No abstract

The multiplicity of systems affected in Alzheimer's disease (AD) brains calls for multi-target therapies. Although mesenchymal stem cells (MSC) are promising candidates, their clinical application is limited because of risks related to their direct implantation in the host. This could be overcome by exploiting their paracrine action. We herein demonstrate that in vivo systemic administration of secretome collected from MSC exposed in vitro to AD mouse brain homogenates (MSC-CS), fully replicates the cell-mediated neuroreparative effects in APP/PS1 AD mice. We found a complete but transient memory recovery by 7 days, which vanished by 14 days, after a single MSC-CS intravenous administration in 12-month or 22-24-month-old mice. Treatment significantly reduced plaque load, microglia activation, and expression of cytokines in astrocytes in younger, but not aged, mice at 7 days. To optimize efficacy, we established a sustained treatment protocol in aged mice through intranasal route. Once-weekly intranasal administration of MSC-CS induced persistent memory recovery, with dramatic reduction of plaques surrounded by a lower density of β-amyloid oligomers. Gliosis and the phagocytic marker CD68 were decreased. We found a higher neuronal density in cortex and hippocampus, associated with a reduction in hippocampal shrinkage and a longer lifespan indicating healthier conditions of MSC-CS-treated compared to vehicletreated APP/PS1 mice. Our data prove that MSC-CS displays a great multi-level therapeutic potential, and lay the foundation for identifying the therapeutic secretome bioreactors leading to the development of an efficacious multi-reparative cocktail drug, towards abrogating the need for MSC implantation and risks related to their direct use.

No abstract

In this study natural-based complex polyphenols, obtained through a smart synthetic approach, have been evaluated for their ability to inhibit the formation of Aβ42 oligomers, the most toxic species causing synaptic dysfunction, neuroinflammation, and neuronal death leading to the onset and progression of Alzheimer’s disease. In vitro neurotoxicity tests on primary hippocampal neurons have been employed to select nontoxic candidates. Solution NMR and molecular docking studies have been performed to clarify the interaction mechanism of Aβ42 with the synthesized polyphenol derivatives, and highlight the sterical and chemical requirements important for their antiaggregating activity. NMR results indicated that the selected polyphenolic compounds target Aβ42 oligomeric species. Combined NMR and docking studies indicated that the Aβ42 central hydrophobic core, namely, the 17–31 region, is the main interaction site. The length of the peptidomimetic scaffold and the presence of a guaiacol moiety were identified as important requirements for the antiaggregating activity. In vivo experiments on an Aβ42 oligomer-induced acute mouse model highlighted that the most promising polyphenolic derivative (PP04) inhibits detrimental effects of Aβ42 oligomers on memory and glial cell activation. NMR kinetic studies showed that PP04 is endowed with the chemical features of true inhibitors, strongly affecting both the Aβ42 nucleation and growth rates, thus representing a promising candidate to be further developed into an effective drug against neurodegenerative diseases of the amyloid type.