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ECRT Kickbox - Junior Scientist Grant
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Karl Hillebrandt receives one of the 2017 Einstein Center for Regenerative Therapies (ECRT) Kickbox – Junior Scientist Grant. The project is entitled "Fighting liver cirrhosis? Establishment and analysis of decellularized human cirrhotic liver slices as a 3-dimensional model to study cell matrix interactions".

Liver cirrhosis is one of the main indications for liver transplantation. Due to the organ shortage, this therapy option is limited to the minority of patients suffering from cirrhosis. Therefore, there is a need of alternative treatment options.The aim of our project is to establish a decellularization protocol for human cirrhotic livers slices, which preserves the natural extracellular matrix (ECM) of cirrhotic livers. These decellularized liver slices will serve as a 3 dimensional model to study cell matrix interactions. If we are able to establish a protocol which will preserve the ECM, we will conduct in vitro recellularization experiments to study how the cirrhotic ECM will change the genotype and phenotype of different cell types. With this knowledge we aim to modify specific cell types in vivo or vitro for example prior to cell transplantation. Our ambition is to steer the cell matrix interaction via these modified cells after their transplantation and thereby halt or even reverse the progress of liver cirrhosis. This approach may offer an alternative treatment option in the future.

Team : Karl Hillebrandt, Oliver Klein, Ben Strücker, Igor Sauer  
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Our manuscript "Depletion of donor dendritic cells ameliorates immunogenicity of both skin and hind limb transplants" has been accepted for publication in Frontiers in Immunology, section Alloimmunity and Transplantation. Authors are Muhammad Imtiaz Ashraf, Joerg Mengwasser, Anja Reutzel-Selke, Dietrich Polenz, Kirsten Führer, Steffen Lippert, Peter Tang, Edward Michaelis, Rusan Catar, Johann Pratschke, Christian Witzel, Igor M. Sauer, Stefan G. Tullius, and Barbara Kern.

Acute cellular rejection remains a significant obstacle affecting successful outcomes of organ transplantation including vascularized composite tissue allografts (VCA). Donor antigen presenting cells (APC), particularly dendritic cells (DC), orchestrate early alloimmune responses by activating recipient effector T cells. Employing a targeted approach, we investigated the impact of donor-derived conventional DC (cDC) and APC on the immunogenicity of skin and skin-containing VCA grafts, using mouse models of skin and hind limb transplantation.
By post-transplantation day 6, skin grafts demonstrated severe rejections, characterized by predominance of recipient CD4 T cells. In contrast, hind limb grafts showed moderate rejection, primarily infiltrated by CD8 T cells. While donor depletion of cDC and APC reduced frequencies, maturation, and activation of DC in all analysed tissues of skin transplant recipients, reduction in DC activities was only observed in the spleen of hind limb recipients. Donor cDC and APC depletion did not impact all lymphocyte compartments but significantly affected CD8 T cells and activated CD4 T in lymph nodes of skin recipients. Moreover, both donor APC and cDC depletion attenuated the Th17 immune response, evident by significantly reduced Th17 (CD4+IL-17+) cells in the spleen of skin recipients and reduced levels of IL-17E and lymphotoxin-α in the serum samples of both skin and hind limb recipients. In conclusion, our findings underscore the highly immunogenic nature of skin component in VCA. The depletion of donor APC and cDC mitigates the immunogenicity of skin grafts while exerting minimal impact on VCA.

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