Stem cells are highly fascinating for science and offer great potential for research into serious diseases that do not yet have a cure. Many research projects work in parallel with adult, embryonic, and induced pluripotent stem cells. The goals of stem cell research are manifold and can currently be described in the following categories:

Basic research
Development of cell replacement therapies
Development of disease models
Drug testing

Basic research focuses on elucidating the molecular mechanisms behind the specialization of individual cells as well as investigating the organization of cells in tissue structures and organs. In addition, the aim is to gain a better understanding of the development and regulation of early stem cell stages and to investigate the mechanisms underlying the ability to proliferate and differentiate. 

ES cells, in particular, can provide valuable insights into embryonic development. The main goal is to understand the mechanisms and molecular bases that lead to the specialization of a totipotent fertilized egg or a very early embryo. In addition, ES cells make it possible to better understand malformations and diseases and to prevent them in the long term. 

Many serious and so far incurable diseases are associated with the loss of cells that the body cannot regenerate naturally. Examples include neurological diseases such as Alzheimer’s and Parkinson’s, as well as diabetes, paraplegia and heart attacks. The basic idea behind cell replacement therapy is to replace or repair the lost tissue with the help of stem cells. Scientists worldwide are researching the development of such cell replacement therapies. Tissue replacement is particularly interesting for those tissues that have little or no regenerative capacity, such as nerve tissue. However, most therapies, e.g. for the treatment of diabetes or Parkinson’s disease, are still in (pre-)clinical research. The transplantation of bone marrow stem cells, skin stem cells, and corneal stem cells in the eye iscurrently permitted. 

The approaches researchers in Germany are working on are either based on the use of adult stem cells or iPS cells. In some countries, cell replacement therapies using embryonic stem cells are also being developed, but this is not permitted in Germany. 

In the meantime, the new biotechnological “tools”, such as the Crispr-Cas9 gene scissors, make it possible to modify the genetic material of stem cells in a targeted manner. This is particularly promising for the treatment of monogenetic diseases, i.e. diseases caused by a defect in exactly one gene. So far, such approaches have only been used in clinical studies under strictly controlled conditions. 

The treatment of a boy suffering from what is known as “butterfly disease” (epidermolysis bullosa) was a great success for stem cell therapy. Since the patient was already at such a risk from the disease (80% skin loss), a therapeutic approach that had not yet been approved clinically was permitted as an exception with the approval of the corresponding ethics committees. Skin stem cells were taken from the boy, they were genetically modified and a skingraft took place, which was produced from genetically modified stem cells (see press release).This experimental therapy led to a considerable improvement in the disease and shows how important research with stem cells is. 

The cellular and molecular causes of many diseases are still not understood well. What exactly happens in Alzheimer’s disease, for example? These questions cannot be investigated in living patients – or only with great difficulty. Instead, researchers can now simulate diseases in the laboratory. They use reprogrammed iPS cells or stem cell lines obtained from a tissue sample. In this way, scientists can gain valuable insights into the causes and progressions of genetic diseases.

Further information on disease models from stem cells can be found here. 

The development of new drugs and active compounds is still largely based on animal experiments, most commonly using mice. After these preclinical studies, a candidate drug is tested in humans under strictly controlled conditions in clinical trials. However, results obtained from animal models can only be translated to humans to a limited extent. Consequently, it is often uncertain whether a substance that appears safe in animal experiments will also be safe and effective in humans.

To address this limitation, stem cells derived from human tissue can be used to generate organ-specific cell types that serve as advanced test systems for new compounds. These human cell-based models provide more reliable and predictive results and, in the long term, can help reduce the number of animal experiments.

Particularly promising for drug testing are so-called organoids—miniaturized, three-dimensional “mini-organs” typically the size of a pea or bean. Organoids allow drugs to be tested not only in conventional two-dimensional cell cultures, but in complex three-dimensional tissue structures composed of multiple cell types that more closely resemble the architecture and function of real human organs. Stem cell lines and organoids also offer powerful opportunities for drug repurposing, enabling already approved medicines to be tested for new therapeutic indications. Using induced pluripotent stem cell (iPSC) technology, it is even possible to assess drug responses in patient-specific tissues, which is particularly valuable for rare diseases where effective treatments are often lacking.