Humoral and cellular immunity of two-dose inactivated COVID-19 vaccination in Chinese children: A prospective cohort study.

Children are the high-risk group for COVID-19, and in need of vaccination. However, humoral and cellular immune responses of COVID-19 vaccine remain unclear in vaccinated children. To establish the rational immunization strategy of inactivated COVID-19 vaccine for children, the immunogenicity of either one dose or two doses of the vaccine in children was evaluated. A prospective cohort study of 322 children receiving inactivated COVID-19 vaccine was established in China. The baseline was conducted after 28 days of the first dose, and the follow-up was conducted after 28 days of the second dose. The median titers of receptor binding domain (RBD)-IgG, and neutralizing antibody (NAb) against prototype strain and Omicron variant after the second dose increased significantly compared to those after the first dose (first dose: 70.0, [interquartile range, 30.0-151.0] vs. second dose: 1261.0 [636.0-2060.0] for RBD-IgG; 2.5 [2.5-18.6] vs. 252.0 [138.6-462.1] for NAb against prototype strain; 2.5 [2.5-2.5] vs. 15.0 [7.8-26.5] for NAb against Omicron variant, all p < 0.05). The flow cytometry results showed that the first dose elicited SARS-CoV-2 specific cellular immunity, while the second dose strengthened SARS-CoV-2 specific IL-2+ or TNF-α+  monofunctional, IFN-γ+ TNF-α+  bifunctional, and IFN-γ- IL-2+ TNF-α+ multifunctional CD4+ T cell responses (p < 0.05). Moreover, SARS-CoV-2 specific memory T cells were generated after the first vaccination, including the central memory T cells and effector memory T cells. The present findings provide scientific evidence for the vaccination strategy of the inactive vaccines among children against COVID-19 pandemic.

Oxidized starch cross-linked porous collagen-based hydrogel for spontaneous agglomeration growth of adipose-derived stem cells.

Many strategies have been employed to artificially reconstruct adipose tissue in tissue engineering. The functionalization and survival of reconstructed adipose tissue depend on sufficient angiogenesis. Notably, agglomeration growth of adipose-derived stem cells (ASCs) is beneficial to promoting angiogenesis. Herein, we present a porous collagen-based hydrogel for spontaneous agglomeration growth of ASCs to promote angiogenesis. Oxidized starch with different oxidation degree was prepared and used to cross-link collagen to fabricate the porous hydrogel. The gelation time and pore size of hydrogels can be controlled by adjusting the oxidation degree of starch. Crosslinking enhances the mechanical properties, inhibits the swelling and biodegradation of the hydrogels. The hydrogels possess good blood compatibility and cytocompatibility. Significantly, ASCs tended to adhere to the hydrogels and spontaneously grew into spheres along with time. Effective expression of vascular endothelial growth and fibroblast growth factors were observed. Overall, the hydrogels have application prospects in vascularized adipose tissue engineering.

pH-Responsive nanoparticles based on cholesterol/imidazole modified oxidized-starch for targeted anticancer drug delivery.

Various nanoparticles have been developed for tumor-targeted drug delivery. However, nanoparticles with effective targeting and intelligent release capacity are still deficient. Herein, we present new pH-responsive and neutral charged nanoparticles for tumor-targeted anticancer drug delivery. Oxidized starch was synthesized and simultaneously modified by cholesterol and imidazole to obtain amphiphilic cholesterol/imidazole modified oxidized-starch (Cho-Imi-OS). Cho-Imi-OS easily self-assembled into nanoparticles by dialysis. Curcumin was selected as model drug to be encapsulated into the hydrophobic core of nanoparticles. The results showed that curcumin would effectively accumulate in cancer cells by encapsulating into the nanoparticles owing to the nano-sized structure and near neutral charged property of nanoparticles. Curcumin was released faster at pH 5.5 than that at pH 7.4 from the curcumin-loaded nanoparticles (Cur-NPs), indicating the pH-triggered release capacity of Cur-NPs after endocytosis by endosomes since the pH is low to 5.0∼6.0 in endosomes. Naturally, Cur-NPs showed significantly strong inhibitory effect on cancer cells.

Controlling the Pore Structure of Collagen Sponge by Adjusting the Cross-Linking Degree for Construction of Heterogeneous Double-Layer Bone Barrier Membranes.

Guided bone regeneration (GBR) has been regarded as a valuable way to effectively induce bone remodeling. The key factor of GBR is to place a barrier membrane between the soft tissue and bone defect, preventing the untimely intrusion of fibroblasts and permitting the prior settlement of internal osteoblasts. Notably, heterogeneous double-layer GBR membranes with a compact upper layer and a loose lower layer exhibit enhanced effectiveness in blocking fibroblasts and promoting the growth of osteoblasts. Herein, we present porous and interconnected collagen-based sponges with controllable pore size for the fabrication of absorbable GBR membranes with a heterogeneous double-layer structure. Dialdehyde carboxymethyl cellulose was used to fix collagen-based sponges. The pore size of the sponges can be well controlled by adjusting the cross-linking degree, which is decreased with an increase of cross-linking degree. The sponges show enhanced mechanical properties, inhibited swelling ability and biodegradation, good blood compatibility, and good cytocompatibility. The sponges are feasible to form a heterogeneous double-layer structure with a loose lower layer and a compact upper layer. Interestingly, the lower layer with the pore size of 200-300 µm can promote the adhesion, proliferation, and differentiation of osteoblasts MC3T3-E1 cells, while the upper layer with the pore size of 20-50 µm makes a great contribution to the growth of myoblast C2C12 cells. Overall, the collagen-based sponges have the potential to be used to fabricate heterogeneous double-layer bone barrier membranes for bone remodeling.

Emulsion Template Method for the Fabrication of Gelatin-Based Scaffold with a Controllable Pore Structure.

The porous microstructure of scaffolds is an essential consideration for tissue engineering, which plays an important role for cell adhesion, migration, and proliferation. It is crucial to choose optimum pore sizes of scaffolds for the treatment of various damaged tissues. Therefore, the proper porosity is the significant factor that should be considered when designing tissue scaffolds. Herein, we develop an improved emulsion template method to fabricate gelatin-based scaffolds with controllable pore structure. Gelatin droplets were first prepared by emulsification and then solidified by genipin to prepare gelatin microspheres. The microspheres were used as a template for the fabrication of porous scaffolds, which were gathered and tightened together by dialdehyde amylose. The results showed that emulsification can produce gelatin microspheres with narrow size distribution. The size of gelatin microspheres was easily controlled by adjusting the concentration of gelatin and the speed of mechanical agitation. The gelatin-based scaffolds presented macroporous and interconnected structure. It is interesting that the pore size of scaffolds was directly related to the size of gelatin microspheres, displaying the same trend of change in size. It indicated that the gelatin microspheres can be used as the proper template to fabricate gelatin-based scaffold with a desired pore structure. In addition, the gelatin-based scaffolds possessed good blood compatibility and cytocompatibility. Overall, the gelatin-based scaffolds exhibited great potential in tissue engineering.

Comparative study of the physicochemical and photocatalytic properties of water-soluble polymer-capped TiO2 nanoparticles.

TiO2 shows great potential as ideal and powerful photocatalyst to degrade and eliminate harmful organic pollutants from waste water. It is desirable to prepare anatase TiO2 with good aqueous solubility and photocatalytic activity for water decontamination. In this paper, water-soluble TiO2 nanoparticles were successfully prepared using polytetramethylene ether glycol (PTMG), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) as stabilizers. The anatase phase of TiO2 was well controlled by introduction of HCl in the reaction system. The results showed that all the polymer-capped TiO2 were well dissolved in water and their aqueous solutions could maintain stable for more than 2 months. The photocatalytic activities of polymer-capped TiO2 were evaluated by monitoring the degradation of Rhodamine B (RhB) with Degussa P25 as a control. The results showed that all the polymer-capped TiO2 presented better photocatalytic activity than that of Degussa P25. PTMG capped TiO2 exhibited the longest average lifetime of charge carriers, indicating the lowest charge recombination rate. Thus, PTMG capped TiO2 presented the best photocatalytic activity. In summary, PTMG, PEG, and PPG can be used as stabilizers to prepare water-soluble TiO2. PTMG is an ideal stabilizer for the synthesis of water-soluble TiO2 with good photocatalytic activity.

The extramacrochaetae gene is required for blastokinesis in silkworm, Bombyx mori.

In silkworm, Bombyx mori Linnaeus (Lepidoptera: Bombycidae), blastokinesis results in embryo reversal from ventrally to dorsally convex flexion. In this study, we showed that the extramacrochaetae (emc) gene is required for blastokinesis in silkworm. Depletion of Bmemc expression via RNA interference led to severe phenotypic defects in blastokinesis. The defective embryos failed to invert their body sides during blastokinesis. This caused the posterior half of the abdomen to abnormally fold back toward the dorsal side, forming a U-shaped morphology. Dorsal closure was also disrupted. Our results suggest that Bmemc is involved in blastokinesis of silkworm embryos. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 405-409, 2015. © 2015 Wiley Periodicals, Inc.