Investigating The Impact Of Immunoregulatory Molecules And The Phagocytic Capacity Of Schwann Cells And Olfactory Ensheathing Cells To Foster Regenerative Approaches For Peripheral Nerve Injury
Tamara Weiss, PhD1, Sabine Taschner-Mandl, PhD2, Christine Radtke, Professor, Dr.1.
1Department of Plastic and Reconstructive Surgery, Medical University of Vienna, Vienna, Austria, 2Department of Tumor Biology, Children's Cancer Research Institute, Vienna, Austria.
PURPOSE: Schwann cell (SCs) and olfactory ensheathing cells (OECs) are the principal glia of the peripheral and olfactory nervous system, respectively. Although both ensure the integrity of nerve fibers, they exhibit additional functional competences that are adapted to the nature of the nerve they support. SCs gained attention as they possess the ability to facilitate axon regeneration by transforming into a dedicated repair phenotype after injury. In contrast, OECs are specialized to the needs of freshly generated neurons because mammalian olfactory receptor neurons are replaced throughout lifetime. In line with their physiological roles, several studies have highlighted beneficial effects of OECs and SCs in regenerative approaches not only for the spinal cord but also for peripheral nerves and they emerged as the leading candidates for autologous transplantation therapies. However, there is still a lot to learn about the neuroprotective and regenerative strategies of these two glial cell types and whether these can be exploited to improve therapeutic approaches. Moreover, accumulating evidence for an immunomodulatory potential of glia holds yet to be determined implications in regenerative medicine. Especially the reported up-regulation of MHCII and cytokines as well as the capacity of phagocytic debris clearance could cause various immunological effects that may influence the therapeutic outcome.Hence, understanding how OECs and SCs exert repair processes and affect the immune response after injury is of utmost interest to assess advantages and limitation of these cell types in transplantation therapies. Thus, we aim to investigate immunoregulatory molecules and the phagocytic capacity of OECs and SCs to exploit the involved pathways and develop novel approaches or auxiliary therapies for peripheral nerve regeneration.
METHODS: Highly pure human primary cultures of SCs were co-cultured with a human neuroblastoma tumor cell line that possesses a high spontaneous apoptosis rate. A multicolor immunofluorescence staining panel was developed to identify SCs, neuroblastoma cells and apoptotic cell nuclei by confocal microscopy. Supernatants of primary repair SC cultures were analyzed with cytokine antibody arrays that identify 274 different factors including cytokines, growth factors and other biomarkers.
RESULTS: After 11 days of culture, multicolor immunofluorescence analysis by confocal microscopy revealed apoptotic neuroblastoma cell nuclei within the cytoplasmic compartment of SCs. In addition, we could confirm the presence of several potent macrophage attracting factors in the medium of human primary repair SCs. CONCLUSION: Our preliminary results suggest, to our knowledge for the first time, that repair SCs are able to phagocytize cellular debris in addition to the well-known clearance of myelin. In a next step, the phagocytic capacities and pathways, cytokine production and regulation of immunomodulatory molecules will be compared between human primary SC and OEC cultures to expand the knowledge of their functional competences and to improve cell based therapies for peripheral nerve regeneration.
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