Magnetic microrobots were developed for three-dimensional culture and the precise delivery of stem cells in vitro, ex vivo, and in vivo. Hippocampal neural stem cells attached to the microrobots proliferated and differentiated into astrocytes, oligodendrocytes, and neurons. Moreover, microrobots were used to transport colorectal carcinoma cancer cells to tumor microtissue in a body-on-a-chip, which comprised an in vitro liver-tumor microorgan network. The microrobots were also controlled in a mouse brain slice and rat brain blood vessel. Last, microrobots carrying mesenchymal stem cells derived from human nose were manipulated inside the intraperitoneal cavity of a nude mouse. The results indicate the potential of microrobots for the culture and delivery of stem cells.

BACKGROUND: Cell-based therapies have been studied for articular cartilage regeneration. Articular cartilage defects have little treatments because articular cartilage was limited regenerative capacity. Damaged articular cartilage is difficult to obtain a successful therapeutic effect. In additionally these articular cartilage defects often cause osteoarthritis. Chondrocyte implantation is a widely available therapy used for regeneration of articular cartilage because this tissue has poor repair capacity after injury. Human nasal septum-drived chondrocytes (hNCs) from the septum show greater proliferation ability and chondrogenic capacity than human articular chondrocytes (hACs), even across different donors with different ages. Moreover, the chondrogenic properties of hNCs can be maintained after extensive culture expansion. METHODS: In this study, 2 dimensional (2D) monolayer cultured hNCs (hNCs-2D) and 3 dimensional (3D) spheroids cultured hNCs (hNCs-3D) were examined for chondrogenic capacity in vitro by PCR and immunofluorescence staining for chondrogenic marker, cell survival during cultured and for cartilage regeneration ability in vivo in a rat osteochondral defect model. RESULTS: hNCs-3D showed higher viability and more uniform morphology than 3D spheroids cultured hACs (hACs-3D) in culture. hNCs-3D also showed greater expression levels of the chondrocyte-specific marker Type II collagen (COL2A1) and sex-determining region Y (SRY)-box 9 (SOX9) than hNCs-2D. hNCs-3D also expressed chondrogenic markers in collagen. Specially, in the osteochondral defect model, implantation of hNCs-3D led to greater chondrogenic repair of focal cartilage defects in rats than implantation of hNCs-2D. CONCLUSION: These data suggest that hNCs-3D are valuable therapeutic agents for repair and regeneration of cartilage defects.

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Stem cell transplantation is a promising therapeutic strategy that includes both cell therapy and tissue engineering for the treatment of many regenerative diseases; however, the efficacy and safety of stem cell therapy depend on the cell type used in therapeutic and translational applications. In this study, we validated the hypothesis that human nasal turbinate-derived mesenchymal stem cells (hTMSCs) are a potential therapeutic source of adult stem cells for clinical use in bone tissue engineering using three-dimensional (3D) cell-printing technology. hTMSCs were cultured and evaluated for clinical use according to their cell growth, cell size, and preclinical safety and were then incorporated into a multicompositional 3D bioprinting system and investigated for bone tissue regeneration in vitro and in vivo. Finally, hTMSCs were compared with human bone marrow-derived MSCs (hBMSCs), which are the most common stem cell type used in regenerative medicine. hTMSCs from three different donors showed greater and faster cell growth than hBMSCs from two different donors when cultured. The hTMSCs were smaller in size than the hBMSCs. Furthermore, the hTMSCs did not exhibit safety issues in immunodeficient mice. hTMSCs in 3D-printed constructs (3D-hTMSC) showed much greater viability, growth, and osteogenic differentiation potential in vitro than hBMSCs in 3D-printed constructs (3D-hBMSC). Likewise, 3D-hTMSC showed better cell survival and alkaline phosphatase activity and greater osteogenic protein expression than 3D-hBMSC upon subcutaneous implantation into the dorsal region of nude mice. Notably, in an orthotopic model involving implantation into a tibial defect in rats, implantation of 3D-hTMSC led to greater bone matrix formation and enhanced bone healing to a greater degree than implantation of 3D-hBMSC. The clinically reliable evidence provided by these results is underlined by the potential for rapid tissue regeneration and ambulation in bone fracture patients implanted with 3D-hTMSC.