The technological singularity is a hypothesized point in the future variously characterized by the technological creation of self-improving intelligence, unprecedentedly rapid technological progress, or some combination of the two.Statistician I. J. Good first wrote of an "intelligence explosion", suggesting that if machines could even slightly surpass human intellect, they could improve their own designs in ways unseen by their designers, and thus recursively augment themselves into far greater intelligences. Vernor Vinge later called this event "the Singularity" as an analogy between the breakdown of modern physics near a gravitational singularity and the drastic change in society he argues would occur following an intelligence explosion. In the 1980s, Vinge popularized the Singularity in lectures, essays, and science fiction. More recently, some AI researchers have voiced concern over the potential dangers of Vinge's Singularity.
Others, most prominently Ray Kurzweil, define the Singularity as a period of extremely rapid technological progress. Kurzweil argues such an event is implied by a long-term pattern of accelerating change that generalizes Moore's Law to technologies predating the integrated circuit and which he argues will continue to other technologies not yet invented.
Critics of Kurzweil's interpretation consider it an example of static analysis, citing particular failures of the predictions of Moore's Law. The Singularity also draws criticism from anarcho-primitivism and environmentalism advocates
Tuesday, March 18, 2008
What is Transhumanism?
Transhumanism (sometimes symbolized by >H or H+),a term often used as a synonym for "human enhancement", is an international intellectual and cultural movement supporting the use of new sciences and technologies to enhance human mental and physical abilities and aptitudes, and ameliorate what it regards as undesirable and unnecessary aspects of the human condition, such as stupidity, suffering, disease, aging and involuntary death. Transhumanist thinkers study the possibilities and consequences of developing and using human enhancement techniques and other emerging technologies for these purposes. Possible dangers, as well as benefits, of powerful new technologies that might radically change the conditions of human life are also of concern to the transhumanist movement.Although the first known use of the term "transhumanism" dates from 1957, the contemporary meaning is a product of the 1980s, when a group of scientists, artists, and futurists based in the United States began to organize what has since grown into the transhumanist movement. Transhumanist thinkers predict that human beings will eventually be transformed into beings with such greatly expanded abilities as to merit the label "posthuman, Transhumanism is therefore sometimes referred to as "posthumanism" or a form of transformational activism influenced by posthumanist ideals..Transhumanist foresight of a profoundly transformed future humanity has attracted many supporters and detractors from a wide range of perspectives. Transhumanism has been described by one outspoken opponent as the world's most dangerous idea,while a proponent counters that it is the "movement that epitomizes the most daring, courageous, imaginative, and idealistic aspirations of humanity
Mind uploading
Mind uploading is the transfer of the human mind/consciousness to a more durable material vessel (stereotypically but not necessarily a silicon computer). The concept is based on materialism, the philosophy of mind that argues that the human spirit is entirely composed of a very complex system of physical and chemical interactions. However, it is not understood how consciousness exists, and thus no existing scientific understanding for "reading" the "contents" of a human mind. With computer power increasing exponentially, and technology in the pipeline to keep up the trend, futurist Ray Kurzweil predicts that computer hardware will be powerful enough to run a functional model of the human mind by the 2020s. Several developing technologies hypothetically allow the complete mapping of human brains on a similar timescale. Uploading the human mind to a computer, if possible, would potentially greatly extend human lifespan due to the ability to construct highly durable computer hardware and the potential to copy or transfer the mind to multiple computers
Suspended animation
Suspended animation is the slowing of life processes by external means without termination. Breathing, heartbeat, and other involuntary functions may still occur, but they can only be detected by artificial means. Extreme cold is used to precipitate the slowing of an individual's functions. Although the technique has not been applied to human, experiments are successful in dogs, pigs and mice. Scientists drain the blood from animals' bodies and put an ice-cold solution into their circulatory systems. After being clinically dead for three hours, their blood is put back into their circulatory systems, and the dogs are revived by delivering an electric shock to their hearts. Scientists also have done similar experiments on pigs and tested 200 times with a 90 percent success rate. There are also experiments reports success towards inducing suspended animation in mice by using chemical method, according to an article published in the scientific journal Science on April 22, 2005
SENS (Strategies for Engineered Negligible Senescence)
Cell loss can be repaired (reversed) just by suitable exercise, in the case of muscle. For other tissues, it needs various growth factors to stimulate cell division; in some cases it needs stem cells.
Senescent cells can be removed by activating the immune system against them. Or they can be destroyed by gene therapy to introduce "suicide genes" that only kill senescent cells.
Protein cross-linking can largely be reversed by drugs that break the links. But to break some of the cross-links we may need to develop enzymatic methods.
Extracellular garbage (like amyloid) can be eliminated by vaccination that gets immune cells to "eat" the garbage.
For intracellular junk we need to introduce new enzymes, possibly enzymes from soil bacteria, that can degrade the junk (lipofuscin) that our own natural enzymes cannot degrade.
For mitochondrial mutations the plan is not to repair them but to prevent harm from the mutations by putting suitably modified copies of the mitochondrial genes into the cell nucleus by gene therapy. The mitochondrial DNA experiences a high degree of mutagenic damage because most free radicals are generated in the mitochondria and because the DNA repair mechanisms of mitochondrial DNA are significantly inferior to those of nuclear DNA. A copy of the mitochondrial DNA located in the nucleus will be better protected from free radicals, and there will be better DNA repair when damage occurs. All mitochondrial proteins would then be imported into the mitochondria.
For cancer (the most lethal consequence of mutations) the strategy is to use gene therapy to delete the genes for telomerase and to eliminate telomerase-independent mechanisms of turning normal cells into "immortal" cancer cells. To compensate for the loss of telomerase in stem cells we would introduce new stem cells every decade or so.
Senescent cells can be removed by activating the immune system against them. Or they can be destroyed by gene therapy to introduce "suicide genes" that only kill senescent cells.
Protein cross-linking can largely be reversed by drugs that break the links. But to break some of the cross-links we may need to develop enzymatic methods.
Extracellular garbage (like amyloid) can be eliminated by vaccination that gets immune cells to "eat" the garbage.
For intracellular junk we need to introduce new enzymes, possibly enzymes from soil bacteria, that can degrade the junk (lipofuscin) that our own natural enzymes cannot degrade.
For mitochondrial mutations the plan is not to repair them but to prevent harm from the mutations by putting suitably modified copies of the mitochondrial genes into the cell nucleus by gene therapy. The mitochondrial DNA experiences a high degree of mutagenic damage because most free radicals are generated in the mitochondria and because the DNA repair mechanisms of mitochondrial DNA are significantly inferior to those of nuclear DNA. A copy of the mitochondrial DNA located in the nucleus will be better protected from free radicals, and there will be better DNA repair when damage occurs. All mitochondrial proteins would then be imported into the mitochondria.
For cancer (the most lethal consequence of mutations) the strategy is to use gene therapy to delete the genes for telomerase and to eliminate telomerase-independent mechanisms of turning normal cells into "immortal" cancer cells. To compensate for the loss of telomerase in stem cells we would introduce new stem cells every decade or so.
Chemical and genetic interventions in non-human animals
Biotechnologies, particularly those of human cloning and stem cell research, are thought to offer some possibility of replacing aging body parts with 'new' parts grown artificially. Current technology has already demonstrated the feasibility of body part replacement in laboratory experiments, most notably the fabrication of a functioning dog's bladder that proved to be viable after successful implantation. Bladders and other simple biological structures more readily lend themselves to artificial fabrication, whereas complex biological structures such as mammalian joints and limbs are not yet possible to fabricate artificially. Given the exponential progression of technology, it is probable that the artificial fabrication of replacement body parts, both simple and complex, along with successful implantation technology will one day be possible. In one popular scenario, an individual's brain is transplanted from his or her aging body into a new, youthful body cloned from his or her own tissues. Experiments were conducted in the mid-20th century to transplant brains from one body to another (conducted in both monkeys and dogs), but failed due to rejection and the inability to restore nerve connections - research into the nervous system and homogenisation may make this process more fruitful in the future. Proponents of body part replacement and cloning contend that the required biotechnologies are likely to appear earlier than other life-extension technologies.
Moral controversy surrounding stem cell research and human cloning continues to cloud the issue.
Moral controversy surrounding stem cell research and human cloning continues to cloud the issue.
Calorie restriction
The restriction of energy intake, or calories, in an otherwise healthy diet (a practice generally called Calorie restriction or simply CR) has been shown to extend the maximum lifespan of almost every species on which it has been tested, including rats, yeast, fruit flies, and nematodes. In rodents, a roughly 50% maximum lifespan extension is seen with a roughly 50% restriction of calories from what would be consumed by freely-feeding animals. Experiments are in progress with primates to test whether calorie restriction can extend the lifespan of primates. Some people believe that these experiments will be successful, and further believe that the results will be also true for humans. A group called the Calorie Restriction Society was formed with the help of Brian M. Delaney, Lisa Walford, and Roy Walford in the mid-1990s. They communicate by e-mail and have been flown to Washington University in St. Louis to be studied by Dr. John Holloszy. Calorie restriction is under current study at the UW-Madison and several other universities
Anti-aging nutritional supplementation and medicine
Much of anti-aging medicine has been concerned with the use of nutritional supplements to extend lifespan. The idea that antioxidant supplements, such as Vitamin C, Vitamin E, lipoic acid and N-acetylcysteine, might extend human life stems from the free radical theory of aging.
Other less popular hormones are oxytocin, insulin, human chorionic gonadotropin (hCG), erythropoietin (EPO), and others. Resveratrol is a sirtuin stimulant proposed to extend life in mammals in a similar manner to that claimed for calorie restriction in simple model organisms such as nematodes.[citation needed]
Some supplements have been shown to be of benefit against some aging-related disease conditions, or have extended average lifespan in animals, though none have been proven to do so in humans. Calorie restriction and supplementation with the minerals selenium, chromium and zinc ,have been shown to extend maximum lifespan in mice. Metformin,may also extend life span in mice, and in the first experiments with fish, resveratrol,looks promising. (Resveratrol is presently (2006) being tested in mice.)
Other less popular hormones are oxytocin, insulin, human chorionic gonadotropin (hCG), erythropoietin (EPO), and others. Resveratrol is a sirtuin stimulant proposed to extend life in mammals in a similar manner to that claimed for calorie restriction in simple model organisms such as nematodes.[citation needed]
Some supplements have been shown to be of benefit against some aging-related disease conditions, or have extended average lifespan in animals, though none have been proven to do so in humans. Calorie restriction and supplementation with the minerals selenium, chromium and zinc ,have been shown to extend maximum lifespan in mice. Metformin,may also extend life span in mice, and in the first experiments with fish, resveratrol,looks promising. (Resveratrol is presently (2006) being tested in mice.)
What is Aging?
Aging is an accumulation of damage to macromolecules, cells, tissues and organs. The maximum life span known for humans is in excess of 120 years, whereas the maximum lifespan of a mouse is about four years. Genetic differences between humans and mice that may account for these different aging rates include efficiency of DNA repair, types and quantities of antioxidant enzymes, and different rates of free radical production
What is Life extension?
Life extension refers to an increase in maximum or average lifespan, especially in humans, by slowing down or reversing the processes of aging. Average lifespan is determined by vulnerability to accidents and age-related afflictions such as cancer or cardiovascular disease. Extension of average lifespan can be achieved by good diet, exercise and avoidance of hazards such as smoking and excessive eating of sugar-containing foods. Maximum lifespan is determined by the rate of aging for a species inherent in its genes and probably by certain environmental factors. Currently, the only widely recognized method of extending maximum lifespan is calorie restriction. Theoretically, extension of maximum lifespan could be achieved by reducing the rate of aging damage, by periodic replacement of damaged tissues, or by molecular repair or rejuvenation of deteriorated cells and tissues.
Researchers of life extension are known as biogerontologists. They seek to understand the nature of aging and they develop treatments to reverse aging processes or to at least slow them down, for the improvement of health and the maintenance of youthful vigor at every stage of life. (Biomedical gerontologists are distinguished from biogerontologists in that the latter may take a purely academic interest in the biological mechanisms of aging, without seeking a "cure".) Those who take advantage of life extension findings and seek to apply them upon themselves are called "life extensionists" or "longevists". The primary life extension strategy currently is to apply available anti-aging methods in the hope of living long enough to benefit from a complete cure to aging once it is developed, which given the rapidly advancing state of biogenetic and general medical technology, could conceivably occur within the lifetimes of people living today (around 2020 according to Raymond KurzweilMany biomedical gerontologists and life extensionists believe that future breakthroughs in tissue rejuvenation with stem cells, organs replacement (with artificial organs or xenotransplantations) and molecular repair will eliminate all aging and disease as well as allow for complete rejuvenation to a youthful condition. Whether such breakthroughs can occur within the next few decades is impossible to predict. Many life extensionists arrange to be cryonically preserved upon legal death so that they can await the time when future medicine can eliminate disease, rejuvenate them to a lasting youthful condition and repair damage caused by the cryonics process.
Researchers of life extension are known as biogerontologists. They seek to understand the nature of aging and they develop treatments to reverse aging processes or to at least slow them down, for the improvement of health and the maintenance of youthful vigor at every stage of life. (Biomedical gerontologists are distinguished from biogerontologists in that the latter may take a purely academic interest in the biological mechanisms of aging, without seeking a "cure".) Those who take advantage of life extension findings and seek to apply them upon themselves are called "life extensionists" or "longevists". The primary life extension strategy currently is to apply available anti-aging methods in the hope of living long enough to benefit from a complete cure to aging once it is developed, which given the rapidly advancing state of biogenetic and general medical technology, could conceivably occur within the lifetimes of people living today (around 2020 according to Raymond KurzweilMany biomedical gerontologists and life extensionists believe that future breakthroughs in tissue rejuvenation with stem cells, organs replacement (with artificial organs or xenotransplantations) and molecular repair will eliminate all aging and disease as well as allow for complete rejuvenation to a youthful condition. Whether such breakthroughs can occur within the next few decades is impossible to predict. Many life extensionists arrange to be cryonically preserved upon legal death so that they can await the time when future medicine can eliminate disease, rejuvenate them to a lasting youthful condition and repair damage caused by the cryonics process.
Neuropreservation
Neuropreservation is cryopreservation of the brain, usually within the head, with surgical removal and disposal of the rest of the body. Neuropreservation, sometimes called “neuro,” is one of two distinct preservation options in cryonics, the other being "whole body" preservation.
Neuropreservation is motivated by the fact that the brain is the primary repository of memory and personal identity. (For instance, spinal cord injury victims, organ transplant patients, and amputees retain their personal identity.) It is also motivated by the belief that reversing any type of cryonic preservation is so difficult and complex that any future technology capable of it must by its nature be capable of generalized tissue regeneration, including growth of a new body around a repaired brain. Some suggested revival scenarios for whole body patients even involve discarding the original body and regenerating a new one because tissues are so badly damaged by the preservation process. These considerations, along with lower costs, easier transportation in emergencies, and the specific focus on brain preservation quality, have motivated many cryonicists to choose neuropreservation.
The advantages and disadvantages of neuropreservation are often debated among cryonics advocates. Critics of neuropreservation note that the body is a record of much life experience, including learned motor skills. While few cryonicists doubt that a revived neuro patient would be the same person, there are wider questions about how a regenerated body might feel different from the original.Partly for these reasons (as well as for better public relations), the Cryonics Institute preserves only whole bodies. Some proponents of neuropreservation agree with these concerns, but still feel that lower costs and better brain preservation justify preserving only the brain. About three-quarters of the patients stored at Alcor are "neuros
Neuropreservation is motivated by the fact that the brain is the primary repository of memory and personal identity. (For instance, spinal cord injury victims, organ transplant patients, and amputees retain their personal identity.) It is also motivated by the belief that reversing any type of cryonic preservation is so difficult and complex that any future technology capable of it must by its nature be capable of generalized tissue regeneration, including growth of a new body around a repaired brain. Some suggested revival scenarios for whole body patients even involve discarding the original body and regenerating a new one because tissues are so badly damaged by the preservation process. These considerations, along with lower costs, easier transportation in emergencies, and the specific focus on brain preservation quality, have motivated many cryonicists to choose neuropreservation.
The advantages and disadvantages of neuropreservation are often debated among cryonics advocates. Critics of neuropreservation note that the body is a record of much life experience, including learned motor skills. While few cryonicists doubt that a revived neuro patient would be the same person, there are wider questions about how a regenerated body might feel different from the original.Partly for these reasons (as well as for better public relations), the Cryonics Institute preserves only whole bodies. Some proponents of neuropreservation agree with these concerns, but still feel that lower costs and better brain preservation justify preserving only the brain. About three-quarters of the patients stored at Alcor are "neuros
Ischemic injury
Ischemia means inadequate or absent blood circulation that deprives tissue of oxygen and nutrients. At least several minutes of ischemia is an unavoidable part of cryonics because of the legal requirement that cryonics procedures do not begin until after blood circulation stops. The heart must stop beating so that legal death can be declared. When there is advance notice of impending clinical death, it is sometimes possible to deploy a team of technicians to perform a “standby”. The team artificially restores blood circulation and breathing using techniques similar to CPR as soon as possible after the heart stops..The aim is to keep tissues alive after legal death by analogy to conventional medical procedures in which viable organs and tissues are obtained for transplant from legally deceased donors. Contrary to popular belief, legal death does not mean that all the cells of the body have died.Often in cryonics the brain is without oxygen for many minutes at warm temperatures, or even hours if the heart stops unexpectedly. This causes ischemic injury to the brain and other tissues that makes resuscitation impossible by present medical technology. Cryonicists justify preservation under such conditions by noting recent advances that allow brain resuscitation after longer periods of ischemia than the traditional 4 to 6 minute limit, and persistence of brain structure and even some brain cell function after long periods of clinical death.They argue that definitions of death change as technology advances, and the early stages of what is called “death” today is actually a form of ischemic injury that will be reversible in the future.They claim that personal survival during long periods of clinical death is determined by information theoretic criteria
Preservation injury
Long-term cryopreservation requires cooling to near −196 °C (−321 °F), the boiling point of liquid nitrogen. Cooling whole people to this temperature causes injuries that are not reversible with present technology. The common belief that water freezes inside cells causing them to burst is a myth,but damage from freezing can still be serious. When untreated tissue is slowly cooled below the freezing point of water, ice forms between cells, causing mechanical and chemical damage. Cryonics uses cryoprotectants to reduce this damage. Cryoprotectant solutions are circulated through blood vessels to remove and replace water inside cells with chemicals that prevent freezing. This can reduce damage greatly, but not enough for whole people to recover spontaneously from cryopreservation. When used at high concentrations, cryoprotectants stop ice formation completely. Cooling and solidification without freezing is called vitrification. The first cryoprotectant solutions able to vitrify at very slow cooling rates while still being compatible with tissue survival were developed in the late 1990s by cryobiologists Gregory Fahy and Brian Wowk for the purpose of banking transplantable organs.These solutions were adopted for use in cryonics by the Alcor Life Extension Foundation, for which they are believed to permit vitrification of some parts of the human body, especially the brain. This has allowed animal brains to be vitrified, warmed back up, and examined for ice damage using light and electron microscopy. No ice crystal damage was found.. The Cryonics Institute also uses a vitrification solution developed by their staff cryobiologist, Dr. Yuri Pichugin, applying it principally to the brain..Vitrification in cryonics is different than vitrification in mainstream cryobiology because vitrification in cryonics is not reversible with current technology. It is only structural vitrification. When successful it can prevent freezing injury in some body parts, but at the price of toxicity caused by cryoprotectant chemicals. The nature of this toxicity is still poorly understood. Cryonicists assume that toxicity is more subtle and repairable than obvious structural damage that would otherwise be caused by freezing. If, for example, toxicity is due to denatured proteins, those proteins could be repaired or replaced.
Premises of cryonics
The central premise of cryonics is that memory, personality, and identity are stored in cellular structures and chemistry, principally in the brain. (Neuropreservation relies entirely on the brain, while "whole body" preservation addresses the possibility that some attributes, such as muscle memory, might reside at least partially elsewhere in the body.) While this view is widely accepted in medicine, and brain activity is known to stop and later resume under certain conditions, it is not generally accepted that current methods preserve the brain well enough to permit revival in the future. Cryonics advocates point to studies showing that high concentrations of cryoprotectant circulated through the brain before cooling can largely prevent freezing injury, preserving the fine cell structures of the brain in which memory and identity presumably reside.To its detractors, the justification for the actual practice of cryonics is unclear, given present limitations of preservation technology. Currently cells, tissues, blood vessels, and some small animal organs can be reversibly cryopreserved. Some frogs can survive for a few months in a partially frozen state a few degrees below freezing, but this is not true cryopreservation. Cryonics advocates counter that demonstrably reversible preservation is not necessary to achieve the present-day goal of cryonics, which is preservation of basic brain information that encodes memory and personal identity. Preservation of this information is said to be sufficient to prevent information theoretical death until future repairs might be possible
What is Cryonics?
Cryonics is the low-temperature preservation of humans and other animals that can no longer be sustained by contemporary medicine until resuscitation may be possible in the future. Human cryopreservation is not currently reversible. In the United States, cryonics can only be legally performed on humans after pronounced legally dead. The rationale for cryonics is that the process may be reversible in the future if performed soon enough, and that cryopreserved people are not dead by the modern information-theoretic definition of death.Cryonics is derived from the Greek word κρύος (kryos), meaning cold..There is a high representation of scientists among cryonics supporters.Scientific support for cryonics is based on studies showing substantial preservation of brain cell structure by current methods, and projections of future technology, especially molecular nanotechnology and nanomedicine. Some scientists believe that future medicine. will enable molecular-level repair and regeneration of damaged tissues and organs decades or centuries in the future. Disease and aging are also assumed to be reversible. Many ethical questions revolve around the issue of whether cryonics can work.
The modern concept of cryonics as a general procedure to apply whenever patients are considered beyond help by the medicine of their time was originated in 1962 by Robert Ettinger. The largest current practitioners of cryonics are two member-owned, non-profit organizations, the Alcor Life Extension Foundation in Scottsdale, Arizona, with 77 cryopreserved patients and 842 members, and the Cryonics Institute in Clinton Township, Michigan with 86 patients and 718 members. In Europe, the Russian company KrioRus (founded 2005) maintains four cryopreserved patients in Moscow
The modern concept of cryonics as a general procedure to apply whenever patients are considered beyond help by the medicine of their time was originated in 1962 by Robert Ettinger. The largest current practitioners of cryonics are two member-owned, non-profit organizations, the Alcor Life Extension Foundation in Scottsdale, Arizona, with 77 cryopreserved patients and 842 members, and the Cryonics Institute in Clinton Township, Michigan with 86 patients and 718 members. In Europe, the Russian company KrioRus (founded 2005) maintains four cryopreserved patients in Moscow
Adult stem cells
The term adult stem cell refers to any cell which is found in a developed organism that has two properties: the ability to divide and create another cell like itself and also divide and create a cell more differentiated than itself. Also known as somatic (from Greek Σωματικóς, "of the body") stem cells and germline (giving rise to gametes) stem cells, they can be found in children, as well as adults..Pluripotent adult stem cells are rare and generally small in number but can be found in a number of tissues including umbilical cord blood.Most adult stem cells are lineage-restricted (multipotent) and are generally referred to by their tissue origin (mesenchymal stem cell, adipose-derived stem cell, endothelial stem cell, etc.
A great deal of adult stem cell research has focused on clarifying their capacity to divide or self-renew indefinitely and their differentiation potential. In mice, pluripotent stem cells are directly generated from adult fibroblast cultures..While embryonic stem cell potential remains untested, adult stem cell treatments have been used for many years to treat successfully leukemia and related bone/blood cancers through bone marrow transplants. The use of adult stem cells in research and therapy is not as controversial as embryonic stem cells, because the production of adult stem cells does not require the destruction of an embryo. Consequently, more US government funding is being provided for adult stem cell research
A great deal of adult stem cell research has focused on clarifying their capacity to divide or self-renew indefinitely and their differentiation potential. In mice, pluripotent stem cells are directly generated from adult fibroblast cultures..While embryonic stem cell potential remains untested, adult stem cell treatments have been used for many years to treat successfully leukemia and related bone/blood cancers through bone marrow transplants. The use of adult stem cells in research and therapy is not as controversial as embryonic stem cells, because the production of adult stem cells does not require the destruction of an embryo. Consequently, more US government funding is being provided for adult stem cell research
Embryonic stem cells
Embryonic stem cell lines (ES cell lines) are cultures of cells derived from the epiblast tissue of the inner cell mass (ICM) of a blastocyst or earlier morula stage embryos..A blastocyst is an early stage embryo—approximately four to five days old in humans and consisting of 50–150 cells. ES cells are pluripotent and give rise during development to all derivatives of the three primary germ layers: ectoderm, endoderm and mesoderm. In other words, they can develop into each of the more than 200 cell types of the adult body when given sufficient and necessary stimulation for a specific cell type. They do not contribute to the extra-embryonic membranes or the placenta.
Nearly all research to date has taken place using mouse embryonic stem cells (mES) or human embryonic stem cells (hES). Both have the essential stem cell characteristics, yet they require very different environments in order to maintain an undifferentiated state. Mouse ES cells are grown on a layer of gelatin and require the presence of Leukemia Inhibitory Factor (LIF)..Human ES cells are grown on a feeder layer of mouse embryonic fibroblasts (MEFs) and require the presence of basic Fibroblast Growth Factor (bFGF or FGF-2)..Without optimal culture conditions or genetic manipulation. embryonic stem cells will rapidly differentiate.
A human embryonic stem cell is also defined by the presence of several transcription factors and cell surface proteins. The transcription factors Oct-4, Nanog, and SOX2 form the core regulatory network that ensures the suppression of genes that lead to differentiation and the maintenance of pluripotency. The cell surface antigens most commonly used to identify hES cells are the glycolipids SSEA3 and SSEA4 and the keratan sulfate antigens Tra-1-60 and Tra-1-81. The molecular definition of a stem cell includes many more proteins and continues to be a topic of research..After twenty years of research, there are no approved treatments or human trials using embryonic stem cells. ES cells, being totipotent cells, require specific signals for correct differentiation - if injected directly into the body, ES cells will differentiate into many different types of cells, causing a teratoma. Differentiating ES cells into usable cells while avoiding transplant rejection are just a few of the hurdles that embryonic stem cell researchers still face. Many nations currently have moratoria on either ES cell research or the production of new ES cell lines. Because of their combined abilities of unlimited expansion and pluripotency, embryonic stem cells remain a theoretically potential source for regenerative medicine and tissue replacement after injury or disease.
Nearly all research to date has taken place using mouse embryonic stem cells (mES) or human embryonic stem cells (hES). Both have the essential stem cell characteristics, yet they require very different environments in order to maintain an undifferentiated state. Mouse ES cells are grown on a layer of gelatin and require the presence of Leukemia Inhibitory Factor (LIF)..Human ES cells are grown on a feeder layer of mouse embryonic fibroblasts (MEFs) and require the presence of basic Fibroblast Growth Factor (bFGF or FGF-2)..Without optimal culture conditions or genetic manipulation. embryonic stem cells will rapidly differentiate.
A human embryonic stem cell is also defined by the presence of several transcription factors and cell surface proteins. The transcription factors Oct-4, Nanog, and SOX2 form the core regulatory network that ensures the suppression of genes that lead to differentiation and the maintenance of pluripotency. The cell surface antigens most commonly used to identify hES cells are the glycolipids SSEA3 and SSEA4 and the keratan sulfate antigens Tra-1-60 and Tra-1-81. The molecular definition of a stem cell includes many more proteins and continues to be a topic of research..After twenty years of research, there are no approved treatments or human trials using embryonic stem cells. ES cells, being totipotent cells, require specific signals for correct differentiation - if injected directly into the body, ES cells will differentiate into many different types of cells, causing a teratoma. Differentiating ES cells into usable cells while avoiding transplant rejection are just a few of the hurdles that embryonic stem cell researchers still face. Many nations currently have moratoria on either ES cell research or the production of new ES cell lines. Because of their combined abilities of unlimited expansion and pluripotency, embryonic stem cells remain a theoretically potential source for regenerative medicine and tissue replacement after injury or disease.
What is Stem cell?
The practical definition of a stem cell is the functional definition - the ability to regenerate tissue over a lifetime. For example, the gold standard test for a bone marrow or hematopoietic stem cell (HSC) is the ability to transplant one cell and save an individual without HSCs. In this case, a stem cell must be able to produce new blood cells and immune cells over a long term, demonstrating potency. It should also be possible to isolate stem cells from the transplanted individual, which can themselves be transplanted into another individual without HSCs, demonstrating that the stem cell was able to self-renew.
Properties of stem cells can be illustrated in vitro, using methods such as clonogenic assays, where single cells are characterized by their ability to differentiate and self-renew. As well, stem cells can be isolated based on a distinctive set of cell surface markers. However, in vitro culture conditions can alter the behavior of cells, making it unclear whether the cells will behave in a similar manner in vivo. Considerable debate exists whether some proposed adult cell populations are truly stem cells.
Properties of stem cells can be illustrated in vitro, using methods such as clonogenic assays, where single cells are characterized by their ability to differentiate and self-renew. As well, stem cells can be isolated based on a distinctive set of cell surface markers. However, in vitro culture conditions can alter the behavior of cells, making it unclear whether the cells will behave in a similar manner in vivo. Considerable debate exists whether some proposed adult cell populations are truly stem cells.
What is Potency Species?
Potency specifies the differentiation potential (the potential to differentiate into different cell types) of the stem cell.
Totipotent stem cells are produced from the fusion of an egg and sperm cell. Cells produced by the first few divisions of the fertilized egg are also totipotent. These cells can differentiate into embryonic and extraembryonic cell types.
Pluripotent stem cells are the descendants of totipotent cells and can differentiate into cells derived from any of the three germ layers.
Multipotent stem cells can produce only cells of a closely related family of cells (e.g. hematopoietic stem cells differentiate into red blood cells, white blood cells, platelets, etc.).
Unipotent cells can produce only one cell type, but have the property of self-renewal which distinguishes them from non-stem cells (e.g. muscle stem cells).
Totipotent stem cells are produced from the fusion of an egg and sperm cell. Cells produced by the first few divisions of the fertilized egg are also totipotent. These cells can differentiate into embryonic and extraembryonic cell types.
Pluripotent stem cells are the descendants of totipotent cells and can differentiate into cells derived from any of the three germ layers.
Multipotent stem cells can produce only cells of a closely related family of cells (e.g. hematopoietic stem cells differentiate into red blood cells, white blood cells, platelets, etc.).
Unipotent cells can produce only one cell type, but have the property of self-renewal which distinguishes them from non-stem cells (e.g. muscle stem cells).
Properties of stem cells
The classical definition of a stem cell requires that it possess two properties:
Self-renewal - the ability to go through numerous cycles of cell division while maintaining the undifferentiated state.
Potency - the capacity to differentiate into specialized cell types. In the strictest sense, this requires stem cells to be either totipotent or pluripotent - to be able to give rise to any mature cell type, although multipotent or unipotent progenitor cells are sometimes referred to as stem cells
Self-renewal - the ability to go through numerous cycles of cell division while maintaining the undifferentiated state.
Potency - the capacity to differentiate into specialized cell types. In the strictest sense, this requires stem cells to be either totipotent or pluripotent - to be able to give rise to any mature cell type, although multipotent or unipotent progenitor cells are sometimes referred to as stem cells
Stem cell
Stem cellular structures are cells found in most multi-cellular organisms. They are capable of retaining the ability to reinvigorate themselves through mitotic cell division and can differentiate into a diverse range of specialized cell types. Research in the stem cell field grew out of findings by Canadian scientists Ernest A. McCulloch and James E. Till in the 1960s. The two broad types of mammalian stem cells are: embryonic stem cells that are found in blastocysts, and adult stem cells that are found in adult tissues. In a developing embryo, stem cells can differentiate into all of the specialized embryonic tissues. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells, but also maintain the normal turnover of regenerative organs, such as blood, skin or intestinal tissues.
As stem cells can be grown and transformed into specialized cells with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture, their use in medical therapies has been proposed. In particular, embryonic cell lines, autologous embryonic stem cells generated through therapeutic cloning, and highly plastic adult stem cells from the umbilical cord blood or bone marrow are touted as promising candidates.
As stem cells can be grown and transformed into specialized cells with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture, their use in medical therapies has been proposed. In particular, embryonic cell lines, autologous embryonic stem cells generated through therapeutic cloning, and highly plastic adult stem cells from the umbilical cord blood or bone marrow are touted as promising candidates.
SCNT in reproductive cloning
This technique is currently the basis for cloning animals (such as the famous Dolly the sheep and in theory could be used to clone humans. However, most researchers believe that in the foreseeable future it will not be possible to use this technique to produce a human clone that will develop to term.
SCNT in stem cell research
Some researchers use SCNT in stem cell research. The aim of carrying out this procedure is to obtain stem cells that are genetically matched to the donor organism. Presently, no human stem cell lines have been derived from SCNT research.
Human Embryonic Stem cell colony on mouse embryonic fibroblast feeder layer.
A potential use of genetically-customized stem cells would be to create cell lines that have genes linked to the particular disease. For example, if a person with Parkinson's disease donated his or her somatic cells, then the stem cells resulting SCNT would have genes that contribute to Parkinson's disease. In this scenario, the disease-specific stem cell lines would be studied in order to better understand the disease.In another scenario, genetically-customized stem cell lines would be generated for cell-based therapies to transplant to the patient. The resulting cells would be genetically identical to the somatic cell donor, thus avoiding any complications from immune system rejection.Only a handful of the labs in the world are currently using SCNT techniques in human stem cell research. In the United States, scientists at the Harvard University Stem Cell Institute, the University of California San Francisco, and possibly Advanced Cell Technology are currently researching a technique to use somatic cell nuclear transfer to produce embryonic stem cells. In the United Kingdom, the Human Fertilisation and Embryology Authority has granted permission to research groups at the Roslin Institute and the Newcastle Centre for Life. SCNT may also be occurring in China.In 2005, a South Korean research team led by Professor Hwang Woo-suk, published claims to have derived stem cell lines via SCNT. but supported those claims with fabricated data..Recent evidence has proved that he in fact created a stem cell line from a parthenote.
Human Embryonic Stem cell colony on mouse embryonic fibroblast feeder layer.
A potential use of genetically-customized stem cells would be to create cell lines that have genes linked to the particular disease. For example, if a person with Parkinson's disease donated his or her somatic cells, then the stem cells resulting SCNT would have genes that contribute to Parkinson's disease. In this scenario, the disease-specific stem cell lines would be studied in order to better understand the disease.In another scenario, genetically-customized stem cell lines would be generated for cell-based therapies to transplant to the patient. The resulting cells would be genetically identical to the somatic cell donor, thus avoiding any complications from immune system rejection.Only a handful of the labs in the world are currently using SCNT techniques in human stem cell research. In the United States, scientists at the Harvard University Stem Cell Institute, the University of California San Francisco, and possibly Advanced Cell Technology are currently researching a technique to use somatic cell nuclear transfer to produce embryonic stem cells. In the United Kingdom, the Human Fertilisation and Embryology Authority has granted permission to research groups at the Roslin Institute and the Newcastle Centre for Life. SCNT may also be occurring in China.In 2005, a South Korean research team led by Professor Hwang Woo-suk, published claims to have derived stem cell lines via SCNT. but supported those claims with fabricated data..Recent evidence has proved that he in fact created a stem cell line from a parthenote.
What is Somatic cell nuclear transfer?
In genetics and developmental biology, somatic cell nuclear transfer (SCNT) is a laboratory technique for creating an ovum with a donor nucleus (see process below) . It can be used in embryonic stem cell research, or in regenerative medicine where it is sometimes referred to as "therapeutic cloning." It can also be used as the first step in the process of reproductive cloning
Therapeutic cloning
Somatic cell nuclear transfer can also be used to create a clonal embryo. The most likely scenario for this is to produce embryos for use in research, particularly stem cell research. This process is also called "research cloning" or "therapeutic cloning."
Therapeutic cloning is the production of human embryos for use in research. The goal of this process is not to create cloned human beings, but rather to harvest stem cells that can be used to study human development and to treat disease. Stem cells are important to biomedical researchers because they can be used to generate virtually any type of specialized cell in the human body. Stem cells are extracted from the egg after it has divided for 5 days. The egg at this stage of development is called a blastocyst. Many researchers hope that one day stem cells can be used to serve as replacement cells to treat heart disease, Alzheimer's, cancer, and other diseases
Therapeutic cloning is the production of human embryos for use in research. The goal of this process is not to create cloned human beings, but rather to harvest stem cells that can be used to study human development and to treat disease. Stem cells are important to biomedical researchers because they can be used to generate virtually any type of specialized cell in the human body. Stem cells are extracted from the egg after it has divided for 5 days. The egg at this stage of development is called a blastocyst. Many researchers hope that one day stem cells can be used to serve as replacement cells to treat heart disease, Alzheimer's, cancer, and other diseases
Cellular cloning
Cloning a cell means to derive a population of cells from a single cell. In the case of unicellular organisms such as bacteria and yeast, this process is remarkably simple and essentially only requires the inoculation of the appropriate medium. However, in the case of cell cultures from multi-cellular organisms, cell cloning is an arduous task as these cells will not readily grow in standard media.
A useful tissue culture technique used to clone distinct lineages of cell lines involves the use of cloning rings (cylinders). According to this technique, a single-cell suspension of cells which have been exposed to a mutagenic agent or drug used to drive selection is plated at high dilution to create isolated colonies; each arising from a single and potentially clonally distinct cell. At an early growth stage when colonies consist of only a few of cells, sterile polystyrene rings (cloning rings), which have been dipped in grease are placed over an individual colony and a small amount of trypsin is added. Cloned cells are collected from inside the ring and transferred to a new vessel for further growth
A useful tissue culture technique used to clone distinct lineages of cell lines involves the use of cloning rings (cylinders). According to this technique, a single-cell suspension of cells which have been exposed to a mutagenic agent or drug used to drive selection is plated at high dilution to create isolated colonies; each arising from a single and potentially clonally distinct cell. At an early growth stage when colonies consist of only a few of cells, sterile polystyrene rings (cloning rings), which have been dipped in grease are placed over an individual colony and a small amount of trypsin is added. Cloned cells are collected from inside the ring and transferred to a new vessel for further growth
Molecular cloning
Molecular cloning refers to the procedure of isolating a defined DNA sequence and obtaining multiple copies of it in vivo. Cloning is frequently employed to amplify DNA fragments containing genes, but it can be used to amplify any DNA sequence such as promoters, non-coding sequences and randomly fragmented DNA. It is utilised in a wide array of biological experiments and practical applications such as large scale protein production. Occasionally, the term cloning is misleadingly used to refer to the identification of the chromosomal location of a gene associated with a particular phenotype of interest, such as in positional cloning. In practice, localization of the gene to a chromosome or genomic region does not necessarily enable one to isolate or amplify the relevant genomic sequence.
In essence, in order to amplify any DNA sequence in a living organism, that sequence must be linked to an origin of replication, a sequence element capable of directing the propagation of itself and any linked sequence. In practice, however, a number of other features are desired and a variety of specialised cloning vectors exist that allow protein expression, tagging, single stranded RNA and DNA production and a host of other manipulations.
Cloning of any DNA fragment essentially involves four steps: fragmentation, ligation, transfection, and screening/selection. Although these steps are invariable among cloning procedures a number of alternative routes can be selected, these are summarized as a ‘cloning strategy’.
Initially, the DNA of interest needs to be isolated to provide a DNA segment of suitable size. Subsequently, a ligation procedure is used where the amplified fragment is inserted into a vector. The vector (which is frequently circular) is linearised using restriction enzymes, and incubated with the fragment of interest under appropriate conditions with an enzyme called DNA ligase. Following ligation the vector with the insert of interest is transfected into cells. A number of alternative techniques are available, such as chemical sensitivation of cells, electroporation and biolistics. Finally, the transfected cells are cultured. As the aforementioned procedures are of particularly low efficiency, there is a need to identify the cells that have been successfully transfected with the vector construct containing the desired insertion sequence in the required orientation. Modern cloning vectors include selectable antibiotic resistance markers, which allow only cells in which the vector has been transfected, to grow. Additionally, the cloning vectors may contain colour selection markers which provide blue/white screening (α-factor complementation) on X-gal medium. Nevertheless, these selection steps do not absolutely guarantee that the DNA insert is present in the cells obtained. Further investigation of the resulting colonies is required to confirm that cloning was successful. This may be accomplished by means of PCR, restriction fragment analysis and/or DNA sequencing.
In essence, in order to amplify any DNA sequence in a living organism, that sequence must be linked to an origin of replication, a sequence element capable of directing the propagation of itself and any linked sequence. In practice, however, a number of other features are desired and a variety of specialised cloning vectors exist that allow protein expression, tagging, single stranded RNA and DNA production and a host of other manipulations.
Cloning of any DNA fragment essentially involves four steps: fragmentation, ligation, transfection, and screening/selection. Although these steps are invariable among cloning procedures a number of alternative routes can be selected, these are summarized as a ‘cloning strategy’.
Initially, the DNA of interest needs to be isolated to provide a DNA segment of suitable size. Subsequently, a ligation procedure is used where the amplified fragment is inserted into a vector. The vector (which is frequently circular) is linearised using restriction enzymes, and incubated with the fragment of interest under appropriate conditions with an enzyme called DNA ligase. Following ligation the vector with the insert of interest is transfected into cells. A number of alternative techniques are available, such as chemical sensitivation of cells, electroporation and biolistics. Finally, the transfected cells are cultured. As the aforementioned procedures are of particularly low efficiency, there is a need to identify the cells that have been successfully transfected with the vector construct containing the desired insertion sequence in the required orientation. Modern cloning vectors include selectable antibiotic resistance markers, which allow only cells in which the vector has been transfected, to grow. Additionally, the cloning vectors may contain colour selection markers which provide blue/white screening (α-factor complementation) on X-gal medium. Nevertheless, these selection steps do not absolutely guarantee that the DNA insert is present in the cells obtained. Further investigation of the resulting colonies is required to confirm that cloning was successful. This may be accomplished by means of PCR, restriction fragment analysis and/or DNA sequencing.
What is Cloning?
Cloning is the process of creating an identical copy of something. In biology, it collectively refers to processes used to create copies of DNA fragments (molecular cloning), cells (cell cloning), or organisms. The term also covers when organisms such as bacteria, insects or plants reproduce asexually
What is Biomedical technology?
Biomedical technology involves the application of engineering and technology principles to the domain of living or biological systems. Usually biomedical denotes a greater stress on problems related to human health and diseases. Biomedical engineering combined with Biotechnology is often called Biomedical Technology or Bioengineering. It has two wings: Biomedical Engineering (dealing more with the Biophysics), and Biotechnology (dealing more with the Biochemistry).
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