Biomimetic Composite Chitosan-Clay Films to Direct Human Mesenchymal Stem Cell and Osteoblast Spread Area and Morphology

Advances in engineering complex tissues that can mimic native tissue functions hold enormous promise in biomedicine. Treatment of bone disorders and injuries often requires bone-tissue engineering at the chondral interface. In this study, our research group is exploring the use of chitosan, a hydrophilic glucosamine polymer which can minimize cell adhesion, and Laponite„¢, a clay which has been shown to improve homogeneity across a film surface, to construct nanocomposites as interfacial films to improve osteointegration on titanium alloy substrates. Human mesenchymal stem cells (hMSCs) were seeded atop our samples to assess cell-material interactions. Fluorescence microscopy was used to visualize actin and cell nuclei. Film morphologies were assessed via atomic force microscopy (AFM). Cell area and circularity were determined using automated functions in CellProfiler„¢. Investigations of film surface morphology with AFM have demonstrated homogeneous film formation. Significant size and shape differences were observed between hMSCs seeded atop Cs, Cs-Lap, and Lap surfaces without a corresponding difference in number of cells. Most notably, hMSCs atop chitosan-containing films adopt budding morphologies that depart from the typical elongated morphology observed on rigid 2D substrates. The respective contributions of chitosan and LaponiteTM to film and cell behavior is a focus of ongoing work and may enable tunability of advanced cell functions toward bone regenerative applications.