title: Biomineralized hydroxyapatite nanoclay composite scaffolds with polycaprolactone for stem cell-based bone tissue engineering.
abstract: Nanoclay modified with unnatural amino acid was used to design a nanoclay-hydroxyapatite (HAP) hybrid by mineralizing HAP in the nanoclay galleries mimicking biomineralization. This hybrid (in situ HAPclay) was used to fabricate polycaprolactone (PCL)/in situ HAPclay films and scaffolds for bone regeneration. Cell culture assays and imaging were used to study interactions between human mesenchymal stem cells (hMSCs) and PCL/in situ HAPclay composites (films and scaffolds). SEM imaging indicated MSC attachment, formation of mineralized extracellular (ECM) on PCL/in situ HAPclay films, and infiltration of MSCs to the interior of PCL/in situ HAPclay scaffolds. Mineralized ECM was formed by MSCs without use of osteogenic supplements. AFM imaging performed on this in vitro generated mineralized ECM on PCL/in situ HAPclay films revealed presence of components (collagen and mineral) of hierarchical organization reminiscent of natural bone. Cellular events observed during two-stage seeding experiments on PCL/in situ HAPclay films indicated similarities with events occurring during in vivo bone formation. PCL/in situ HAPclay films showed significantly increased (100-595% increase in elastic moduli) nanomechanical properties and PCL/in situ HAPclay scaffolds showed increased degradation. This work puts forth PCL/in situ HAPclay composites as viable biomaterials for bone tissue engineering.
authors.affiliation: Department of Civil and Environmental Engineering, North Dakota State University, Fargo, North Dakota, 58105.
authors.forename: Avinash H
authors.initials: AH
authors.lastname: Ambre
authors.forename: Dinesh R
authors.initials: DR
authors.lastname: Katti
authors.forename: Kalpana S
authors.initials: KS
authors.lastname: Katti
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000538:Aluminum Silicates / Q000494:pharmacology; D001842:Bone and Bones / Q000187:drug effects / Q000502:physiology*; D002113:Calcification, Physiologic / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D000077215:Clay; D019245:Compressive Strength / Q000187:drug effects; D017886:Durapatite / Q000494:pharmacology*; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D011091:Polyesters / Q000494:pharmacology*; D016062:Porosity; D017550:Spectroscopy, Fourier Transform Infrared; D013194:Staining and Labeling; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D011091:Polyesters; C016240:polycaprolactone; D017886:Durapatite; D000469:Alkaline Phosphatase; D000077215:Clay
keywords: biomineralization; bone tissue engineering; hydroxyapatite composite; mesenchymal stem cell; nanoclay