Inflammation Models and Immunodiagnostics

Establishing a model for chronic kidney disease (CKD)

Histological HE stain to provide an overview of the kidneys. Aa and Ab healthy animals. Ba and Bb animals with induced CKD
© Fraunhofer IZI

Histological HE stain to provide an overview of the kidneys. Aa and Ab healthy animals. Ba and Bb animals with induced CKD.

Von Kossa stain on aorta cross-sections. Aa and Ab healthy animals. Ba and Bb animals with induced CKD
© Fraunhofer IZI

Von Kossa stain on aorta cross-sections. Aa and Ab healthy animals. Ba and Bb animals with induced CKD.

Chronic Kidney Disease (CKD) is the progressive, non-reversible loss of glomerular functional units of the kidney. Worldwide ≥ 2 million humans (2011) are kept alive through kidney replacement therapies, which represents only 10 percent of all final CKD patients whose organs need to be replaced. Consequently, preventing or delaying the CKD progression from stage G I-G IV/A I-A II to the final stage G V and A III by drug or dietary therapies is relevant worldwide from a medical and economic perspective. The efficacy and safety of these drug or dietary therapies has to be tested preclinically in in vivo models. Our group established such an in vivo model for a lethal or moderate CKD.

We injected different concentrations of adenine into six-month-old WISTAR rats for several weeks. This injection model is less stressful to the individual animal than other models regarding the indication CKD. The rats used are adult and are held for a relatively long time in our animal house. Therefore, we invested in better housing conditions for the animals and got a two-floor cage system appropriate for large, adult rats.

In the model, we could induce several pathological changes similar to the ones in patients with CKD. Dependent on the adenine concentration, we were able to induce symptoms indicating a final, lethal CKD or symptoms indicating a moderate kidney disease similar CKD stadium 3 in patients. In this context, we could develop new imaging techniques as well as test first diets.

From now on, this established model will be available to test different therapeutical approaches to help CKD patients worldwide.

Establishing and characterizing the humanized mouse

Human stem cells are ob­tained from umbilical cord blood. This involves the blood being separated by means of density gradient centrifugation. The first stage of this separation process is shown in the image.
© Fraunhofer IZI

Human stem cells are ob­tained from umbilical cord blood. This involves the blood being separated by means of density gradient centrifugation. The first stage of this separation process is shown in the image.

Animal models have long since been an important instrument in biomedical research. They are used on the one hand in basic research, and on the other for testing new therapeutic agents, thus proving to be essential from an ethical point of view. Nevertheless, it is quite common that the findings resulting from these models are not able to be applied in the human context. For instance, even if a drug has not caused side effects during animal testing, severe side effects may still occur in the case of humans during the clinical testing period. In less serious cases, there is merely a difference between the pathological mechanism that causes a disease in the animal model and the actual human pathological mechanism. In an effort to avoid these inadequacies, the concept of the humanized mouse was developed in the 1980s. This model is based on the idea of recreating a human immune system in a useful format in the laboratory.

The NOD-scid Il2r-gamma-0 mouse strain produces excellent insights into the growth of a human stem cell transplant. These animals are highly immune deficient. The mice are therefore less able to respond to the human stem cells, rendering a rejection of the transplant unlikely. Furthermore, a functional human immune system develops in the mouse from the stem cells which are usually extracted from umbilical cord blood.

In order to determine whether the existing human cells are indeed functional, several parameters are tested. Different, activated immune cells have been found during testing. Moreover, human cytokines and antibodies can be detected. The humanized mouse thus opens up a broad range of research areas. On the one hand, it can be regarded as a contribution to the research of malign tumor diseases and HIV or Dengue virus infections. On the other hand, it can be vital for gaining a new understanding of the symptoms of sepsis. Despite the fact that establishing a new model is an extensive procedure that is dependent upon a number of variables, it offers an excellent opportunity to gain a more comprehensive understanding of human disease mechanisms and will shed light on several topic areas due to its flexible use.

In case of rheumatoid arthritis

Dense cellular infiltration of inflamed joints in collagen-induced arthritis in mice
© Fraunhofer IZI

Dense cellular infiltration of inflamed joints in collagen-induced arthritis in mice.

Rheumatoid arthritis (RA) is the inflammatory joint disease with the highest incidence in western populations and is very painful for the patient. Primary therapy for RA currently consists of the treatment of inflammatory symptoms (e.g. using so-called TNF blockers). However, the pattern of the disease indicates autoimmunological causes, wherein inherent substances such as articular cartilage and cells of the immune system are attacked. It has not yet been clarified how this destruction of cartilage which define rheumatic diseases, can be stopped or even reversed; such a therapy would constitute a complete cure of RA. In addition to already existing animal models and respective investigative research, the Fraunhofer IZI can also offer in vitro models, wherein anti-destructive mechanisms of action and grades of activity of RA medications are observed in a test tube in direct interaction with human cells. In the medium term, this targeted screening of active agents promises the identification of optimized therapeutics.

This project is co-financed by tax revenues on the basis of the budget approved by members of the Saxon state parliament.