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Recent advances in inorganic nanomaterial-based theranostics enabled imaging-guided molecular targeting and drug delivery, and various combinations of theranostic systems. The term “theranostics” is defined as diagnosis processed with therapy simultaneously with a specific connection between therapy and diagnosis. The inorganic nanomaterials, representatively carbon, metal, ceramic, and semiconductor-based nanomaterials, exhibit their unique characteristics to be used in theranostic applications. However, the unveiled human biosafety of nanomaterials for clinical use has become a major concern. Therefore, in this review, we compiled recent research on in vitro and in vivo biosafety of inorganic nanomaterials in various theranostic applications, along with a discussion of how the particle formulation, size, surface functionalization, test species, and test condition affect biocompatibility. Furthermore, the progress and challenges of the development of biocompatible inorganic nanomaterials for theranostic applications were discussed. In conclusion, with appropriate precautions on the biosafe condition to be administered, inorganic nanomaterials can be proposed to have excellent potential in the future theranostic application.

Human spinal-cord-like tissues induced from human pluripotent stem cells are typically insufficiently mature and do not mimic the morphological features of neurulation. Here, we report a three-dimensional culture system and protocol for the production of human spinal-cord-like organoids (hSCOs) recapitulating the neurulation-like tube-forming morphogenesis of the early spinal cord. The hSCOs exhibited neurulation-like tube-forming morphogenesis, cellular differentiation into the major types of spinal-cord neurons as well as glial cells, and mature synaptic functional activities, among other features of the development of the spinal cord. We used the hSCOs to screen for antiepileptic drugs that can cause neural-tube defects. hSCOs may also facilitate the study of the development of the human spinal cord and the modelling of diseases associated with neural-tube defects.

Background Regeneration of defective neurons in central nervous system is a highlighted issue for neurodegenerative disease treatment. Various tissue engineering approaches have focused on neuritogenesis to achieve the regeneration of damaged neuronal cells because damaged neurons often fail to achieve spontaneous restoration of neonatal neurites. Meanwhile, owing to the demand for a better diagnosis, studies of super-resolution imaging techniques in fluorescence microscopy have triggered the technological development to surpass the classical resolution dictated by the optical diffraction limit for precise observations of neuronal behaviors. Herein, the multifunctional nanodiamonds (NDs) as neuritogenesis promoters and super-resolution imaging probes were studied. Methods To investigate the neuritogenesis-inducing capability of NDs, ND-containing growing medium and differentiation medium were added to the HT-22 hippocampal neuronal cells and incubated for 10 d. In vitro and ex vivo images were visualized through custom-built two-photon microscopy using NDs as imaging probes and the direct stochastic optical reconstruction microscopy (dSTORM) process was performed for the super-resolution reconstruction owing to the photoblinking properties of NDs. Moreover, ex vivo imaging of the mouse brain was performed 24 h after the intravenous injection of NDs. Results NDs were endocytosed by the cells and promoted spontaneous neuritogenesis without any differentiation factors, where NDs exhibited no significant toxicity with their outstanding biocompatibility. The images of ND-endocytosed cells were reconstructed into super-resolution images through dSTORM, thereby addressing the problem of image distortion due to nano-sized particles, including size expansion and the challenge in distinguishing the nearby located particles. Furthermore, the ex vivo images of NDs in mouse brain confirmed that NDs could penetrate the blood–brain barrier (BBB) and retain their photoblinking property for dSTORM application. Conclusions It was demonstrated that the NDs are capable of dSTORM super-resolution imaging, neuritogenic facilitation, and BBB penetration, suggesting their remarkable potential in biological applications. Graphical Abstract

Ectopic expression of Oct4, Sox2, Klf4 and c-Myc can reprogram somatic cells into induced pluripotent stem cells (iPSCs). Attempts to identify genes or chemicals that can functionally replace each of these four reprogramming factors have revealed that exogenous Oct4 is not necessary for reprogramming under certain conditions or in the presence of alternative factors that can regulate endogenous Oct4 expression. For example, polycistronic expression of Sox2, Klf4 and c-Myc can elicit reprogramming by activating endogenous Oct4 expression indirectly. Experiments in which the reprogramming competence of all other Oct family members tested and also in different species have led to the decisive conclusion that Oct proteins display different reprogramming competences and species-dependent reprogramming activity despite their profound sequence conservation. We discuss the roles of the structural components of Oct proteins in reprogramming and how donor cell epigenomes endow Oct proteins with different reprogramming competences., Stem cells: Mechanisms for reprogramming cells Cells can be reprogrammed into induced pluripotent stem cells (iPSCs), embryonic-like stem cells that can turn into any cell type and have extensive potential medical uses, without adding the transcription factor OCT4. Although other nearly identical OCT family members had been tried, only OCT4 could induce reprogramming and was previously thought to be indispensable. However, it now appears that the reprogramming can be induced by multiple pathways, as detailed in a review by Hans Schöler, Max Planck Institute for Biomolecular Medicine, Münster, and Johnny Kim, Max Planck Institute for Heart and Lung Research, Bad Nauheim, in Germany. They report that any factors that trigger cells to activate endogeous OCT4 can produce iPSCs without exogeously admistration of OCT4. The mechanisms for producing iPSCs can differ between species. These results illuminate the complex mechanisms of reprogramming.

Bone is a complex structure with unique cellular and molecular process in its formation. Bone tissue regeneration is a well-organized and routine process at the cellular and molecular level in humans through the activation of biochemical pathways and protein expression. Though many forms of biomaterials have been applied for bone tissue regeneration, electrospun nanofibrous scaffolds have attracted more attention among researchers with their physicochemical properties such as tensile strength, porosity, and biocompatibility. When drugs, antibiotics, or functional nanoparticles are taken as additives to the nanofiber, its efficacy towards the application gets increased. Polyphenol is a versatile green/phytochemical small molecule playing a vital role in several biomedical applications, including bone tissue regeneration. When polyphenols are incorporated as additives to the nanofibrous scaffold, their combined properties enhance cell attachment, proliferation, and differentiation in bone tissue defect. The present review describes bone biology encompassing the composition and function of bone tissue cells and exemplifies the series of biological processes associated with bone tissue regeneration. We have highlighted the molecular mechanism of bioactive polyphenols involved in bone tissue regeneration and specified the advantage of electrospun nanofiber as a wound healing scaffold. As the polyphenols contribute to wound healing with their antioxidant and antimicrobial properties, we have compiled a list of polyphenols studied, thus far, for bone tissue regeneration along with their in vitro and in vivo experimental biological results and salient observations. Finally, we have elaborated on the importance of polyphenol-loaded electrospun nanofiber in bone tissue regeneration and discussed the possible challenges and future directions in this field.

Background Two-dimensional black phosphorus nanosheets (BPNSs) have recently emerged as a successive novel nanomaterial owing to their uniqueness in optical and electrical properties. Although BPNSs have found a wide range of biomedical applications, their biosafety is still a major concern to be addressed. Methods In this study, we have prepared layered BPNSs using liquid exfoliation procedure, and evaluated their physicochemical properties using Fourier Transform-infrared (FTIR) spectroscopy, Raman spectroscopy, atomic force microscopy, and Zetasizer analyses. We have investigated potential cytotoxicity of BPNSs against three different types of fibroblast cells, i.e. mouse embryonic fibroblast (NIH3T3), primary cultured normal human dermal fibroblast (nHDF), and fibrosarcoma (HT1080). Cell counting kit-8 (CCK-8) assay was carried out to assess cellular metabolic activity in cells whereas lactate dehydrogenase (LDH) activity assay was helpful to study plasma membrane integrity. Results Our salient research findings showed that BPNSs were polydispersed in solution due to aggregation. Toxic response of BPNSs against fibroblast cells was in the order, HT1080>nHDF>NIH3T3. The nanosheets reduced the number of cancerous cells with significant difference to normal cells. Conclusions We suggest that BPNSs can be considered for cancer treatment as they destroy cancerous cells effectively. However, a comprehensive study is required to elucidate other biological effects of BPNSs.

The purpose of this study was to describe a novel bone lengthening plate (BLP) and to evaluate the biomechanical performance of the plate before clinical use. A finite element model was obtained from values of the compression test. It was used to evaluate the performance of the BLP, such as biomechanical stability and structural stiffness, according to materials of the shaft and column used for lengthening (type I: all Titanium-alloys, type II and III: Titanium-alloys and Cobalt-Chrome-alloys, type IV: all Cobalt-Chrome-alloys). Furthermore, Peak von Mises Stress, risk of screw breakage, and micro-motion between the bone and screw were evaluated. Structural stiffness and strain of the finite element model of the femur were similar to cadaveric femurs. Structural stiffness increased from type I (Titanium alloys) to type IV (Cobalt-Chrome-alloys) by at least 128%. First locking screw, which was inserted at the osteotomy site of the proximal femur (proximal to distal direction), showed the highest risk of breakage (75%). This study investigated biomechanical stability of the novel BLP in relation to properties of the supporting structures. It was most biomechanically stable when the column and lengthening shaft were composed of Cobalt-Chrome-alloys (type IV).

Aquaporin-3 (AQP3) is an integral membrane protein that facilitates the transport of water and glycerol across cell membranes. However, the precise localization and function of AQP3 in skeletal muscles is currently unknown. In this study, we investigated the capacity of AQP3 knockout mice to perform a single bout of exhausting exercise and analyzed the parameters related to skeletal muscle energy metabolism during exhausting exercise. Mice were exposed to a single bout of treadmill running at a speed of 12 m/min with 10° inclination until exhaustion, and sacrificed immediately, 24 h and 48 h after exercise. Both immunohistochemistry and double immunofluorescence staining revealed that AQP3 is expressed at the cell surface with no evidence of colocalization with either AQP1 or AQP4 in hamstring skeletal muscles. When exposed to a single bout of exhaustive exercise, AQP3 knockout mice fatigued more easily with the average time to exhaustion shorter than the wild-type mice. After exhausting exercise, plasma glucose, muscle glycogen, muscle triglyceride, and muscle free fatty acid levels decreased compared with the values before exercise in both AQP3 knockout and wild-type mice. However, muscle glycerol concentration after exercise decreased in the wild-type mice, but rather increased in AQP3 knockout mice. These findings suggest that decreased glycerol efflux from the skeletal muscles in AQP3 knockout mice may result in low exercise capacity, presumably due to the limitations in the constant energy supply through hepatic gluconeogenesis from glycerol during the prolonged endurance exercise.

Neural tissue regeneration is a significant challenge, because severe nerve injury is quite difficult to regenerate spontaneously. Although, many studies have been devoted to promote nerve regeneration, there are still many technical challenges to achieve satisfactory results. In this study, we designed biomimetic matrices composed of aligned laminin core-polydioxanone/collagen shell (Lam-PDO/Col) fibers, which can provide both topographical and biochemical cues for promoting neuritogenesis. The aligned Lam-PDO/Col core-shell fiber matrices were fabricated by magnetic field-assisted electrospinning with the coaxial system, and their potential as biofunctional scaffolds for promoting neuritogenesis was explored. It was demonstrated that the aligned Lam-PDO/Col core-shell fibers were successfully fabricated, and the laminin in the core of fibers was steadily and continuously released from fibers. In addition, the cellular behaviors of hippocampal neuronal cells on the matrices were significantly enhanced. Moreover, the aligned Lam-PDO/Col fiber matrices effectively improved and guided neurite outgrowth as well as the neurogenic differentiation by providing both topographical and biochemical cues through aligned fiber structure and sustained release of laminin. Collectively, it is suggested that the aligned Lam-PDO/Col core-shell fiber matrices are one of the most promising approaches for promoting neuritogenesis and neural tissue regeneration.

For the treatment of periodontitis, local delivery of antibiotics and their sustained release are preferable to enhance microbial susceptibility and to reduce possible side effects occurrence in systemic drug delivery. To address these issues, antibiotic loaded polymeric matrices implantable into periodontal pocket have been commercially used in dentistry and oral medicine. Recently, keratin has been drawing attention as a natural polymer for its ability to mediate cell behavior with minor or no immunogenicity enabling further process towards autologous implantation. In this study, human hair keratin was extracted with a cocktail of reducing agents, and antibiotic eluting keratin-based biofilms were fabricated. Physicochemical analysis and release test showed proper physical stability and sustained release of the loaded antibiotics. In addition, the released antibiotic suppressed the growth of various types of oral bacteria including porphyromonas gingivalis. Cellular interaction studies showed that human oral epithelial cell, human gingival fibroblast and periodontal ligament cells proliferated and guided well on biofilms. This study propose that antibiotic eluting keratin-based biofilms are provisional device for the treatment of chronic periodontitis offering advantages such as local controlled drug delivery and biocompatibility, and human hair keratin is able to be a good biomaterial for the potent applications to tissue engineering and regenerative medicine. Open image in new window

Over the past few decades, naturally derived biomaterials have been extensively used in tissue engineering and regenerative medicine owing to their biological function, structural support, excellent biocompatibility, and favorable biodegradability characteristics. Traditionally, keratin has been extracted from wool, feathers, horns, and other animal sources for industrial use, and it has also been used as a biomaterial to develop scaffolds, hydrogels, and other forms for biomedical applications. Recently, keratin extracted from human hair has emerged as a fascinating biomaterial, which as a human-derived protein, exhibits excellent biocompatibility, no immune reaction upon transplantation, good cellular interaction activity, and biodegradability. Recent development of well-defined and proficient processes for human hair keratin extraction has led to the fabrication of various types of keratin-based biomaterials, which have been employed in successful approaches for tissue regeneration. The use of human hair keratin-based biomaterials for translational biomedical applications requires better understanding of the molecular properties and biological function of keratin. This review provides a critical summary of molecular characteristics, cellular interactions, various extraction strategies, and recent advances in biomedical applications of human hair keratin that could be used to improve tissue regeneration for regenerative medicine.

Terminally differentiated cells can be directly converted into different types of somatic cells by using defined factors, thus circumventing the pluripotent state. However, low reprogramming efficiency, along with the absence of proliferation of some somatic cell types, makes it difficult to generate large numbers of cells with this method. Here we describe a protocol to directly convert mouse fibroblasts into self-renewing induced neural stem cells (iNSCs) that can be expanded in vitro, thereby overcoming the limitations associated with low reprogramming efficiency. The four transcription factors required for direct conversion into iNSCs (Sox2, Klf4, Myc (also known as c-Myc) and Pou3f4 (also known as Brn4)) do not generate a pluripotent cell state, and thus the risk for tumor formation after transplantation is reduced. By following the current protocol, iNSCs are observed 4-5 weeks after transduction. Two additional months are required to establish clonal iNSC cell lines that exhibit retroviral transgene silencing and that differentiate into neurons, astrocytes and oligodendrocytes.

Recently, many cervical total disc replacement (TDR) devices have been introduced in a variety of designs in an attempt to recreate motion behavior of the normal cervical spine thereby to limit the progression of adjacent degeneration. The purposes of this study were to evaluate and compare the range of motion (ROM) and location of instant center of rotation (COR), and load sharing characteristics of two major products with different design concepts in cervical TAR-Prodisc-C® and Prestige-LP®. A 3-D finite element (FE) model of intact cervical spine (C3-6) was made from CT scans of a normal person and validated. Based on this model, postoperative FE models simulating TDR implantation at the C4-5 disc space were made for Prodisc-C® (Synthes Spine, Paoli, PA) and Prestige-LP® (Medtronic Sofamor Danek, Memphis, TN), respectively. These two TDR devices feature different design concepts that affect kinematics: Rotations and some translations were allowed at the articulating surface of Prestige LP® as the ‘concave down’ articulating surface is less constrained whereas only rotations were allowed with Prodisc-C® that features ball & socket articulating surface in ‘concave up’ orientation. Hybrid protocol (intact: 1Nm) with a compressive follower load of 73.6N were applied at the superior endplate of the C3 vertebral body. The inferior endplate of C6 vertebral body was constrained in all directions. At the index level, Prestige-LP® showed 15% less motion than Prodisc-C® in extension and about the same in flexion. Differences in ROM were negligible at the adjacent level. Here, the COR of Prestige-LP® was located more postero-inferiorly than that of Prodisc-C® by about 1-mm during extension at the index level. Facet load was less with Prestige-LP® by about 10% at the index level but 14% more at the adjacent level. The results of this study indicated that the biomechanical behavior of the postoperative cervical spine can be indeed influenced by the design features such as concavity orientation and extent of constraint of the articulating surfaces. Particularly, ROM and COR location as well as the facet loads at the index level and adjacent levels were more sensitive during extension. It would be interesting to note that resulting differences in facet load at the index and adjacent levels between the two designs will manifest to different clinical results in terms of postoperative facet degeneration.

For distraction osteogenesis, external fixators such as mono or circular type were used popularly. However, there are many reported complications such as infection of pin site, vascular and neurological injury and the discomfort during walking. The purpose of this study is to introduce a novel internal distractible plate system (IDPS) and to validate of the finite element model of the femur and IDPS before clinical application and finite element analysis with multiple biomechanical factors. After validating the finite element model of femur and femur with IDPS using the structural stiffness and strain of cadaveric femur during compression test, biomechanical stability of a novel IDPS was analyzed. Reconstructed finite element models showed similar result comparing with the values of cadaveric test in vitro. Through validation procedures using the finite element model of the intact femur and the 30mmdistracted femur with the IDPS, the material properties and the coefficient of friction of the finite element models for finite element analysis can be understood as reliable. Also, clinical stability of a novel IDPS was confirmed.

Somatic cells can be reprogrammed into induced pluripotent stem (iPS) cells by the transcription factors Oct4, Sox2, and Klf4 in combination with c-Myc. Recently, Sox2 plus Oct4 was shown to reprogram fibroblasts and Oct4 alone was able to reprogram mouse and human neural stem cells (NSCs) into iPS cells. Here, we report that Bmi1 leads to the transdifferentiation of mouse fibroblasts into NSC-like cells, and, in combination with Oct4, can replace Sox2, Klf4 and c-Myc during the reprogramming of fibroblasts into iPS cells. Furthermore, activation of sonic hedgehog signaling (by Shh, purmorphamine, or oxysterol) compensates for the effects of Bmi1, and, in combination with Oct4, reprograms mouse embryonic and adult fibroblasts into iPS cells. One- and two-factor iPS cells are similar to mouse embryonic stem cells in their global gene expression profile, epigenetic status, and in vitro and in vivo differentiation into all three germ layers, as well as teratoma formation and germline transmission in vivo. These data support that converting fibroblasts with Bmi1 or activation of the sonic hedgehog pathway to an intermediate cell type that expresses Sox2, Klf4, and N-Myc allows iPS generation via the addition of Oct4.

To investigate the effects of (-)epigallocatechin-3-gallate (EGCG), the main polyphenol in green tea, on cell growth, cell cycle and phosphorylated nuclear factor-κB (pNF-κB) expression in neonatal human dermal fibroblasts (nHDFs).The proliferation and cell-cycle of nHDFs were determined using WST-8 cell growth assay and flow cytometry, respectively. The apoptosis was examined using DNA ladder and Annexin V-FITC assays. The expression levels of pNF-κB and cell cycle-related genes and proteins in nHDFs were measured using cDNA microarray analyses and Western blot. The cellular uptake of EGCG was examined using fluorescence (FITC)-labeled EGCG (FITC-EGCG) in combination with confocal microscopy.The effect of EGCG on the growth of nHDFs depended on the concentration tested. At a low concentration (200 μmol/L), EGCG resulted in a slight decrease in the proportion of cells in the S and G(2)/M phases of cell cycle with a concomitant increase in the proportion of cells in G(0)/G(1) phase. At the higher doses (400 and 800 μmol/L), apoptosis was induced. The regulation of EGCG on the expression of pNF-κB was also concentration-dependent, whereas it did not affect the unphosphorylated NF-κB expression. cDNA microarray analysis showed that cell cycle-related genes were down-regulated by EGCG (200 μmol/L). The expression of cyclins A/B and cyclin-dependent kinase 1 was reversibly regulated by EGCG (200 μmol/L). FITC-EGCG was found to be internalized into the cytoplasm and translocated into the nucleus of nHDFs.EGCG, through uptake into cytoplasm, reversibly regulated the cell growth and expression of cell cycle-related proteins and genes in normal fibroblasts.

Animal tumor bioassays and in vitro cell culture systems have demonstrated that epigallocatechin-3-O-gallate (EGCG), the predominant catechin in green tea, possesses anti-proliferative and pro-apoptotic effects on various cancer cells and tumors. In this study, we investigated the effects of EGCG on cell growth, cell cycle progression, and apoptosis in human fibrosarcoma HT-1080 cells. The involvement of p53, Bcl-2, Bax, caspases, and nuclear factor-κB (NF-κB) was examined as a mechanism for the anti-cancer activity of EGCG. Time-dependent intracellular trafficking of EGCG was also determined using fluorescein isothiocyanate (FITC)-conjugated EGCG (FITC-EGCG). Our data show that EGCG treatment caused dose-dependent cell growth inhibition, cell cycle arrest at the G(0)/G(1) phase, and DNA fragmentation suggesting the induction of apoptosis in HT-1080 cells. Immunoblot analysis revealed that the expression of p53, caspase-7 and -9 as well as the ratio of Bax/Bcl-2 protein increased significantly with higher EGCG concentrations and longer incubation times. Moreover, expression of phosphorylated NF-κB/p65 in HT-1080 cells was inhibited by EGCG treatment in a dose-dependent manner, while that of unphosphorylated NF-κB/p65 remained unaffected. Here we also reveal time-dependent internalization of FITC-EGCG into the cytosol of HT-1080 cells and its subsequent nuclear translocation. These results suggest that EGCG may interrupt exogenous signals directed towards genes involved in proliferation and cell cycle progression. Taken together, our data indicate that HT-1080 apoptosis may be mediated through the induction of p53 and caspases by the pro-oxidant activity of internalized EGCG, as well as suppression of Bcl-2 and phosphorylated NF-κB by the antioxidant activity of EGCG.

Many studies have been performed to accelerate osteoinduction and osteoconduction into porous ceramic scaffolds by seeding them with cells. In this study, we compared available cell-seeding methods on a porous β-tricalcium phosphate (β-TCP) scaffold and evaluated the effects of cell-seeding on the mechanical properties of the porous β-TCP scaffold. Three types of porous bioceramic scaffolds were used: dry scaffold, scaffold wetted with media, and scaffold cultivated with normal human osteoblasts (NHOs). Cell-seeding into the porous β-TCP scaffolds was performed by conventional, centrifuge, high-density, and vacuum methods. After confirming cell proliferation with MTT assay and cell staining, a compressive test was performed after 2 and 4 weeks of cell culture. The vacuum method based on the high-density cell culture inserted effectively NHOs into the β-TCP scaffolds. The compressive elastic modulus of wetted β-TCP scaffolds decreased significantly (p < 0.05) about 20∼30% after 2 and 4 weeks of incubation in comparison with that of the dry scaffold. However, the compressive strength of the scaffolds cultivated with NHOs for 3 weeks was significantly (p < 0.05) higher than that of scaffolds without NHOs. The vacuum with the high-density of cell-seeding seems to be a suitable method for seeding cells into complex porous ceramic scaffolds. Cell proliferation and uniform distribution in the scaffolds can change the initial mechanical properties of porous ceramic scaffolds.

Tissue engineering represents an innovative approach for the development of novel clinical modalities for the reconstruction of adipose tissue defects. Each year a variety of medical procedures are required for the repair of adipose tissue traumas and abnormalities, including cosmetic facial reconstructions of the cheek, chin and jaw. Currently, there has been a growing interest in in vitro differentiation of adipose-derived stem cells (ADSCs) into adipogenic, myogenic, neurogenic and osteogenic cells among other cell types. The fast growing interest in the use of adipose precursor cells in tissue engineering applications creates a need for more research in the development of scaffolds that can support the attachment and proliferation of these adult stem cells in vitro and in situ. Cell-based approaches utilizing adipogenic progenitor cells in combination with biomaterial carriers for fat tissue engineering have been developed and were reported to repair defect sites. Plasma treatment has the advantage of modifying the surface region to a depth of only a few nanometers without affecting the bulk properties. A commonly used method is to introduce hydrogen peroxides at the surface either by inert gas plasma treatment followed by exposure to oxygen or by corona discharge treatment. This advantage can benefit the fabrication of scaffolds with interpenetrating porous structure for tissue engineering. Plasma technique can be easily used to induce the desired groups or chains onto the surface of a material, so it has a special application to improve the cell affinity of the scaffold. β-Glucans are polymers of glucose that mainly construct the outer cell wall of fungi and certain bacteria. They have been demonstrated to have immune stimulatory activity, especially to enhance wound healing by increasing macrophage infiltration into the injury sites and stimulating tissue granulation and re-epithelialization. The present study concentrated on enhancing the cellular responses of ADSCs on the surface-modified composites of β-glucan and PLGA by microwave-induced argon plasma treatment.

Background Hydrogels can serve as three-dimensional (3D) scaffolds for cell culture and be readily injected into the body. Recent advances in the image technology for 3D scaffolds like hydrogels have attracted considerable attention to overcome the drawbacks of ordinary imaging technologies such as optical and fluorescence microscopy. Multiphoton microscopy (MPM) is an effective method based on the excitation of two-photons. In the present study, C2C12 myoblasts differentiated in 3D gelatin hydroxyphenylpropionic acid (GHPA) hydrogels were imaged by using a custom-built multiphoton excitation fluorescence microscopy to compare the difference in the imaging capacity between conventional microscopy and MPM. Results The physicochemical properties of GHPA hydrogels were characterized by using scanning electron microscopy and Fourier-transform infrared spectroscopy. In addition, the cell viability and proliferation of C2C12 myoblasts cultured in the GHPA hydrogels were analyzed by using Live/Dead Cell and CCK-8 assays, respectively. It was found that C2C12 cells were well grown and normally proliferated in the hydrogels. Furthermore, the hydrogels were shown to be suitable to facilitate the myogenic differentiation of C2C12 cells incubated in differentiation media, which had been corroborated by MPM. It was very hard to get clear images from a fluorescence microscope. Conclusions Our findings suggest that the gelatin-based hydrogels can be beneficially utilized as 3D scaffolds for skeletal muscle engineering and that MPM can be effectively applied to imaging technology for tissue regeneration.

Fertilized eggs and early blastomeres, that have the potential to develop to fetuses when placed into a uterus, are totipotent. Those cells in the embryo, that can give rise to all cell types of an organism, but not to an organism itself, are pluripotent. Embryonic stem (ES), embryonic carcinoma (EC), and embryonic germ (EG) cells are powerful in vitro artifacts derived from different embryonic stages and are pluripotent. Totipotent and pluripotent cells have the potential to greatly benefit biological research and medicine. One powerful feature is that the genetic program of somatic cells can be converted into that of totipotent or pluripotent cells, as shown by nuclear transfer or cell fusion experiments. During reprogramming by cell fusion various features of pluripotent cells are acquired. These include the typical morphology of the respective pluripotent fusion partner, a specific epigenetic state, a specific gene profile, inactivation of tissue-specific genes expressed in the somatic fusion partner, and the developmental as well as differentiation potential of pluripotent cells. In this review, we will discuss what is known about the reprogramming process mediated by cell fusion and the potential use of fusion-induced reprogramming for therapeutic applications.

Neural cortical cells, isolated from prenatal rat cerebra, were grown on surface-modified poly(lactic-co-glycolic acid, 65:35) (PLGA) films coated with poly-D: -lysine (PDL) with either laminin (LN), fibronectin (FN) or collagen (CN). Immunocytochemistry showed that the isolated cells were highly immunopositive for both neurofilament and MAP-2 with well-organized neurites and somatodendritic localization. The presence of PDL with LN or FN on the PLGA films was essential for increased neural cell growth. Also, PLGA films coated with either PDL/LN or PDL/FN mixtures had higher neurite outgrowth and regular differentiation.

Arising from: S. Conrad et al. , 344–349 (2008)10.1038/nature07404 ; Conrad et al. reply Conrad et al. have generated human adult germline stem cells (haGSCs) from human testicular tissue, which they claim have similar pluripotent properties to human embryonic stem cells (hESCs)1. Here we investigate the pluripotency of haGSCs by using global gene-expression analysis based on their gene array data1 and comparing the expression of pluripotency marker genes in haGSCs and hESCs, and in haGSCs and human fibroblast samples derived from different laboratories, including our own. We find that haGSCs and fibroblasts have a similar gene-expression profile, but that haGSCs and hESCs do not. The pluripotency of Conrad and colleagues’ haGSCs is therefore called into question.