural varieties. This destruction is antagonistic to nature. Bt crops are transgenic varieties of crops.
Applications of Biotechnology in Animals
Transgenic animals contain genes from another source. In animal biotechnology animals can be used as “bioreactors” to produce important products. For example, goats, cattle, sheep, and chickens are being used as sources of medically valuable proteins such as antibodies and protective proteins that recognize and help body cells to destroy foreign materials. Antibody treatments are being used to help improve immunity in patients with immune system disorders.
Many other human therapeutic proteins produced from animals are in use, yet most of these proteins are needed in quantities that exceed hundreds of kilograms. To achieve this large-scale production, scientists can create female transgenic animals that express therapeutic proteins in their milk. For instance, human genes for clotting proteins can be introduced into goats for the production of these proteins in their milk. Transgenic animals are extensively used in the laboratory to model diseases and to study biological mechanisms at the cellular and molecular levels.
1. Both cattle and goats have been genetically modified to express human lysozyme in their milk. Lysozyme, an enzyme that protects from infection by destroying the peptidoglycan in bacterial cell walls, is found in high concentrations in human milk. It is thought that this helps prevent diarrheal diseases, such as E. coli. Antithrombin is a protein that blocks blood coagulation, and people who have antithrombin deficiency are more susceptible to blood clots.
2. An example of an application of transgenic technology is Biosteel, an extraordinary new product that can be used to strengthen bulletproof vests and suture silk in operation theatres.
3. Genetically modified Mouse (Mou Sens or) and Zebra fish act as biosensors to detect explosives & environment polluting chemicals respectively.
4. DNA Fingerprinting:
DNA fingerprinting is a collection of methods for detecting an organism’s unique DNA pattern is a primary tool used in forensic biotechnology. Forensic biotechnology is a powerful tool for law enforcement that can lead to the inclusion or exclusion of a person from suspicion, based on DNA evidence. DNA fingerprinting can be accomplished using trace amounts of tissue, hair, blood, or body fluids left behind at a crime scene. It was first used in 1987 to convict a rapist in England but is now routinely introduced as evidence in court cases throughout the world to convict criminals as well as to free those wrongly accused of a crime.
DNA fingerprinting has many other applications, including use in paternity cases for pinpointing a child’s father and identifying human remains. Another application is the DNA fingerprinting of endangered species. This has already reduced poaching and led to convictions of criminals by analyzing the DNA fingerprints of their “catches.” Scientists also use DNA fingerprinting to track and confirm organisms that spread disease, such as Escherichia coli in contaminated meat, and to track diseases such as AIDS, meningitis, tuberculosis, Lyme disease, and the West Nile virus.
Bioremediation means the usage of living organisms like microorganisms (microbial remediation) or plants (phytoremediation) to give solutions to the problems of pollution of water, soil, or oil spills.
Applications of Aquatic Biotechnology
Aquatic biotechnology has helped us to use genetic engineering to produce disease-resistant strains of oysters and vaccines against viruses that infect salmon and other finfish. Transgenic salmon have been created that overproduce growth hormone, leading to extraordinary growth rates over short growing periods and thus decreasing the time and expense required to grow salmon for market sale.
Applications of Biotechnology in Medicine
Medical biotechnology has many applications and is involved in the production of recombinant pharmaceuticals, tissue engineering products, the treatment of human disease conditions using regenerative medicines such as stem cell and gene therapy, and the diagnosis of health and illness. Gene therapy approaches, in which genetic disease conditions can be treated by inserting normal genes into a patient or replacing diseased genes with normal genes, are a boon to us.
Vaccine refers to a product from a microbial pathogen that may produce immunity against the disease by a pathogen. British physician Edward Jenner in 1796 first discovered the vaccine for smallpox. Subsequently, vaccines for many other diseases were discovered. Inoculation of vaccine in the body develops immunity against a pathogenic organism. Therefore, a vaccinated individual gets protection against some pathogenic disease. This is known as active immunization. How vaccination develops immunity in humans may be elaborated as follows.
Types of Vaccines
In some cases, toxins developed by pathogens are the cause of disease symptoms, examples, are tetanus and diphtheria toxins. Toxins are proteins and they act like antigens. During vaccine production, these toxins are inactivated with formaldehyde and then they are called toxoids. The toxoids may be used as a vaccine to develop immunity in man.
Attenuated Live Vaccines:
Attenuated live vaccines are live bacteria or viable viruses that have been modified to remove pathogenicity. They generally produce better immunity than killed organisms, e.g., BCG. Subunit vaccines consist of an antigenic subcomponent of the pathogen, produced either by fractionation or by biotechnology. Subunit vaccines include the first of the ‘second-generation’ vaccines, in which the purified antigens are produced by recombinant DNA technology. For example, a subunit of hepatitis B isolated from blood was later superseded by the same antigen expressed in yeast.
An attenuated virus is an inactive virus without having the capability to develop infection. Therefore, such viruses induce immunity in the body without developing disease conditions, e.g., Sabin’s polio vaccine, measles vaccine, mumps vaccine, etc.
Many vaccines are given in combinations, during early infancy. This is for convenience, to reduce the number of visits needed to an immunization clinic. Examples are the trivalent DTP3 vaccine for diphtheria, tetanus, and pertussis.
Production of Vaccines by Modern Biotechnology
Vaccines stimulate the immune system to produce antibodies against disease-causing organisms and thereby confer immunity against specific diseases. Traditionally, two types of vaccines have been used: inactivated vaccines, which are prepared from killed samples of the infectious virus or bacteria; and attenuated vaccines, which are live viruses or bacteria that can no longer reproduce but can cause a mild form of the disease. Inactivated vaccines include vaccines for rabies and influenza; vaccines for tuberculosis, cholera, and chickenpox are examples of attenuated vaccines.
Genetic engineering is being used to produce a relatively new type of vaccine called a subunit vaccine, which consists of one or more surface proteins from the virus or bacterium but not the entire virus or bacterium. This surface protein acts as an antigen that stimulates the immune system to make antibodies that act against the organism from which it was derived. One of the first subunit vaccines was made against the hepatitis B virus, which causes liver damage and cancer. The gene that encodes the hepatitis B surface protein was cloned into a yeast expression vector, and the cloned gene was expressed in yeast host cells. The protein was then extracted and purified from the host cells and packaged for use as a vaccine.
In 2005, the FDA approved Gardasil, a subunit vaccine that targets four strains of Fluman papillomavirus (F1PV) that cause 70 percent of cervical cancers. Approximately 70 percent of sexually active women will be infected by an HPV strain during their lifetime. Gardasil is designed to provide immune protection against HPV prior to infection but is not effective against existing infections.
Scientists are attempting to develop vaccines that can be synthesized in edible food plants. These vaccines would be inexpensive to produce, would not require refrigeration, and would not have to be given under sterile conditions by trained medical personnel. Vaccine-producing bananas and potatoes have been developed. Bananas are considered to be perhaps the best edible vaccine candidate for a hepatitis B vaccine. Genetically engineered edible plants are being used for trials to vaccinate infants, children, and adults against many infectious diseases (Reference Pic Page 835).
To create DNA-based vaccines DNA encoding proteins from a particular pathogen are inserted into a plasmid vector, which is then injected directly into an individual or delivered via a viral vector similar to the way certain viruses are used for gene therapy. The idea here is that pathogen proteins encoded by the delivered DNA would be produced endogenously within the individual and trigger an immune response that could provide protection should an immunized person be exposed to the pathogen in the future.
It may be of two types Classical gene therapy and Non-classical gene therapy.
- Classical gene therapy: In this method in order to repair a genetic default the corrected gene is directly introduced into the target cell of the body.
- Non-Classical gene therapy: In this case, the gene for which a disease appears is repaired. There may be three types Sometimes cell therapy, Germ cell therapy, and Stem cell therapy.
Gene Therapy in the Treatment of Disease
Gene therapy is defined as a therapeutic strategy in which a patient’s cells are genetically modified in an attempt to alleviate or cure a disease. When a mutation in a gene is the cause of a disease, gene therapy may be a way to treat the disease. There is an important distinction between somatic gene therapy, where modifications are introduced into somatic cells and are confined to the patient, and germ-line gene therapy, where modifications are introduced into the cells that give rise to gametes and can therefore be passed to subsequent generations.
The body cell containing the defective gene is isolated from the body and the correct form of the gene may be introduced into the cell. After this, these genetically modified cells may be inserted into the body. This is known as ex vivo gene therapy. This ex vivo gene therapy strategy is applicable for the treatment of blood and immune system disorders because hematopoietic stem cells can be removed, cultured, and transformed relatively easily.
For inaccessible cells or cells that cannot be cultured efficiently, gene therapy involves the direct introduction of DNA into cells while they are still in the body. In this case, the defective gene for the disease is identified and a correct form of the gene may be directly introduced into the body of the affected person. This is known as in vivo gene therapy. Scientists have used various viruses such as adenovirus, as vectors for gene delivery. Nonviral gene delivery methods are considered to be safer than viruses. They include transfection (where cells are persuaded to take up DNA from their surroundings) and direct transfer (where DNA is introduced into cells by physical means, e.g., by injection). DNA can be enclosed within artificial lipid vesicles known as liposomes which are able to fuse to the plasma membrane, depositing their cargo into the cytosol.
Example of Human Gene Therapy
Human gene therapy began in 1990 with the treatment of a young girl named Ashanti DeSilva, who has a heritable disorder called severe combined immunodeficiency (SCID). Individuals with SCID have no functional immune system and usually die from what would normally be minor infections. Ashanti has an autosomal form of SCID caused by a mutation in the gene encoding the enzyme adenosine deaminase (ADA). Her gene therapy began when clinicians isolated some of her white blood cells, called T cells. These cells, which are key components of the immune system, were mixed with a retroviral vector carrying an inserted copy of the normal ADA gene.
The virus infected many of the T cells, and a normal copy of the ADA gene was inserted into the genome of some T cells. After being mixed with the vector, the T cells were grown in the laboratory and analyzed to make sure that the transferred ADA gene was expressed. Then a billion or so genetically altered T cells were injected into Ashanti’s bloodstream. Some of these T cells migrated to her bone marrow and began dividing and producing daughter cells that also produce ADA. She now has ADA protein expression in 25 to 30 percent of her T cells, which is enough to allow her to lead a normal life. To date, gene therapy has successfully restored the health of about 20 children affected by SCID. However, there are some disadvantages of this therapy like the therapy is not completely curative and periodic infusion of the enzyme is required.
Stem Cell Therapy:
Stem cell technologies are expected to provide powerful tools for treating and curing disease. Stem cells are immature cells that can grow and divide to produce different types of cells, such as skin, kidney, and blood cells. Most stem cells are obtained from embryos(embryonic stem cells, or ESCs), and because this process involves the death of the embryo they are controversial. Scientists have successfully isolated stem cells from adult tissues (adult-derived stem cells, or ASCs) that are being compared with their embryonic counterparts for their potential for regenerating nervous tissue and other tissues lost to disease or damage.
Stem cells can be induced to form almost any tissue of interest depending on how they are treated. Imagine growing skin cells, blood cells, and even whole organs in the lab and using these to replace damaged tissue or failing organs such as the liver, pancreas, and retina. Regenerative medicine is a discipline of medical biotechnology that involves repairing or replacing damaged tissues and organs by using tissues and organs grown from stem cells through biotechnological approaches.
Detection of Diseases:
Real-time PCR, PET-Scan, ELISA, MRI, amniocentesis, chorionic villus sampling, karyotyping, and fluorescence in situ hybridization (FISH) are only a few of the techniques developed through biotechnological advancements to detect various disease conditions like viral and bacterial infections, presence of genetic anomalies in the fetus, cancer and other genetic disorders and many more.