Multicellular organisms have undifferentiated cells which can divide into cells of the same kind indefinitely. From these cells, whole tissues or organs develop through differentiation. Such kinds of cells are called stem cells. Different types of stem cells are totipotent, pluripotent and multipotent.
YEAR - EVENT
• 1968 - Two siblings underwent the 1st bone marrow transplant to treat severe combined immunodeficiency
• 1978 - In human cord blood, stem cells were found
• 1981 - Manufacturing of invitro stem cell line through mice
• 1988 - Generation of embryonic stem cell lines through a hamster
• 1995 - A primates cells give rise to the embryonic stem cell line
• 1997 - A Lamb is created through stem cell cloning
• 1997 - Haematopoietic stem cells found to be the genesis of leukemia
• 2002 - Suggestion for a complete full stop on human reproductive cloning but a go-ahead for medical therapeutic cloning
• 2013 - Generation of embryonic stem cell through human skin cells
Methods of stem cell transplantation:
1) Allogenic - In this, hemopoietic stem cells of a healthy donor are matched for HLA type and are drawn from the bone marrow, peripheral blood or umbilical cord blood. This person can be a member of the family or an unrelated volunteer.
2) Autologous - Stem cells are derived from the bone marrow or the peripheral blood of the patient itself.
Cure for Leukemia through Bone Marrow Transplant:
The stand alone treatment using stem cells at present is transplantation of the bone marrow (5). As the growth and functioning of leukocytes becomes abnormal, this gives rise to leukemia. Such cancerous cells cannot keep infection at bay, hence the search for cure for leukemia. Chemotherapy is a type of treatment that makes use of drugs to spot and kill the cancerous cells. Doctors do utilize the option of bone marrow transplants when chemotherapy cannot get rid of the cancerous cells by itself.
During the process of bone marrow transplant, a healthy, matching donor's stem cells are put in place of the patient's diseased ones (in the blood stream). Chemotherapy and radiation are used in tandem to get rid of these diseased cells. If the stem cells go into the bone marrow of the patient and start giving rise to healthy leukocytes, then the result of the process of bone marrow transplant is a positive one. Researchers are looking for better utilization of these cells that break the boundaries of the diseases of the blood stream.
1) For generating liver and pancreatic cells:
Researchers have found a new pathway for generating human liver and pancreatic stem cells. The 'foregut stem cells' could be made in huge quantities in the near future, in bioreactors. This could lead to them being utilized in regenerative therapies for type I diabetes or diseases of the liver.
However, there are hurdles in this method. It is very hard to generate an uncontaminated batch of the necessary progenitors and in the cell culture itself, one can normally see the infecting cells as well. This compounds the problem in separating out the target cells which, can be used for invitro differentiation in the future.
The scientists could salvage the situation by generating a non-contaminated batch of stem cells of the human foregut which could regenerate itself. These stem cells did not give rise to tumors, hence a strong case for them being used in therapy (the adverse effects being nil). This was done by changing the cells' signal pathways and altering the environment and substrate as well.
This method at least gives rise to a non-infecting batch of cells which is a genesis for giving rise to cells of the liver and pancreas.
2) For arthritis:
Increased amount of cartilage can be generated through stem cells which would maintain the original hip & knee joints. This in turn would postpone or totally remove the requirement for surgeries like joint replacements. This method promotes the gristle-articular cartilage, to come back to its original shape & size. Gristle covers the hip ball & socket; along with that, various joints of the knees, shoulders, elbows etc. also come under its area of influence. If the gristle covering is broken & is left unattended to, arthritis takes over.
To make the patient feel normal again, a combination of his/her own stem cells along with keyhole surgery and microfracture has been brought into clinical trials.
3) Neural Stem Cells for ALS (Amyotrophic Lateral Sclerosis):
In this method, the aim is to stop the neurons from degenerating more and more as well as restricting the advancement of disability. One can find self-regeneration of neural stem cells, which breaks up into glial & neuronal progenitor cells finally giving astrocytes, oligodendrocytes & functional neurons. Maximum patients can benefit from this method, if it is used before the bulbar symptoms are seen.
Scientists also proved that spinal cord function due to mechanical or chemical injury could be maintained by intraspinal stem cell injections.
4) For Inflammatory Bowel Disease (IBD) gut damage:
IBD is a set of conditions involving chronic inflammation of the digestive tract. Two types of IBDs are Ulcerative colitis and Crohn's disease. Scientists have found a very good remedy: stem cells that are present originally in the intestines. In mice, they have found a method to restrict the growth of cells to repair colon injuries.
Before such patches are tested in humans, one needs to see if human intestinal stem cells act in a similar manner as the mouse cells. The permutations and combinations could be endless and go much further than colon repair.
5) Stem cell treatment against Down's syndrome:
Stem cells could shut off the genetic defect in Down's syndrome invitro. Patients are born with a chromosome 21, due to which a spectrum of physical and cognitive defects arises. With the help of the patient's stem cells, the effects of the extra gene can be balanced. As soon as the chromosome is shut off, the abnormalities vanish.
Scientists see this as a stepping stone towards the making of a chromosomal treatment for this condition.
1. Definition of Stem cell: http://www.oxforddictionaries.com/definition/english/stem-cell
2. History of Stem Cell Research: http://www.explorestemcells.co.uk/historystemcellresearch.html
3. Stem Cells Fast Facts: http://edition.cnn.com/2013/07/05/health/stem-cells-fast-facts/
4. Lennard A L, Jackson G H. Stem cell transplantation. West J Med. July 2001; 175(1): 42-46.
5. Turning stem cells into therapies: http://www.cirm.ca.gov/our-progress/stem-cells-therapies
6. Stem Cells in use: http://learn.genetics.utah.edu/content/tech/stemcells/sctoday/
7. Stem cell breakthrough could set up future transplant therapies: http://www.cam.ac.uk/research/news/stem-cell-breakthrough-could-set-up-future-transplant-therapies
8. Stem cell work could help to stop arthritis in its tracks: http://www.cambridge-news.co.uk/Health/Health-news/Stem-cell-work-could-help-to-stop-arthritis-in-its-tracks-20130901060000.htm
9. Neural Stem Cells look promising in ALS: http://www.medscape.com/viewarticle/812678
10. Stem Cells used to repair IBD gut damage: http://www.healthline.com/health-news/crohns-gut-stem-cells-could-repair-ibd-damage-102413
11. Advances in therapy against Down Syndrome introduced: http://www.plenglish.com/index.php?option=com_content&task=view&id=1983451&Itemid=1
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