The mother cells Are a type of cells found naturally in all multicellular living beings and is characterized by the property of differentiating into any type of cell and dividing to produce more stem cells.
Stem cells are important since before birth, because, within a few days of joining the two Gametes Begin to divide and multiply creating stem cells that will specialize that will give rise to the different organs and tissues of the body of the embryo.
The importance of stem cells lies in their astonishing potential to develop and form almost any type of cell. This ability can be used to repair and replace damaged or destroyed cells.
The clinical application of stem cells in multiple diseases such as Parkinson's , he Alzheimer's Or some congenital conditions.
In adult individuals, stem cells still exist, although in lesser amounts and with less potential than in the embryonic stage. These stem cells are present in certain structures such as bone marrow , Muscles and brain , And thanks to them the damaged cells can be replaced and the organs continue to function normally.
In general, it could be said that stem cells have three main properties that differentiate them from the rest of cells:
- They can be reproduced for long periods of time.
- They are not specialized.
- They can specialize in any type of cell.
These properties make them potentially beneficial to treat some diseases caused by the wear or degeneration of some cells such as neurodegenerative diseases.
These incredible properties of stem cells were first investigated only 35 years ago, in 1981, when a group of researchers discovered that it was possible to extract stem cells from a mouse embryo.
It was not until 1998 when studies with mice could be extrapolated to humans, when the first stem cells were extracted from human embryos and cultured in vitro to study their functioning and their properties. These stem cells are called embryonic stem cells.
Another milestone occurred in 2006 in the history of stem cell research, a group of researchers discovered how some adult cells could be genetically reprogrammed to give rise to stem cells that can specialize in some types of cells. This type of stem cell is called Induced pluripotent stem cell (IPS).
Although much progress has been made in stem cell research over the last 35 years, more studies are needed to better understand them and to use them in the creation of new therapies and in the study of human normative development.
Types of stem cells
Stem cells can be categorized generally according to their level of maturation in embryonic, fetal, adult stem cells and induced pluripotent stem cells.
In addition, not all stem cells have the same potential to differentiate into any type of cell. Depending on the type of cells in which the stem cells can be differentiated, they can be:
- Totipotent (or omnipotent) , If they can differentiate into any type of cell. These cells can only be found in the Morula (The set of cells that occurs after the union of the two gametes) and, theoretically, in the embryos, although embryonic stem cells have not yet been developed and created all types of cells.
- Pluripotent , Are the next step of totipotent stem cells and can differentiate into almost any type of cells. Embryonic cell cultures and induced stem cells are pluripotent.
- Multipotents , If they can differentiate into a wide variety of cells, but only those belonging to a group of related cells. For example, multipotent cells of the heart can only be differentiated into tissues that form the organ. These cells can be extracted from fetuses.
- Oligopotent , If they can be differentiated into several cell types, for example to form a single tissue. Adult stem cells are oligopotent.
- Unipotentes , If they can only differentiate into one type of cell. These stem cells differ from normal adult cells in that they maintain their reproductive property over an extended period of time (before differentiation). This type of stem cells can be found, for example, in some muscles.
Embryonic stem cell
Embryonic stem cells are extracted from embryos. Most come from gametes that have been fertilized in vitro and not from naturally pregnant women. And, in theory, they are totipotent, that is to say they can give rise to any type of cells, although in the laboratory at the moment only some types of cells can be cultivated.
Once the stem cells are removed, a culture is performed in which cells and nutrient material (culture medium) are introduced into a laboratory dish. In the culture the cells grow and begin to divide created a thin layer that extends throughout the surface of the plate.
Stem cell cultures are not 100% effective, there are times when cells do not grow or divide. But when the culture has been effective, stem cell groups are taken and new populations are created that will continue to divide and begin to differentiate. Stem cells can be frozen and stored at any point in the process.
During the culture, the stem cells can be grouped and specialized spontaneously in any type of tissue (muscular, nervous...). Being able to specialize is a sign that the cells are kept in good condition, but ideally the process of specialization is controlled by researchers to create specific cell populations.
To control the differentiation of embryonic stem cells, researchers modulate the chemical composition of the culture medium, the square or the cells themselves by inserting specific genes.
Through multiple studies, protocols have been developed that indicate which parameters need to be modified and how to create specific cell cultures.
At this time embryonic stem cell transplants are not performed in humans because in some animal studies it has been observed that they can lead to the development of cancers. They are still under investigation and are very promising for future treatments.
Fetal Stem Cells
As its name implies, fetal stem cells are obtained from fetuses (from the 10th week of gestation). These cells can be found in most tissues of the fetus.
These stem cells are multipotent, i.e. they can be differentiated into some cell types which are related, for example, to several similar tissues to form the same organ.
Adult Stem Cells
In some adult tissues, such as the skin, muscles, intestine and bone marrow, there are adult stem cells that can proliferate and differentiate into cells of the same tissue to replace dead or damaged cells, so that they are oligopoid. Adult stem cells can also be found in umbilical cord blood.
For example, in the bone marrow there are blood stem cells that mature and become mature blood cells (red blood cells, white blood cells or platelets).
Research with this type of cell is very advanced and currently transplants of adult bone marrow or umbilical cord blood stem cells are used to treat blood diseases such as Myelodysplastic syndromes Y Myeloproliferative .
The therapeutic potential of other adult stem cells such as Mesenchymal , Which produce bone cells, cartilage and fat to treat diseases such as arthritis.
Induced pluripotent stem cells
Induced pluripotent stem cells (iPS) are specialized adult cells (eg skin) that have been reprogrammed genetically in vitro to have the properties of embryonic stem cells.
To reprogram the adult cells, these are extracted from adults and cultured on a plate, where viruses are created in the laboratory with specific genes to integrate with the cells and modify their genetic information.
Although iPS cells and embryonic cells share many characteristics are not entirely the same, these differences are currently being investigated as well as new procedures for creating iPS.
Although further research is needed, iPS cells are already being used to check the effect of some drugs in clinical trials and in the near future are expected to be useful for transplantation.
IPS cell transplants are not currently performed because some animal studies have led to cancerous formations, possibly due to the technique used to reprogram cells.
Stem Cell Treatments
Currently, the most studied and practiced clinical use of stem cells is the transplantation of blood (hematopoietic) stem cells from the bone marrow or umbilical cord. They are used to treat problems of the blood and the immune system, as well as to renew the damaged cells after a treatment with chemotherapy or radiotherapy .
Each year more than 26,000 people are treated in Europe with a hemetapoietic stem cell transplant every year. The diseases currently treated with a transplant are:
- Leukemias and linformas, such as:
- Acute myelogenous leukemia.
- Acute lymphoblastic leukemia.
- Chronic myelogenous leukemia.
- Chronic lymphoblastic leukemia.
- Juvenile myelomonocytic leukemia.
- Lymphoma of Hodgkin.
- Non-Hodgkin's lymphoma.
- Diseases related to the bone marrow, such as:
- Severe aplastic anemia.
- Anemia of Fanconi.
- Paroxysmal nocturnal hemoglobinuria.
- Aplasia of pure red blood cells.
- Congenital thrombocytopenia / amegacaryocytosis.
- Myeloproliferative and myelodysplastic syndrome.
- Multiple myeloma.
- Inherited immune system diseases, such as:
- Severe combined immunodeficiency.
- Wiskott-Aldrich syndrome.
- Hemoglobinopathies (diseases of red blood cells), such as:
- Beta thalassemia major.
- Sickle cell disease.
- Hereditary metabolic diseases, such as:
- Krabbe disease .
- Hurler syndrome.
- Adrenoleukodystrophy.
- Metachromatic leukodystrophy.
- Other conditions and cancers.
Another of the applications of stem cell transplants are skin grafts. This application is perhaps the oldest application since it was used before really understanding how the stem cells worked.
Skin grafts are usually performed only in extreme cases in which the person has damaged large areas of skin, for example, by a severe burn.
The first skin grafting was done in 1970 and since then the technique has been perfected, although there is still a long way to go, since the grafted skin is currently unable to develop Hair follicles or sweat glands .
The last application of the stem cells that has been approved in Europe has been Holoclar, a treatment to repair the damage that could have suffered the cornea already be injuries or burns.
The procedure consists of extracting a small portion of Limbal cells In good condition, in charge of repairing the cornea, and cultivate them in the laboratory until they form a thin horny layer that can be transplanted into the patient's eye.
Other possible applications of stem cells are being investigated in clinical trials. The main applications that are in research are the regeneration of tissues and organs, the treatment of cardiovascular diseases And the treatment of brain diseases.
The use of stem cells for the regeneration of tissues and organs is perhaps their most studied application. If organs or tissues are created from stem cells, they can be transplanted to people who need them, in fact, the first stem cell kidney has already been created and the results are promising.
The results obtained in research on the use of stem cells in the treatment of cardiovascular diseases are also very encouraging.
In 2013, a group of researchers at Massachusetts General Hospital created blood vessels to parts of human stem cells that were implanted into mice and functioned correctly. Currently the research is ongoing and are intended to be applied without risk to humans.
The use of stem cells for the treatment of brain diseases such as Parkinson's or Alzheimer's is being studied using embryonic stem cells because of their potential for differentiation. The results appear promising, although studies are still at a very early stage.
The study of stem cells is not only performed to treat diseases, are also studied to know the normal development of healthy cells and better understand some processes such as cell division and differentiation.
References
- De Luca, M. (September 1, 2015). What diseases and conditions can be treated with stem cells? Obtained from EuroStemCell.
- International Society for Stem Cell Research, ISSCR. (S.f.). Types of Stem Cells. Retrieved on June 20, 2016, from A Closer Look At Stem Cells.
- Ministry of Science, Technology and Productive Innovation of the Argentine Republic. (S.f.). Recovered on June 20, 2016, incucai.
- National Institutes of Health. (March 5, 2015). Stem Cell Information. Retrieved from National Institutes of Health.
- Schöler, H. R. (2007). The Potential of Stem Cells: An Inventory. In N. Knoepffler, D. Schipanski, & S. L. Sorgner, Humanbiotechnology as Social Challenge (page 28). Ashgate Publishing.
- About Stem Cells. (S.f.). Stem cell treatments. Retrieved on June 20, 2016, from sobrecélulasmadre.com.
- Terms of use Privacy policy EEO / Affirmative Action Employer. (S.f.). Diseases treatable by transplants. Retrieved on June 20, 2016, from Be the match.