Role of PAMAM-OH dendrimers against the fibrillation pathway of biomolecules

Cationic Carbosilane Dendritic Systems as Promising Anti-Amyloid Agents in Type 2 Diabetes

The most common denominator of many of the neurodegenerative diseases is badly folded protein accumulation, which results in the formation of insoluble protein deposits located in different parts of the organism, causing cell death and tissue degeneration. Dendritic systems have turned out to be a promising new therapeutic approach for the treatment of these diseases due to their ability to modulate the folding of these proteins. With this perspective, and focused on type 2 diabetes (T2D), characterized by the presence of deposits containing the amyloidogenic islet amyloid polypeptide (IAPP), we demonstrate how different topologies of cationic carbosilane dendrimers inhibit the formation of insoluble protein deposits in pancreatic islets isolated from transgenic Tg-hIAPP mice. Also, the results obtained by the modification of dendritic carbosilane wedges with the chemical chaperone 4-phenylbutyric acid (4-PBA) at the focal point confirmed their potential as anti-amyloid agents with a concentration efficiency in their therapeutic action five orders of magnitude lower than that observed for free 4-PBA. Computational studies, which determined the main interaction between IAPP and dendrimers at the atomic level, support the experimental work.

The inhibitory effect of carboxyl-terminated polyamidoamine dendrimers on dentine host-derived matrix metalloproteinases in vitro in an etch-and-rinse adhesive system

The biomimetic remineralization of collagen fibrils has increased interest in restoring the demineralized dentine generated by dental caries. Carboxyl-terminated polyamidoamine dendrimers (PAMAM-COOH), hyperbranched polymeric macromolecules, can act as non-collagenous proteins to induce biomimetic remineralization on a dentine organic matrix. However, in vivo remineralization is an extremely time-consuming process; before complete remineralization, demineralized dentine collagen fibrils are susceptible to degradation by host-derived matrix metalloproteinases (MMPs). Therefore, we examined the effect of fourth-generation PAMAM-COOH (G4-PAMAM-COOH) on the collagenolytic activities of endogenous MMPs, the interaction between G4-PAMAM-COOH and demineralized dentine collagen and the influence of G4-PAMAM-COOH pre-treatment on resin-dentine bonding. G4-PAMAN-COOH not only inhibited exogenous soluble rhMMP9 but also hampered the proteolytic activities of dentine collagen-bound MMPs. Cooperated with the results of G4-PAMAM-COOH absorption and desorption, FTIR spectroscopy provided evidence for the exclusive electrostatic interaction rather than hydrogen or covalent bonding between G4-PAMAM-COOH and dentine collagen. Furthermore, G4-PAMAM-COOH pre-treatment showed no damage to resin-dentine bonding because it did not significantly decrease the elastic modulus of the demineralized dentine, degree of conversion, penetration of the adhesive into the dentinal tubules or ultimate tensile strength. Thus, G4-PAMAM-COOH can effectively inactivate MMPs, retard the enzymolysis of collagen by MMPs and scarcely influence the application of resin-dentine bonding.