2.- WHY ARE STEM CELLS SO IMPORTANT?
According to Mayo Clinic they are the “New Frontier of Medicine”. Their ability to repair the cells of tissues damaged by diseases, accidents or other causes, has originited a new medical field called: The Regenerative Medicine.
Cellular therapy consists in replacing damaged cells with new ones, taking advantage of the “plasticity” of the stem cells. Which means the capacity to transform themselves into specialized types of cells. The strong experimental evidence plus the recent publications show good results.
3.- WHERE ARE THE STEM CELLS?
There are three main known sources of stem cells:
Embyonic stem cells obtained from an embryo in its first days of life. Although they have an enormous capacity of division and specialization, their use has strong ethical and religious concerns, due to the fact that it is necessary to destroy the human embryo to obtain the stem cells.
Adult stem cells are usually obtained from bone marrow or peripheral blood, using a specialized procedure. Bone marrow transplant has succesfully been used for many years in severe hematological diseases when a compatible donor was found. These adult stem cells, obtained from the patient, after a complex purification and concentration procedure, are used. There is no ethical or rejection problem, due to the fact that they belong to the own blood of the patient.
Umbilical cord stem cells, are obtained from the cord and placenta, normally discarted immediately after delivery. Due to the fact that there are no ethical concerns, even the Vatican has accepted medical research and therapy with these cells. Storing those cells at very low temperatures allows them to be used after many years. There is no rejection of the cells when used in the same person, and some have and are being used in compatible direct relatives.
4.- WHERE DO STEM CELLS COME FROM?
A human person is the product of the fertilization of a male spermatozoid cell and a feminine sexual cell called ovum. This mixture produces one cell called zygote, that can make the whole human person. The zygote is totipotent, that means that its potential is compplete to produce all the cells. After fertilization, in the first hours, the zygote divides itself in totipotent identical cells and any of those cells implanted in the female uterus, has the potential to become a fetus. In fact, identical twins come from the division of two totipotent cells, that turn into two genetically identic human bodies.
5.- HOW MANY TYPES OF STEM CELLS ARE THERE?
There are three types of stem cells
•Totipotent: cells with the ability to make a complete human body. They exist only very few days after fertilization till the zygote has divided in sixteen cells.
|
