How it is Done
Therapeutic cloning uses the nuclear transfer cloning technology to create embryos for the purpose of extracting stem cells from it.
Steps
Steps
- Disease free somatic cells from the patient are extracted.(Parson 2007) The nuclei of these somatic cells are then extracted.
- An egg cell (ovum) is also obtained. The egg is held in place by the light suction produced by a holding pipette tip. A glass needle is used to penetrate through the zona pellucida of the ovum (the membrane made of glycoprotein which surrounds the egg) and remove the nucleus from the ovum.
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In this image, an ovum is being held in place by a holding pipette, (on the left). The needle, also known as a drilling pipette, on the right first drills a hole into the zona pellucida and then enters the ovum and extracts its nucleus.
http://www.drmalpani.com/eggsandembryos.htm
http://www.drmalpani.com/eggsandembryos.htm
- The nucleus of the somatic cell is inserted into the enucleated ovum through the process of electrofusion (Robinson 2000) or through injection. The egg which now contains the genetic information of the patient is the same as a cell which would form from normal fertilisation of an egg by a sperm. The expression of genes within the mature body cell is controlled. Specific cells, in specific conditions, during specific times of a life only express specific genes according to its function. A skin cell will not express the gene coding for the production of human insulin. When the nucleus of the body cell from the patient is placed into an ovum, genes that were not previously activated can get activated. As a result, undifferentiated embryonic cells are produced.
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In this image the nucleus from the somatic cell of the patient is being injected into the enucleated ovum.
http://www.drmalpani.com/eggsandembryos.htm
http://www.drmalpani.com/eggsandembryos.htm
- The ovum containing the nucleus from the patient's somatic cell is shocked to stimulate it to begin division. The cell undergoes mitosis in vitro for around 7 days until it forms a blastocyst.
- The blastocyst has 40- 150 cells and contains stem cells which are pluripotent in nature. These pluripotent stem cells are extracted from the blastocyst. (Kinnear J.K, Martin M.M 2006)
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- The stem cells are cultured and placed in specific environments which induces the cells to differentiate into specific types of cells. This can eventually lead to the generation of tissues such as blood vessels, skin and organs.
- These specialised cells or tissues are introduced into the patient.(Kinnear J.K, Martin M.M 2006)
- Because the produced cells/tissues are genetically identical to the patient, there will be no immunological reaction when the treatment is made.(Robinson 2000)
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A simplified diagram showing a summary of the process of somatic cell nuclear transfer.
http://www.lef.org/magazine/mag2002/mar2002_report_cloning_01.html
http://www.lef.org/magazine/mag2002/mar2002_report_cloning_01.html