Polycaprolactone-chitosan nanofibers influence cell morphology to induce early osteogenic differentiation.

Osteogenic differentiation is highly correlated with cell morphology. Morphological changes are a stimulus as well as a consequence of the differentiation process. Besides, geometrical, biochemical and mechanical properties of a substrate can modulate cell adhesion and morphology. Therefore, in the current study, nanofibrous substrate properties were used to implement necessary changes in cell morphology which induced osteogenic differentiation without biological supplements. A polycaprolactone-chitosan nanofiber substrate had been fabricated with an average diameter of ∼75 nm and an appropriate ratio of polymers that balances surface biocompatibility as well as mechanical strength. DSC and wide-angle XRD analysis revealed miscibility between polymers; whereas a degradation study confirmed the structural integrity of nanofibers. Nanofibers did not cause any cytotoxicity to MC3T3-E1 cells as confirmed by Live/Dead® staining. Morphological studies by SEM and confocal microscopy showed significant changes in terms of cell shape, area, compactness, aspect ratio and nucleus area in cells grown on nanofibers which indicated the osteogenic differentiation inducing potential of nanofibers. This was further confirmed by enhanced mineral deposition and alkaline phosphatase activity up to three weeks. In summary, polycaprolactone-chitosan nanofibers could induce early osteogenic differentiation in MC3T3-E1 pre-osteoblasts without any biological supplements by modulating cell morphology. Moreover, cell morphological features can be used as a predictive and informative approach at the early stages of differentiation experiments.

A biocompatibility study of new nanofibrous scaffolds for nervous system regeneration.

The development of therapeutic approaches for spinal cord injury (SCI) is still a challenging goal to achieve. The pathophysiological features of chronic SCI are glial scar and cavity formation: an effective therapy will require contribution of different disciplines such as materials science, cell biology, drug delivery and nanotechnology. One of the biggest challenges in SCI regeneration is to create an artificial scaffold that could mimic the extracellular matrix (ECM) and support nervous system regeneration. Electrospun constructs and hydrogels based on self-assembling peptides (SAPs) have been recently preferred. In this work SAPs and polymers were assembled by using a coaxial electrospinning setup. We tested the biocompatibility of two types of coaxially electrospun microchannels: the first one made by a core of poly(ε-caprolactone) and poly(d,l-lactide-co-glycolide) (PCL-PLGA) and a shell of an emulsion of PCL-PLGA and a functionalized self-assembling peptide Ac-FAQ and the second one made by a core of Ac-FAQ and a shell of PCL-PLGA. Moreover, we tested an annealed scaffold by PCL-PLGA microchannel heat-treatment. The properties of coaxial scaffolds were analyzed using scanning electron microscopy (SEM), Fourier transform spectroscopy (FTIR), contact angle measurements and differential scanning calorimetry (DSC). In vitro cytotoxicity was assessed via viability and differentiation assays with neural stem cells (NSCs); whereas in vivo inflammatory response was evaluated following scaffold implantation in rodent spinal cords. Emulsification of the outer shell turned out to be the best choice in terms of cell viability and tissue response: thus suggesting the potential of using functionalized SAPs in coaxial electrospinning for applications in regenerative medicine.