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.
We herein developed an iontophoretic transdermal drug delivery system for the effective delivery of electrically mobile drug nanocarriers (DNs). Our system consists of a portable and disposable reverse electrodialysis (RED) battery that generates electric power for iontophoresis through the ionic exchange. In addition, in order to provide a drug reservoir to the RED-driven iontophoretic system, an electroconductive hydrogel composed of polypyrrole-incorporated poly(vinyl alcohol) (PYP) was used. The PYP hydrogel facilitated electron transfer from the RED battery and accelerated the mobility of electrically mobile DNs released from the PYP hydrogel. In this study, we showed that fluconazoleor rosiglitazone-loaded DNs could be functionalized with charge-inducing agents, and DNs with charge modification resulted in facilitated transdermal transport via repulsive RED-driven iontophoresis. In addition, topical application and RED-driven iontophoresis of rosiglitazone-loaded DNs resulted in an effective antiobese condition displaying decreased bodyweight, reduced glucose level, and increased conversion of white adipose tissues to brown adipose tissues in vivo. Consequently, we highlight that this transdermal drug delivery platform would be extensively utilized for delivering diverse therapeutic agents in a noninvasive way.
Endothelial progenitor cells (EPCs) can induce a pro-angiogenic response during tissue repair. Recently, EPC transplantations have been widely investigated in wound healing applications. To maximize the healing efficacy by EPCs, a unique scaffold design that allows cell retention and function would be desirable for in situ delivery. Herein, we fabricated an alginate/poly-L-ornithine/gelatin (alginate-PLO-gelatin) hydrogel sheet with a groove pattern for use as a cell delivery platform. In addition, we demonstrate the topographical modification of the hydrogel sheet surface with a groove pattern to modulate cell proliferation, alignment, and elongation. We report that the patterned substrate prompted morphological changes of endothelial cells, increased cell−cell interaction, and resulted in the active secretion of growth factors such as PDGF-BB. Additionally, we incorporated magnetic nanoparticles (MNPs) into the patterned hydrogel sheet for the magnetic field-induced transfer of cellseeded hydrogel sheets. As a result, enhanced wound healing was observed via efficient transplantation of the EPCs with an MNP-embedded patterned hydrogel sheet (MPS). Finally, enhanced vascularization and dermal wound repair were observed with EPC seeded MPS.
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