Citric acid modification of a polymer exhibits antioxidant and anti-inflammatory properties in stem cells and tissues.

Biomaterials can be used as carriers of antioxidant or drug to the oxidative injury site of tissue and decrease intracellular oxidative stress levels, however, low dosage delivery or unstable molecular structure of antioxidant or drug limited the long-term sustained release. A chemically stable antioxidant molecule is essential to serve as antioxidant structure components of biomaterials that may provide the relatively high antioxidant content and persisting local antioxidant release with the degradation of materials. In this study, we used citric acid modified polyvinyl alcohol (PVA-C) as a model biomaterial to investigate the role of citric acid on the material stimulated antioxidant and anti-inflammatory effects. In cellular-based assays, PVA-C extracts showed a protective effects on bone marrow mesenchymal stem cells (BMSCs) under oxidative stress. It could enhance the antiapoptotic ability of stem cells by inhibiting reactive oxygen species. Further studies revealed that PVA-C extracts upregulated the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) and superoxide dismutase [Mn] (SOD2). in vivo animal assays, PVA-C extracts showed significant inhibitory effects on the oxidative stress and inflammatory reaction which were induced by lipopolysaccharide (LPS). These findings suggest that the citric acid modified polymer can regulate the redox signaling of stem cells and tissues by the release of citric acid from materials, leading to enhanced oxidative stress-induced degenerative diseases and inflammatory diseases therapy.

In vitro and in vivo mechanism of hepatocellular carcinoma inhibition by ß-TCP nanoparticles.

Background: Studies have showed that nanoparticles have a certain anti-cancer activity and can inhibit many kinds of cancer cells. ß-tricalcium phosphate nanoparticles (nano-ß-TCP) displays better biodegradation, but the application and mechanism of nano-ß-TCP in anti-cancer activity are still not clear. Purpose: The objective of this study was to synthesize nano-ß-TCP and investigate its inhibitory properties and mechanism on hepatocellular carcinoma (HepG2) cells in vitro and in vivo. Methods: Nano-ß-TCP was synthesized using ethanol-water system and characterized. The effects of nano-ß-TCP on cell viability, cell uptake, intracellular oxidative stress (ROS), cell cycle and apoptosis were also investigated with HepG2 cells and human hepatocyte cells (L-02). Intratumoral injection of nano-ß-TCP was performed on the xenograft liver cancer model to explore the inhibitory effect and mechanism of nano-ß-TCP on liver tumors. Results: In vitro results revealed that nano-ß-TCP caused reduced cell viability of HepG2 cells in a time-and dose-dependent manner. Nano-ß-TCP was internalized through endocytosis and degraded in cells, resulting in obvious increase of the intracellular Ca2+ and PO4 3- ions. Nano-ß-TCP induced cancer cells to produce ROS and induced apoptosis of tumor cells by an apoptotic signaling pathways both in extrinsic and intrinsic pathway. In addition, nano-ß-TCP blocked cell cycle of HepG2 cells in G0/G1 phase and disturbed expression of some related cyclins. In vivo results showed that 40 mg/kg of nano-ß-TCP had no significant toxic side effects, but could effectively suppress hepatocellular carcinoma growth. Conclusion: These findings revealed the anticancer effect of nano-ß-TCP and also clarified the mechanism of its inhibitory effect on hepatocellular carcinoma.

Magnesium phosphate based cement with improved setting, strength and cytocompatibility properties by adding Ca(H2PO4)2·H2O and citric acid.

Inorganic phosphate cements have become prevalent as bone filling materials in clinical applications, owing to beneficial properties such as self-setting, biodegradability and osteoconductivity. However, the further development of phosphate cements with higher strength and improved cytocompatibility is expected. In this paper, we reported the preparation of a novel magnesium phosphate based cement (MPBC), which has similar compositions with magnesium phosphate cement (MPC) but Ca(H2PO4)2·H2O and citric acid were additionally added to modulate the performance. The physicochemical and biological properties of MPBC were investigated, the influences of the added Ca(H2PO4)2·H2O and citric acid on the performances of MPBC were analyzed, and the differences of performance between MPBC and MPC were discussed. Experimental results show that the setting time and compressive strength of MPBC were effectively enhanced by the addition of citric acid. In vitro biological degradation indicates that about 15 wt% of MPBC was reduced in 4 weeks. Compared with MPC, MPBC has weaker alkalinity and less dissolution of phosphate, leading to better suitability for cell proliferation and adhesion. These results suggest that as a bone filling material, MPBC shows better performance than MPC in many key indicators and has promising application prospects.

Manipulating Mesenchymal Stem Cells Differentiation Under Sinusoidal Electromagnetic Fields Using Intracellular Superparamagnetic Nanoparticles.

In this study, hollow mesoporous ferrite nanoparticles (HMFNs) were prepared. It showed a spherical morphology with a diameter about 320 nm, with a negatively charged surface, and with a great superparamagnetic property. Negative charge attribute to the free -OH group of the HMFNs shell, which improved nanoparticles hydrophilic and biocompatibility. Superparamagnetic property could avoids particle agglomeration. The particles were shown to be internalized into the bone marrow mesenchymal stem cells (BMSCs) in vitro. We found that the intracellular HMFNs can improve the osteogenic differentiation of BMSCs in the presence of an electromagnetic fields. To determine the optimal intensity of the sinusoidal electromagnetic field (SEMF), the exposure levels of 50 Hz SEMF in the range of 0∼4 mTs (60 min/day) were utilized to investigate its effects on the proliferation and osteogenic differentiation of rat BMSCs. The result showed that the 1 mT and 2 mT SEMF stimulated the BMSCs proliferation significantly. The internalized HMFNs in conjunction with SEMF exposure enhanced the osteogenic differentiation, as evidenced by elevated alkaline phosphatase activity, calcium deposition, and the expression protein levels of the expression profile of osteopontin, osteocalcin and runt-related transcription factor 2. We believe that the electromagnetic fields can manipulate osteogenic differentiation of BMSCs using intracellular superparamagnetic nanoparticles.

Total Synthesis of Endolides A and B.

The total synthesis of endolides A and B has been achieved in a concise, highly stereoselective fashion (12 steps, 16.2% and 16.0% overall yields, respectively). Key features of the route include a modified Negishi coupling between 3-bromofuran and an organozinc reagent derived from an iodoalanine derivative for the synthesis of 3-(3-furyl)-alanine derivative, and a judicious choice of reaction conditions to surmount the conformational constraints placed by converting a linear peptide into the corresponding macrocycle.

Citrate reduced oxidative damage in stem cells by regulating cellular redox signaling pathways and represent a potential treatment for oxidative stress-induced diseases.

Chemical substances containing citrate such as calcium citrate, citrate esters and citric acid exhibit anti-oxidant and anti-inflammatory properties in different cells and tissues. However, data on the anti-oxidant and anti-inflammatory properties and mechanisms of action of citrate are insufficient. In this study, we systematically evaluated the anti-oxidant capacity of citrate using chemical, cellular and animal assays. Citrate showed a stable molecular structure and did not directly react with oxides. Citrate exerted protective and anti-apoptotic effects on BMSCs and also showed significant inhibitory effects on the oxidative stress and inflammatory reactions in the rat air pouch model. By using proteomics, we found that PPARγ contributed to the upregulation of various free radical scavenging proteins and the downregulation of diverse components of the inflammatory responses. Citrate-regulated global PPARγ expression was evidenced by the significant increase expression of PPARγ in PC12 cell line. Our results provide novel insights into the role of citrate in regulating cellular redox signaling and the function of PPARγ signaling in this process and also provide basic molecular cell biology information to improve the applications of biomaterials or stem cells as treatments for oxidative stress-induced degenerative diseases and inflammatory diseases.

Magnetically targeted co-delivery of hydrophilic and hydrophobic drugs with hollow mesoporous ferrite nanoparticles.

A magnetically targeted drug delivery system (DDS) is developed to solve the delivery problem of hydrophobic drugs by using hollow mesoporous ferrite nanoparticles (HMFNs). The HMFNs are synthesized by a one-pot hydrothermal method based on the Ostwald ripening process. The biocompatibility of the synthesized HMFNs was determined by MTT assay, lactate dehydrogenase (LDH) leakage assay and hemolyticity against rabbit red blood cells. Moreover, Prussian blue staining and bio-TEM observations showed that the cell uptake of nanocarriers was in a dose and time-dependent manner, and the nanoparticles accumulate mostly in the cytoplasm. A typical highly hydrophobic anti-tuberculosis drug, rifampin (RFP) was loaded into HMFNs using supercritical carbon dioxide (SC-CO2) impregnation, and the drug loading amount reached as high as 18.25 wt%. In addition, HMFNs could co-encapsulate and co-deliver hydrophobic (RFP) and hydrophilic (isoniazide, INH) drugs simultaneously. The in vitro release tests demonstrated extra sustained co-release profiles of rifampicin and isoniazide from HMFNs. Based on this novel design strategy, the co-delivery of drugs in the same carrier enables a drug delivery system with efficient enhanced chemotherapeutic effect.

A Highly Hydrophilic and Biodegradable Novel Poly(amide-imide) for Biomedical Applications.

A novel biodegradable poly(amide-imide) (PAI) with good hydrophilicity was synthesized by incorporation of l-glycine into the polymer chain. For comparison purposes, a pure PAI containing no l-glycine was also synthesized with a three-step method. In this study, we evaluated the novel PAI's thermal stability, hydrophilicity, solubility, biodegradability and ability to support bone marrow mesenchymal stem cell (BMSC) adhesion and growth by comparing with the pure PAI. The hydrophilic tests demonstrated that the novel PAI has possible hydrophilicity at a 38° water contact angle on the molecule surface and is about two times more hydrophilic than the pure PAI. Due to an extra unit of l-glycine in the novel PAI, the average degradation rate was about 2.4 times greater than that of the pure PAI. The preliminary biocompatibility studies revealed that all the PAIs are cell compatible, but the pure PAI exhibited much lower cell adhesion than the l-glycine-incorporated novel PAI. The hydrophilic surface of the novel PAI was more suitable for cell adhesion, suggesting that the surface hydrophilicity plays an important role in enhancing cell adhesion and growth.