Electrospinning can be used to mimic the architecture of an acellular nerve graft, combining microfibers for guidance, and pores for cellular infiltration. We made electrospun nerve guides, from polycaprolactone (PCL) or poly-L-lactic acid (PLLA), with aligned fibers along the insides of the channels and random fibers around them. We bridged a 10 mm rat sciatic nerve defect with the guides, and, in selected groups, added a cell transplant derived from autologous stromal vascular fraction (SVF). For control, we compared to hollow silicone tubes; or autologous nerve grafts. PCL nerve guides had a high degree of autotomy (8/43 rats), a negative indicator with respect to future usefulness, while PLLA supported axonal regeneration, but did not outperform autologous nerve grafts. Transplanted cells survived in the PLLA nerve guides, but axonal regeneration was not enhanced as compared to nerve guides alone. The inflammatory response was partially enhanced by the transplanted cells in PLLA nerve grafts; Schwann cells were poorly distributed compared to nerve guide without cells. Tailor-made electrospun nerve guides support axonal regeneration in vivo, and can act as vehicles for co-transplanted cells. Our results motivate further studies exploring novel nerve guides and the effect of stromal cell-derived factors on nerve generation.

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Congenital or acquired hearing loss is often associated with a progressive degeneration of the auditory nerve (AN) in the inner ear. The AN is composed of processes and axons of the bipolar spiral ganglion neurons (SGN), forming the connection between the hair cells in the inner ear cochlea and the cochlear nuclei (CN) in the brainstem (BS). Therefore, replacement of SGNs for restoring the AN to improve hearing function in patients who receive a cochlear implantation or have severe AN malfunctions is an attractive idea. A human neural precursor cell (HNPC) is an appropriate donor cell to investigate, as it can be isolated and expanded in vitro with maintained potential to form neurons and glia. We recently developed a post-natal rodent in vitro auditory BS slice culture model including the CN and the central part of the AN for initial studies of candidate cells. Here we characterized the survival, distribution, phenotypic differentiation, and integration capacity of HNPCs into the auditory circuitry in vitro. HNPC aggregates (spheres) were deposited adjacent to or on top of the BS slices or as a monoculture (control). The results demonstrate that co-cultured HNPCs compared to monocultures (1) survive better, (2) distribute over a larger area, (3) to a larger extent and in a shorter time-frame form mature neuronal and glial phenotypes. HNPC showed the ability to extend neurites into host tissue. Our findings suggest that the HNPC-BS slice co-culture is appropriate for further investigations on the integration capacity of HNPCs into the auditory circuitry.

New nanomaterials are constantly developed with applications in everything from cosmetics to high tech electronics. Assessing their biological impact has been done by analysis of their adsorbed protein corona, in vitro cell assays, and larger scale ecotoxicological studies. This has proved to be a huge challenge due to the wide range of available nanomaterials and their unpredictable behaviour in different environments. Furthermore, the enormous number of experimental variables make comparisons difficult. Concentration is one of these variables and can vary greatly depending on the aim of the study. When analysing the protein corona, concentrations are often higher than in cell assays. Using a combination of complementary techniques, we have characterised 20 nm gold nanoparticles in a concentration level commonly used in cell studies. We compare their behaviour in a commonly used, protein rich medium and one protein poor medium over 24 hours. Under these conditions, the NPs were stable in protein rich environment but underwent gradual aggregation in protein poor medium. We characterise the biomolecular corona in both media. In protein poor medium, we can describe the often overlooked aggregation. The aggregates’ morphology is confirmed by cryo-TEM. Finally, in the protein poor medium, by infrared spectroscopy, we have identified the amino acid arginine in the biomolecular corona which drives the aggregation.

Retinal ischemia arises from circulatory failure. As the retinal blood vessels are key organs in circulatory failure, our aim was to study the retinal vasculature separately from the neuroretina to elucidate the role of hypoxia-inducible factor (HIF) 1α and 1β and vascular endothelial growth factor (VEGF) in retinal ischemia. Retinal ischemia was induced in porcine eyes by applying an intraocular pressure, followed by 12 h of reperfusion. HIF-1α mRNA expression was not affected by ischemia, while immunofluorescence staining was higher after ischemia in the neuroretina. HIF-1β immunoreactivity and mRNA expression were unaffected. VEGF protein levels in the vitreous humor and VEGF staining in the neuroretina were more pronounced in eyes subjected to ischemia than in the sham eyes. VEGF may be activated downstream of HIF-1 and is known to stimulate retinal neovascularization, which causes sight-threatening complications. These results emphasize the need for pharmacological treatment to block the HIF and VEGF signaling pathways in retinal ischemia.