For muscle regeneration, a uniaxially arranged micropattern is important to mimic the structure of the natural extracellular matrix. Recently, cell electrospinning (CE) has been tested to fabricate ...cell‐laden fibrous structures by embedding cells directly into micro/nanofibers. Although homogenous cell distribution and a reasonable cell viability of the cell‐laden fibrous structure fabricated using the CE process are achieved, unique topographical cues formed by an aligned fibrous structure have not been applied. In this study, a CE process to achieve not only homogeneous cell distribution with a high cell viability, but also highly aligned cells, which are guided by aligned alginate fibers is employed. To attain the aligned cell‐laden fibrous structure, various processing conditions are examined. The selected condition is applied using C2C12 myoblast cells to ensure the biocompatibility and guidance of cell elongation and alignment. As a control, a cell‐printed scaffold using a 3D bioprinter is used to compare the efficiency of cell alignment and differentiation of myoblasts. Highly arranged, multinucleated cell morphology is confirmed in the CE scaffold, which successively facilitates myogenic differentiation. It is believed that this study will be a new platform for obtaining cell alignment and will significantly benefit the efforts on muscle regeneration.
Cell electrospinning (CE) is an innovative tool that directly embeds cells into micro/nanofibers. Herein, CE is investigated to achieve not only homogeneous myoblast distribution with a high cell viability, but also highly aligned cells guided by the aligned fibers for muscle regeneration. Using a CE scaffold, highly arranged, multinucleated myoblast morphology is confirmed, which successively facilitates myogenic differentiation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Electrospinning has gained great interest in the field of regenerative medicine, due to its fabrication of a native extracellular matrix-mimicking environment. The micro/nanofibers generated through ...this process provide cell-friendly surroundings which promote cellular activities. Despite these benefits of electrospinning, a process was introduced to overcome the limitations of electrospinning. Cell-electrospinning is based on the basic process of electrospinning for producing viable cells encapsulated in the micro/nanofibers. In this review, the process of cell-electrospinning and the materials used in this process will be discussed. This review will also discuss the applications of cell-electrospun structures in tissue engineering. Finally, the advantages, limitations, and future perspectives will be discussed.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The development of the three‐dimensional (3D) printer has resulted in significant advances in a number of fields, including rapid prototyping and biomedical devices. For 3D structures, the inclusion ...of dynamic responses to stimuli is added to develop the concept of four‐dimensional (4D) printing. Typically, 4D printing is useful for biofabrication by reproducing a stimulus‐responsive dynamic environment corresponding to physiological activities. Such a dynamic environment can be precisely designed with an understanding of shape‐morphing effects (SMEs), which enables mimicking the functionality or intricate geometry of tissues. Here, 4D bioprinting is investigated for clinical use, for example, in drug delivery systems, tissue engineering, and surgery in vivo. This review presents the concept of 4D bioprinting and smart materials defined by SMEs and stimulus‐responsive mechanisms. Then, biomedical smart materials and applications are discussed along with future perspectives.
Four‐dimensional printing has been developed from a three‐dimensional structure with the addition of fourth‐dimension, time. In terms of biofabrication, this technology aims to create a stimulus‐responsive dynamic environment for reproducing physiological activities. The dynamic environment can be precisely designed with an understanding of shape‐morphing effect providing possibilities in various biomedical applications like drug delivery system and tissue engineering.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Cell-printing is an emerging technique that enables to build a customized structure using biomaterials and living cells for various biomedical applications. In many biomaterials, alginate has been ...widely used for rapid gelation, low cost, and relatively high processability. However, biocompatibilities enhancing cell adhesion and proliferation were limited, so that, to overcome this problem, an outstanding alternative, collagen, has been extensively investigated. Many factors remain to be proven for cell-printing applications, such as printability, physical sustainability after printing, and applicability of in vitro cell culture. This study proposes a cell-laden collagen scaffold fabricated via cell-printing and tannic acid (TA) crosslinking process. The effects of the crosslinking agent (0–3wt% TA) in the cell-laden collagen scaffolds on physical properties and cellular activities using preosteoblasts (MC3T3-E1) were presented. Compared to the cell-laden collagen scaffold without TA crosslinking, the scaffold with TA crosslinking was significantly enhanced in mechanical properties, while reasonable cellular activities were observed. Concisely, this study introduces the possibility of a cell-printing process using collagen and TA crosslinking and in vitro cell culture for tissue regeneration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In tissue engineering, biomimetic scaffolds are developed to provide cells with a microenvironment that promotes cellular activities. In this study, we present a three-dimensional (3D) fibrous bundle ...structure fabricated using an electrohydrodynamic process and a cell printing process using myoblast-laden collagen bioink. An anisotropic topographical cue in a 3D structure is an important factor for muscle tissue regeneration, and therefore, the fibrous bundle structure was uniaxially stretched using optimized conditions for fiber alignment. In addition, for stable cell attachment to facilitate the effect of topological cues, the myoblasts were efficiently released from the collagen bioink. We observed that the 3D fibrous bundle structure was an effective in vitro platform that induced cell proliferation and the formation of myotubes. The synergistic combination of the aligned topological cues and high biocompatibility of collagen enhanced the formation of myotubes, which was represented by the relative expression of myogenic genes (Myf5, Myh2, MyoD, and Myogenin). Therefore, we could confirm the feasibility of the 3D fibrous bundle structure for the regeneration of skeletal muscle tissues.
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IJS, KILJ, NUK, PNG, UL, UM
Craniomaxillofacial (CMF) reconstruction is a challenging clinical dilemma. It often necessitates skin replacement in the form of autologous graft or flap surgery, which differ from one another based ...on hypodermal/dermal content. Unfortunately, both approaches are plagued by scarring, poor cosmesis, inadequate restoration of native anatomy and hair, alopecia, donor site morbidity, and potential for failure. Therefore, new reconstructive approaches are warranted, and tissue engineered skin represents an exciting alternative. In this study, we demonstrated the reconstruction of CMF full-thickness skin defects using intraoperative bioprinting (IOB), which enabled the repair of defects via direct bioprinting of multiple layers of skin on immunodeficient rats in a surgical setting. Using a newly formulated patient-sourced allogenic bioink consisting of both human adipose-derived extracellular matrix (adECM) and stem cells (ADSCs), skin loss was reconstructed by precise deposition of the hypodermal and dermal components under three different sets of animal studies. adECM, even at a very low concentration such as 2 % or less, has shown to be bioprintable via droplet-based bioprinting and exhibited de novo adipogenic capabilities both in vitro and in vivo. Our findings demonstrate that the combinatorial delivery of adECM and ADSCs facilitated the reconstruction of three full-thickness skin defects, accomplishing near-complete wound closure within two weeks. More importantly, both hypodermal adipogenesis and downgrowth of hair follicle-like structures were achieved in this two-week time frame. Our approach illustrates the translational potential of using human-derived materials and IOB technologies for full-thickness skin loss.
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•Craniomaxillofacial reconstruction is a challenging clinical dilemma•Skin was built by precise deposition of hypodermal and dermal components•AdECM was bioprintable and exhibited de novo adipogenic capabilities•Combinatorial delivery of adECM and ADSCs facilitated the reconstruction of skin•Adipogenesis and downgrowth of hair follicle-like structures were achieved
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The esophagus exhibits peristalsis via contraction of circularly and longitudinally aligned smooth muscles, and esophageal replacement is required if there is a critical-sized wound. In this study, ...we proposed to reconstruct esophageal tissues using cell electrospinning (CE), an advanced technique for encapsulating living cells into fibers that allows control of the direction of fiber deposition. After treatment with transforming growth factor-β, mesenchymal stem cell-derived smooth muscle cells (SMCs) were utilized for cell electrospinning or three-dimensional bioprinting to compare the effects of aligned micropatterns on cell morphology. CE resulted in SMCs with uniaxially arranged and elongated cell morphology with upregulated expression levels of SMC-specific markers, including connexin 43, smooth muscle protein 22 alpha (SM22α), desmin, and smoothelin. When SMC-laden nanofibrous patches were transplanted into a rat esophageal defect model, the SMC patch promoted regeneration of esophageal wounds with an increased number of newly formed blood vessels and enhanced the SMC-specific markers of SM22α and vimentin. Taken together, CE with its advantages, such as guidance of highly elongated, aligned cell morphology and accelerated SMC differentiation, can be an efficient strategy to reconstruct smooth muscle tissues and treat esophageal perforation.
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•Cell electrospinning induces anisotropic alignment of smooth muscle cells.•Alignment stimulates phenotypic maturation of smooth muscle cells.•Transplantation of the smooth muscle patch stimulates repair of esophageal wounds.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Uniaxially aligned micro/nanoscale topological patterns for mimicking the native skeletal muscle structure.•Alginate nanofibers inducing highly arranged cell morphology in uniaxial ...direction.•PCL microstructure enhancing mechanical strength and myotube formation.•Hierarchical structure synergistically facilitating cell alignment and fusion.
For regenerating skeletal muscle tissue, cell alignment and myotube formation in a scaffold are required. To achieve this goal, various studies have focused on controlling the myoblast orientation by manipulating the topographical structures of scaffolds. In the present study, a combined process involving electrospinning and three-dimensional (3D) printing was used to obtain a hierarchical structure consisting of microscale and nanoscale topographical structures by using alginate nanofibers and a polycaprolactone (PCL)-fibrillated micro-strut. In the structure, a micropatterned PCL strut, which was obtained using 3D printing and a leaching process supplemented with a sacrificial material, was employed for not only enhancing the mechanical stability, but also inducing myotube formation, while highly aligned alginate nanofibers fabricated using a modified electrospinning process facilitated myoblast attachment and alignment. The cell orientation and myotube formation of C2C12 cells cultured in the 3D hierarchical structure were significantly better than those of two controls (alginate-coated PCL strut and alginate nanofiber-deposited PCL strut, not fibrillated). These results confirm that the hierarchical scaffold has immense potential as a biomaterial for muscle-tissue regeneration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, a fully aligned microfibrous structure fabricated using fibrin-assisted alginate bioink and electrohydrodynamic direct-printing was proposed for skeletal muscle tissue engineering. To ...safely construct the aligned alginate/fibrin microfibrous structure laden with myoblasts or endothelial cells, various printing conditions, such as an applied electric field, distance between the nozzle and target, and nozzle moving speed, were selected appropriately. Furthermore, to accelerate the formation of myotubes more efficiently, the alginate/fibrin bioink with vascular endothelial cells was co-printed into a spatially patterned structure within a myoblast-laden structure. The myoblast-laden structure co-cultured with endothelial cells presented fully aligned myotube formation and significantly greater myogenic differentiation compared to the myoblast-laden structure without the endothelial cells owing to the more abundant secretion of angiogenic cytokines. Also, when adipose stem cell- and endothelial cell-laden fibrous structure was implanted in a mouse volumetric muscle loss model, accelerated volumetric muscle repair was observed compared to the defect model. Based on the results, this study demonstrates an alginate-based bioink and new bio-fabricating method to obtain microfibrous cell-laden alginate/fibrin structures with mechanically stable and topographical cues. The proposed method can provide a myoblast/endothelial cell-laden fibrous alginate structure to efficiently induce engineering of skeletal muscle tissue, which could be used in muscle-on-a-chip or recovering structures of volumetric muscle defects.
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•Alginate-bioink supplemented with fibrinogen was prepared.•Electric-field-assisted printing was used to fabricate a cell-laden microfibrous structure.•C2C12-endothelial cells-laden structure showed outstanding cell growth and myogenic differentiation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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