Natural-based nanocomposites for bone tissue engineering and regenerative medicine: a review

Tissue engineering and regenerative medicine has been providing exciting technologies for the development of functional substitutes aimed to repair and regenerate damaged tissues and organs. Inspired by the hierarchical nature of bone, nanostructured biomaterials are gaining a singular attention for tissue engineering, owing their ability to promote cell adhesion and proliferation, and hence new bone growth, compared with conventional microsized materials. Of particular interest are nanocomposites involving biopolymeric matrices and bioactive nanosized fi llers. Biodegradability, high mechanical strength, and osteointegration and formation of ligamentous tissue are properties required for such materials. Biopolymers are advantageous due to their similarities with extracellular matrices, specifi c degradation rates, and good biological performance. By its turn, calcium phosphates possess favorable osteoconductivity, resorbability, and biocompatibility. Herein, an overview on the available natural polymer/calcium phosphate nanocomposite materials, their design, and properties is presented. Scaffolds, hydrogels, and fi bers as biomimetic strategies for tissue engineering, and processing methodologies are described. The specifi c biological properties of the nanocomposites, as well as their interaction with cells, including the use of bioactive molecules, are highlighted. Nanocomposites in vivo studies using animal models are also reviewed and discussed.  The research leading to this work has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS, and from QREN (ON.2 - NORTE-01-0124-FEDER-000016) cofinanced by North Portugal Regional Operational Program (ON.2 - O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF)

Gellan gum : hydroxyapatite composite hydrogels for bone tissue engineering

The modification of polymeric matrices by adding calcium-phosphate derivatives has been proven an effective strategy for tailoring the properties of scaffolds employed in bone tissue engineering. In this regard and, considering the biomechanics of bone as well as the durotactic response of osteoblasts, this study builds on the hypothesis that the preparation of novel Gellan Gum (GG)-Hydroxyapatite (HA) hydrogel composites could benefit the mechanical profile of matrices as well as the cell-substrate interaction in favor of cell recruitment and growth. To this purpose, HA microparticles at different concentrations (10 and 20%) were successfully incorporated into GG based hydrogels. The composites were characterized by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS), Fourier Transformed Infrared Spectroscopy (FTIR), X-Ray Diffraction Analysis (XRD), Micro Computed Tomography (μ-CT) Analysis and Thermogravimetric Analysis (TGA). In vitro degradation and swelling studies were conducted in PBS solution, while the GG/HA composites were subjected to Dynamic Mechanical Analysis (DMA). The efficacy of the GG/HA matrices to precipitate apatite in Simulated Body Fluid (SBF) was evaluated, while the cell-matrix interactions were studied by seeding the composites with human osteoblast-like cells. The cell-viability was assayed by staining the cell-loaded composites with calcein-AM, Texas Red-Phalloidin and DAPI-blue and observing by confocal microscope. The image (SEM, μ-CT)-assisted microstructural characterization of the GG/HA composites reveals hydrogels with high porosity (>80%) and average pore size of 260 μm. GG/HA composites demonstrate high water retention ability during swelling studies, while the weight loss did not exceed 8% during the degradation studies. FTIR and XRD detected peaks typical of hydroxyapatite. The thermal curves of the composites disclose an initial weight loss due to moisture removal and two subsequent degradation phases due to the polymeric component decomposition. The matrices exhibit increasing storage modulus (E’) and decreasing loss factor (tan δ) as a function of frequency during DMA analysis, while composites containing 20% HA possess always higher E’ and lower tan δ values. GG/HA composites develop bioactivity in the form of multiple agglomerates of apatite crystals since the 3rd post-immersion day in SBF. Viability assays indicated that the human osteoblast-like cells seeded on the GG/HA composites were metabolically active. Concluding, the modification of GG-based hydrogels by HA in different concentration appears to result in composites that meet several scaffold-design criteria and to allow the tailoring of their mechanical performance. However, further optimization is required in order to improve cell adhesion and to promote cell growth

Gellan gum-based hydrogels for tissue engineering applications

Hydrogels have been attracting great deal of attention in tissue engineering for its resemblance to tissueâ s extracellular matrix. In this chapter, it is provided an overview of the current advances on the gellan gum (GG) based hydrogels preclinical research. Although this exopolysaccharide possess many advantages, blending with other polymers and ceramics, chemical modification and functionalization have been the most attempted strategies for optimizing its physicochemical and biological properties. The GG-based hydrogels showed so far, great promise as tunable biomaterials in a wide range of regenerative strategies. But, its wider use in tissue regeneration will be greatly determined by the advances on microscale processing techniques that will enable to best mimic living tissues multiscale organization and certainly improve its functionality.(undefined)info:eu-repo/semantics/publishedVersio