Three medical advances which rely on cloning

In the future, we may drink altered milk to ward off diseases such as gastric ulcers or to treat autoimmune diseases such as some forms of arthritis. But animals are generally not susceptible to the diseases that afflict humans.

AIDS is a good example. HIV, the virus that causes AIDS, either does not infect or does not cause the same disease symptoms in laboratory animals that it does in humans. It is therefore difficult to test vaccines or therapies for their potential to alleviate the symptoms of the disease.

Cloning technology may be utilized to produce useful genetically modified animal models, which would greatly facilitate the development of treatments or innoculations for many diseases.

Scientists are already at work developing a genetically modified rabbit model that expresses the human receptor for the virus and is susceptible to infection. Sign up for our email newsletter. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Go Paperless with Digital. Many readers have asked variants on this question. In the weeks to come, we plan to run several responses that will indicate the variety of viewpoints in the scientific community about cloning's ultimate potential to provide concrete medical benefits.

The egg is then stimulated to divide so that development proceeds. This sounds simple, but in fact it takes many attempts before each of the steps is completed successfully.

The first cloned agricultural animal was Dolly, a sheep who was born in The success rate of reproductive cloning at the time was very low. Dolly lived for six years and died of a lung tumor Figure There was speculation that because the cell DNA that gave rise to Dolly came from an older individual, the age of the DNA may have affected her life expectancy.

Since Dolly, several species of animals such as horses, bulls, and goats have been successfully cloned. There have been attempts at producing cloned human embryos as sources of embryonic stem cells. In the procedure, the DNA from an adult human is introduced into a human egg cell, which is then stimulated to divide.

The technology is similar to the technology that was used to produce Dolly, but the embryo is never implanted into a surrogate mother. The cells produced are called embryonic stem cells because they have the capacity to develop into many different kinds of cells, such as muscle or nerve cells.

The stem cells could be used to research and ultimately provide therapeutic applications, such as replacing damaged tissues. The benefit of cloning in this instance is that the cells used to regenerate new tissues would be a perfect match to the donor of the original DNA. For example, a leukemia patient would not require a sibling with a tissue match for a bone-marrow transplant. Addition of foreign DNA in the form of recombinant DNA vectors that are generated by molecular cloning is the most common method of genetic engineering.

If the foreign DNA that is introduced comes from a different species, the host organism is called transgenic. Bacteria, plants, and animals have been genetically modified since the early s for academic, medical, agricultural, and industrial purposes.

These applications will be examined in more detail in the next module. Watch this short video explaining how scientists create a transgenic animal. One example of this method is analogous to damaging a body part to determine its function. The classic genetic method compares insects that cannot fly with insects that can fly, and observes that the non-flying insects have lost wings.

Similarly in a reverse genetics approach, mutating or deleting genes provides researchers with clues about gene function. Alternately, reverse genetics can be used to cause a gene to overexpress itself to determine what phenotypic effects may occur. Nucleic acids can be isolated from cells for the purposes of further analysis by breaking open the cells and enzymatically destroying all other major macromolecules.

Fragmented or whole chromosomes can be separated on the basis of size by gel electrophoresis. DNA can be cut and subsequently re-spliced together using restriction enzymes. The molecular and cellular techniques of biotechnology allow researchers to genetically engineer organisms, modifying them to achieve desirable traits.

Cloning may involve cloning small DNA fragments molecular cloning , or cloning entire organisms reproductive cloning. In molecular cloning with bacteria, a desired DNA fragment is inserted into a bacterial plasmid using restriction enzymes and the plasmid is taken up by a bacterium, which will then express the foreign DNA.

Using other techniques, foreign genes can be inserted into eukaryotic organisms. In each case, the organisms are called transgenic organisms. In reproductive cloning, a donor nucleus is put into an enucleated egg cell, which is then stimulated to divide and develop into an organism. In reverse genetics methods, a gene is mutated or removed in some way to identify its effect on the phenotype of the whole organism as a way to determine its function.

Skip to content Chapter Introduction to Biotechnology. Learning Objectives By the end of this section, you will be able to: Explain the basic techniques used to manipulate genetic material Explain molecular and reproductive cloning. If a cloned embryo was produced using the nucleus of a cell from a patient, the genetic make-up of the stem cells extracted from it would be almost identical to that of the cells in the patient's body.

Although some people have suggested that this might one day become a routine therapy, the process of cloning and cultivating stem cells to produce replacement tissues and organs would remain extremely difficult and time-consuming. But therapeutic cloning may lead to even more useful advances.

Ultimately, researchers would like to learn the secret of reprogramming the nucleus, since it is this that controls the cell. We know that the process of cloning, in which a nucleus is transferred from an adult cell into an egg cell and an electrical current or chemical stimulation is applied, produces this reprogramming.

The adult nucleus is reset and becomes the nucleus of a single-celled embryo. If therapeutic cloning allows the secret of this reprogramming process to be unlocked, then potentially a whole range of medical leaps forward could be explored.

Could cells adjacent to the damaged part of an organ be reprogrammed to produce replacement cells, such as in spinal injuries?

Could defective cells be reprogrammed to act normally, to tackle cancer for instance? The possibilities would be truly amazing. More work, including further investigation of yesterday's results, is now needed. They may only have stimulated a process called parthenogenesis, in which an egg cell starts to undergo development, but without the involvement of the adult nucleus.

In this case it would not be the adult nucleus in control, and the embryo would not be a true clone. But we remain hopeful that they have truly taken the first steps towards successful therapeutic cloning.