A MILE STONE IN EMBRYONIC STEM CELL RESEARCH.
Medical science saw another milestone when James Thomson of the University
of Wisconsin-Madison declared on Nov 6, 1998 that he had successfully inferred and affirmed the culturing of human embryonic stem cells. Then there was hope of using the technique to treat/cure certain diseases. How ever Clinical application of embryonic stem cells reached now where. Much knowledge about how human embryonic stem cells become any of the specialised human cells are available. But this knowledge is still only on the beginning stage.
The obstacles in stem cell research There are two ethical issues related to human embryonic stem cells are
· The immediate association with dread of embryonic stem cells being researched in wrong way. For example for creation of many Hitlers, Sadam hussains terrorists etc being cloned using the technique was the first challenge that this field had to tackle.
· Then came the issue of embryo destruction. Harvesting human embryonic stem cells (hESC) from embryos destroys the embryos. Saving a cluster of cells that people interpret as representing life seemed more important than using them to treat/save people living with certain diseases.
Role model The U.K. has been a good model as far as research on hESC is concerned. It has a tightly regulated environment and has issued licences for every kind of research. The licence to create embryonic stem cells through somatic cell nuclear transfer (also called parthenogenesis) in 2004 speaks for itself. The latest has been its approval of using animal eggs to produce hybrid embryos.
Parthenogenesis: also called as somatic cell nuclear transfer (SCNT) or
therapeutic cloning, kills the embryo when embryonic stem cells (ESC) are harvested. Hence it is entangled in ethical controversy.
STEPS IN PARTHENOGENESIS OR THERAPEUTIC CLONING
STEP 1: Nucleus or genetic material of the egg removed.
STEP 2: Adult cell from patients or individuals introduced into the egg.
STEP3: The egg exposed to a mixture of chemicals and growth factors to make it divide.
STEP 4: Keep it four 24hours.The activated egg start to divide. By fourth of fifth day, a ball of about 100 cells form. The inner cell mass contain ECS.
STEP 5: ECS (EMBRYONIC STEM CELLS) grown in lab to produce cell lines.
ADULT STEM CELLS
The ethical issues of using human eggs are overcome by using animal eggs. With embryonic stem cell research repressed, scientists in the U.S. had to turn their attention to adult stem cells. They have achieved a lot in this area, but adult stem cells have a limitation. They cannot become any of the 250-odd cells like in the case of the embryonic stem cells.
The scientists appear to have overcome this limitation. A new technique —
induced Pluripotent Stem Cell (iPSC) — can reprogramme adult cells to make them as versatile as embryonic stem cells.
Induced Pluripotent Stem Cell (ipsc) Technique: Induced Pluripotent Stem Cell (iPSC) genetically reprogrammes adult cells (fibroblasts) to make them behave like embryonic stem cells. Does not need embryos hence no ethical issue.
STEPS IN INDUCED PLURIPOTENT STEM CELL (iPSC) TECHNIQUE
STEP 1: Fibroblasts derived from adult skin cells used as a starting material.
STEP 2: Four genes introduced into fibroblasts using viral vectors.
STEP 3: Fibroblast genetically reprogrammed into embryonic stem cells/ESC-like cells
STEP 4: Genetically resembling the mother cells produced. iPSC, like embryonic stem cells, can form any specialized cells.
Recent development Very recently, researchers at Kyoto University have improved the iPSC technique by not using viral vectors to introduce the four genes into cells. These two techniques, along with the usage of adult stem cells, will go a long way in our understanding of how diseases set in, how they progress and how they can be treated. It will be a long while before complete organs can be grown using stem cells.
Research has shown that mouse embryonic stem cells can be used to predict human breast cancer risk.
RECENT CLINICAL DEVELOPMENT
In May 2008, American scientists have been able to induce hESCs to become human heart progenitor cells. These progenitor cells can produce all the three main heart cell types. Early this year, scientists developed a cell culture method to make sure that hESC that became neurons did not turn cancerous when transplanted.