Development of an In Vitro Blood Vessel Model Using Autologous Endothelial Cells Generated from Footprint-Free hiPSCs to Analyze Interactions of the Endothelium with Blood Cell Components and Vascular Implants.

Cardiovascular diseases are the leading cause of death globally. Vascular implants, such as stents, are required to treat arterial stenosis or dilatation. The development of innovative stent materials and coatings, as well as novel preclinical testing strategies, is needed to improve the bio- and hemocompatibility of current stents. In this study, a blood vessel-like polydimethylsiloxane (PDMS) model was established to analyze the interaction of an endothelium with vascular implants, as well as blood-derived cells, in vitro. Using footprint-free human induced pluripotent stem cells (hiPSCs) and subsequent differentiation, functional endothelial cells (ECs) expressing specific markers were generated and used to endothelialize an artificial PDMS lumen. The established model was used to demonstrate the interaction of the created endothelium with blood-derived immune cells, which also allowed for real-time imaging. In addition, a stent was inserted into the endothelialized lumen to analyze the surface endothelialization of stents. In the future, this blood vessel-like model could serve as an in vitro platform to test the influence of vascular implants and coatings on endothelialization and to analyze the interaction of the endothelium with blood cell components.

Integrin activation enables rapid detection of functional Vδ1+ and Vδ2+ γδ T cells.

Conformational change of the ß2 integrin lymphocyte function-associated antigen 1 (LFA-1) is an early marker of T cell activation. A protocol using the mAb clone m24 recognizing the active, extended high-affinity conformation has been previously described for the assessment of functional CD4+ and CD8+ T cells in response to MHC-peptide stimulation. We investigated the applicability of the m24 mAb to detect the activation of γδ T cells in response to different soluble and immobilized stimuli. m24 mAb staining was associated with the expression of cytokines and was detectable as early as 10 min after stimulation, but with different kinetics depending on the nature of the stimulus. Hence, we conclude that this assay is suitable for the detection of functional γδ T cells and allows the assessment of activation more rapidly than alternative methods such as cytokine detection. Intracellular staining, protein trafficking inhibitors, or prior knowledge of the stimulating moiety recognized are no longer required for monitoring γδ T cell activation.