Medical recycling – stem cells from human waste material

The human body contains many trillions of cells with a wide variety of specialisations. Cartilage cells, skin cells, blood cells – the list is too long to enumerate completely here. They all live in interaction with each other and with their environment in the tissue.

It is therefore also obvious that research was aware of the immense importance of these smallest functional units of our body early on. Since then, attempts have been made to make use of them for healing processes – for many cells have great regenerative potential.

At the Ludwig Boltzmann Institute for Experimental and Clinical Traumatology (LBI Trauma), intensive research is being done on the regeneration of human tissue. In line with the motto “Regenerate instead of repair!”, damaged tissue should not simply be patched up, but its full functionality restored. If it is irreparably damaged, for example in the case of a severe peripheral nerve injury or a cartilage defect, the formation of new tissue must be stimulated by intervention – for example by stem cells.

When the term stem cells is mentioned, many people probably first think of embryonic stem cells and the ethical concerns associated with them. But stem cells, i.e. cells that can further develop (“differentiate”) into different specialised cell types depending on the stimulus, are found in the organism in every phase of life. And – what is even more important for the safety of the application – they are even found in tissue that normally ends up in medical waste.

The placenta is a typical example of such material. It is usually simply discarded after the baby is born. Part of it is the amnion, the innermost of the membranes surrounding the amniotic fluid. It has been used for years in clinical practice as a wound dressing or corneal graft. Further applications are currently being tested in the laboratory. At AUVA Unfallkrankenhaus Graz, for example, the effectiveness of amnion as a sliding layer for painful adhesions of the nerves is being investigated. There are also stem cells on the amnion. Under suitable conditions, they can differentiate into various cells of the connective and supporting tissue, as well as into muscle or nerve cells or cells of the liver, pancreas or lung. The amnion also owes its anti-inflammatory properties to the stem cells. This results in faster healing, regeneration of functional tissue and reduced scarring. Amnion can only be used for clinical purposes after a caesarean section and is obtained through donations. New mothers can use their donation to help a patient with a burn or corneal defect or to advance stem cell research.

Another rich source of stem cells is fat tissue. Liposuction is usually carried out to get rid of undesired fat deposits. Millions of valuable stem cells and bioactive substances thereby end up in the waste. One of the advantages of fat stem cells is that they are easily available – fat tissue is found in all patients, and many are not so reluctant to part with it. Moreover, the extraction of the cells is comparatively simple, because they can be easily detached from the loose matrix. At LBI Trauma, a method has been developed in which the cells can be extracted purely mechanically, without the use of enzymes. This is not only easy on the health system (because enzymes are expensive), but also on the cells, as it affects their quality to a lesser extent. Like the cells of the amnion, fat stem cells can differentiate into a wide variety of tissue cells, and generally help repair these tissues. Particularly notable is their ability to generate entire networks of blood vessels to ensure good blood flow when tissues are being rebuilt. Their anti-inflammatory properties are already being used clinically. Their use in building new tissue has been proven in the laboratory, for example in a study at LBI Trauma on the regeneration of articular cartilage, and is currently being tested in numerous clinical trials.