Interventional Radiologists are physicians who received a 3 year training in radiology, and the completed it with Interventional radiology. They specialize in minimally invasive, treatments and diagnosis using imaging guidance (MRI, CAT, Ultrasonography or Fluoroscopy) allowing them to sail on the inside of the blood vessels or on the inside of digestive tract, biliary routes, urinary system, etc.
Interventional radiology procedures can replace open surgical procedures. They have small incisions; have less risk, less pain and shorter recovery times.
The Interventional Radiologist can get to an affected area via the blood vessels and implant a concentrated serum of stem cells with precision virtually anywhere in the organism.
WHAT HAVE WE BEEN DOING IN THE CENTRAL NERVOUS SYSTEM ?
We have implanted stem cells in different parts of the brain and the spinal cord, in a very selective form by means of endovascular navigation with catheters and coaxial microcatheters, obtaining with this a great concentration of stem cells in the needed area. Although still early, the results are very encouraging to treat diseases that seriously affect our patients.
Questions and Answers, STEM CELLS
1. - What are Stem Cells ?
Stem cells have three general properties:
- They are unspecialized, undifferentiated cells.
- They renew themselves for long periods of time through cell division. When dividing, cells usually do so in a symmetrical way, they will create 2 identical daughters. Stem cells are capable of this type of division or of asymmetrical division in which one daughter is identical to the mother cell and the other will differentiate into a type of cell needed by the organism at the moment.
- They can give rise to specialized cell types, such as cardiac or hepatic cells.
2. - Why are Stem Cells important ?
According to the Mayo Clinic Stem Cells are the “New frontier in Medicine”. Their potential in cell and tissue repair caused by accidents or disease has meant the development of a new area: the Regenerative Medicine.
The cellular therapy consists of replacing damaged cells by stem cells, taking advantage of the “plasticity” of stem cells; which is their capacity to differentiate into different types of cells. The solid experimental evidence and recent studies in patients show very hopeful results.
3. - Where are Stem Cells found ?
Three main sources exist:
- Embryonic Stem Cells: they are obtained from an embryo during the first days of development in the blastocyst stage. They have a great capacity for division and have the ability to generate any terminally differentiated cell in the body from any of the three germ layers. Its use has strong ethical and religious issues, because the embryo must be destroyed to obtain them.
A germ layer is a collection of cells, formed during animal embryogenesis. Germ layers will eventually give rise to all of an animal’s tissues and organs, through a process called organogenesis. They are the ectoderm, endoderm and mesoderm.
- Adult Stem Cells: they are part of tissue-specific cells of the postnatal organism into which they are committed to differentiate and are generally obtained of the bone marrow, or the blood, by means of a special procedure. Bone marrow transplants have been used for many years in the treatment of serious or mortal hematological diseases, when it is possible to locate a compatible donor. These stem cells are called autologous when they are from the bone marrow of the patient himself. After a process of purification and concentration, they are implanted into the patient; this does not have ethical or rejection problems, since it is his own purified blood.
- Umbilical Cord Stem Cells: they are obtained from the otherwise discarded placenta and umbilical cord. Its origin is therefore free of ethical controversies (the investigation in these and the adult Stem Cells has been supported by the Vatican). The preservation of these cells at - 196º C can maintain them viable and useful during many years. This usually has no rejection problems because they are used in the same person or in compatible siblings and relatives.
4. - How many types of Stem Cells exist ?
Three types of stem cells exist.
- Totipotent cells: They are able to give rise to a complete organism or any cell of the three germ layers; called Embryonic Stem Cells. They exist during 1 to 2 days after the fertilization or when the fertilized egg has been divided to up to 16 cells.
- Pluripotent cells: are found on the internal mass of the embryo in the Blastocyst phase. They can give rise to any tissue of the organism, like epithelial and the muscular tissue. These are also called Embryonic Stem Cells.
- Multipotent cells: they are the ones found in the umbilical cord or the bone marrow of adults. The primary roles of adult stem cells in a living organism are to maintain and repair the tissue in which they are found. They are the only stem cells that remain in an adult body.
5. - Where do stem cells come from ?
The human development begins when a masculine sexual cell or spermatozoon fertilizes a feminine sexual cell or ovum, forming a fertilized egg that has the potential to form a whole organism.
This fertilized egg is totipotent, meaning that it can give rise to a whole organism. In the first hours after the fertilization, this cell divides in identical totipotent cells, this means that if any one of these cells is placed in the uterus of a woman it will have the potential to become a fetus. In fact, the identical twins are developed when two totipotent cells separate and they become two individuals, genetically identical human beings.
Adult Stem Cells are obtained from tissue of an adult organism. Every tissue is known to contain stem cells, which have the job of maintaining the cellular population and repairing from normal wear and tear of everyday life. At first, these stem cells were thought to be restricted to differentiate into cells from within the organ of origin. The tissue from which stem cells are more readily available and best characterized is the bone marrow.
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The lateral walls of the lateral ventricles, contain the subventricular zone.
N Engl J Med 2005, 353:811-22
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Traditionally bone marrow has been characterized for having two prototypes of stem cells.
The hemapoietic lineage; in charge of making blood cells and the supporting lineage in charge of giving support to hematopoiesis; generating mesenquimal derivatives. This has made bone marrow the only tissue in which two types of stem cells coexist and cooperate. Initially stromal or mesenquimal stem cells were studied for their capacity to generate skeletal tissue like muscle and bone. However, in the last years several studies have shown that they still have the capacity to transdifferentiate into tissue derived from different germ layers.
So organ specific differentiation is being reformulated. Besides their now known capacity to transdifferentiate, mesenquimal stem cells are known for an important migration capacity into lesioned or damaged tissue. This is why they are being used for tissue repair in regenerative medicine.
6. - Advantages of the Adult Stem Cells ?
Adult Stem Cells possess the great advantage of not having the ethical problems of working with sacrificed embryos.
Strictly from the scientist point of view, the Adult Stem Cells offer two great advantages. On the one hand, it avoids the serious problem of histocompatibility, being the donor also the receptor, no rejection occurs. On the other hand, the adult stem cells do not have to make as long a trip as the embryonic ones to transform into cells of a determined tissue or organ, because they are more differentiated, which facilitates much of the work of the scientists to orient the cellular development.
Still there is doubt to whether adult stem cells will be able to transform into any desired cell of the organism. Every month there is new progresses in this field.
The adult Stem Cells are now winning the race over embryonic stem cells because they are crediting their enormous versatility and already offering some therapeutic successes.
7. - In which diseases are Stem Cells usefull ?
Until now successful clinical treatments with Stem Cells have been reported in Medical Literature in the following diseases, aside from transplants for Bone Marrow regeneration:
- Nervous System (where we have been working with surprising results): it is used in cases of Cerebral Infarct, Parkinson Disease, Multiple Sclerosis, Brain Hipoxia.
- Myocardial Infarction: cardiac repair through the implant of Stem Cells in the coronary arteries or directly in the damaged cardiac muscle.
- Arthrosis: therapy to restore cartilages of the joints, specially knees and
- Rheumatoid Arthritis.
- Ischemic Artheriosclerotic lesions.
- Crohn’s Disease.
- Diabetes type II.
- Systemic Lupus Erythematosus.
- Muscular Dystrophies.
- Hepatic, lung and Renal tissue regeneration.
- Ischemic Retinopathy.
- Autoimmune diseases.
9. - What is Regenerative Medicine ?
This is an innovative scientific field that focuses on new approaches to repairing and replacing cells, tissues and organs. Regenerative medicine helps natural healing processes to work faster, or uses special materials to regrow damaged tissue. Doctors use it to speed the healing process. Regenerative therapy has been used to heal bones, skin, blindness, deafness, heart damage, nerve damage, Parkinson's Disease and other conditions, although still in trial.
Naturally our tissues undergo a wearing down from which we defend by developing the intrinsic capacity to renovate those damaged tissues. If this renovation did not occur, the life expectancy of all living beings would be considerably reduced. The organism’s mechanism of regeneration, repair and renovation is limited and dependent on the establishment of damage. The damage or death of great portions of tissue in an acute manner like strokes, are not susceptible for repair with our natural mechanism of regeneration.
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N Engl J Med 2003, 349:570-582 |
This is where regenerative medicine comes in handy; stem cells are used in Cellular Therapy because of their ability to create any tissue. This consists of replacing damaged cells by stem cells, taking advantage of their plasticity.
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