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The Potential Of IPSC-derived Macrophages To Assess The Immunocompatibility Of Tissue Engineered Matrices In Vitro
Nikolaos Poulis, Maximilian Y. Emmert, Simon P. Hoerstrup, Emanuela S. Fioretta.
Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland, Zurich, Switzerland.

OBJECTIVE: Tissue-engineered heart valves based on in-vitro grown matrices demonstrated adaptive remodelling potential in sheep. However, it has not been fully elucidated how the complexity of TEM composition, comprising extra- and intra-cellular proteins, and polymeric remnants, may affect the human tissue-resident macrophage (hTRM) response. Here we aim to assess TEM immunocompatibility using hiPSC-derived macrophages (IPSCDMs) as a model for hTRM-like cells.
METHODS: TEMs were produced by culturing human dermal fibroblasts on PGA-P4HB for 2, 4, and 6-weeks and then decellularized. Histology and mass spectrometry (LC-MS/MS) were used to assess TEM composition. IPSCDMs were differentiated and co-cultured with different TEMs for 3 and 7 days (n=3/time-point). Flow cytometry and ELISA (TNF-?,IL-8) were performed to determine IPSCDM polarization after exposure to TEMs. IPSCDMs polarized towards M1 (LPS/INF-g,72hrs) and M2 (IL-4/IL-13,72hrs) polarization states and PGA-P4HB scaffolds were used as controls.
RESULTS: Over tissue culture time, ECM quantity and maturity increased while polymer degraded. TEM proteome was characterized mostly by intracellular proteins (92%). Mass spectrometry indicated potentially immunogenic proteins (ACTA2,HSPB1,HSPA8) and xenogenic (bovine) proteins (FGB,HBA1). IPSCDMs were characterized (CD34-,CD45+,CD163+) and polarized towards M1(CD86+) and M2(CD206+) prior to exposure to TEMs. Independently on TEM composition, both CD34-/CD45+/CD86+ and CD34-/CD45+/CD206+ populations were detected and CD86+ cells were less represented compared to CD206+. ELISA indicated IL-8 secretion in all samples.
CONCLUSIONS: hTRMs is not an easily accessible cell source. Here, we demonstrate the use of IPSCDMs as a model for hTRM for assessment of TEM composition in relation to immunocompatibility. Our early findings suggest that IPSCDM polarization is independent of TEM composition, in the presence of immunogenic proteins and polymeric remnants. Future studies will validate these results under native-like hemodynamic conditions.


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