You are here: MEDICA Portal. Part VIII: Regenerative Medicine. Stem Cells.
Of Potency and New Organs (Part 1)
Some have the power to do anything, others to do something and many have it to do just a few things: the equivalents in biology are called toti-, pluri- or multipotent stem cells. „These are cells that constantly renew themselves and are capable of differentiating in distinct cell types“, Thomas Skutella says. These cells are supposed to be the medical key to regenerate or replace malfunctioning parts of the body by, for example, generating dopamine producing cells for the brain of patients suffering from Parkinson's, insulin producing islet cells for the pancreas of diabetics or a new heart muscle to heal the pumping organ of heart attack patients.
The anatomy professor and director of the Center for Regenerative Biology and Regenerative Medicine at the university hospital in Tübingen, Germany feels certain that one day it will be possible to grow whole organs. „We obtained so much knowledge during the last century that we will in future be in a position to do so.“ However, there are still many obstacles to overcome such as to initiate the required differentiation in stem cells: Regarding the fact that a human body consists of more than 200 cell types, the technologies behind these processes are not perfect yet. „On one hand one needs the right factors to keep stem cells in their immortal state, on the other hand one requires stimulating factors to push them at the right moment into a certain direction“, Skutella explains. This is so far the only way to transform a progenitor cell into a muscle, heart or liver cell.
Up to now embryonic stem cells have been regarded scientifically as being some kind of all-rounder – they are pluripotent and can develop into any known tissue. But they are also the centre of controversial debates regarding ethics and morality since they are obtained from human embryos being left over from in vitro fertilisation. Therefore, adult stem cells could provide an alternative beyond ethical controversies – as long as you reprogram them.
Morally defensible: adult stem cells
„Each human being has a certain potential for regeneration“, Skutella says. Thanks to adult stem cells - cells are present in different amounts in all organs - skin wounds can heal. However, these cells are at best multipotent which means that they can develop into different cell types of one lineage - a blood stem cell gives rise to blood and immune cells, a brain stem cell to the cell types occurring in the brain -, but it cannot differentiate into nearly all different body tissues.
The not so potent condition of an adult stem cell can be improved though by transferring the genes that renders an embryonic stem cell to be pluripotent. „The method is totally impressive because the biology behind it is so easy“, Skutella says. The result are induced pluripotent stem cells (iPS) which give new hope for stem cell research. The only drawback: researchers use viral vectors to bring in the genetic information and these are connected to a raised risk of cancer amongst other things. But Skutella does not doubt that „research will come up with technologies that enables us to reprogram cells without any danger to health.“ Which seems to prove true since meanwhile it has also been shown that harmless plasmids can be used in order to render adult stem cells pluripotent.
- Part 1: Of Potency and New Organs
- Part 2:
- 3. Teil: Man muss das Blut zähmen