Physiochemical and morphological dependent growth of NIH/3T3 and PC-12 on polyaniline-chloride/chitosan bionanocomposites.

Biomimetic scaffolds inspired by fields and forces of the natural environment of cells is essential in tissue engineering. This study reports on controlled growth of two model cell lines, NIH/3T3 (promiscuous, fibroblast) and PC-12 (electroresponsive, neural progenitor) cells, given electrical and topographical cues that were delivered from a bionanocomposite of polyaniline-chloride and chitosan (PAn-Cl/CHI). The conductivity and morphology of the scaffold were controlled by varying the wt% of PAn-Cl (0-50 wt%) in CHI and processing methods, air-drying (nanofeatured) versus lyophilization (microporous-reticulated), respectively. Bionanocomposites supported the growth of both cell types independent of the availability of receptor-mediated ligands (laminin). NIH/3T3 cells were less elongated on lyophilized (microporous-reticulated) and more conductive (higher wt% PAn-Cl) composites. PC-12 cells had higher viability and less aggregation when grown on conductive substrates. Air-dried bionanocomposites were more supportive of growth but not attachment of PC-12 cells, suggesting that processing of composites could provide an additional level of engineering control to alter the PC-12 cell attachment and growth. In general, PC-12 cells responded more distinctly and dramatically to the substrate properties than NIH/3T3 cells, supporting a clear role for electrical conductivity on neural cell behavior. Nerve growth factor(NGF)-induced differentiation of PC-12 cells resulted in extensive neurite extension in the presence of adsorbed laminin. In a substrate composition-dependent manner, extension and rate of neurite outgrowth were higher when cultured on the conductive substrates. Overall, this study demonstrates the suitability of conductive PAn-Cl/CHI scaffold to host different cell types and support their responses.

The altered expression of perineuronal net elements during neural differentiation.

BACKGROUND: Perineuronal nets (PNNs), which are localized around neurons during development, are specialized forms of neural extracellular matrix with neuroprotective and plasticity-regulating roles. Hyaluronan and proteoglycan link protein 1 (HAPLN1), tenascin-R (TNR) and aggrecan (ACAN) are key elements of PNNs. In diseases characterized by neuritogenesis defects, the expression of these proteins is known to be downregulated, suggesting that PNNs may have a role in neural differentiation. METHODS: In this study, the mRNA and protein levels of HAPLN1, TNR and ACAN were determined and compared at specific time points of neural differentiation. We used PC12 cells as the in vitro model because they reflect this developmental process. RESULTS: On day 7, the HAPLN1 mRNA level showed a 2.9-fold increase compared to the non-differentiated state. However, the cellular HAPLN1 protein level showed a decrease, indicating that the protein may have roles in neural differentiation, and may be secreted during the early period of differentiation. By contrast, TNR mRNA and protein levels remained unchanged, and the amount of cellular ACAN protein showed a 3.7-fold increase at day 7. These results suggest that ACAN may be secreted after day 7, possibly due to its large amount of post-translational modifications. CONCLUSIONS: Our results provide preliminary data on the expression of PNN elements during neural differentiation. Further investigations will be performed on the role of these elements in neurological disease models.