Amyloid‐Hydroxyapatite Bone Biomimetic Composites

Abstract

A "bottom up" strategy is proposed to synthesize high aspect ratio hydroxyapatite (and brushite) platelets, and combine them with amyloid fibrils into layered hybrid nanocomposites. Their hierarchical structure, despite the differences from natural bone, confers to the nanocomposites a density and elastic modulus matching those of cancellous bone. Evidence of good adhesion and spreading of human trabecular bone-derived pre-osteoblasts cells on these nanocomposites is provided.

Cell Adhesion on Amyloid Fibrils Lacking Integrin Recognition Motif

“…Peptide/Protein Fibril Formation-To test the adhesion of cells on amyloid fibrils, the amyloid fibrils were prepared by dissolving the peptides of kassinin (2 mg/ml), GLP 1 (0.25 mg/ml), rat UCN (2 mg/ml), oCRF (2 mg/ml), glucagon (2 mg/ml), GIP (2 mg/ml), mouse UCN III (2 mg/ml), and A␤ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) (1 mg/ml) in 5% D-mannitol with 0.01% sodium azide and incubated at 37°C with slight rotation. The peptides of somatostatin (2 mg/ml), human GRF (2 mg/ml), bombesin (2 mg/ml), VIP (2 mg/ml), helodermin (2 mg/ml), GRP (2 mg/ml), galanin (1 mg/ml), ␤-endorphin (2 mg/ml), and Sub P (1 mg/ml) were also similarly dissolved in 5% D-mannitol with 0.01% sodium azide and incubated in the presence of 400 M low molecular weight heparin at 37°C in 1.5-ml Eppendorf tubes.…”

“…A␤ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) was purchased from BACHEM. For amyloid fibril preparation, 0.5 mg of this peptide was dissolved in 500 l of sterile Milli-Q water to obtain 1 mM solution.…”

“…In this context, amyloid fibrils functionalized with cell-adhesive RGD motifs were shown to support cell adhesion (31,32). Recent studies also suggest that amyloid fibrils alone (without any functionalization) are also capable of supporting cell adhesion due to their unique nanotopographic features (33)(34)(35)(36)(37). However, it remains unclear whether this celladhesive property is dependent on the sequence composition or is a consequence of the amyloid nature.…”

“…Whereas ␣-Syn is associated with Parkinson disease (77), A␤42 is asso-ciated with Alzheimer disease (78). A␤ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)) is a short peptide derived from A␤42 that shows similar toxicity to the fulllength A␤42 and hence is used as a model peptide to study A␤ toxicity in cells (79). When SH-SY5Y cells were cultured on ␣-Syn, A␤42, and A␤ (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) fibril-coated surface for 24 h, cell survival was found to be greater on ␣-Syn and A␤42 fibrils compared with A␤(25-35) fibrils (Fig.…”

Implantable amyloid hydrogels for promoting stem cell differentiation to neurons

“…[16][17][18] Recently, amyloid-based biomimetic hybrid materials have also been used for bone tissue engineering applications. 19 We also previously designed self-healing amyloid hydrogels from the Aβ42 C-terminus that promote the adhesion and differentiation of mesenchymal stem cells (MSCs) in vitro. 17 Notably, the higher-order alignment and unique mechanical strength of these amyloid hydrogels enable them to direct stem cell differentiation to neuronal lineages.…”