RESUMEN
Porous hydroxyapatite (HA) scaffolds prepared by three-dimensional (3D) printing have wide application prospects owing to personalized structural design and excellent biocompatibility. However, the lack of antimicrobial properties limits its widespread use. In this study, a porous ceramic scaffold was fabricated by digital light processing (DLP) method. The multilayer chitosan/alginate composite coatings prepared by layer-by-layer method were applied to scaffolds and Zn2+ was doped into coatings in the form of ion crosslinking. The chemical composition and morphology of coatings were characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Energy dispersive spectroscopy (EDS) analysis demonstrated that Zn2+ was uniformly distributed in the coating. Besides, the compressive strength of coated scaffolds (11.52 ± 0.3 MPa) was slightly improved compared with that of bare scaffolds (10.42 ± 0.56 MPa). The result of soaking experiment indicated that coated scaffolds exhibited delayed degradation. In vitro experiments demonstrated that within the limits of concentration, a higher Zn content in the coating has a stronger capacity to promote cell adhesion, proliferation and differentiation. Although excessive release of Zn2+ led to cytotoxicity, it presented a stronger antibacterial effect against Escherichia coli (99.4%) and Staphylococcus aureus (93%).
RESUMEN
The scaffold for bone tissue engineering should possess proper porosity, adequate mechanical properties, cell affinity for cell attachment, and the capability to bind bioactive agents to induce cell differentiation. In this study, we successfully prepared a porous hydroxyapatite (HA) scaffold that is functionalized by poly(L-lysine)/polydopamine (PLL/PDA) hybrid coating. The PLL/PDA coating takes advantages of the high protein and cell affinity of PDA, as well as the biodegradability of PLL. Therefore, the coating can anchor bone morphogenic protein-2 (BMP2) to the HA scaffold via catechol chemistry under a mild condition so as to protect the bioactivity of BMP2. Meanwhile, the coating can also release BMP2 in a tunable and sustainable manner as the PLL degrades in the physiological environment. The BMP2-entrapped PLL/PDA coating on the HA scaffold can more efï¬ciently promote osteogenic differentiation of bone marrow stromal cells (BMSCs) in vitro and induce ectopic bone formation to a much greater level in vivo compared with a bare HA scaffold that delivers BMP2 in a burst manner. All of these results suggest that the PDA-mediated catechol modification of the HA scaffold can be an effective strategy to develop sustainable protein delivery system, and that the PLL/PDA-coated HA scaffold could be a promising candidate for bone tissue engineering applications.
Asunto(s)
Bivalvos/química , Regeneración Ósea/efectos de los fármacos , Huesos/fisiología , Materiales Biocompatibles Revestidos/farmacología , Durapatita/farmacología , Andamios del Tejido/química , Animales , Proteína Morfogenética Ósea 2/farmacología , Huesos/efectos de los fármacos , Células Cultivadas , Liberación de Fármacos , Indoles/química , Polilisina/química , Polímeros/química , Porosidad , Ratas Sprague-DawleyRESUMEN
In the process of bone regeneration, relatively early biological events including inflammatory response, angiogenesis, or stem cell homing, help the accompanying target actions of cell differentiation and calcification. Herein, we proposed a novel cell-guided tissue engineering system based on a surface-functionalized porous hydroxyapatite (HA) scaffolds with the ability to recruit cells and accelerate the differentiation of them along the osteoblastic lineage for optimizing large-sized bone defect repair. Inspired by microstructural properties of natural bone, HA scaffolds similar to the trabecular bone structure were prepared via a sugar sphere leaching technique, in which the inter-pore opening size was controllable. Dexamethasone (Dex)-loaded hydroxypropyl-ß-cyclodextrin microspheres (Dex@CDMs) and stromal cell derived factor-1 (SDF-1) were uniformly immobilized onto HA surface by a cross-linked alginate coating. The resulting scaffold (SDF-1/Dex@CDMs-HA) enabled the on-demand dual-delivery of SDF-1 and Dex. In vitro cell culture assays showed that initially released SDF-1 markedly stimulated the migration of mesenchymal stem cells (MSCs) to the deep interior of the scaffold, providing abundant target cells for the function of Dex which was subsequently released. Osteogenic differentiation potential of these cells was also further facilitated via a synergistic action of SDF-1 and Dex. Additionally, in vivo studies demonstrated that the cell-guided system effectively improved the early cell recruitment and vascularization within the deep interior of scaffold and significantly accelerated the extensive formation of osteoid and mineralized tissue compared with the controls. Accordingly, such a microsphere coating-decorated multifunctional scaffold shows a promising potential for cell-free bone tissue engineering applications.
Asunto(s)
Quimiocina CXCL12/química , Dexametasona/química , Durapatita/química , Fosfatasa Alcalina/genética , Fosfatasa Alcalina/metabolismo , Animales , Células de la Médula Ósea/citología , Regeneración Ósea/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Quimiocina CXCL12/metabolismo , Quimiocina CXCL12/farmacología , Subunidad alfa 1 del Factor de Unión al Sitio Principal/genética , Subunidad alfa 1 del Factor de Unión al Sitio Principal/metabolismo , Dexametasona/metabolismo , Dexametasona/farmacología , Perros , Portadores de Fármacos/química , Masculino , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/efectos de los fármacos , Células Madre Mesenquimatosas/metabolismo , Microesferas , Osteogénesis/efectos de los fármacos , Porosidad , Ratas , Ratas Sprague-Dawley , Ingeniería de Tejidos , beta-Ciclodextrinas/químicaRESUMEN
Presently, commercially available porous bone substitutes are manufactured by the sacrificial template method, direct foaming method, and polymer replication method (PRM). However, current manufacturing methods provide only the simplest form of the bone scaffold and cannot easily control pore size. Recent developments in medical imaging technology, computer-aided design, and solid freeform fabrication (SFF), have made it possible to accurately produce porous synthetic bone scaffolds to fit the defected bone shape. Porous scaffolds were fabricated by SFF and PRM for a comparison of physical and mechanical properties of scaffold. The suggested three-dimensional model has interconnected cubic pores of 500 µm and its calculated porosity is 25%. Whereas hydroxyapatite scaffolds fabricated by SFF had connective macropores, those by PRM formed a closed pore external surface with internally interconnected pores. SFF was supposed to be a proper method for fabricating an interconnected macroporous network. Biocompatibility was confirmed by testing the cytotoxicity, hemolysis, irritation, sensitization, and implantation. In summary, the aim was to verify the safety and efficacy of the scaffolds by biomechanical and biological tests with the hope that this research could promote the feasibility of using the scaffolds as a bone substitute.