Novel Chitosan Dermal Filler with Enhanced Moldability and Elasticity.

Currently, dermal fillers are largely based on commercialized cross-linked hyaluronic acid (HA) injections, which require a large injection force. Additionally, HA can be easily decomposed by enzymes, and HA-treated tissues present a risk of developing granuloma. In this study, a chitosan-based dermal filler is presented that operates on a liquid-to-gel transition and allows the injection force to be kept ≈4.7 times lower than that required for HA injections. Evaluation of the physical properties of the chitosan filler indicates high viscoelasticity and recovery rate after gelation at 37 °C. Furthermore, in an in vivo evaluation, the liquid injection-type chitosan filler transitions to a gel state within 5 min after injection into the body, and exhibits a compressive strength that is ≈2.4 times higher than that of cross-linked HA. The filler also exhibits higher moldability and maintains a constant volume in the skin for a longer time than the commercial HA filler. Therefore, it is expected that the chitosan filler will be clinically applicable as a novel material for dermal tissue restoration and supplementation.

The Regeneration of Large-Sized and Vascularized Adipose Tissue Using a Tailored Elastic Scaffold and dECM Hydrogels.

A dome-shaped elastic poly(l-lactide-co-caprolactone) (PLCL) scaffold with a channel and pore structure was fabricated by a combinative method of 3D printing technology and the gel pressing method (13 mm in diameter and 6.5 mm in thickness) for patient-specific regeneration. The PLCL scaffold was combined with adipose decellularized extracellular matrix (adECM) and heart decellularized extracellular matrix (hdECM) hydrogels and human adipose-derived stem cells (hADSCs) to promote adipogenesis and angiogenesis. These scaffolds had mechanical properties similar to those of native adipose tissue for improved tissue regeneration. The results of the in vitro real-time PCR showed that the dECM hydrogel mixture induces adipogenesis. In addition, the in vivo study at 12 weeks demonstrated that the tissue-engineered PLCL scaffolds containing the hydrogel mixture (hdECM/adECM (80:20)) and hADSCs promoted angiogenesis and adipose tissue formation, and suppressed apoptosis. Therefore, we expect that our constructs will be clinically applicable as material for the regeneration of patient-specific large-sized adipose tissue.

BMP-2 and hMSC dual delivery onto 3D printed PLA-Biogel scaffold for critical-size bone defect regeneration in rabbit tibia.

3D printing technology has various advantages, and the incorporation of bioactive substances into the 3D printed scaffold provides the biological and architectural characteristics of the scaffolds, which is very important for obtaining a good osseointegration effect. In this relation, this study prepared a novel porous hollow cage poly(lactic acid) (PLA) 3D printed scaffold and combined recombinant human bone morphogenetic protein-2 (rhBMP-2) and/or mesenchymal stem cells (MSCs) with Biogel composed of gelatin and alginate. Then, the scaffolds were used to evaluate the resulting bone regeneration through both in vitro and in vivo tests. The experimental group was divided into four groups as follows: only PLA scaffold (PLA); PLA scaffold filled with BMP-2 loaded on Biogel (P-BG-B2); PLA scaffold filled with MSCs encapsulated Biogel (P-BG-M); PLA scaffold filled with both BMP-2 and MSCs loaded on Biogel (P-BG-B2-M). Then in vitro results showed that the PLA-Biogel-based scaffold increased cell proliferation, and the P-BG-B2-M group showed a higher alkaline phosphatase activity and bone-related gene expression than was seen with the P-BG-M group at all the time points. It was shown that four weeks post-operative micro-CT analysis showed that within the defect site the P-BG-B2 group had a significantly higher percent bone volume (BV/TV) than the PLA group and P-BG-M group. And, out of the defect site, the P-BG-B2-M group BV/TV was shown significantly higher than the PLA group (p < 0.05). Histologically, defects in the P-BG-B2-M group showed a homogeneous new bone distribution, however the P-BG-B2 group and P-BG-M group presented a notably higher bone formation in the internal region than in the proximal region of the bone defect site. In conclusion, the 3D PLA-Biogel-based scaffold adapted rhBMP-2 and MSCs with carrier PLA showed good biocompatibility and high possibility as an effective and satisfactory bone graft material.

Neuroprotective effect of single-wall carbon nanotubes with built-in peroxidase-like activity against ß-amyloid-induced neurotoxicity.

Carbon nanotubes (CNTs) have emerged as a leading nanomaterial for biomedical applications because of their extraordinary properties, which make them useful as delivery vehicles for drugs, proteins, and DNA into cells. However, the numerous applications of carbon nanotubes inevitably increase the potential risk of this nanomaterial. To address this issue, it is necessary to develop protocols for the effective and safe degradation of CNTs. In this study, we demonstrate a self-degradation route for single-wall carbon nanotubes mediated by the built-in peroxidase-like activity of bacterial magnetic nanoparticles (BMPs). Biocompatible BMPs which originated from Magnetospirillum sp. AMB-1 were directly conjugated through covalent bonding to functionalized SWNTs (f-SWNTs) without any additional functionalization processes. This SWNT-BMP hybrid was proven to exhibit highly synergetic peroxidase-like activity, and BMPs act as a highly effective intrinsic peroxidase for the self-degradation of BMP-decorated SWNTs. Moreover, it was shown to be an inhibitor that reduces the formation of ß-amyloid (Aß) fibrils, which are considered a key element in Alzheimer's disease. Thereby the SWNT-BMP hybrid exerts neuroprotective effects against ß-amyloid (Aß) fibrillation-induced neurotoxicity in SH-SY5Y human neuroblastoma cells. These results suggest that the SWNT-BMP hybrid could offer a new approach for treating or preventing neurodegenerative diseases.

Tracking of STAT3 signaling for anticancer drug-discovery based on localized surface plasmon resonance.

Signal transducer and activator of transcription 3 (STAT3) protein signaling is crucial for the survival, invasion, and growth of human cancer cells; thus, STAT3 protein is an ideal target for a new drug screening system. Herein, we developed a label-free sensor for anticancer drug-discovery based on the localized surface plasmon resonance (LSPR) shift response by tracking of STAT3 signaling including phosphorylation and dimerization. This enables ultrasensitive monitoring of the molecular interactions that occur on the surface of single gold nanoparticles. The red shift of the LSPR λmax was observed as 3.46 nm and 9.00 nm, respectively, indicating phosphorylation and dimerization of the STAT3 signaling pathway. In screening of anticancer candidates, the system worked well in the presence of STA-21 which inhibits STAT3 dimerization. The LSPR λmax shift in the inhibition condition is three times lower than that in the absence of an inhibitor. Interestingly, the system reveals high specificity, reproducibility and compatibility with real samples (MCF-7 cell line). Therefore, these results demonstrated that this system has strong potential to be an accurate and effective sensor for tracking of signaling pathways and drug screening of anticancer candidates for anticancer therapy.

Effect of graphitic layers encapsulating single-crystal apatite nanowire on the osteogenesis of human mesenchymal stem cells.

An ideally designed scaffold for tissue engineering must be able to provide an environment that recapitulates the physiological conditions to control stem cell function. Here, we compared vertically aligned single-crystal apatite nanowires sheathed in graphitic layers (SANGs) with single-crystal apatite nanowires (SANs), which had the same geometric properties as--but differing nanotopographic surface chemistry than--SANGs, in order to evaluate the effect of the graphitic layer on the behavior of human mesenchymal stem cells (hMSCs). The difference in nanotopographic surface chemistry did not affect hMSC adhesion, growth, or morphology. However, hMSCs were more effectively differentiated into bone cells on SANGs through interaction with graphitic layers, which later degraded and thereby allowed the cells to continue differentiation on the bare apatite nanowires. Thus, SANGs provide an excellent microenvironment for the osteogenic differentiation of hMCS.

Magnetic manipulation of bacterial magnetic nanoparticle-loaded neurospheres.

Specific targeting of cells to sites of tissue damage and delivery of high numbers of transplanted cells to lesion tissue in vivo are critical parameters for the success of cell-based therapies. Here, we report a promising in vitro model system for studying the homing of transplanted cells, which may eventually be applicable for targeted regeneration of damaged neurons in spinal cord injury. In this model system, neurospheres derived from human neuroblastoma SH-SY5Y cells labeled with bacterial magnetic nanoparticles were guided by a magnetic field and successfully accumulated near the focus site of the magnetic field. Our results demonstrate the effectiveness of using an in vitro model for testing bacterial magnetic nanoparticles to develop successful stem cell targeting strategies during fluid flow, which may ultimately be translated into in vivo targeted delivery of cells through circulation in various tissue-repair models.

Single-crystal apatite nanowires sheathed in graphitic shells: synthesis, characterization, and application.

Vertically aligned one-dimensional hybrid structures, which are composed of apatite and graphitic structures, can be beneficial for orthopedic applications. However, they are difficult to generate using the current method. Here, we report the first synthesis of a single-crystal apatite nanowire encapsulated in graphitic shells by a one-step chemical vapor deposition. Incipient nucleation of apatite and its subsequent transformation to an oriented crystal are directed by derived gaseous phosphorine. Longitudinal growth of the oriented apatite crystal is achieved by a vapor-solid growth mechanism, whereas lateral growth is suppressed by the graphitic layers formed through arrangement of the derived aromatic hydrocarbon molecules. We show that this unusual combination of the apatite crystal and the graphitic shells can lead to an excellent osteogenic differentiation and bony fusion through a programmed smart behavior. For instance, the graphitic shells are degraded after the initial cell growth promoted by the graphitic nanostructures, and the cells continue proliferation on the bare apatite nanowires. Furthermore, a bending experiment indicates that such core-shell nanowires exhibited a superior bending stiffness compared to single-crystal apatite nanowires without graphitic shells. The results suggest a new strategy and direction for bone grafting materials with a highly controllable morphology and material conditions that can best stimulate bone cell differentiation and growth.

Magnetic response of mitochondria-targeted cancer cells with bacterial magnetic nanoparticles.

We first demonstrate the effects of magnetic trapping of mitochondria using aptamer conjugated to bacterial magnetic nanoparticles that allowed targeting of the mitochondrial cytochrome c in the treatment of cancer cells. Our findings offer a new approach for targeted cell therapy, with the advantage of remote control over subcellular elements.

Cell response induced by internalized bacterial magnetic nanoparticles under an external static magnetic field.

Magnetic nanoparticles are widely used in bioapplications such as imaging and targeting tool. Their magnetic nature allows for the more efficient bioapplications by an external field gradient. However their combined effects have not yet been extensively characterized. Herein, we first demonstrate the biological effects of the communications between internalized bacterial magnetic nanoparticles (BMPs) and an external static magnetic field (SMF) on a standard human cell line. Combination of the BMPs and SMF act as the key factor leading to the alteration of cell structure and the enhanced cell growth. Also, their interaction reduced the apoptotic efficiency of human tumor cells induced by anticancer drugs. Microarray analysis suggests that these phenomena were caused by the alterations of GPCRs-mediated signal transduction originated in the interaction of internalized BMPs and the external SMF. Our findings may offer new approach for targeted cell therapy with the advantage of controlling cell viability by magnetic stimulation.