Vascular Endothelial Growth Factor Mimetic Peptide and Parathyroid Hormone (1-34) Delivered via a Blue-Light-Curable Hydrogel Synergistically Accelerate Bone Regeneration.

Safe and effective biomaterials are in urgent clinical need for tissue regeneration and bone repair. While numerous advances have been made on hydrogels promoting osteogenesis in bone formation, co-stimulation of the angiogenic pathways in this process remains to be exploited. Here, we have developed a gelatin-based blue-light-curable hydrogel system, functionalized with an angiogenic vascular endothelial growth factor (VEGF) mimetic peptide, KLTWQELYQLKYKGI (KLT), and an osteoanabolic peptide, parathyroid hormone (PTH) 1-34. We have discovered that the covalent modification of gelatin scaffold with peptides can modulate the physical properties and biological activities of the produced hydrogels. Furthermore, we have demonstrated that those two peptides orchestrate synergistically and promote bone regeneration in a rat cranial bone defect model with remarkable efficacy. This dual-peptide-functionalized hydrogel system may serve as a promising lead to functional biomaterials in bone repair and tissue engineering.

Estimation of Plant Biomass Lignin Content using Thioglycolic Acid (TGA).

Lignin is a natural polymer that is the second most abundant polymer on Earth after cellulose. Lignin is mainly deposited in plant secondary cell walls and is an aromatic heteropolymer primarily composed of three monolignols with significant industrial importance. Lignin plays an important role in plant growth and development, protects from biotic and abiotic stresses, and in the quality of animal fodder, the wood, and industrial lignin products. Accurate estimation of lignin content is essential for both fundamental understanding of the lignin biosynthesis and industrial applications of biomass. The thioglycolic acid (TGA) method is a highly reliable method of estimating the total lignin content in the plant biomass. This method estimates the lignin content by forming thioethers with the benzyl alcohol groups of lignin, which are soluble in alkaline conditions and insoluble in acidic conditions. The total lignin content is estimated using a standard curve generated from commercial bamboo lignin.

Estimation of Crystalline Cellulose Content of Plant Biomass using the Updegraff Method.

Cellulose is the most abundant polymer on Earth generated by photosynthesis and the main load-bearing component of cell walls. The cell wall plays a significant role in plant growth and development by providing strength, rigidity, rate and direction of cell growth, cell shape maintenance, and protection from biotic and abiotic stressors. The cell wall is primarily composed of cellulose, lignin, hemicellulose and pectin. Recently plant cell walls have been targeted for the second-generation biofuel and bioenergy production. Specifically, the cellulose component of the plant cell wall is used for the production of cellulosic ethanol. Estimation of cellulose content of biomass is critical for fundamental and applied cell wall research. The Updegraff method is simple, robust, and the most widely used method for the estimation of crystalline cellulose content of plant biomass. The alcohol insoluble crude cell wall fraction upon treatment with Updegraff reagent eliminates the hemicellulose and lignin fractions. Later, the Updegraff reagent resistant cellulose fraction is subjected to sulfuric acid treatment to hydrolyze the cellulose homopolymer into monomeric glucose units. A regression line is developed using various concentrations of glucose and used to estimate the amount of the glucose released upon cellulose hydrolysis in the experimental samples. Finally, the cellulose content is estimated based on the amount of glucose monomers by colorimetric anthrone assay.

Comparison of procedural, clinical and valve performance results of transcatheter aortic valve replacement in patients with bicuspid versus tricuspid aortic stenosis.

BACKGROUND: Limited date describing the procedural, clinical and valve performance results of transcatheter aortic valve replacement (TAVR) in patients with bicuspid versus tricuspid aortic stenosis (TAV). METHODS: Procedural and clinical results were defined and reported according to VARC-2 criteria. RESULTS: Consecutive 87 patients with BAV and 70 patients with TAV were included. Compared to patients with TAV, patients with BAV had similar incidence of second valve implantation (14.9% vs 12.9%, p=0.708), more than mild paravalvular leakage (PVL, 40.2% vs 31.9%, p=0.288), permanent pacemaker implantation (PPM, 24.1% vs 28.6%, p=0.53). Furthermore, the procedural and clinical results of TAVR also did not differ between patients with type 0 and type 1 (second valve implantation: 18.4% vs 11.8%, p=0.71, PVL: 38.8% vs 41.2%, p=0.83, PPM: 18.4% vs 31.6%, p=0.16). The hemodynamic outcomes were similar in patients with BAV and TAV at 1-year (maximum velocity, 2.3 vs 2.2m/s, p=0.307) and 2-year (2.3 vs 2.1m/s, p=0.184) follow-up respectively. Adjusted binary logistic regression analysis found oversizing ratio at 14.45-20.57% is at lower risk for more than mild PVL (OR, 0.069, 95% CI, 0.011-0.428, p=0.004). Moreover, the Kaplan-Meier survival analysis revealed that TAVR in type 0 BAV, type 1 BAV and TAV have comparable risk for midterm mortality (Log rank, p=0.772). CONCLUSION: TAVR in whatever type of BAV appeared to be safe and efficacy, and TAVR in BAV was associated with comparable bioprosthetic function during follow up compared to patients with TAV.

[Modification of calcium sulfate bone cement by gentamicin and oxygen-carboxymethylated chitosan].

Objective: To extend its application in the field of bone repair by adding oxygen-carboxymethylated chitosan (O-CMC) and gentamicin for modification of the calcium sulfate cement (CSC). Methods: The O-CMC/CSC was prepared by adding O-CMC with different concentrations (0.1wt%, 0.3wt%, 0.5wt%, 0.7wt%, and 1.0wt%) in the CSC liquid phase. The effect of O-CMC on the CSC was evaluated by testing the injectability, compressive strength, degradation rate, pH value, cytotoxicity and osteogenesis. After the optimal concentration of O-CMC was determined, gentamicin with different concentrations (0.5wt%, 1.5wt%, and 2.5wt%) was added in the O-CMC/CSC, and then the compressive strength and antibacterial properties were investigated. Results: After adding O-CMC in the CSC liquid phase, the injection time of O-CMC/CSC was increased to more than 5 minutes; it significantly prolonged with increased concentration of O-CMC ( P<0.05). The compressive strength of the modified bone cement was in the range of 11-18 MPa and it was the highest when the concentration of O-CMC was 0.5wt% ( P<0.05). The degradation rate of O-CMC/CSC was not influenced obviously by O-CMC ( P>0.05). The pH value was in the range of 7.2-7.4 and Ca 2+ concentration was in the range of 6-8 mmol/L. In vitro mineralization experiment indicated that the induced mineralization ability of O-CMC/CSC was much higher than that of pure CSC. The 0.5wt% O-CMC/CSC had the best performance; the compressive strength of the composite bone cement was above 5 MPa after gentamicin was added, which had antibacterial effect. Conclusion: O-CMC is able to effectively improve the injection, compressive strength, and osteogenic activity of CSC; in addition, antibacterial properties is obtained in the CSC after adding gentamicin.

The Incorporation of Strontium in a Sodium Alginate Coating on Titanium Surfaces for Improved Biological Properties.

Orthopedic implant failure is mainly attributed to the poor bonding of the implant to bone tissue. An effective approach to minimize the implant failure would be modifying the surface of the implant. Strontium (Sr) can stimulate the proliferation and differentiation of osteoblasts and reduce the activity of osteoclasts. In this study, a titanium (Ti) surface was successively functionalized by covalently grafting dopamine, sodium alginate (SA), and Sr2+ via the electrostatic immobilization method. The as-prepared coatings on the Ti surface were characterized by using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and contact angle. The results indicated that the Sr-incorporated coatings were successfully prepared and that Sr distributed uniformly on the surface. A long-lasting and sustained Sr release had been observed in Sr2+ release studies. The Ti/DOPA/SA/Sr exhibited little cytotoxicity and a robust effect of Sr incorporation on the adhesion and spreading of MG63 cells. The proliferation and alkaline phosphatase (ALP) activity of MG63 cells were enhanced by immobilizing Sr2+ on the SA-grafted Ti. The Sr-containing coatings, which displayed excellent biocompatibility and osteogenic activity, may provide a promising solution for promoting the tissue integration of implants.

Preclinical evaluation of strontium-containing bioactive bone cement.

Strontium (Sr) has become more attractive for orthopaedic applications as they can simultaneously stimulate bone formation and prevent bone loss. A Sr-containing bioactive bone cement (Sr-BC) has been designed to fix osteoporotic bone fracture. Sr is a trace element, so the safety of containing Sr is concerned when Sr-BC is implanted in human body. The preclinical assessment of biocompatibility of Sr-BC was conducted according to ISO 10993 standards. MTT assay showed that this bioactive bone cement was non-toxic to mouse fibroblasts, and it met the basic requirement for the orthopaedic implant. The three independent genetic toxicity studies including Ames, chromosome aberration and bone marrow micronucleus assays demonstrated absence of genotoxic components in Sr-BC, which reassured the safety concerns of this novel bone cement. The muscle implantation results in present study were also encouraging. The acute inflammation around the cement was observed at 1 week post-implantation; however, no significant difference was observed between control and Sr-BC groups. These responses may be attributed to the presence of the foreign body, but the tissue healed after 12 weeks implantation. In summary, the above preclinical results provide additional assurance for the safety of this implant. Sr-BC can be used as a potential alternative to the traditional bone cement.

Encapsulation in liposomal nanoparticles enhances the immunostimulatory, adjuvant and anti-tumor activity of subcutaneously administered CpG ODN.

Immunostimulatory oligodeoxynucleotides (ODN) containing cytosine-guanine (CpG) motifs are powerful stimulators of innate as well as adaptive immune responses, exerting their activity through triggering of the Toll-like receptor 9. We have previously shown that encapsulation in liposomal nanoparticles (LN) enhances the immunostimulatory activity of CpG ODN (LN-CpG ODN) (Mui et al. in J Pharmacol Exp Ther 298:1185, 2001). In this work we investigate the effect of encapsulation on the immunopotency of subcutaneously (s.c.) administered CpG ODN with regard to activation of innate immune cells as well as its ability to act as a vaccine adjuvant with tumor-associated antigens (TAAs) to induce antigen (Ag)-specific, adaptive responses and anti-tumor activity in murine models. It is shown that encapsulation specifically targets CpG ODN for uptake by immune cells. This may provide the basis, at least in part, for the significantly enhanced immunostimulatory activity of LN-CpG ODN, inducing potent innate (as judged by immune cell activation and plasma cytokine/chemokine levels) and adaptive, Ag-specific (as judged by MHC tetramer positive T lymphocytes, IFN-gamma secretion and cytotoxicity) immune responses. Finally, in efficacy studies, it is shown that liposomal encapsulation enhances the ability of CpG ODN to adjuvanate adaptive immune responses against co-administered TAAs after s.c. immunization, inducing effective anti-tumor activity against both model and syngeneic tumor Ags in murine tumor models of thymoma and melanoma.