Hybrid scaffolds based on PLGA and silk for bone tissue engineering

Abstract

Porous silk scaffolds, which are considered to be natural polymers, cannot be used alone because they have a long degradation rate, which makes it difficult for them to be replaced by the surrounding tissue. Scaffolds composed of synthetic polymers, such as PLGA, have a short degradation rate, lack hydrophilicity and their release of toxic by-products makes them difficult to use. The present investigations aimed to study hybrid scaffolds fabricated from PLGA, silk and hydroxyapatite nanoparticles (Hap NPs) for optimized bone tissue engineering. The results from variable-pressure field emission scanning electron microscopy (VP-FE-SEM), equipped with EDS, confirmed that the fabricated scaffolds had a porous architecture, and the location of each component present in the scaffolds was examined. Contact angle measurements confirmed that the introduction of silk and HAp NPs helped to change the hydrophobic nature of PLGA to hydrophilic, which is the main constraint for PLGA used as a biomaterial. Thermo-gravimetric analysis (TGA) and FT-IR spectroscopy confirmed thermal decomposition and different vibrations caused in functional groups of compounds used to fabricate the scaffolds, which reflected improvement in their mechanical properties. After culturing osteoblasts for 1, 7 and 14 days in the presence of scaffolds, their viability was checked by MTT assay. The fluorescent microscopy results revealed that the introduction of silk and HAp NPs had a favourable impact on the infiltration of osteoblasts. In vivo experiments were conducted by implanting scaffolds in rat calvariae for 4 weeks. Histological examinations and micro-CT scans from these experiments revealed beneficial attributes offered by silk fibroin and HAp NPs to PLGA-based scaffolds for bone induction.

Bioactive polymeric scaffolds for tissue engineering

“…Sheik et al recently presented a novel PLGA/silk hybrid scaffold for bone tissue engineering applications in which the degradation rate of PLGA was combined with the hydrophilic silk polymer, as well as hydroxyapatite nanoparticles to further improve biocompatibility, and effectiveness was evaluated both in vitro and in vivo [183]. Variable-pressure field emission scanning electron microscopy (VP-FE-SEM) was used to demonstrate the porous nature of the scaffold, and contact angle measurements demonstrated that the silk component added further hydrophilicity to the scaffold.…”

Fabrication of 3D porous silk scaffolds by particulate (salt/sucrose) leaching for bone tissue reconstruction

“…Fifteen male Sprague-Dawley rats were housed in separate cages with free access to laboratory rodent food and water under standardized air and light conditions at a constant temperature of 22 • C with a 12-h light/day cycle. Scaffolds that were 0.5 cm thick and cut into 3-mm diameter disks [29] using a tissue punch were incubated with hMSC for two weeks in an osteogenic medium, and each scaffold was then implanted into a rat calvarium. Four weeks later, when transplant materials were placed at the surgical site and osteoblast cells were grown at the implant site, they were observed by micro-CT (Micro CAT II; Siemens Medical Solutions).…”

Hydrogels that allow and facilitate bone repair, remodeling, and regeneration

“…Synthetic scaffolds can be created with a variety of programmable features (i.e., porosity, pore size, degradation rate, and mechanical properties) that can be tailored to intended application sites. 27-31 However, polymers generally have a lower modulus than either metals or ceramics, 32 and thus have been limited in application to areas of low mechanical stress. 33 Given the need to precisely design bone tissue engineering scaffold properties, including morphology, resorption rate, osteoconductivity, and osteoinduction, attention has increasingly focused on the development of composites to tune these properties.…”