Biomimetic Nanofibrous Scaffolds Research Articles

Osteoblasts responses to three‐dimensional nanofibrous gelatin scaffolds

The development of suitable scaffolds for bone tissue engineering requires an in-depth understanding of the interactions between osteoblasts and scaffolding biomaterials. Although there have been a large amount of knowledge accumulated on the cell-material interactions on two-dimensional (2D) planar substrates, our understanding of how osteoblasts respond to a biomimetic nanostructured three-dimensional (3D) scaffold is very limited. In this work, we developed an approach to use confocal microscopy as an effective tool for visualizing, analyzing, and quantifying osteoblast-matrix interactions and bone tissue formation on 3D nanofibrous gelatin scaffolds (3D-NF-GS). Integrin β1, phosphor-paxillin, and vinculin were used to detect osteoblasts responses to the nanofibrous architecture of 3D-NF-GS. Unlike osteoblasts cultured on 2D substrates, osteoblasts seeded on 3D-NF-GS showed less focal adhesions for phospho-paxillin and vinculin, and the integrin β1 was difficult to detect after the first 5 days. Bone sialoprotein (BSP) expression on the 3D-NF-GS was present mainly in the cell cytoplasm at 5 days and inside secretory vesicles at 2 weeks, whereas most of the BSP on the 2D gelatin substrates was concentrated either in cell interface toward the periphery or at focal adhesion sites. Confocal images showed that osteoblasts were able to migrate throughout the 3D matrix within 5 days. By 14 days, osteoblasts were organized as nodular aggregations inside the scaffold pores and a large amount of collagen and other cell secretions covered and remodeled the surfaces of the 3D-NF-GS. These nodules were mineralized and were uniformly distributed inside the entire 3D-NF-GS after being cultured for 2 weeks. Taken together, these results give insight into osteoblast-matrix interactions in biomimetic nanofibrous 3D scaffolds and will guide the development of optimal scaffolds for bone tissue engineering.

Cellular response to poly(vinyl alcohol) nanofibers coated with biocompatible proteins and polysaccharides

A PVA nanofibrous matrix was prepared by electrospinning an aqueous 10wt% PVA solution. The mean diameter of the PVA nanofibers electrospun from the aqueous PVA solution was 240nm. The water resistance of the as-spun PVA nanofibrous matrix was improved by physically crosslinking the PVA nanofibers by heat treatment at 150°C for 10min. In addition, the heat-treated PVA nanofibrous matrix was coated with biocompatible polysaccharides (chitosan (CHI) or hyaluronic acid (HA)) and proteins (collagen (COL) or silk fibroin (SF)) to construct biomimetic nanofibrous scaffolds. The coating of proteins or polysaccharides on the PVA nanofibrous matrix was confirmed by ATR-IR spectra, and the degree of coating was determined by elemental analysis based on nitrogen content. The coated PVA matrices exhibited less hydrophilicity, except for the HA coating, and better tensile properties than the pure PVA nanofibrous matrix. The increase in tensile properties was due to interfiber bonds formed by the coating. The effect of protein and polysaccharide coating on normal human keratinocytes (NHEKs) and fibroblasts (NHEFs) was examined by cytocompatibility assessment in vitro. Among the CHI-, COL-, HA- and SF-coated PVA matrices, the SF-coated PVA nanofibrous matrix was found to be the most promising scaffold for the attachment and spreading of NHEKs and NHEFs as compared to the pure PVA matrix. This approach to controlling the surface properties of nanofibrous structures with SF may be useful in the design and tailoring of novel matrices for skin regeneration.

The development of biocomposite nanofibers for tissue scaffolding applications

The last decade has seen significant progress in the production of nanofibers by electrospinning. One of the major drivers to this progress is the potential use of nanofibrous structures as scaffolds for engineering tissues in regenerative medicine. Electrospun fibers are capable of emulating the nanofibrous architecture of the native extracellular matrix. They can potentially provide in-vivo-like nanomechanical and physicochemical signaling cues to the cells to establish apposite cell-scaffold interactions and promote functional changes between and within cells toward synthesis of a genuine extracellular matrix over time. In this context, this paper presents a brief overview of a scaffold design strategy. It also presents recent research pertaining to developing biomimetic and bioactive nanofibrous tissue scaffolds through electrospinning biocomposite nanofibers of organic-organic and inorganic-organic hybrids, which are potentially applicable to soft and hard tissue engineering.

Collagen-Based Biomimetic Nanofibrous Scaffolds: Preparation and Characterization of Collagen/Silk Fibroin Bicomponent Nanofibrous Structures

Electrospinning of collagen (COL)/silk fibroin (SF) blend solutions in 1,1,1,3,3,3-hexafluoro-2-propanol was investigated for fabrication of a biocompatible and biomimetic nanostructured scaffold for tissue engineering. The morphology of the electrospun COL/SF blend nanofibers was observed by scanning electron microscopy. The average diameters of COL/SF blend fibers ranged from 320 to 360 nm, irrespective of SF content in the blends. Both COL and SF components in the as-spun COL/SF blend matrices were stabilized by glutaraldehyde and water vapor, respectively, under the saturated glutaraldehyde aqueous solution at 25 degrees C. The glutaraldehyde vapor chemically stabilized the COL component via cross-linking, whereas the water vapor physically stabilized the SF component via crystallization to the beta-sheet structure. These structural changes of after-treated COL/SF blend matrices were examined using ATR-IR and CP/MAS (13)C NMR spectroscopy. To assay the cytocompatibility and cellular behavior of the COL/SF blend nanofibrous scaffolds, cell attachment and the spreading of normal human epidermal keratinocytes (NHEK) and fibroblasts (NHEF) seeded on the scaffolds were studied. In addition, both morphological changes and cellular responses of COL/SF blend nanofibrous matrices were also compared with COL/SF hybrid nanofibrous matrices. Generally similar levels of cell attachment and spreading of NHEF were shown in the COL/SF blend nanofibrous matrix compared with those of the pure COL and pure SF matrices; the cellular responses of NHEK were, however, markedly decreased in the COL/SF blend nanofibrous matrix as compared to the pure matrices. In contrast, cell attachment and spreading of NHEK on the COL/SF hybrid nanofibrous matrix were significantly higher than that of the COL/SF blend nanofibrous matrix. Our results indicate that a COL/SF hybrid nanofibrous matrix may be a better candidate than a COL/SF blend nanofibrous matrix for biomedical applications such as wound dressing and scaffolds for tissue engineering.

Biomimetic nanofibrous scaffolds: Preparation and characterization of chitin/silk fibroin blend nanofibers

Electrospinning of chitin/silk fibroin (SF) blend solutions in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was investigated to fabricate a biomimetic nanostructured scaffolds for tissue engineering. The morphology of the electrospun chitin/SF blend nanofibers was investigated with a field emission scanning electron microscope (FE-SEM). The average diameters of chitin/SF blend fibers decreased from 920 to 340 nm, with the increase of chitin content in blend compositions. The miscibility of chitin/SF blend fibers was examined by solution viscosity measurement. The chitin and SF were immiscible in the as-spun nanofibrous structure. The dimensional stability of chitin/SF blend nanofibers, with or without water vapor after-treatment, was conducted by immersing in water. As-spun SF-rich blend nanofibrous matrices were lost their fibrous structure after the water immersion for 24 h, and then changed into membrane-like structure. On the contrary, nanofibrous structures of water vapor-treated SF-rich blends were almost maintained. To assay the cytocompatibility and cell behavior on the chitin/SF blend nanofibrous scaffolds, cell attachment and spreading of normal human epidermal keratinocyte and fibroblasts seeded on the scaffolds were studied. Our results indicate that chitin/SF blend nanofibrous matrix, particularly the one that contained 75% chitin and 25% SF, could be a potential candidate for tissue engineering scaffolds because it has both biomimetic three-dimensional structure and an excellent cell attachment and spreading for NHEK and NHEF.

Biomimetic Nanofibrous Scaffolds: Preparation and Characterization of PGA/Chitin Blend Nanofibers

Electrospinning of poly(glycolic acid) (PGA)/chitin blend solutions in 1,1,1,3,3,3-hexafluoro-2-propanol was investigated to fabricate biodegradable and biomimetic nanostructured scaffolds for tissue engineering. The morphology of the electrospun PGA/chitin blend nanofibers was investigated with a field emission scanning electron microscope. The PGA/chitin blend fibers have average diameters of around 140 nm, and their diameters have a distribution in the range 50-350 nm. The miscibility of PGA/chitin blend fibers was examined by differential scanning calorimetry. The PGA and chitin were immiscible in the as-spun nanofibrous structure. An in vitro degradation study of PGA/chitin blend nanofibers was conducted in phosphate-buffered saline, pH 7.2. It was found that the hydrolytic cleavage of PGA in the blend nanofibers was accelerated by the coexistence of hydrophilic chitin. To assay the cytocompatability and cell behavior on the PGA/chitin blend nanofibrous scaffolds, cell attachment and spreading of normal human epidermal fibroblasts seeded on the scaffolds were studied. Our results indicate that the PGA/chitin blend nanofibrous matrix, particularly the one that contained 25% PGA and 75% chitin with bovine serum albumin coating, could be a good candidate for tissue engineering scaffolds, because it has an excellent cell attachment and spreading for normal human fibroblasts.