Monitoring cell transplantation in swine model via MRI
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Nora Kammer's paper in Artificial Organs on "Labelling of primary human hepatocytes with micron-sized iron oxide particles in suspension culture suitable for large-scale preparation" is available pre-print. Co-authors are Nils Billecke, Mehmet H. Morgul, Michaela K. Adonopoulou, Martina Mogl, Mao D. Huang, Stefan Florek, Katharina R. L. Schmitt, Nathanael Raschzok and Igor M. Sauer.
Protocols for labelling of hepatocytes with micron-sized iron oxide particles (MPIO) in adhesion culture enable cell detection using clinical Magnetic Resonance equipment. For clinical applications, large numbers of cells must be labelled in a simple and rapid manner, which requires new labelling protocols. The aim of this study was to investigate the feasibility of preparing MPIO-labelled primary human hepatocytes in a temporary suspension culture. Human hepatocytes were isolated from 16 donors and labelled with MPIO in suspension, using the Rotary Cell Culture System. Particle incorporation was investigated by light and electron microscopy. Cells were compared to adhesion culture-labelled and subsequently enzymatically resuspended cells. During a five-day culture period, hepatocyte-specific parameters of cell damage (aspartate aminotransferase and alanine aminotransferase) and metabolic activity (urea and albumin) were analysed. Suspension cultures showed a higher outcome in cell recovery compared to the conventional labelling method. When incubated with 180 particles/cell for four hours, the mean particle uptake was 28.8 particles/cell at a labelling efficiency of 95.1%. Labelling in suspension had no adverse effects on cell integrity or metabolic activity. In conclusion, labelling in suspension is a practicable method for fast and efficient preparation of large numbers of labelled cells that are suitable for clinical applications.
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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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