Enhanced Osteogenic Commitment of Human Mesenchymal Stem Cells on Polyethylene Glycol-Based Cryogel with Graphene Oxide Substrate

Graphene oxide (GO) is considered a comparatively recent biomaterial with enormous potential because of its nontoxicity, high dispersity, and enhanced interaction with biomolecules. These characteristics of GO can promote the interactions between the substrates and cell surfaces. In this study, we incorporated GO in a cryogel-based scaffold system to observe their influence on the osteogenic responses of human tonsil-derived mesenchymal stem cells (hTMSCs). Compared to polyethylene glycol (PEG)-based cryogel scaffold, GO-embedded PEG-based (PEGDA-GO) cryogels not only showed improved cell attachment and focal adhesion kinase (FAK) signaling activation but also enhanced cell viability. Taken together, we demonstrated that PEGDA-GO cryogels can stimulate osteogenic differentiation under an osteoinductive condition and enhance osteogenic phenotypes compared to the control group. In summary, we demonstrate that GO embedded in cryogels system is an effective biofunctionalizing scaffold to control osteogenic commitment of stem cells

General and Facile Coating of Single Cells via Mild Reduction

Cell surface modification has been extensively studied to enhance the efficacy of cell therapy. Still, general accessibility and versatility are remaining challenges to meet the increasing demand for cell-based therapy. Herein, we present a facile and universal cell surface modification method that involves mild reduction of disulfide bonds in cell membrane protein to thiol groups. The reduced cells are successfully coated with biomolecules, polymers, and nanoparticles for an assortment of applications, including rapid cell assembly, in vivo cell monitoring, and localized cell-based drug delivery. No adverse effect on cellular morphology, viability, proliferation, and metabolism is observed. Furthermore, simultaneous coating with polyethylene glycol and dexamethasone-loaded nanoparticles facilitates enhanced cellular activities in mice, overcoming immune rejection

Chondroitin Sulfate-Based Biomineralizing Surface Hydrogels for Bone Tissue Engineering

Chondroitin sulfate (CS) is the major component of glycosaminoglycan in connective tissue. In this study, we fabricated methacrylated PEGDA/CS-based hydrogels with varying CS concentration (0, 1, 5, and 10%) and investigated them as biomineralizing three-dimensional scaffolds for charged ion binding and depositions. Due to its negative charge from the sulfate group, CS exhibited an osteogenically favorable microenvironment by binding charged ions such as calcium and phosphate. Particularly, ion binding and distribution within negatively charged hydrogel was dependent on CS concentration. Furthermore, CS dependent biomineralizing microenvironment induced osteogenic differentiation of human tonsil-derived mesenchymal stem cells in vitro. Finally, when we transplanted PEGDA/CS-based hydrogel into a critical sized cranial defect model for 8 weeks, 10% CS hydrogel induced effective bone formation with highest bone mineral density. This PEGDA/CS-based biomineralizing hydrogel platform can be utilized for in situ bone formation in addition to being an investigational tool for in vivo bone mineralization and resorption mechanisms