Luna Ardondi

Titanium surface nanotopography can regulate cellular behavior not only through direct cell–material interactions but also by influencing extracellular vesicle (EV)-mediated communication. Here, we investigated how anodized nanostructured Ti–Nb–Ta–Zr–Hf surfaces affect human endothelial cells and human adipose-derived stem cells (hADSCs), as well as the biological activity of EVs released by each cell type. Nanostructuring increased surface roughness and hydrophilicity while maintaining compatibility with both cellular populations. Endothelial cells progressively adapted to the titanium surfaces, maintaining viability and NOS3 expression while reducing inflammatory, proliferative, and angiogenic activation markers. Although surface topography did not substantially affect endothelial EV size or release, EVs generated on nanostructured titanium displayed increased CD81 expression, enhanced recipient-cell and preserved endothelial monolayer organization compared with EVs generated on the bare surface. In hADSCs, the nanostructured interface induced a rounded morphology associated with reduced expression of focal-adhesion and cytoskeletal-tension mediators, including VCL, PTK2, ACTA2, and ROCK1, together with downregulation of the mechanosensitive transcriptional regulators YAP1 and WWTR1/TAZ. This response was accompanied by upregulation of the pro-osteogenic miRNAs miR-21-5p and miR-20a-5p, downregulation of the osteogenesis-inhibitory miRNAs miR-133a-5p and miR-138-5p, and activation of RUNX2, ALPL, BGLAP, and SPARC. hADSC-derived EVs were efficiently internalized by recipient cells and promoted a concordant osteogenic-priming response. Overall, nanostructured titanium modulates direct cellular mechanotransduction and the biological activity of EV-mediated signals in a cell-type-specific manner. Rather than demonstrating osteogenic–angiogenic coupling, these findings reveal parallel endothelial homeostatic and mesenchymal osteogenic responses that may independently support the establishment of a regenerative peri-implant microenvironment.

Microalgae are considered promising sustainable sources of natural bioactive compounds to be used in biotechnological sectors. In recent years, attention is increasingly given to the search of microalgae-derived compounds with antioxidant and anti-inflammatory properties for nutraceutical or pharmacological issues. In this context, attention is usually focused on the composition and bioactivity of algae or their extracts, while less interest is driven to their biological features, for example, those related to morphology and cultivation conditions. In addition, specific studies on the antioxidant and anti-inflammatory properties of microalgae mainly concern Chlorella or Spirulina. The present work was focused on the characterization of the Chlorophyta Neochloris oleoabundans under two combinations of cultivation modes: autotrophy and glucose-induced mixotrophy, each followed by starvation. Biomass for morphological and biochemical characterization, as well as for extract preparation, was harvested at the end of each cultivation phase. Analyses indicated a different content of the most important classes of bioactive compounds with antioxidant/anti-inflammatory properties (lipids, exo-polysaccharides, pigments, total phenolics, and proteins). In particular, the most promising condition able to prompt the production of antioxidant algal biomass with anti-inflammatory properties was the mixotrophic one. Under mixotrophy, beside an elevated algal biomass production, a strong photosynthetic metabolism with high appression of thylakoid membranes and characteristics of high photo-protection from oxidative damage was observed and linked to the overproduction of exo-polysaccharides and lipids rather than pigments. Overall, mixotrophy appears a good choice to produce natural bioactive extracts, potentially well tolerated by human metabolism and environmentally sustainable.

Microalgae are proposed in several biotechnological fields because of their ability to produce biomass enriched in high-value compounds according to cultivation conditions. Regarding the health sector, an emerging area focuses on natural products exploitable against viruses. This work deals with the characterization of the green microalga Neochloris oleoabundans cultivated under autotrophic and mixotrophic conditions as a source of whole aqueous extracts, tested as antivirals against HCoV-229E (Coronaviridae family). Glucose was employed for mixotrophic cultures. Growth and maximum quantum yield of photosystem II were monitored for both cultivations. Algae extracts for antiviral tests were prepared using cultures harvested at the early stationary phase of growth. Biochemical and morphological analyses of algae indicated a different content of the most important classes of bioactive compounds with antiviral properties (lipids, exo-polysaccharides, and total phenolics, proteins and pigments). To clarify which phase of HCoV-229E infection on MRC-5 fibroblast cells was affected by N. oleoabundans extracts, four conditions were tested. Extracts gave excellent results, mainly against the first steps of virus infection. Notwithstanding the biochemical profile of algae/extracts deserves further investigation, the antiviral effect may have been mainly promoted by the combination of proteins/pigments/phenolics for the extract derived from autotrophic cultures and of proteins/acidic exo-polysaccharides/lipids in the case of mixotrophic ones.