'May I have a new organ please?'

‘May I have a new organ please?’

About 1050 people in the Netherlands are waiting for an organ, more than 200 of these people will die every year because it takes too long before the needed organ is available. The prior needed organ is the kidney. Campaigns to collect more organ donors lead to an increase of donors. Despite this increase there are still not enough organs to handle the huge amount of people on the waiting list. If a person is lucky and an organ will come in time, organ transplantation will take place. This transplantation can be done either with a donor that is still alive or a donor that has already died. Even when the transplantation has taken place, this does not guarantee success. The transplantation can have multiple side effects, such as rejection. To prevent rejection the donor should have DNA that is largely the same as the patient. This to decrease the change that the immune system thinks that the organ does not belong in the body and attacks the transplanted organ. It actually will be wonderful if donors are no longer needed and you can just grow a new organ in the laboratory.

The perfect cells to grow an organ out of are stem cells. Stem cells are the builders under the cells. Builders are able to create a house from scratch, stem cells do the same job during development. They are able to create an entire organism out of nothing during pregnancy. To structure the building processes the stem cells need instructions what to build and where to build it, these instructions are given by several signals. First of all, stem cells can become all different structures in the developing organism, but as the development proceeds the stem cells become more and more specific. They are no longer able to create all tissues of the body, but are limited to form only a few structures. In adults, stem cells are still present in a lot of tissues. Now stem cells are no longer needed to create entire structures, but their task is to maintain the different tissues of the body and to supply new cells during growth and injury. A good example to illustrate the task of stem cells in the adult body, are the cells of the outer layer of the gut wall. This outer layer is renewed every 3-5 days, stem cells will divide rapidly to generate cells for this renewal. Tumours also have stem cells, these stem cells are responsible for the regrowth of the tumour after chemotherapy.

After a long period of research it is now possible to create new tissues out of stem cells of the adult body in the laboratory. The stem cells can be used in two ways. First of all by taking a stem cell which is capable to create a certain type of tissue (for example liver cells) and let it grow until it form that certain tissue. Second of all, the DNA of the adult stem cells can be altered so the cell is able to become different tissues.

It is already possible to create small parts of the gut (organoids) out of adult stem cells in the laboratory. In this case is chosen to use already specified stem cells to create the organoid. The part of the gut where the stem cells are located, is taken out and placed into a dish. (Figure 1).

 

Figure 1: growth process of organoids in the laboratory.

The needed instructions are added to the stem cells by adding certain factors (figure 1). After a while the stem cells grow out to become an organoid. This organoid can function completely as the gut in a living organism. On top of that it is proven that the organoids could be transplanted successfully into a mouse and they could support the function of the gut, this could improve the gut function at mice who’s gut does not work properly. That organoids can be grown out of stem cells is promising because this could lead to a completely new direction in medicine. In this direction, people with a defect organ could be treated with their own stem cells. The benefit of using your own stem cells is that the risk for rejection will be reduced because the used tissue will not be detected as foreign by the immune system. Moreover, you do not have to be put on a waiting list to get the organ you need. Of course we are not that far yet but we are going into the right direction!

                        

Sanne van der Niet 7-10-2015