Bone tissue engineering scaffolding: computer-aided scaffolding techniques

Bi-layered constructs of poly(glycerol-sebacate)-β-tricalcium phosphate for bone-soft tissue interface applications

This study aims to establish a facile protocol for the preparation of a bi-layered poly(glycerol-sebacate) (PGS)/β-tricalcium phosphate (β-TCP) construct and to investigate its potential for bone-soft tissue engineering applications. The layered structure was prepared by distributing the ceramic particles within a prepolymer synthesized in a microwave reactor followed by a cross-linking of the final construct in vacuum (<10mbar). The vacuum stage led to the separation of cross-linked elastomer (top) and ceramic (bottom) phases. Results showed that addition of β-TCP particles to the elastomer matrix after the polymerization led to an increase in compression strength (up to 14±2.3MPa). Tensile strength (σ), Young's modulus (E), and elongation at break (%) values were calculated as 0.29±0.03MPa and 0.21±0.03; 0.38±0.02 and 1.95±0.4; and 240±50% and 24±2% for PGS and PGS/β-TCP bi-layered constructs, respectively. Morphology was characterized by using Scanning Electron Microscopy (SEM) and micro-computed tomography (μ-CT). Tomography data revealed an open porosity of 35% for the construct, mostly contributed from the ceramic phase since the elastomer side has no pore. Homogeneous β-TCP distribution within the elastomeric structure was observed. Cell culture studies confirmed biocompatibility with poor elastomer-side and good bone-side cell attachment. In a further study to investigate the osteogenic properties, the construct were loaded with BMP-2 and/or TGF-β1. The PGS/β-TCP bi-layered constructs with improved mechanical and biological properties have the potential to be used in bone-soft tissue interface applications where soft tissue penetration is a problem.

Modified silk and chitosan scaffolds with collagen assembly for osteoporosis

Currently, many patients suffer from osteoporosis. Osteoporosis is a disease that leads to bone defect. Severe cases of bone defect from osteoporosis need an operation using a performance scaffold for bone tissue engineering. Therefore, to build a performance scaffold for bone defect from osteoporosis is the target of this research. Samples of silk fibroin and chitosan were fabricated into porous scaffolds before modification by coating with collagen self-assembly. The structure and morphology of the samples were characterized and observed by Fourier transform infrared spectroscopy, atomic force microscopy, and scanning electron microscopy. For biological functionality analysis, MC3T3-E1 osteoblasts were cultured on the samples. Afterward, biodegradation, cell proliferation, viability, and mineralization were analyzed. The results demonstrated that collagen organized into a fibril structure covering the pores of the scaffold. The modified scaffolds showed low degradability, high cell proliferation, viability, and mineralization. The results demonstrated that the modified scaffolds with a coating of mimicked collagen self-assembly had good performance and showed promise for bone tissue engineering in osteoporosis.

Fabrication of a composite of nanocrystalline carbonated hydroxyapatite (cHAP) with polylactic acid (PLA) and its surface topographical structuring with direct laser writing (DLW)

The fabrication of a polylactic acid (PLA)–carbonated hydroxyapatite (cHAP) composite material from synthesised phase pure nano-cHAP and melted PLA by mechanical mixing at 220–235 °C has been developed in this study.

Influence of temperature, pH and simulated biological solutions on swelling and structural properties of biomineralized (CaCO3) PVP-CMC hydrogel

Abstract

Biomaterials having stimuli response are interesting in the biomedical field. This paper reports about swelling response and internalstructural of biomineralized (CaCO₃) polyvinylpyrrolidone (PVP) carboxymethylcellulose (CMC) hydrogel having various thicknesses (0.1–0.4 mm). Samples were tested in aqueous solution using temperature ranges from 10 to 40 °C; pH varies from 4 to 9, time 60 min. In addition, an experiment was conducted in the presence of simulated biological solutions (SBS): glucose (GS), physiological fluid (PS) and urea (US) at temperature 37 °C and pH 7.5 for 180 min. It is noticed that the maximum swelling ratio reached in 30–40 °C at pH 7 in aqueous solution. Among biological fluids, the swelling ratio shows: US > PS > GS at temperature 37 °C, pH 7.5, time 150 min. The equilibrium swelling ratio of the test sample in SBS and their non-reformative apparent structure confirm that biomineralized (CaCO₃) PVP–CMC hydrogel can be acclaimed for medical application like bone tissue engineering.

Graphical Abstract

Modulation of Bone-Specific Tissue Regeneration by Incorporating Bone Morphogenetic Protein and Controlling the Shell Thickness of Silk Fibroin/Chitosan/Nanohydroxyapatite Core-Shell Nanofibrous Membranes

The presence of both osteoconductive and osteoinductive factors is important in promoting stem cell differentiation toward the osteogenic lineage. In this study, we prepared silk fibroin/chitosan/nanohydroxyapatite/bone morphogenetic protein-2 (SF/CS/nHAP/BMP-2, SCHB2) nanofibrous membranes (NFMs) by incorporating BMP-2 in the core and SF/CS/nHAP as the shell layer of a nanofiber with two different shell thicknesses (SCHB2-thick and SCHB-thin). The physicochemical properties of SCHB2 membranes were characterized and compared with those of SF/CS and SF/CS/nHAP NFMs. When tested in release studies, the release rate of BMP-2 and the concentration of BMP-2 in the release medium were higher for SCHB2-thin NFMs because of reduced shell thickness. The BMP-2 released from the nanofiber retained its osteoinductive activity toward human-bone-marrow-derived mesenchymal stem cells (hMSCs). Compared with SF/CS and SF/CS/nHAP NFMs, the incorporation of BMP-2-promoted osteogenic differentiation of hMSCs and the SCHB-thin NFM is the best scaffold during in vitro cell culture. Gene expression analysis by real-time quantitative polymerase chain reaction detected the evolution of both early and late marker genes of bone formation. The relative mRNA expression is in accordance with the effect of BMP-2 incorporation and shell thickness, while the same was reconfirmed through the quantification of bone marker protein osteocalcin. In vivo experiments were carried out by subcutaneously implanting hMSC-seeded SCHB2-thin NFMs and acellular controls on the back sides of nude mice. Immunohistochemical and histological staining confirmed ectopic bone formation and osteogenesis of hMSCs in SCHB2-thin NFMs. In conclusion, the SCHB2-thin NFM could be suggested as a promising scaffold for bone tissue engineering.