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Custom made humans - Could it be?


Custom made humans - Could it be?

Abstract:

It has been the dream of mankind, maybe since the start of life, to be able to better understand the mechanism of creation;

 hoping  that maybe through this information long lost answers can be found, answers like: Why is this happening to me? Why is it that MY child has this disease and no one else? Why do I have cancer? Is it bad luck? Is there something that can be done about it? These questions are only a part of what genetic science promises to tell us now, along with all the numbers relevant to a specific disease and ways of treatment and prevention that were mere dreams only a few years ago.

 

What are genes?

Genes, (Which  are carried on chromosomes), are the basic physical and functional units of heredity. They are specific sequences of bases that encode instructions on how to make proteins. Although genes get a lot of attention, it’s the proteins that perform most life functions and even make up the majority of cellular structures. When genes are altered so that the encoded proteins are unable to carry out their normal functions, genetic disorders can result.

Human Genes  Gene

 

What is genetic engineering?

It is the alteration of genetic code by artificial means. The idea here is to move a gene of interest from its original (or source DNA molecule) into another (target DNA molecule) for some specific purpose. Genetic engineering may be one of the greatest breakthroughs in recent history alongside the discovery of the atom and space flight!
During the 20th century, man harnessed the power of the atom; and not long after, soon realized the power of genes. Genetic engineering is going to become a very mainstream part of our lives sooner or later, because there are so many possible advantages (and disadvantages) involved. Here are just some of the advantages:

 

  • Disease could be prevented by detecting people/plants/animals that are genetically prone to certain hereditary diseases, and preparing for the inevitable. Also, infectious diseases can be treated by implanting genes that code for antiviral proteins specific to each antigen.
  • Animals and plants can be 'tailor made' to show desirable characteristics. Genes could also be manipulated in trees for example, to absorb more CO2 and reduce the threat of global warming.
  • Genetic engineering could increase genetic diversity. It is possible to alter the genetics of wheat plants to grow insulin for example.

 

Of course there are two sides to the coin; here are some possible eventualities and disadvantages:

 

  • Nature is an extremely complex inter-related chain consisting of many species linked in the food chain. Some scientists believe that introducing genetically modified genes may have an irreversible effect with consequences yet unknown.
  • Genetic engineering borderlines on many moral issues, particularly involving religion, which questions whether man has the right to manipulate the laws and course of nature.

Genetic engineering has been impossible until recent times due to the complex and microscopic nature of DNA and its component nucleotides. A genome is an organism’s complete set of DNA, including all of its genes, containing all the information needed to build and maintain that organism. In humans, a copy of the entire genome—more than 3 billion DNA base pairs—is contained in all cells that have a nucleus. The Human Genome Project was an international research effort, was coordinated by the National Institutes of Health and the U.S. Department of Energy, to determine the sequence of the human genome and identify the genes that it contains.  The project formally began in 1990 and was completed in 2003, 2 years ahead of its original schedule.

 

The main goals of the Human Genome Project were:

  1. To provide a complete and accurate sequence of the 3 billion DNA base pairs that make up the human genome and to find all of the estimated 20,000 to 25,000 human genes.
  2. To sequence the genomes of several other organisms that are important to medical research, such as the mouse and the fruit fly.
  3. To develop new tools to obtain and analyze the data and to make this information widely available.
  4. Exploring the consequences of genomic research through its Ethical, Legal, and Social Implications (ELSI) program.

 

In April 2003, researchers announced that the Human Genome Project had completed a high-quality sequence of essentially the entire human genome, closing the gaps from a working draft of the genome published in 2001.

 

The process of genetic engineering involves:

  • Splicing an area of a chromosome that controls a certain characteristic of the body (cutting of gene in fragments and rejoining them according to need). An enzyme called endonuclease is used to split a DNA sequence and split the gene from the rest of the chromosome.
  • Programming the gene to perform a certain function; for example, producing an antiviral protein.
  • This gene is removed and can be placed into another organism, bacteria for example, where it is sealed into the DNA chain using an enzyme called ligase.
  • When the chromosome is once again sealed, the bacteria are now effectively re-programmed to replicate this new antiviral protein. The bacteria can continue to live a healthy life (though genetic engineering and human intervention has actively manipulated what the bacteria actually are).

 

What is gene therapy?

Gene therapy is an experimental technique that uses genes to treat or prevent disease (the use of genes as medicine). In the future, this technique may allow doctors to treat a disorder by inserting a gene into a patient’s cells instead of using drugs or surgery. Researchers are testing several approaches to gene therapy, including:

  • 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.

Gene Therapy

Although gene therapy is a promising treatment option for a number of diseases (including inherited disorders, some types of cancer, and certain viral infections), the technique remains risky and is still under study to make sure that it will be safe and effective. Gene therapy is currently only being tested for the treatment of diseases that have no other cures.

 

A gene that is inserted directly into a cell usually does not function. Instead, a carrier called a vector is genetically engineered to deliver the gene. Vectors can be viral or nonviral.

 

Viral vectors:

  • Retroviruses - A class of viruses that can create double-stranded DNA copies of their RNA genomes. These copies of its genome can be integrated into the chromosomes of host cells. Human immunodeficiency virus (HIV) is a retrovirus.
  • Adenoviruses - A class of viruses with double-stranded DNA genomes that cause respiratory, intestinal, and eye infections in humans. The virus that causes the common cold is an adenovirus.
  • Adeno-associated viruses - A class of small, single-stranded DNA viruses that can insert their genetic material at a specific site on chromosome 19.
  • Herpes simplex viruses - A class of double-stranded DNA viruses that infect neurons. Herpes simplex virus type 1 is a common human pathogen that causes cold sores.

 

Non-viral vectors:

  • The simplest method is the direct introduction of therapeutic DNA into target cells. This approach is limited in its application because it can be used only with certain tissues and requires large amounts of DNA.
  • Creation of a liposome; an artificial lipid sphere with an aqueous core. This liposome, which carries the therapeutic DNA, is capable of passing the DNA through the target cell's membrane.
  • Chemically linking the DNA to a molecule that will bind to special cell receptors. Once bound to these receptors, the therapeutic DNA constructs are engulfed by the cell membrane and passed into the interior of the target cell. This delivery system tends to be less effective than other options.


The vector can be injected or given intravenously (by IV) directly into a specific tissue in the body, where it is taken up by individual cells. Alternately, a sample of the patient’s cells can be removed and exposed to the vector in a laboratory setting. The cells containing the vector are then returned to the patient. If the treatment is successful, the new gene delivered by the vector will make a functioning protein.

 

Gene therapy using an adenovirus vector
A new gene is injected into an adenovirus vector, which is used to introduce the modified DNA into a human cell. If the treatment is successful, the new gene will make a functional protein.

 

What factors have kept gene therapy from becoming an effective treatment for genetic disease?

  • Short-lived nature of gene therapy - Before gene therapy can become a permanent cure for any condition, the therapeutic DNA introduced into target cells must remain functional and the cells containing the therapeutic DNA must be long-lived and stable. Problems with integrating therapeutic DNA into the genome and the rapidly dividing nature of many 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 tissues, the immune system is designed to attack the invader. The risk of stimulating the immune system in a way that reduces gene therapy effectiveness is always a potential risk. Furthermore, the immune system's enhanced response to invaders it has seen before makes it difficult for gene therapy to be repeated in patients.
  • Problems with viral vectors - Viruses, while the carrier of choice in most gene therapy studies, present a variety of potential problems to the patient --toxicity, immune and inflammatory responses, and gene control and targeting issues. In addition, there is always the fear that the viral vector, once inside the patient, may recover its ability to cause disease.
  • Multigene disorders - Conditions or disorders that arise from mutations in a single gene are the best candidates for gene therapy. Unfortunately, some of  the most commonly occurring disorders, such as heart disease, high blood pressure, Alzheimer's disease, arthritis, and diabetes, are caused by the combined effects of variations in many genes; making gene therapy very difficult in these cases.

 

History of trials:

In 1972 Friedmann and Roblin authored a paper in Science titled "Gene therapy for human genetic disease?"  They cite Rogers S for proposing  that exogenous "good" DNA be used to replace the defective DNA in those who suffer from genetic defects.

 


In 1982, gene therapy pioneer French Anderson introduced the four well-known categories of human gene therapy into the scientific literature. This is Maurice A. M. De Wachter's summary:

  1. somatic cell gene therapy: here a genetic defect in the somatic or body cells of a patient is being corrected.
  2. germ-line gene therapy: here a genetic defect in the germ, or reproductive cells of a patient are being corrected so that offspring of the patient would also be corrected.
  3. enhancement genetic engineering: here a gene is being inserted in order to try to enhance or improve a specific characteristic, for example adding an additional growth hormone to increase height.
  4. eugenic genetic engineering: here genes are being inserted in order to try to alter or improve complex human traits that depend on a large number of genes as well as on extensive interactions with the environment, for example intelligence, personality, character.

 

The first approved gene therapy case in the United States took place on September 14, 1990, at the National Institute of Health. It was performed on a four year old girl named Ashanti DeSilva. It was a treatment for a genetic defect that left her with an Immune System deficiency. The effects were only temporary, but successful. But, in 1995, the gene therapy community had to face facts that there was no evidence that gene therapy was working!  Ashanti and others treated with gene therapy were also being given the conventional treatment for the disorder which might have been responsible for their good health.

 

Monogenic disorders for which gene therapy has been attempted include cystic fibrosis, familial hypercholesterolaemia, mucopolysaccharidosis types I and II, alpha-1-antitrypsin deficiency, severe combined immunodeficiency and Gaucher's disease.

 

Indeed, whereas during the second half of the 1980s the majority of research was on single-gene disorders, from 1990 onwards attention has shifted towards acquired disorders such as cancer and HIV. Globally, as of 1 June 1999, 380 trials had been performed involving a total of 3173 patients. Of these 240 were cancer therapies involving 2166 patients and 53 were on monogenic diseases involving 296 patients.  Mankind in general awaited the results with eagerness.

 

In 1999, gene therapy suffered a major setback with the death of 18-year-old Jesse Gelsinger. Jesse was participating in a gene therapy trial for ornithine transcarboxylase deficiency (OTCD). He died from multiple organ failures 4 days after starting the treatment. His death is believed to have been triggered by a severe immune response to the adenovirus carrier.

 

In 2000, a French research group used gene therapy in the treatment of a form of immune deficiency due to a mutation in a gene located on the X chromosome (Severe Combined Immune Deficiency). When two of the children treated developed leukaemia in 2002 and 2003, caused when the virus used to deliver the therapeutic gene activated a Cancer-causing gene, the clinical trials were stopped but have now been resumed only for patients with no other treatment options.

 

FDA's Biological Response Modifiers Advisory Committee (BRMAC) met at the end of February 2003 to discuss possible measures that could allow a number of retroviral gene therapy trials for treatment of life-threatening diseases to proceed with appropriate safeguards. In April of 2003 the FDA eased the ban on gene therapy trials using retroviral vectors in blood stem cells.

 

What is the current status of gene therapy research?

  • Researchers at Rush University Medical Center, in June 2006, have successfully used gene therapy to preserve motor function and stop the anatomic, cellular changes that occur in the brains of mice with Huntington's disease (HD). This is the first study to demonstrate that symptom onset might be prevented in HD mice with this treatment.
  • University of Pittsburgh School of Medicine researchers have successfully used gene therapy to accelerate muscle regeneration in experimental animals with muscle damage, suggesting this technique may be a novel and effective approach for improving skeletal muscle healing, particularly for serious sports-related injuries. This also took place in June 2006.
  • John Wiley & Sons, Inc. in February 2007 published a study stating that carbon nanotubes transport gene therapy drug into T-cells was shown to block HIV from entering cells in-vitro.
  • In what could be a breakthrough in the treatment of neurological disease; in June 2007,  a team led by physician-scientists at New York-Presbyterian Hospital/Weill Cornell Medical Center has completed the first-ever phase 1 clinical trial using gene therapy to battle Parkinson's disease. The study of 11 men and one woman with the progressive neurodegenerative illness found that the procedure, in which surgeons inject a harmless gene-bearing virus into the brain, was both safe and resulted in improved motor function for Parkinson's patients over the course of one year.
  • Scientists at the University of Michigan have developed a method of gene delivery that appears safe for regenerating tooth-supporting gum tissue in April 2009.
  • “Progress and prospects: graft-versus-host disease “  by S Mastaglio, M T L Stanghellini, and colleagues  from University Vita-Salute, Milano, Italy; stated that current therapies to prevent and treat graft-versus-host disease (GvHD) are insufficient, and new cell and gene therapy approaches are currently being developed. The results were published in May 2010.
  • On August 18th 2010, in one of only two studies of its kind, a study from researchers at Tufts University School of Medicine and the Sackler School of Graduate Biomedical Sciences at Tufts demonstrates that non-viral gene therapy can delay the onset of some forms of eye disease and preserve vision. The team developed nanoparticles to deliver therapeutic genes to the retina and found that treated mice temporarily retained more eyesight than controls.
  • In November 2010, a study titled “Regeneration of pancreatic islets in vivo by ultrasound-targeted gene therapy” by S Chen, M Shimoda and colleagues used a novel approach to gene therapy in which plasmid DNA is targeted to the pancreas in vivo using ultrasound-targeted microbubble destruction (UTMD) to achieve islet regeneration.

 

Questions raised by the issue of gene therapy:

  • 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?
  • Is somatic gene therapy (which is done in the adult cells of persons known to have the disease) more or less ethical than germline gene therapy (which is done in egg and sperm cells and prevents the trait from being passed on to further generations?
  • Preliminary attempts at gene therapy are exorbitantly expensive. Who will have access to these therapies? Who will pay for their use?

Conclusion:

We may toy around with the idea that we have managed to figure it all out, and that we now have the answers to almost anything that can harm or affect the well being of human beings; but, scientists beware!! It will never be possible to turn man into a man –made invention!
While it may be fun to think that we can ask for a baby that will grow up to be tall, blond, athletic, intelligent and free of disease (or whatever other characteristics one may fancy), we have not seen the end of creator’s tricks and surprises. Things may take a different course of action from here rendering us, again, helpless and praying for mercy.


اضغط هنا للقراءة باللغة العربية

Prepared by: Dr. Zaina Habrawi


Source :

  1. The Australasian Genetics Resource Book – © 2007 www.genetics.edu.au
  2. Genetic engineering-advantages and disadvantages. http://www.biology-online.org/2/13_genetic_engineering.htm
  3. Gene therapy I, September 2010 http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GeneTherapy.html
  4. Smith, A. E. (1999), 'Gene therapy—where are we?, Supplement to the Lancet: Molecular medicine, 354: SI1. http://www.wiley.co.uk/genetherapy/clinical/diseases.phpl.
  5. Nabel, E. G. (1999), 'The Development of Human Gene Therapy', Nature Medicine, 5 (7): 728.
  6. House of Commons Science and Technology Committee, Third Report: Human Genetics: The Science and its Consequences, 1, London, HMSO, 1995: xlvi.
  7. De Wachter, M. A. M. (1993), 'Ethical Aspects of Human Germ-Line Gene Therapy', Bioethics, 7 (2/3): 166-177.
  8. Wivel, N. A. and Walters, L. (1993), 'Germ-Line Gene Modification and Disease Prevention: Some Medical and Ethical Perspectives', Science, 262: 533-538.
  9. McLaren, A. (1998), 'Problems of germline therapy', Nature, 392: 645.
  10. Billings, P. R., Hubbard, R., and Newman, S. A. (1999), 'Human germline gene modification: a dissent', The Lancet, 353: 1873-1874.
  11. Human genome project information, genomics.energy.gov.
  12. Progress and prospects: graft-versus-host disease; S Mastaglio, M T L Stanghellini, C Bordignon, A Bondanza , F Ciceri  and C Bonini .
  13. Regeneration of pancreatic islets in vivo by ultrasound-targeted gene therapy; S Chen , M Shimoda , M-Y Wang , J Ding, H Noguchi , S Matsumoto and P A Grayburn
  14. Carbon nanotubes transport gene therapy drug into T-cells known to block HIV from entering cells in vitro,Feb 2007;John Wiley and Sons,Inc.
  15. Gene therapy protects neurons in Huntington's disease
  16. June 2006, Rush University Medical Center.
  17. Promising results from first gene therapy clinical trial for Parkinson's disease reported,June 2007 ,By New York- Presbyterian Hospital/Weill Cornell Medical Center/Weill Cornell Medical College.
  18. Gene therapy appears safe to regenerate gum tissue
  19. Apr 7, 2009, By University of Michigan
  20. Breakthrough Gene Therapy Prevents Retinal Degeneration, ScienceDaily (Aug. 18, 2010)
  21. Using gene therapy to accelerate damaged muscle regeneration, Jun 2006;  By University of Pittsburgh Medical Center






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