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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.

Magnetic nanoparticles have been subjected to extensive studies in the past few decades owing to their promising potentials in biomedical applications. The versatile intrinsic properties of magnetic nanoparticles enable their use in many biomedical applications. Recently, magnetic nanoparticles were utilized to control the cell's function. In addition, intracellular delivery of magnetic nanoparticles allowed cell's positioning by appropriate use of magnetic field and created cellular cluster. Furthermore, magnetic nanoparticles have been utilized to assemble more complex tissue structures than those that are achieved by conventional scaffold-based tissue engineering strategies. This review addresses recent work in the use magnetic nanoparticle for controlled tissue assembly and complex tissue formation.

Recent developments in stem cell technologies have demonstrated human mesenchymal stem cells (hMSCs) as a possible cell source for cell-based therapies and regenerative medicine applications. Self-renewal and differentiation abilities of hMSCs have enabled hMSCs to be applied in regeneration of musculoskeletal tissue. hMSCs are able to myogenically differentiate via various approaches; however, the most efficient method has not been developed. Here, we describe the efficient commitment of hMSCs to the myogenic lineage on biomimetic substrates replicating myoblast topography. We have created a tissue culture platform that replicates the micro-and nanoscale topography of fully differentiated skeletal myoblasts. Using UV-assisted capillary force lithography, an optically transparent cellular model of fully differentiated myoblasts was developed using a UV curable poly(urethane acrylate) resin, which was fabricated and employed as a cell-culture substrate for the myogenic pattern of hMSCs. When hMSCs were cultured and differentiated on these biomimetic patterns, cells followed the underlying myoblast pattern and more efficiently committed to myogenic fate. These results demonstrate that myogenic potentials of hMSCs are highly depended on the micro- and nanoscale topographical cues. Furthermore, the described tissue culture platform can be used in larger culture settings with consistent results and easily applied to other lineage of hMSCs.

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