Stem cells are the body’s raw materials — cells from which all other cells with specialized functions are generated. Under the right conditions in the body or a laboratory, stem cells divide to form more cells called daughter cells.
These daughter cells become either new stem cells or specialized cells (a process called differentiation) with a more specific function, such as blood cells, brain cells, heart muscle cells or bone cells. No other cell in the body has the natural ability to generate new cell types.
The turning point in stem cell therapy appeared in 2006, when scientists Shinya Yamanaka, together with Kazutoshi Takahashi, discovered that it is possible to reprogram multipotent adult stem cells (cells that can only generate some of the more advanced cell types) to the pluripotent state (cells that can generate more advanced cell types than multipotent cells).
This new form of stem cells was named iPSCs.
After this success, this method opened a new field in stem cell research, with a generation of iPSC lines that can be customized and biocompatible with the patient. Recently, studies have focused on reducing carcinogenesis and improving the conduction system.
Stem cells are used in medical research in the so-called “regenerative medicine” sector, and with them, scientist hope to be able to replace malfunctioning organs or obtain tissues.
Embryonic stem cells are mainly used in research on the central nervous system, to regenerate structures damaged by degenerative diseases such as Parkinson’s, or on the peripheral nervous system, to repair the spinal cord in case of irreversible injury.
Results so far have been below expectations for some issues. Because these cells divide so much (and so fast), they can easily give rise to cancer. Furthermore, research has been limited by the ethical and legal debate on the use of human embryos to heal diseases that are now incurable.
Within the limits allowed by the law, research goes on, for example in attempts to reproduce tissues such as the heart, which in adulthood in the event of damage or disease does not regenerate itself. Since embryonic stem cells reproduce very quickly, they are also used as a model to study the genes involved in cell proliferation. This information is invaluable for cancer research, as tumors are characterized by uncontrolled cell proliferation, often caused by the reactivation of genes that are only supposed to function in the embryonic stage of an individual’s life.
In recent years, research has made progress in overcoming the ethical problems associated with the use of embryonic cells. Some laboratories have successfully used cells taken during prenatal tests, which have characteristics similar to embryonic ones.
To date, in Italy it is not permitted to use embryos obtained in the country for research, but it is possible to purchase cell lines abroad obtained by cultivating embryonic cells in the laboratory, taken even long ago from an embryo.
The blood present in the umbilical cord contains adult hematopoietic stem cells; that means that they are capable of transforming themselves into all the elements of blood and can be useful in treating blood cancers and other diseases. For this reason, in Italian hospitals, where children are born, it is recommended that they should be taken at the time of delivery and donated to cord blood banks, which are public in Italy. Many people are convinced that it is better to store cord blood to treat a possible future illness of their child but there are no scientifically valid reasons for doing so.
In fact, cord blood is sometimes used to treat rare forms of nanism but more commonly to treat leukemia patients. It is generally much easier to find a compatible donor in a public bank, well connected to a worldwide network, than to use cord blood that has been stored in a private facility abroad. Keeping cord blood for your child in case they become ill therefore reduces the chances of recovery for everyone else, without increasing their own. It should also be remembered that, actually, there are no practical applications of cord blood stem cells in regenerative medicine. Furthermore, since it is not yet clear for how many years cord blood cells can be stored properly, it is not certain that any future applications will be successful with biological material that was set aside decades earlier. Assuming, however, that these structures do not fail for commercial reasons.