While human enteroviruses are generally regarded as a lytic virus, and persistent non-cytolytic enterovirus infection in pancreatic beta cells has been suspected of playing a role in type 1 diabetes pathogenesis. However, it is still unclear how enteroviruses could exit the pancreatic beta cell in a non-lytic manner. This study aimed to investigate the role of beta cell-derived extracellular vesicles (EVs) in the non-lytic enteroviral spread and infection. Size-exclusion chromatography and antibody-based immunoaffinity purification were used to isolate EVs from echovirus 16-infected human beta EndoC-βH1 cells. EVs were then characterized using transmission electron microscopy and Multiplex Bead-Based Flow Cytometry Assay. Virus production and release were quantified by 50% cell culture infectious dose (CCID50) assay and qRT-PCR. Our results showed that EVs from echovirus 16-infected EndoC-βH1 cells harbor infectious viruses and promote their spread during the pre-lytic phase of infection. Furthermore, the EVs-mediated infection was not inhibited by virus-specific neutralizing antibodies. In summary, this study demonstrated that enteroviruses could exit beta cells non-lytically within infectious EVs, thereby thwarting the access of neutralizing antibodies to viral particles. These data suggest that enterovirus transmission through EVs may contribute to viral dissemination and immune evasion in persistently infected beta cells.

Human enteroviruses (HEV), especially coxsackievirus serotype B (CVB) and echovirus (E), have been associated with diseases of both the exocrine and endocrine pancreas, but so far evidence on HEV infection in human pancreas has been reported only in islets and ductal cells. This study aimed to investigate the capability of echovirus strains to infect human exocrine and endocrine pancreatic cells. Infection of explanted human islets and exocrine cells with seven field strains of E6 caused cytopathic effect, virus titer increase and production of HEV protein VP1 in both cell types. Virus particles were found in islets and acinar cells infected with E6. No cytopathic effect or infectious progeny production was observed in exocrine cells exposed to the beta cell-tropic strains of E16 and E30. Endocrine cells responded to E6, E16 and E30 by upregulating the transcription of interferon-induced with helicase C domain 1 (IF1H1), 2′-5′-oligoadenylate synthetase 1 (OAS1), interferon-β (IFN-β), chemokine (C–X–C motif) ligand 10 (CXCL10) and chemokine (C–C motif) ligand 5 (CCL5). Echovirus 6, but not E16 or E30, led to increased transcription of these genes in exocrine cells. These data demonstrate for the first time that human exocrine cells represent a target for E6 infection and suggest that certain HEV serotypes can replicate in human pancreatic exocrine cells, while the pancreatic endocrine cells are permissive to a wider range of HEV.

In neuroscience research, cell culture systems are essential experimental platforms. It is of great interest to explore in vivo-like culture substrates. We explored how basic properties of neural cells, nuclei polarization, phenotypic differentiation and distribution/migration, were affected by the culture at poly-L-lactic acid (PLLA) fibrous scaffolds, using a multipotent mitogen-expanded human neural progenitor cell (HNPC) line. HNPCs were seeded, at four different surfaces: two different electrospun PLLA (d = 1.2 -1.3 µm) substrates (parallel or random aligned fibers), and planar PLL-and PLLA surfaces. Nuclei analysis demonstrated a non-directed cellular migration at planar surfaces and random fibers, different from cultures at aligned fibers where HNPCs were oriented parallel with the fibers. At aligned fibers, HNPCs displayed the same capacity for phenotypic differentiation as after culture on the planar surfaces. However, at random fibers, HNPCs showed a significant lower level of phenotypic differentiation compared with cultures at the planar surfaces. A clear trend towards greater neuronal formation at aligned fibers, compared to cultures at random fibers, was noted. We demonstrated that the topography of in vivo-resembling PLLA scaffolds significantly influences HNPC behavior, proven by different migration behavior, phenotypic differentiation potential and nuclei polarization.This knowledge is useful in future exploration of in vivo-resembling neural cell system using electrospun scaffolds.