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Alginate‐based nanofibers with an average diameter of ca. 75 nm (see figure) have been fabricated by electrospinning. The nanofiber network has mechanical properties comparable to cartilage. The cellular compatibility is demonstrated with chondrocytes. This natural polymer‐based nanofiber network may find application in tissue engineering and regenerative medicine.

The ability to produce well‐blended nanofibers from natural and synthetic polymers represents a significant advancement in development of composite materials with desired structures and material properties. The nanofiber presented here exhibits excellent structural stability and mechanical and biological properties favorable for biomedical applications, and offers a new nanofibrous platform for development of matrices for various biomedical applications.

In vitro models that accurately mimic the microenvironment of invading glioblastoma multiform (GBM) cells will provide a high-throughput system for testing potential anti-invasion therapies. Here, we investigate the ability of chitosan-polycaprolactone polyblend nanofibers to promote a migratory phenotype in human GBM cells by altering the nanotopography of the nanofiber membranes. Fibers were prepared with diameters of 200 nm, 400 nm, and 1.1 µm, and were either randomly oriented or aligned to produce six distinct nanotopographies. Human U-87 MG GBM cells, a model cell line commonly used for invasion assays, were cultured on the various nanofibrous substrates. Cells showed elongation and alignment along the orientation of aligned fibers as early as 24 hrs and up to 120 hrs of culture. After 24 hrs of culture, human GBM cells cultured on aligned 200 nm and 400 nm fibers showed marked upregulation of invasion-related genes including β-catenin, Snail, STAT3, TGF-β, and Twist, suggesting a mesenchymal change in these invading cells. After 120 hrs, there was only a slight upregulation of these genes in human GBM cells cultured on 400 nm and 1.1 µm aligned and random fibers, indicating slower, less pronounced transformation. The decrease in expression of these genes from 24 hrs to 120 hrs on 200 nm and 400 nm aligned fibers was attributed to asymmetric cell division, a hallmark of mesenchymal-like cells. Therefore, small (200 and 400 nm) diameter aligned nanofibers induce the greatest degree of phenotype change indicative of cell invasion behavior in human GBM. Additionally, cells cultured on 400 nm aligned fibers showed similar migration profiles as those reported in vivo, and thus these nanofibers should provide a unique high-throughput in vitro culture substrate for developing anti-invasion therapies for the treatment of GBM.

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