In vivo circulation, clearance, and biodistribution of polyglycerol grafted functional red blood cells

The in vivo circulation of hyperbranched polyglycerol (HPG) grafted red blood cells (RBCs) was investigated in mice. The number of HPG molecules grafted per RBC was measured using tritium labeled HPGs (³H-HPG) of different molecular weights; the values ranged from 1 × 10⁵ to 2 × 10⁶ molecules per RBC. HPG-grafted RBCs were characterized in vitro by measuring the electrophoretic mobility, complement mediated lysis, and osmotic fragility. Our results show that RBCs grafted with 1.5 × 10⁵ HPG molecules per RBC having molecular weights 20 and 60 kDa have similar characteristics as that of control RBCs. The in vivo circulation of HPG-grafted RBCs was measured by a tail vain injection of ³H-HPG60K-RBC in mice. The radioactivity of isolated RBCs, whole blood, plasma, different organs, urine and feces was evaluated at different time intervals. The portion of ³H-HPG60K-RBC that survived the first day in mice (52%) remained in circulation for 50 days. Minimal accumulation radioactivity in organs other than liver and spleen was observed suggesting the normal clearance mechanism of modified RBCs. Animals gained normal weights and no abnormalities observed in necropsy analysis. The stability of the ester-amide linker between the RBC and HPG was evaluated by comparing the clearance rate of ³H-HPG60K-RBC and PKH-26 lipid fluorescent membrane marker labeled HPG60K-RBCs. HPG modified RBCs combine the many advantages of a dendritic polymer and RBCs, and hold great promise in systemic drug delivery and other applications of functional RBC.     

The effect of hyperbranched polyglycerol coatings on drug delivery using degradable polymer nanoparticles

A key attribute for nanoparticles (NPs) that are used in medicine is the ability to avoid rapid uptake by phagocytic cells in the liver and other tissues. Poly(ethylene glycol) (PEG) coatings has been the gold standard in this regard for several decades. Here, we examined hyperbranched polyglycerols (HPG) as an alternate coating on NPs. In earlier work, HPG was modified with amines and subsequently conjugated to poly(lactic acid) (PLA), but that approach compromised the ability of HPG to resist non-specific adsorption of biomolecules. Instead, we synthesized a copolymer of PLA–HPG by a one-step esterification. NPs were produced from a single emulsion using PLA–HPG: fluorescent dye or the anti-tumor agent camptothecin (CPT) were encapsulated at high efficiency in the NPs. PLA–HPG NPs were quantitatively compared to PLA–PEG NPs, produced using approaches that have been extensively optimized for drug delivery in humans. Despite being similar in size, drug release profile and in vitro cytotoxicity, the PLA–HPG NPs showed significantly longer blood circulation and significantly less liver accumulation than PLA–PEG. CPT-loaded PLA–HPG NPs showed higher stability in suspension and better therapeutic effectiveness against tumors in vivo than CPT-loaded PLA–PEG NPs. Our results suggest that HPG is superior to PEG as a surface coating for NPs in drug delivery.     

Influence of polymer architecture on antigens camouflage, CD47 protection and complement mediated lysis of surface grafted red blood cells

Hyperbranched polyglycerol (HPG) and polyethylene glycol (PEG) polymers with similar hydrodynamic sizes in solution were grafted to red blood cells (RBCs) to investigate the impact of polymer architecture on the cell structure and function. The hydrodynamic sizes of polymers were calculated from the diffusion coefficients measured by pulsed field gradient NMR. The hydration of the HPG and PEG was determined by differential scanning calorimetry analyses. RBCs grafted with linear PEG had different properties compared to the compact HPG grafted RBCs. HPG grafted RBCs showed much higher electrophoretic mobility values than PEG grafted RBCs at similar grafting concentrations and hydrodynamic sizes indicating differences in the structure of the polymer exclusion layer on the cell surface. PEG grafting impacted the deformation properties of the membrane to a greater degree than HPG. The complement mediated lysis of the grafted RBCs was dependent on the type of polymer, grafting concentration and molecular size of grafted chains. At higher molecular weights and graft concentrations both HPG and PEG triggered complement activation. The magnitude of activation was higher with HPG possibly due to the presence of many hydroxyl groups per molecule. HPG grafted RBCs showed significantly higher levels of CD47 self-protein accessibility than PEG grafted RBCs at all grafting concentrations and molecular sizes. PEG grafted polymers provided, in general, a better shielding and protection to ABO and minor antigens from antibody recognition than HPG polymers, however, the compact HPGs provided greater protection of certain antigens on the RBC surface. Our data showed that HPG 20kDa and HPG 60kDa grafted RBCs exhibited properties that are more comparable to the native RBC than PEG 5kDa and PEG 10kDa grafted RBCs of comparable hydrodynamic sizes. The study shows that small compact polymers such as HPG 20kDa have a greater potential in the generation of functional RBC for therapeutic delivery applications. The intermediate sized polymers (PEG or HPG) which showed greater antigen camouflage at lower grafting concentrations have significant potential in transfusion as universal red blood donor cells.     

Antibacterial effects and biocompatibility of titanium surfaces with graded silver incorporation in titania nanotubes

Most commercial dental implants are made of titanium (Ti) because Ti possesses excellent properties such as osseointegration. However, many types of Ti products still suffer from insufficient antibacterial capability and bacterial infection after surgery remains one of the most common and intractable complications. In this study, a dual process encompassing anodization and silver plasma immersion ion implantation (Ag PIII) is utilized to produce titania nanotubes (TiO₂-NTs) containing Ag at different sites and depths. The concentration and depth of the incorporated Ag can be tailored readily by changing the PIII parameters. The Ag-embedded TiO₂-NTs which retain the nanotubular morphology are capable of sterilizing oral pathogens as opposed to pure Ti plates and pristine TiO₂-NTs. Biological assays indicate that the in vitro and in vivo biocompatibility of the sample plasma-implanted at a lower voltage of 0.5 kV (NT-Ag-0.5) is significantly compromised due to the large amount of surface Ag. On the other hand, the sample implanted at 1 kV (NT-Ag-1.0) exhibits unimpaired effects due to the smaller surface Ag accumulation. Sample NT-Ag-1.0 is further demonstrated to possess sustained antibacterial properties due to the large embedded depth of Ag and the technique and resulting materials have large potential in dental implants.     

A midgut lysate of the Riptortus pedestris has antibacterial activity against LPS O-antigen-deficient Burkholderia mutants

Riptortus pedestris, a common pest in soybean fields, harbors a symbiont Burkholderia in a specialized posterior midgut region of insects. Every generation of second nymphs acquires new Burkholderia cells from the environment. We compared in vitro cultured Burkholderia with newly in vivo colonized Burkholderia in the host midgut using biochemical approaches. The bacterial cell envelope of in vitro cultured and in vivo Burkholderia differed in structure, as in vivo bacteria lacked lipopolysaccharide (LPS) O-antigen. The LPS O-antigen deficient bacteria had a reduced colonization rate in the host midgut compared with that of the wild-type Burkholderia. To determine why LPS O-antigen-deficient bacteria are less able to colonize the host midgut, we examined in vitro survival rates of three LPS O-antigen-deficient Burkholderia mutants and lysates of five different midgut regions. The LPS O-antigen-deficient mutants were highly susceptible when cultured with the lysate of a specific first midgut region (M1), indicating that the M1 lysate contains unidentified substance(s) capable of killing LPS O-antigen-deficient mutants. We identified a 17 kDa protein from the M1 lysate, which was enriched in the active fractions. The N-terminal sequence of the protein was determined to be a soybean Kunitz-type trypsin inhibitor. These data suggest that the 17 kDa protein, which was originated from a main soybean source of the R. pedestris host, has antibacterial activity against the LPS O-antigen deficient (rough-type) Burkholderia.     

Long-term biodistribution in vivo and toxicity of radioactive/magnetic hydroxyapatite nanorods

Although nanoscale hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂; HA] has been widely investigated as a carrier in the delivery of drugs, genes, or siRNA, the in vivo toxicity of nanoscale HA is not clear and the long-term dynamic distribution in vivo has not hitherto been visualized. In this work, gadolinium-doped HA nanorods (HA:Gd) with an r₁ value of 5.49 s⁻¹ (mm)⁻¹ have been prepared by a hydrothermal method. Samarium-153 (¹⁵³Sm) was then effectively post-labeled onto the HA:Gd (¹⁵³Sm-HA:Gd) with a labeling rate of ∼100% and a radio-labeling stability in vitro of ∼100% over 48 h. The product could serve as a new dual-modality probe for SPECT and MR imaging in vivo. By means of SPECT and MRI, the HA:Gd nanorods were found to be quickly taken up by the mononuclear phagocyte system, especially the liver and spleen. The nanorods in the liver and lung tended to be eliminated within 24 h, but nanorods in the spleen behaved differently and proved difficult to excrete. In vitro studies by cell transmission electron microscopy (TEM) and methyl thiazolyl tetrazolium (MTT) assay showed good biocompatibility of the HA:Gd nanorods with HeLa cells, even at a high concentration. The indicators of body weight, histology, and serology demonstrated that the HA:Gd nanorods exhibited excellent biocompatibility in vivo for at least 61 days. Therefore, ¹⁵³Sm-HA:Gd nanorods with excellent relaxivity, γ-emission, and biosafety offer clear advantages and potential for bioapplications.     

Molecular weight of polydisperse icodextrin effects its oncotic contribution to water transport

Icodextrin, a mixture of polysaccharides of alpha-(1 --> 4) polyglucopyranose having 10% branched chains, is clinically available as a D-glucose substitute for peritoneal dialysis (PD). Due to the high intraperitoneal retention time of this glucose polymer (GP), water transport from the vessels to the peritoneal cavity is prolonged even in PD patients with high peritoneal permeability. The purpose of this study was to elucidate why 7.5% icodextrin solution has such a broad distribution of molecular weights. A gel permeation chromatography study indicated that the average molecular weight was about 18.0 kDa in terms of number average (Mn) and 31.3 kDa in terms of weight average (Mw), respectively, resulting in a polydispersity index (Mn/Mw) of 1.74. Five fractions of GP having Mn values of 41.3, 19.3, 8.3, 3.8, and 2.1 kDa, respectively, produced 0.24, 0.49, 0.50, 0.08, and 0.03 mOsmol/kg H2O of colloid osmotic pressure. Water transport through a membrane having a molecular cutoff of 15 kDa was simulated using the mass transfer coefficient and reflection coefficient for each fraction. Fractions with Mn values of 19.3 and 8.3 kDa contributed to water transport dominantly (approximately 76%), while only 18%, 5%, and 3% of total water removal was contributed by fractions with Mn values of 41.3, 3.8 and 2.1 kDa, respectively. As a result of enzymatic degradation for 10 h by 2, 10, or 20 U/l alpha-amylase, a decrease in the high molecular weight zone (40-60 kDa) and a rise in the low molecular weight zone (1-2 kDa) were seen with few change in the distribution profile between 4 and 30 kDa. These results suggested that fractions in the molecular range between 8.3 and 19.3 kDa, where the distribution profile was less influenced by enzymatic degradation, preferably contributed to water transport.     

Development of curcumin loaded sodium hyaluronate immobilized vesicles (hyalurosomes) and their potential on skin inflammation and wound restoring

In the present work new highly biocompatible nanovesicles were developed using polyanion sodium hyaluronate to form polymer immobilized vesicles, so called hyalurosomes. Curcumin, at high concentration was loaded into hyalurosomes and physico-chemical properties and in vitro/in vivo performances of the formulations were compared to those of liposomes having the same lipid and drug content. Vesicles were prepared by direct addition of dispersion containing the polysaccharide sodium hyaluronate and the polyphenol curcumin to a commercial mixture of soy phospholipids, thus avoiding the use of organic solvents. An extensive study was carried out on the physico-chemical features and properties of curcumin-loaded hyalurosomes and liposomes. Cryogenic transmission electron microscopy and small-angle X-ray scattering showed that vesicles were spherical, uni- or oligolamellar and small in size (112–220 nm).The in vitro percutaneous curcumin delivery studies on intact skin showed an improved ability of hyalurosomes to favour a fast drug deposition in the whole skin. Hyalurosomes as well as liposomes were biocompatible, protected in vitro human keratinocytes from oxidative stress damages and promoted tissue remodelling through cellular proliferation and migration. Moreover, in vivo tests underlined a good effectiveness of curcumin-loaded hyalurosomes to counteract 12-O-tetradecanoilphorbol (TPA)-produced inflammation and injuries, diminishing oedema formation, myeloperoxydase activity and providing an extensive skin reepithelization. Thanks to the one-step and environmentally-friendly preparation method, component biocompatibility and safety, good in vitro and in vivo performances, the hyalurosomes appear as promising nanocarriers for cosmetic and pharmaceutical applications.     

A novel Bruch's membrane-mimetic electrospun substrate scaffold for human retinal pigment epithelium cells

Various artificial membranes have been used as scaffolds for retinal pigment epithelium cells (RPE) for monolayer reconstruction, however, long-term cell viability and functionality are still largely unknown. This study aimed to construct an ultrathin porous nanofibrous film to mimic Bruch's membrane, and in particular to investigate human RPE cell responses to the resultant substrates. An ultrathin porous nanofibrous membrane was fabricated by using regenerated wild Antheraea pernyi silk fibroin (RWSF), polycaprolactone (PCL) and gelatin (Gt) and displayed a thickness of 3–5 μm, with a high porosity and an average fiber diameter of 166 ± 85 nm. Human RPE cells seeded on the RWSF/PCL/Gt membranes showed a higher cell growth rate (p < 0.05), and a typical expression pattern of RPE signature genes, with reduced expression of inflammatory mediators. With long-term cultivation on the substrates, RPE cells exhibited characteristic polygonal morphology and development of apical microvilli. Immunocytochemisty demonstrated RPE-specific expression profiles in cells after 12-weeks of co-culture on RWSF/PCL/Gt membranes. Interestingly, the cells on the RWSF/PCL/Gt membranes functionally secreted polarized PEDF and phagocytosed labeled porcine POS. Furthermore, RWSF/PCL/Gt membranes transplanted subsclerally exhibited excellent biocompatibility without any evidence of inflammation or rejection. In conclusion, we established a novel RWSF-based substrate for growth of RPE cells with excellent cytocompatibility in vitro and biocompatibility in vivo for potential use as a prosthetic Bruch's membrane for RPE transplantation.     

Novel bilayer bacterial nanocellulose scaffold supports neocartilage formation in vitro and in vivo

Tissue engineering provides a promising alternative therapy to the complex surgical reconstruction of auricular cartilage by using ear-shaped autologous costal cartilage. Bacterial nanocellulose (BNC) is proposed as a promising scaffold material for auricular cartilage reconstruction, as it exhibits excellent biocompatibility and secures tissue integration. Thus, this study evaluates a novel bilayer BNC scaffold for auricular cartilage tissue engineering. Bilayer BNC scaffolds, composed of a dense nanocellulose layer joined with a macroporous composite layer of nanocellulose and alginate, were seeded with human nasoseptal chondrocytes (NC) and cultured in vitro for up to 6 weeks. To scale up for clinical translation, bilayer BNC scaffolds were seeded with a low number of freshly isolated (uncultured) human NCs combined with freshly isolated human mononuclear cells (MNC) from bone marrow in alginate and subcutaneously implanted in nude mice for 8 weeks. 3D morphometric analysis showed that bilayer BNC scaffolds have a porosity of 75% and mean pore size of 50 ± 25 μm. Furthermore, endotoxin analysis and in vitro cytotoxicity testing revealed that the produced bilayer BNC scaffolds were non-pyrogenic (0.15 ± 0.09 EU/ml) and non-cytotoxic (cell viability: 97.8 ± 4.7%). This study demonstrates that bilayer BNC scaffolds offer a good mechanical stability and maintain a structural integrity while providing a porous architecture that supports cell ingrowth. Moreover, bilayer BNC scaffolds provide a suitable environment for culture-expanded NCs as well as a combination of freshly isolated NCs and MNCs to form cartilage in vitro and in vivo as demonstrated by immunohistochemistry, biochemical and biomechanical analyses.     

Polycation-functionalized nanoporous silicon particles for gene silencing on breast cancer cells

Nanoporous silicon particles (pSi), with a pore size in the range of 20–60 nm, were modified with polyethyleneimine (PEI) to yield pSi–PEI particles, which were subsequently complexed with siRNA. Thus, pSi–PEI/siRNA particles were fabricated, with the PEI/siRNA nanocomplexes mainly anchored inside the nanopore of the pSi particles. These hybrid particles were used as carriers to deliver siRNA to human breast cancer cells. Due to the gradual degradation of the pSi matrix under physiological conditions, the PEI/siRNA nanocomplexes were released from the pore interior in a sustained manner. Physicochemical characterization revealed that the released PEI/siRNA nanocomplexes exhibited well-defined spherical shape and narrow particle size distribution between 15 and 30 nm. Gene knockdown against the ataxia telangiectasia mutated (ATM) cancer gene showed dramatic gene silencing efficacy. Moreover, comprehensive biocompatibility studies were performed for the pSi–PEI/siRNA particles both in vitro and in vivo and demonstrated that the pSi–PEI particles exhibited significantly enhanced biocompatibility. As a consequence, PEI-modified porous silicon particles may have substantial potential as safe and effective siRNA delivery systems.     

Specific lipase-responsive polymer-coated gadolinium nanoparticles for MR imaging of early acute pancreatitis

Currently, available methods for diagnosis of acute pancreatitis (AP) are mainly dependent on serum enzyme analysis and imaging techniques that are too low in sensitivity and specificity to accurately and promptly diagnose AP. The lack of early diagnostic tools highlights the need to search for a highly effective and specific diagnostic method. In this study, we synthesized a conditionally activated, gadolinium-containing, nanoparticle-based MRI nanoprobe as a diagnostic tool for the early identification of AP. Gadolinium diethylenetriaminepentaacetic fatty acid (Gd-DTPA-FA) nanoparticles were synthesized by conjugation of DTPA-FA ligand and gadolinium acetate. Gd-DTPA-FA exhibited low cytotoxicity and excellent biocompatibility when characterized in vitro and in vivo studies. L-arginine induced a gradual increase in the intensity of the T1-weighted MRI signal from 1 h to 36 h in AP rat models. The increase in signal intensity was most significant at 1 h, 6 h and 12 h. These results suggest that the Gd-DTPA-FA as an MRI contrast agent is highly efficient and specific to detect early AP.     

含糖透析液对慢性腹膜透析大鼠腹膜功能及间皮细胞形态的影响

目的:探讨含糖透析液对慢性大鼠腹膜透析模型腹膜功能和腹膜间皮细胞形态的影响及它们之间的关系。方法:40只SD大鼠随机分为4组,除对照组外,余3组每天分别腹腔内注入20mL4.25%透析液(HG)、1.5%透析液(LG)、林格氏液(RG)。8周后进行腹膜功能试验,并行细胞印片进行形态学分析。结果:HG组及LG组腹腔内透出液量和净出超量明显低于对照组和RG组(P<0.01),4h透析液与血浆尿素氮浓度之比(D/P_urea)显著高于对照组和RG组(P<0.05),尿素氮清除率(C_urea)显著低于对照组和RG组(P<0.01)。细胞印片上HG组及LG组间皮细胞的细胞密度显著少于对照组和RG组,表面积显著大于对照组和RG组(P<0.01)。但以上改变在HG组及LG组间无显著差异。使用含糖透析液8周所致的腹膜超滤功能下降和间皮细胞肥大呈负相关(r=-0.896,P<0.05)。结论:长期应用含糖透析液可使腹膜超滤功能下降,这一作用可能与腹膜间皮细胞肥大有关。     

Striatal shape in Parkinson's disease

Parkinson's disease (PD) is marked pathologically by nigrostriatal dopaminergic terminal loss. Histopathological and in vivo labeling studies demonstrate that this loss occurs most extensively in the caudal putamen and caudate head. Previous structural studies have suggested reduced striatal volume and atrophy of the caudate head in PD subjects. The spatial distribution of atrophy in the putamen, however, has not been characterized. We aimed to delineate the specific locations of atrophy in both of these striatal structures. T1- and T2-weighted brain MR (3T) images were obtained from 40 PD and 40 control subjects having no dementia and similar age and gender distributions. Shape analysis was performed using doubly segmented regions of interest. Compared to controls, PD subjects had lower putamen (p = 0.0003) and caudate (p = 0.0003) volumes. Surface contraction magnitudes were greatest on the caudal putamen (p ≤ 0.005) and head and dorsal body of the caudate (p ≤ 0.005). This spatial distribution of striatal atrophy is consistent with the known pattern of dopamine depletion in PD and may reflect global consequences of known cellular remodeling phenomena.     

Prostate stem cell antigen antibody-conjugated multiwalled carbon nanotubes for targeted ultrasound imaging and drug delivery

Multiwalled carbon nanotubes (MWCNTs) are cut short and grafted with polyethylenimine (PEI) for further covalent conjugation to fluorescein isothiocyanate (FITC) and prostate stem cell antigen (PSCA) monoclonal antibody (mAb). The in vitro and in vivo toxicity data reveal that the as-prepared CNT-PEI(FITC)-mAb has good biocompatibility. Combined flow cytometry and confocal luminescence imaging experiments confirm that the CNT-PEI(FITC)-mAb can specifically target the cancer cells which overexpress PSCA. The results of in vitro and in vivo ultrasound (US) imaging indicate that CNT-PEI(FITC)-mAb has great potential to be used as a targeted US contrast agent. The in vivo anti-cancer efficacy testing using PC-3 tumor-bearing mice as animal models demonstrates that CNT-PEI(FITC)-mAb can targetedly deliver drug to the tumors and suppress tumor growth. Findings from this study suggest that the CNT-PEI(FITC)-mAb could be used as a multifunctional platform for simultaneous US imaging and drug delivery applications.     

Release behavior and intra-articular biocompatibility of celecoxib-loaded acetyl-capped PCLA-PEG-PCLA thermogels

In this study, we investigated the in vitro and in vivo properties and performance of a celecoxib-loaded hydrogel based on a fully acetyl-capped PCLA-PEG-PCLA triblock copolymer. Blends of different compositions of celocoxib, a drug used for pain management in osteoarthritis, and the acetyl-capped PCLA-PEG-PCLA triblock copolymer were mixed with buffer to yield temperature-responsive gelling systems. These systems containing up to 50 mg celecoxib/g gel, were sols at room temperature and converted into immobile gels at 37 °C. In vitro, release of celecoxib started after a ∼10-day lag phase followed by a sustained release of ∼90 days. The release was proven to be mediated by polymer dissolution from the gels. In vivo (subcutaneous injection in rats) experiments showed an initial celecoxib release of ∼30% during the first 3 days followed by a sustained release of celecoxib for 4–8 weeks. The absence of a lag phase and the faster release seen in vivo were likely due to the enhanced celecoxib solubility in biological fluids and active degradation of the gel by macrophages. Finally, intra-articular biocompatibility of the 50 mg/g celecoxib-loaded gel was demonstrated using μCT-scanning and histology, where no cartilage or bone changes were observed following injection into the knee joints of healthy rats. In conclusion, this study shows that celecoxib-loaded acetyl-capped PCLA-PEG-PCLA hydrogels form a safe drug delivery platform for sustained intra-articular release.     

Extracellular matrix deposition of bone marrow stroma enhanced by macromolecular crowding

Decellularized extracellular matrices (ECM) from in vitro cell cultures can serve as in vivo-like matrix scaffolds for modulating cell-ECM interactions. Macromolecular crowding (MMC), the supplementation of synthetic or naturally occurring molecules resulting in excluded volume effects (EVE), has been demonstrated to provide valuable options for recapitulating the physiological environment of cells during matrix secretion. Human mesenchymal stem cell (MSC)-derived ECM was produced upon supplementation of standard culture medium with three different macromolecules of various size (10–500 kDa). Matrix secretion, ECM morphology and composition were compared for matrices obtained from crowded and non-crowded MSC cultures. In the context of generating functional stem cell niches, the MSC-derived bone marrow mimetic ECM scaffolds were tested for their supportive effect to maintain and expand human hematopoietic stem and progenitor cells (HSPC) in vitro. MMC in combination with metabolic stimulation of MSC was found to result in tissue-specific, highly organized ECM capable of retaining glycosaminoglycans and growth factors to effectively build in vitro microenvironments that support HSPC expansion.     

Multifunctional PEG-GO/CuS nanocomposites for near-infrared chemo-photothermal therapy

The synergistic therapy, the combination of photothermal therapy and chemotherapy, has become a potential treatment in the battles with cancer. Here, we developed a synergistic therapy tool that based on CuS nanoparticles-decorated graphene oxide functionalized with polyethylene glycol (PEG-GO/CuS) for cervical cancer treatment. The as-synthesized PEG-GO/CuS nanocomposites with excellent biocompatibility was revealed to have high storage capacity for anticancer drug of doxorubicin (Dox) and high photothermal conversion efficiency, and were effectively employed for the ablation of tumor. In addition, the therapeutic efficacy of Dox-loaded PEG-GO/CuS (PEG-GO/CuS/Dox) nanocomposites was evaluated in vitro and in vivo for cervical cancer therapy. In vitro cell cytotoxicity tests of PEG-GO/CuS/Dox demonstrate about 1.3 and 2.7-fold toxicity than PEG-GO/CuS and free Dox under 5 min irradiation with NIR laser at 1.0 W/cm², owing to both PEG-GO/CuS-mediated photothermal ablation and cytotoxicity of light-triggered Dox release. In mouse models, mouse cervical tumor growth was found to be significantly inhibited by the chemo-photothermal effect of PEG-GO/CuS/Dox nanocomposites, resulting in effective tumor reduction. Overall, compared with chemotherapy or photothermal therapy alone, the combined treatment demonstrates better therapeutic efficacy of cancer in vitro and in vivo. These findings highlight the promise of the highly versatile multifunctional nanoparticles in biomedical application.     

上调表达Smad7显著抑制TGF-β介导的大鼠腹膜间皮细胞Smad2的表达

目的： 探讨外源性转入并上调表达抑制性信号蛋白Smad7对TGF-β₁作用下大鼠腹膜间皮细胞Smad2表达的影响。 方法： 通过脂质体介导的方法，将表达Smad7的重组质粒（PCDNA3-Smad7）转染培养的大鼠腹膜间皮细胞，分别培养于不同浓度TGF-β₁培养液(0、1.25、2.5和10 μg/L)，用RT-PCR及Western blotting的方法检测不同时间（0、5、15、30、60和120 min）Smad2、Smad7表达的水平。 结果： 正常间皮细胞Smad2 mRNA和蛋白在TGF-β₁刺激后5 min开始表达，呈时间依赖性，在30 min达到高峰，而后逐渐减弱；Smad7 mRNA和蛋白也在TGF-β₁刺激后5 min可见表达，但此后逐渐减弱，30 min达到最低，60 min又开始逐渐增强。Smad2 和Smad7 mRNA和蛋白，随TGF-β₁浓度的增高而表达增强。转染后大鼠腹膜间皮细胞可见Smad7 mRNA和蛋白表达显著上调，并可持续高表达。转染后的腹膜间皮细胞在TGF-β₁刺激下，Smad2 mRNA及蛋白的表达均低下，刺激0、5、15、30、60 和120 min后Smad2 mRNA表达分别低33%、56%、67%、71%、63%和57%（P<0.05）。Smad2蛋白表达分别低78%、89%、89%、88%和76%（P<0.05）。 结论： 上调表达抑制性信号蛋白Smad7可显著抑制腹膜间皮细胞中受体调控信号蛋白Smad2的表达和活性，提示Smad7可能对TGF-β₁起反向调控作用。     

Bioactivity and circulation time of PEGylated NELL-1 in mice and the potential for osteoporosis therapy

Osteoporosis is a progressive bone disease due to low osteoblast activity and/or high osteoclast activity. NELL-1 is a potential therapy for osteoporosis because it specifically increases osteoblast differentiation. However, similar to other protein drugs, the bioavailability of NELL-1 may be limited by its in vivo half-life and rapid clearance from body. The purpose of the present study is to prolong NELL-1 circulation time in vivo by PEGylation with three monomeric PEG sizes (5, 20, 40 kDa). While linear PEG 5k yielded the most efficient PEGylation and the most thermally stable conjugate, linear PEG 20k resulted in the conjugate with the highest M_w and longest in vivo circulation. Compared to non-modified NELL-1, all three PEGylated conjugates showed enhanced thermal stability and each prolonged the in vivo circulation time significantly. Furthermore, PEGylated NELL-1 retained its osteoblastic activity without any appreciable cytotoxicity. These findings motivate further studies to evaluate the efficacy of PEGylated NELL-1 on the prevention and treatment of osteoporosis.