A special report on stem cells was published Iin the September issue of Świat Nauki (World of Science) a special report on stem cells was published

See it on www.swiatnauki.pl

It will take one or two generations to pass before embryonic stem cell research brings humanity significant profit

Clive Cookson
Let’s start with some basic definitions. Stem cells can transform into many types of specialized cells, and thus are serving as a biological repair system. Theoretically, they can divide limitlessly to replace dying cells. When a stem cell divides, each one of its offspring can remain a stem cell or, depending on the presence of some biochemical factors, become a more specialized cell e.g. muscle, nervous or blood cell. Explaining the mechanisms controlling this process is a big challenge for researchers.
The use of stem cells in therapy is no novelty. It has been performed for decades.

Transplants of tissues cloned from stem cells are not susceptible to rejection
One way of reducing the risk of rejection of a stem cell transplant is modifying them so they are less immunogenic or more compatible with the immune system. A more drastic way would be “resetting” the patient’s own immune system and reconstructing it so it is compatible with the transplanted cells. Some scientists are propagating a vision of creating “all-purpose donor cells” which could be compatible with any immune system.

Somatic stem cells pose less controversy compared to their embryonic counterparts, although there’s no certainty it is possible to use them in therapy.

Christine Soares

Luckily, most scientists recognize the basic definition: stem cells (both somatic and embryonic) renew after each division, eternally retaining the ability to create offspring cells of more specialized types. Descendant cells are differentiating partially, but still flexible enough to become precursors of many kinds of cells within a designated organ or system. For example bone marrow derived mesenchymal stem cells can transform into bone, cartilage, fatty tissue, various kinds of muscles or blood vessel cells.
Even though tissues that develop from bone marrow stem cells are very different, they have one common character: when a human body develops, they are developed from the medial germ layer of the foetus – the mesoderm. This is a very important issue, as scientists are arguing whether mature stem cells can transdifferentiate, i.e. can produce functional tissues normally, developing from different germ layers. The answer will judge if some ambitious regeneration medicine plans are real. Traditionally, it was assumed that somatic stem cells can only create cells of their own germ line.  Thus, they were considered multipotent as compared to embryonic stem cells which are pluripotent. However, recently, many research teams reported of crossing the boundary e.g. transforming hematopoietic stem cells into liver cells, neural stem cells into blood vessel cells and mesenchymal stem cells into neurons.

Stem cells on order
Thanks to research on de-differentiation of stem cells transformation of bone into muscle and organ, regeneration will be possible

What can a little newt do that a human cannot? This small amphibian is capable of regenerating a whole lost limb or organ thanks to properties of normal, differentiated somatic cells: bone muscle or epidermis, which can return from a mature state into stem cells. In newts, this phenomenon occurs near the wound and starts an instant rebuilding of the lost part.
Mammal cells, on the contrary, when mature cannot regress. We call them ultimately differentiated. If we could reverse differentiation, doctors would not have to seek rare and difficult ways to distinguish stem cells and force stem cells of one tissue to regenerate another one. Then, for example, normal pancreas cells could be transformed into insulin-secreting precursor cells, which diabetes sufferers lack, and correct neurons could create new neurons repairing the brain or spinal cord.