Cell Differentiation

Core Competencies

  • Utilization of human sweat gland-derived stem cells for the development of novel cell therapies
  • Cell-mediated colonization of implants and characterization thereof
  • New cell labeling methods and validation thereof
  • Establishment and optimization of organotypic model systems

Development of cell-based therapies and organotypic test systems for academia and industry

Adult stem cells play an increasingly important role for medical applications. In the field of cell therapies, our working group has focused on enabling the utilization of adult stem cells for industrial applications in the health care sector. In fact, our working group has initially been describing the pluripotent differentiation capacity of human sweat gland-derived stem cells (SGSCs), which marked the sweat gland as a new source of human stem cells.

The undisputable advantages of SGSCs are the fact that they may easily be accessed, as well as their ethical innocuousness. In animal experiments, SGSCs were shown to exert a positive effect on wound healing, which was closely linked to an accelerated formation of new blood vessels (revascularization) in animals undergoing stem cell therapy. This may further imply applicability of SGSCs in treating ischemic diseases (as seen for example after a heart attack), with the aim to improve local revascularization. In order to eventually make sweat gland-derived stem cells available for clinical applications, harvest, propagation and subsequent storage of stem cells will need to be performed according to GMP guidelines. Thus, it will be necessary to extensively automate cell isolation and handling, as well as to standardize documentation procedures. Initial attempts at process adaptation have shown very promising results. Next, the working group is concerned with establishing an in situ sweat gland test system for pre-clinical testing of for example cosmetics and chemicals.

Such in vitro test system will further gain in importance, as new legislation is increasingly calling for feasible alternatives to animal testing.

The working group’s portfolio of in vitro test systems does also span into the area cardiac test systems. A setup of spontaneously contracting aggregates from the rainbow trout (SCCs) with multi-electrode arrays (MEAs) has already been pharmacologically characterized and was found suitable for detecting pro-arrhythmic substances. Latest studies have shown that this system may also be used for experiments performed on cardiac muscle cells affected by ischemia. Here, the typical human pathophysiology could also be demonstrated. Lastly, experiments performed under culture conditions involving the anesthetic isoflurane indicated a possible pharmacological modulation of SCCs under hypoxia. In future studies, the characterization of additional substances in the SCC setup will also be of interest to broaden the spectrum of potential applications for cardiac research.

Another focus area of this working group is concerned with the colonization of solid implants. In order to mitigate the risk of an adverse reaction directed against the implant, autologous human stem cells can be used to coat the outer surface area of a solid implant, prior to introducing it into the patient’s body. In an animal study performed with biologically coated brain probes, the advantage of disguising implants by covering them in stem cells could already be demonstrated. Further, especially also in the area of peripheral nerve regeneration, positive effects have been obtained by colonizing nerve tubes with stem cells in vitro. Here, it has been shown that stem cells are able to promote regeneration in nerve cell cultures.

Novel cell labeling methods are needed for improved and simplified tracing of stem cells in animals and tissue models. The particular challenge lies in developing a technique that does not influence the cells themselves, while reliably enabling cell tracking over prolonged periods of time. Here, a feasible solution could be electroporation of adherent cells. Compared to other established methods, electroporation is particularly gentle on cells, since the technique does not require cell detachment prior to treatment.

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Cell-based therapies

Human adult sweat gland-derived stem cells (SGSCs) hold a great potential for regenerative therapies. In animal experiments it has already been shown that SGSCs promote wound healing through enhanced revascularization and exhilarated wound closure. SGSCs should thus eventually be made available for clinical use. In preparation for clinical translation, the manufacturing and cultivation process of SGSCs will need to be adapted to meet GMP guidelines. Next to wound healing, also other fields of application will benefit from continuous refinement of stem cell-based therapies (such as the biological coating of implants).

Cell-mediated colonization of implants

Accidents may sever peripheral nerves, which often results in loss of sensory or motor function. Should important body areas be affected by such damage, large defective gaps can be filled with autologous grafts. In general terms, this does however entail a functional loss of the donor location. Artificial nerve tubes can serve as alternative grafts, but these have not yet reached the quality of autologous nerve grafts. In order to improve the biocompatibility of artificial nerve tubes, they can be colonized with autologous stem cells. By this approach, the working group aims to promote nerve growth and minimize scar formation. The effect of stem cell-coated nerve tubes will be evaluated by means of novel in vitro test systems and animal experiments.

Organotypic test systems

There will be a growing demand for in vitro methods to replace animal experiments in medical and pharmacological research. Organotypic test systems are an attractive alternative to existing animal models and hold the potential to help meet the evolving need for robust in vitro systems. At the Fraunhofer EMB, manufacturing and culture conditions of tissue slices derived from various organs (e.g. heart, liver and brain) have been established to enable recordings of vital tissue parameters. Starting from cardiac tissue slices, differences between species could be overcome and the methodology has successfully been translated to human tissue. Eventually the test system may also be applied to other types of tissues (e.g. skin).

Electroporation of adherent human cells

The selective insertion of defined macromolecules into living cells has paved the way for cutting-edge experimental design in biochemical and biomedical research. The concept of this approach is based on selective and reversible permeabilization of the cell membrane. At the electroporation unit of the Fraunhofer EMB, a particularly gentle electroporation procedure has been established for modifying adherent cells and tissue slices. This opens up new possibilities in working with cells and tissues that are difficult to transfect without having to expose them to stressful pre-treatments such as trypsinization. Chemically inefficient and membrane-damaging means of permeabilization may thus be disregarded in future experiments. Main focus of our working group is the electroporation of adherent human stem cells to gain further insights into mechanisms associated with wound healing. In addition, electroporation of tissue slices may add another dimension to the study of complex multi-layered interactions of various cell types within a single organ. Here, the EMB does benefit from its long-standing expertise on in vitro cultures of cardiac, brain and liver slices.

Co-culture systems – cells learn from tissue

Stem cell differentiation can be induced through an either direct or indirect co-culture system with tissue biopsies, or differentiated cells thereof. Under such culture conditions, soluble factors and cell-to-cell contacts provoke an increased differentiation of stem cells into cell types of the target tissue. By employing this technology, our working group has thus far managed to induce the differentiation of gland-derived stem cells into cardiac muscle, nerve and endothelial cells.

Co-culture systems – stem cells heal tissue

Co-culture systems can be used to investigate the influence of stem cells on tissue regeneration. This effect can be induced through indirect co-culture of stem cells and the target tissue. Mechanistically, stem cells interact with cells of the co-cultured target tissue through soluble factors. By this means, it has been shown that gland-derived stem cells foster the regeneration potential of nerve cell cultures.


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