Fabrication of 3D chitosan/polyvinyl alcohol/brushite nanofibrous scaffold for bone tissue engineering by electrospinning using a novel falling film collector.

Despite its advantages, electrospinning has limited effectiveness in 3D scaffolding due to the high density of fibers it produces. In this research, a novel electrospinning collector was developed to overcome this constraint. An aqueous suspension containing chitosan/polyvinyl alcohol nanofibers was prepared employing a unique falling film collector. Suspension molding by freeze-drying resulted in a 3D nanofibrous scaffold (3D-NF). The mineralized scaffold was obtained by brushite deposition on 3D-NF using wet chemical mineralization by new sodium tripolyphosphate and calcium chloride dihydrate precursors. The 3D-NF was optimized and compared with the conventional electrospun 2D nanofibrous scaffold (2D-NF) and the 3D freeze-dried scaffold (3D-FD). Both minor fibrous and major freeze-dried pore shapes were present in 3D-NFs with sizes of 16.11-24.32 µm and 97.64-234.41 µm, respectively. The scaffolds' porosity increased by 53 % to 73 % compared to 2D-NFs. Besides thermal stability, mineralization improved the 3D-NF's ultimate strength and elastic modulus by 2.2 and 4.7 times, respectively. In vitro cell studies using rat bone marrow mesenchymal cells confirmed cell infiltration up to 290 µm and scaffold biocompatibility. The 3D-NFs given nanofibers and brushite inclusion exhibited considerable osteoinductivity. Therefore, falling film collectors can potentially be applied to prepare 3D-NFs from electrospinning without post-processing.

Preparation of bilayer tissue-engineered polyurethane/poly-L-lactic acid nerve conduits and their in vitro characterization for use in peripheral nerve regeneration.

BACKGROUND: Due to loss of peripheral nerve structure and/or function resulting from trauma, accidents, and other causes, peripheral nerve injuries continue to be a major clinical problem. These injuries can cause partial or total loss of sensory, motor, and autonomic capabilities as well as neuropathic pain. PNI affects between 13 and 23 out of every 100,000 people annually in developed countries. Regeneration of damaged nerves and restoration of function after peripheral nerve injury remain significant therapeutic challenges. Although autologous nerve graft transplantation is a viable therapy option in several clinical conditions, donor site morbidity and a lack of donor tissue often hinder full functional recovery. Biomimetic conduits used in tissue engineering to encourage and direct peripheral nerve regeneration by providing a suitable microenvironment for nerve ingrowth are only one example of the cutting-edge methods made possible by this field. Many innate extracellular matrix (ECM) structures of different tissues can be successfully mimicked by nanofibrous scaffolds. Nanofibrous scaffolds can closely mimic the surface structure and morphology of native ECMs of many tissues. METHODS: In this study, we have produced bilayer nanofibrous nerve conduit based on poly-lactic acid/polyurethane/multiwall carbon nanotube (PLA/PU/MWCNT), for application as composite scaffolds for static nerve tissue engineering. The contact angle was indicated to show the hydrophilicity properties of electrospun nanofibers. The SEM images were analyzed to determine the fiber's diameters, scaffold morphology, and endometrial stem cell adhesion. Moreover, MTT assay and DAPI staining were used to show the viability and proliferation of endometrial stem cells. RESULTS: The constructed bilayer PLA/PU/MWCNT scaffolds demonstrated the capacity to support cell attachment, and the vitality of samples was assessed using SEM, MTT assay, and DAPI staining technique. CONCLUSIONS: According to an in vitro study, electrospun bilayer PLA/PU/MWCNT scaffolds can encourage the adhesion and proliferation of human endometrial stem cells (hEnSCs) and create the ideal environment for increasing cell survival.

Plate-shape carbonated hydroxyapatite/collagen nanocomposite hydrogel via in situ mineralization of hydroxyapatite concurrent with gelation of collagen at pH = 7.4 and 37°C.

The objective of this study was to develop a collagen/hydroxyapatite (HA) nanocomposite scaffold for bone tissue engineering applications. For this purpose, in situ mineralization of HA was accompanied with formation of collagen hydrogel at condition similar to the physiological condition, pH = 7.4, and 37°C. The physicochemical and biological properties of the in situ scaffold were compared with nanocomposite fabricated by mixing HA powder and collagen hydrogel (powder-mixed scaffold). The HA in this method was formed in the same condition as the in situ method. X-ray diffraction and FTIR analysis of in situ scaffold showed the formation of carbonated HA, similar to bone, while the HA powder in powder-mixed scaffold showed non-carbonated structure. Scanning electron microscopy revealed the formation of fibrillated collagen in both composites. HA was observed in both scaffolds, but with different morphology. The in situ formed HA had a plate-like morphology while the preformed HA showed spherical morphology in the powder-mixed scaffold. The in-vitro cytocompatibility and osteogenesis activity of scaffolds using osteoblast-like cells (MG-63) showed higher cytocompatibility and more osteogenesis capability of the in situ scaffold in comparison with the powder-mixed scaffold. The results suggest the in situ method as a proper approach for fabrication of HA/collagen scaffolds with similar properties like bone. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1920-1929, 2019.