Modulation of Cell Behavior by 3D Biocompatible Hydrogel Microscaffolds with Precise Configuration

Three-dimensional (3D) micronano structures have attracted much attention in tissue engineering since they can better simulate the microenvironment in vivo. Two-photon polymerization (TPP) technique provides a powerful tool for printing arbitrary 3D structures with high precision. Here, the desired 3D biocompatible hydrogel microscaffolds (3D microscaffold) with structure design referring to fibroblasts L929 have been fabricated by TPP technology, particularly considering the relative size of cell seed (cell suspension), spread cell, strut and strut spacing of scaffold. Modulation of the cell behavior has been studied by adjusting the porosity from 69.7% to 89.3%. The cell culture experiment results reveal that the obvious modulation of F-actin can be achieved by using the 3D microscaffold. Moreover, cells on 3D microscaffolds exhibit more lamellipodia than those on 2D substrates, and thus resulting in a more complicated 3D shape of single cell and increased cell surface. 3D distribution can be also achieved by employing the designed 3D microscaffold, which would effectively improve the efficiency of information exchange and material transfer. The proposed protocol enables us to better understand the cell behavior in vivo, which would provide high prospects for the further application in tissue engineering.

Direct and Indirect Biomimetic Peptide Modification of Alginate: Efficiency, Side Reactions, and Cell Response

In the fast-developing field of tissue engineering there is a constant demand for new materials as scaffolds for cell seeding, which can better mimic a natural extracellular matrix as well as control cell behavior. Among other materials, polysaccharides are widely used for this purpose. One of the main candidates for scaffold fabrication is alginate. However, it lacks sites for cell adhesion. That is why one of the steps toward the development of suitable scaffolds for cells is the introduction of the biofunctionality to the alginate structure. In this work we focused on bone-sialoprotein derived peptide (TYRAY) conjugation to the molecule of alginate. Here the comparison study on four different approaches of peptide conjugation was performed including traditional and novel modification methods, based on 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxy succinimide (EDC/NHS), 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride (DMTMM), thiol-Michael addition and Cu-catalyzed azide–alkyne cycloaddition reactions. It was shown that the combination of the alginate amidation with the use of and subsequent Cu-catalyzed azide–alkyne cycloaddition led to efficient peptide conjugation, which was proven with both NMR and XPS methods. Moreover, the cell culture experiment proved the positive effect of peptide presence on the adhesion of human embryonic stem cells.

Therapeutic hypothermia after cardiac arrest increases the plasma level of B-type natriuretic peptide

Natriuretic peptides (NPs) regulate blood pressure and fluid homeostasis and exert various effects on the cardiovascular system. Recently, the relationship between NPs and the energy metabolism has been reported, and using a cell culture experiment system, we previously showed that NP activated brown cells in a low temperature environment while also suppressing a decrease in the cell temperature. However, few reports have described the secretion of NPs in cold environments, and there have been almost no studies of B-type natriuretic peptide (BNP) in humans. We investigated how NPs respond to cold environments in 21 patients who underwent therapeutic hypothermia (TH) after cardiac arrest. The plasma BNP levels were significantly increased (more than fivefold) during TH (logarithmically from 1.98 ± 0.79 to 2.63 ± 0.59, P < 0.01). During TH, diastolic pulmonary artery pressure (PAP) significantly decreased, and there were no significant changes in the stroke volume index (SVI). This increase of BNP was not associated with any hemodynamic changes. In contrast to our findings for BNP, the change in A-type NP (ANP) was quite small. We detected a significant increase in the plasma BNP levels during TH, unrelated to hemodynamics. This elevation of BNP levels seems to be potential influenced by hypothermia.

New Zr-Ti-Nb Alloy for Medical Application: Development, Chemical and Mechanical Properties, and Biocompatibility

The concept of mechanical biocompatibilities is considered an important factor for orthopedics and dental implants. The high Young modulus of traditional Ti-based alloys can lead to stress-shielding syndrome and late postoperative complications. The development of new Al- and V-free Ti alloys with a low elastic modulus is a critical task for implantology. Despite the relatively low Young modulus and appropriate biological response of metastable beta-Ti alloys, their production requires complex metallurgical solutions and a high final cost that limit commercial application. The current research aimed to develop a Zr-Ti-Nb system with a low Young modulus suitable for biomedical application, including orthopedics and dental implantology. Two different charges were used for new alloy production with melting in a vacuum-arc furnace VDP-1 under atmospheric control (argon + helium) with a non-consumable tungsten electrode and a water-cooled copper crystallizer. Post-treatment included a forging-rolling process to produce a bar suitable for implant production. SEM with EDX and the mechanical parameters of the new alloy were evaluated, and a cell culture experiment provided a biocompatibility assessment. The chemical composition of the new alloy can be represented as 59.57-19.02-21.41 mass% of Zr-Ti-Nb. The mechanical properties are characterized by an extremely low Young modulus—27,27 GPa for the alloy and 34.85 GPa for the bar. The different master alloys used for Zr-Ti-Nb production did not affect the chemical compound and mechanical parameters so it was possible to use affordable raw materials to decrease the final price of the new product. The cell culture experiment demonstrated a full biocompatibility, indicating that this new alloy can be used for dental and orthopedics implant production.

Mechanism of Hyaluronic Acid Protect Rabbit Chondrocyte Apoptosis Induced by NO

AIM: To investigate the mechanism of hyaluronic acid on rabbit chondrocyte apoptosis in vitro induced by NO. METHODS: We cultured rabbit chondrocytes as normal group and added SNP after cultured 24 h as model group. Treated group was added HA. We used cell culture experiment. We tested the activity of mitochondria though MTT. The flow cytometry detected mitochondrial membrane potential, the percentage of apoptosis and intracellular free calcium concentration.RESULTS: HA could elevate the active of chondrocyte mitochondria and MMP; it could decrease the rate of chondrocyte apoptosis and intracellular free calcium concentration.CONCLUSION: HA can inhibit the lowering of the MMP in chondrocyte, which has a stable role on MMP and inhibit apoptosis occurred. This effect may be related to inhibiting of intracellular calcium overload chondrocytes.

Enhanced Intracellular Uptake of CdTe Quantum Dots by Conjugation of Oligopeptides

Arg-Gly-Asp-Ser (RGDS), a typical membrane-permeable carrier peptide, was conjugated with mercaptoisobutyric acid-immobilized CdTe quantum dot (CTNPs) to enhance the intracellular uptake of quantum dots. Mean size of mercaptoisobutyric acid-immobilized quantum dots (37 nm) as determined by dynamic light scattering was increased up to 54 nm after RGDS immobilization. It was found, fromin vitrocell culture experiment, that fibroblast (NIH 3T3) cells were well proliferated in the presence of RGDS-conjugated quantum dots (RCTNPs), and the intracellular uptake of CTNPs and RCTNPs was studied by means of ICP and fluorescence microscopy. As a result, the RCTNPs specifically bound to the membrane of NIH 3T3 cells and almost saturated after 6 hours incubation. The amount of RCTNPs uptaken by the cells was higher than that of CTNPs, demonstrating the enhancing effect of RGDS peptide conjugation on the intracellular uptake of quantum dots (QDs).

Gradient Rare-Earths Bioceramic Composite Coating Fabricated by Wide-Band Laser Cladding and its Bioactivity

A gradient bioceramic composite coating was prepared by wide-band laser cladding technique on TC4 alloy surface. The influence of rare earths oxide CeO2 on microstructure of bioceramic coating was studied. The experimental results indicated that CeO2 plays an important role in inducing HA + β-TCP formation. There is almost no HA+β-TCP in bioceramic coating without CeO2. When CeO2 content is higher than 0.2 wt.%, the amount of HA+β-TCP catalyzed by CeO2 gradually increases. The amount of HA+β-TCP becomes largest when CeO2 content is up to 0.4wt%. However, when CeO2 content ranges from 0.6 wt.% to 0.8 wt.%, the amount of synthesizing HA+β-TCP conversely goes down. Through cell culture experiment in vitro, the effect of bioceramic coating with different CeO2 contents on the expression of characteristic protein is investigated. The results show that the largest amount of expression of hydroxyproline(Hyp) at 2d and alkaline phosphatase(ALP) at 6d on coating is complied with 0.4wt.% CeO2, The result indicates that bioactivity of bioceramic coating is dependent on the amount of HA + β-TCP catalyzed by different CeO2 contents.

Surface Modification of Magnetite Nanoparticles with Doxorubicin and RGD Peptide and their Biomedical Application

In the present study, superparamagnetic maltotrionic acid-coated magnetite nanoparticles (MAM) were surface modified with doxorubicin (DOX) and RGD peptide to improve their intracellular uptake, ability to target tumor cells and antitumer effect. RGD was added to the distal end of MAM aiming to construct an enhanced tumor targeting delivery system. To test its targeting effect, DOX, a widely used anticancer drug, was immobilized on the RGD-modified magnetite nanoparticles. DOX-coated magnetite nanoparticles were also prepared as a control. KB cell culture experiment showed that both DOX-modified nanoparticles and DOX-RGD peptide-modified magnetite nanoparticles (DRMAM) were internalized into the cells. But the uptake amount of DRMAMs was higher than that of DOX-modified nanoparticles. This result indicates that DRMAMs have a great potential to be used as contrast agent and antitumor medicine.