In vivo behaviors of Ca(OH) 2 activated nano SiO 2 (n Ca /n Si = 3) cement in rabbit model

Silica Nanoparticles Promote the Megakaryocyte Maturation and Differentiation: Potential Implications for Hematological Homeostasis

Silica nanoparticles (SiO₂ NPs) have been widely applied in diverse areas, thus causing the extensive release through multiple routes. Their toxicological effects, especially for the disturbance in hematological homeostasis, have raised public concern. Considering the detrimental role of excessive platelets in many cardiovascular diseases, the regulation of platelet formation offers a unique aspect for studying the blood compatibility of nanomaterials. In this study, the effects of SiO₂ NPs with four sizes (80, 120, 200, and 400 nm) were investigated on the maturation and differentiation of the megakaryocytes into platelets. The results showed that SiO₂ NPs promoted megakaryocyte development as manifested by the occurrence of irregular cell morphology, enlargement of cell size, increases in DNA content and DNA ploidy, and formation of spore-like protrusions. The expression of megakaryocyte-specific antigen (CD41a) was up-regulated, due to SiO₂ NP treatments. The correlation analysis of SiO₂ NP size with the above test bioindicators showed that the smaller the SiO₂ NPs were, the stronger effects they induced. Moreover, exposure to SiO₂ NPs induced the up-regulation of both GATA-1 and FLI-1, while the transcriptional expressions of aNF-E2 and fNF-E2 remained unchanged. The significant positive correlation of GATA-1 and FLI-1 with megakaryocytic maturation and differentiation suggested their crucial roles in the SiO₂ NP-promoted effect. The finding herein provided new insight into the potential health risk of SiO₂ NPs by perturbing the platelet-involved hematological homeostasis.

The in vivo dissolution of tricalcium silicate bone cement

This study aimed to investigate the in vivo dissolution of tricalcium silicate (Ca₃ SiO₅ , C₃ S) bone cement in the rabbit femoral defect. Results indicated that C₃ S paste directly integrated with the bone tissue without the protection of the bone-like apatite. Calcium silicate hydrate gel (C-S-H gel) and Ca(OH)₂ were the main components of C₃ S paste. The dissolution model of C₃ S paste was a mass loss rather than a decrease in volume. The initial dissolution of C₃ S paste (0 ~ 6 weeks) was greatly attributed to the release of Ca(OH)₂ , and the later dissolution (>6 weeks) was attributed to the decalcification of C-S-H gel. Although the mass of C₃ S paste could decrease by more than 19 wt % after 6 weeks of implantation, the created pores (<1 μm) were not large enough for the bone tissue to migrate into C₃ S paste. The loss of Ca ions also resulted in the transformation of SiO₄ tetrahedrons from Q¹ and Q² to Q⁰ , Q³ , and Q⁴ in C-S-H gel. Because only isolated SiO₄ tetrahedrons (Q⁰ ) and Ca ions could be absorbed by the bone tissue, C₃ S paste gradually transformed into a silica-rich gel. The fundamental reason for no decrease in volume of C₃ S paste was that the SiO₄ tetrahedron network still maintained the frame structure of C₃ S paste during the implantation.

Hinokitiol-Loaded Mesoporous Calcium Silicate Nanoparticles Induce Apoptotic Cell Death through Regulation of the Function of MDR1 in Lung Adenocarcinoma Cells

Hinokitiol is a tropolone-related compound found in heartwood cupressaceous plants. Hinokitiol slows the growth of a variety of cancers through inhibition of cell proliferation. The low water solubility of hinokitiol leads to less bioavailability. This has been highlighted as a major limiting factor. In this study, mesoporous calcium silicate (MCS) nanoparticles, both pure and hinokitiol-loaded, were synthesized and their effects on A549 cells were analyzed. The results indicate that Hino-MCS nanoparticles induce apoptosis in higher concentration loads (>12.5 μg/mL) for A549 cells. Hino-MCS nanoparticles suppress gene and protein expression levels of multiple drug resistance protein 1 (MDR1). In addition, both the activity and the expression levels of caspase-3/-9 were measured in Hino-MCS nanoparticle-treated A549 cells. The Hino-MCS nanoparticles-triggered apoptosis was blocked by inhibitors of pan-caspase, caspase-3/-9, and antioxidant agents (N-acetylcysteine; NAC). The Hino-MCS nanoparticles enhance reactive oxygen species production and the protein expression levels of caspase-3/-9. Our data suggest that Hino-MCS nanoparticles trigger an intrinsic apoptotic pathway through regulating the function of MDR1 and the production of reactive oxygen species in A549 cells. Therefore, we believe that Hino-MCS nanoparticles may be efficacious in the treatment of drug-resistant human lung cancer in the future.