Electrospun fibers modified with polydopamine for enhancing human mesenchymal stem cell culture.

In this study, we coated electrospun polycaprolactone (PCL) fibers with polydopamine (PDA) to modify their hydrophobicity and fabricated a matrix for culturing mesenchymal stem cells (MSCs). Additionally, we incorporated Arg-Gly-Asp (RGD) peptides into PDA to enhance MSCs culture performance on PCL fibers. PDA and RGD were successfully coated in one step by immersing the electrospun fibers in a coating solution, without requiring an additional surface activation process. The characteristics of functionalized PCL fibers were analyzed by scanning electron microscopy with energy-dispersive x-ray analysis, Fourier transform infrared spectroscopy, water contact angle measurement, and fluorescence measurements using a carboxylic-modified fluorescent microsphere. MSCs cultured on the modified PCL fibers demonstrated enhanced cell adhesion, proliferation, and osteogenic- and chondrogenic differentiation. This study provides insight into potential applications for scaffold fabrication in MSCs-based tissue engineering, wound dressing, implantation, and a deeper understanding of MSCs behaviorin vitro.

Chitosan: a green adhesive for surface functionalization and fabrication of thermoplastic biomedical microdevices.

Chitosan (CS) is a natural polymer that exhibits many biological properties and is used as a biomaterial for antibacterial coatings, tissue engineering, cell research, drug delivery, and negatively charged molecule capture. In our previous study, we used a CS-polydopamine mixture to realize UV-assisted bonding between poly(methyl methacrylate) (PMMA) substrates to fabricate microdevices for self-assembled stem cell spheroid cultures. Herein, we attained reliable adhesive bonding between PMMAs using CS at room temperature assisted by oxygen plasma. The bond strength of adhesion was as high as 2.1 MPa, which could be stable for over two months according to the leak test. The adhesive bonding and surface functionalization of the microchannels were simultaneously completed such that the microdevices could be directly used for mesenchymal stem cell culture for spheroid generation and DNA purification for point-of-care testing (POCT) devices. Surface characterization was performed by contact angle measurements, Fourier-transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. The POCT device allows sequential on-chip DNA purification, amplification, and colorimetric detection of pathogenic bacteria. This method provides a convenient and reliable strategy for the fabrication of PMMA microdevices that can be directly implemented in biological studies and POCT applications without involving prior surface modification steps.

PDMS Micropatterns Coated with PDA and RGD Induce a Regulatory Macrophage-like Phenotype.

Regulatory macrophages (Mreg) are a special cell type that present a potential therapeutic strategy for various inflammatory diseases. In vitro, Mreg generation mainly takes 7-10 days of treatment with chemicals, including cytokines. In the present study, we established a new approach for Mreg generation using a three-dimensional (3D) micropatterned polydimethylsiloxane (PDMS) surface coated with a natural biopolymer adhesive polydopamine (PDA) and the common cell adhesion peptide motif arginylglycylaspartic acid (RGD). The 3D PDMS surfaces were fabricated by photolithography and soft lithography techniques and were subsequently coated with an RGD+PDA mixture to form a surface that facilitates cell adhesion. Human monocytes (THP-1 cells) were cultured on different types of 2D or 3D micropatterns for four days, and the cell morphology, elongation, and Mreg marker expression were assessed using microscopic and flow cytometric analyses. The cells grown on the PDA+RGD-coated 3D micropatterns (20-µm width/20-µm space) exhibited the most elongated morphology and strongest expression levels of Mreg markers, such as CD163, CD206, CD209, CD274, MER-TK, TREM2, and DHRS9. The present study demonstrated that PDA+RGD-coated 3D PDMS micropatterns successfully induced Mreg-like cells from THP-1 cells within four days without the use of cytokines, suggesting a time- and cost-effective method to generate Mreg-like cells in vitro.

Fabrication of a Cell-Friendly Poly(dimethylsiloxane) Culture Surface via Polydopamine Coating.

In this study, we fabricated a poly(dimethylsiloxane) (PDMS) surface coated with polydopamine (PDA) to enhance cell adhesion. PDA is well known for improving surface adhesion on various surfaces due to the abundant reactions enabled by the phenyl, amine, and catechol groups contained within it. To confirm the successful surface coating with PDA, the water contact angle and X-ray photoelectron spectroscopy were analyzed. Human umbilical vein endothelial cells (HUVECs) and human-bone-marrow-derived mesenchymal stem cells (MSCs) were cultured on the PDA-coated PDMS surface to evaluate potential improvements in cell adhesion and proliferation. HUVECs were also cultured inside a cylindrical PDMS microchannel, which was constructed to mimic a human blood vessel, and their growth and performance were compared to those of cells grown inside a rectangular microchannel. This study provides a helpful perspective for building a platform that mimics in vivo environments in a more realistic manner.