An injectable bioactive poly(γ-glutamic acid) modified magnesium phosphate bone cement for bone regeneration.

As potential alternatives for calcium phosphate bone cements, magnesium phosphate bone cements (MPC) have attracted considerable attention in recent years. However, their several defects, such as rapid setting times, highly hydration temperature and alkaline pH due to the part of the unreacted phosphate, restricted their applications in human body. With aim to overcome these defects, a novel polypeptite poly(γ-glutamic acid) (γ-PGA) modified MPC were developed. Effect of γ-PGA content on the injectability, anti-washout ability, setting times, hydration temperature, mechanical compressive strength, in vitro bioactivity and degradation were investigated. Moreover, in vitro cyto-compatibility was evaluated using MC3T3-E1 cells by CCK-8 and Live/Dead staining. All these results indicated that the 10%PGA-MPC with an improved handling performances, low hydration temperature, high mechanical compressive strength, and good cyto-compatibility hold a great potential for bone repair and regeneration.

Synthesis, characterization, and in vitro anti-tumor activity studies of the hyaluronic acid-mangiferin-methotrexate nanodrug targeted delivery system.

In this study, to increase the accumulation of MTX in the tumor site and reduce the toxicity to normal tissues by MA, a novel nano-drug delivery system comprised of hyaluronic acid (HA)-mangiferin (MA)-methotrexate (MTX) (HA-MA-MTX) was developed by a self-assembly strategy. The advantage of the nano-drug delivery system is that MTX can be used as a tumor-targeting ligand of the folate receptor (FA), HA can be used as another tumor-targeting ligand of the CD44 receptor, and MA serves as an anti-inflammatory agent. 1HNMR and FT-IR results confirmed that HA, MA, and MTX were well coupled together by the ester bond. DLS and AFM images revealed that the size of HA-MA-MTX nanoparticles was about ~138 nm. In vitro cell experiments proved that HA-MA-MTX nanoparticles have a positive effect on inhibiting K7 cancer cells while having relatively lower toxicity to normal MC3T3-E1 cells than MTX does. All these results indicated that the prepared HA-MA-MTX nanoparticles can be selectively ingested by K7 tumor cells through FA and CD44 receptor-mediated endocytosis, thus inhibiting the growth of tumor tissues and reducing the nonspecific uptake toxicity caused by chemotherapy. Therefore, these self-assembled HA-MA-MTX NPs could be a potential anti-tumor drug delivery system.

Validation of the polarized Monte Carlo model of shipborne oceanic lidar returns.

The polarized Monte Carlo (PMC) model has been applied to study the backscattering measurement of oceanic lidar. This study proposes a PMC model for shipborne oceanic lidar simulation. This model is validated by the Rayleigh scattering experiment, lidar equation, and in-situ lidar LOOP (Lidar for Ocean Optics Profiler) returns [Opt. Express30, 8927 (2022)10.1364/OE.449554]. The relative errors of the simulated Rayleigh scattering results are less than 0.07%. The maximum mean relative error (MRE) of the simulated single scattering scalar signals and lidar equation results is 30.94%. The maximum MRE of simulated total scattering signals and LOOP returns in parallel and cross channels are 33.29% and 22.37%, respectively, and the maximal MRE of the depolarization ratio is 24.13%. The underwater light field of the laser beam is also simulated to illustrate the process of beam energy spreading. These results prove the validity of the model. Further analyses show that the measured signals of shipborne lidar LOOP are primarily from the particle single scatterings. This model is significant for analyzing the signal contributions from multiple scattering and single scattering.

Demonstrating the Interfacial Polymer Thermal Transition from Coil-to-Globule to Coil-to-Stretch under Shear Flow Using SFG and MD Simulation.

Revealing interfacial shear-induced structural responsiveness has long been an important topic in that most fluids in nature and human life are in motion and cause interesting boundary phenomena. It is amazing how the polymer chain conformation or local structural features at a boundary change under the effective shear condition. In this study, microfluidic-assisted sum frequency generation (SFG) vibrational spectroscopy and all-atom molecular dynamics (MD) simulation are combined to reveal that the shear flow can effectively block the so-called thermal coil-to-globule transition of the poly(N-isopropylacrylamide) (PNIPAM) brushes on the solid substrate, and the normal coil-to-globule transition transfers to a coil-to-stretch one under shear flow with increasing ambient temperature. Such findings are attributed to the balance between the shear flow and the molecular interaction with respect to the polymer chains and adjacent water molecules, thus demonstrating the significant effect of the shear flow on the structural and dynamic behaviors of the polymer chains at the boundaries from the molecular level.

3D-Printed Degradable Anti-Tumor Scaffolds for Controllable Drug Delivery.

In this study, porous polylactic acid/methotrexate (PLA/MTX) scaffolds were successfully fabricated by three-dimensional (3D) printing technology as controllable drug delivery devices to suppress tumor growth. Scanning electron microscopy and energy-dispersive spectrometer confirmed that MTX drug was successfully incorporated into the PLA filament. 3D-printed PLA/MTX scaffolds allow sustained release of drug molecules in vitro for more than 30 days, reducing systemic toxic side effects caused by injection or oral administration. In vitro cytotoxicity assay revealed that PLA/MTX scaffolds have a relatively high inhibitory effect on the tumor cells (MG-63, A549, MCF-7, and 4T1) and relatively low toxic effect on the normal MC3T3-E1 cells. Furthermore, results of in vivo experiments confirmed that PLA/MTX scaffolds highly suppressed tumor growth and no obvious side effects on the organs. All these results suggested that 3D-printed PLA/MTX scaffolds could be used as controllable drug delivery systems for tumor suppression.

Preparation, characterization and in vitro antitumor activity evaluation of hyaluronic acid-alendronate-methotrexate nanoparticles.

As an anti-metabolic drug, methotrexate (MTX) plays an important role in the treatment of various malignant tumors. However, several side effects such as low selectivity and high toxic of MTX limited its further applications. With aims to increase its accumulation in the tumor sites and reduce the toxicity of normal tissue nonspecific uptake, a self-assembled hyaluronic acid-alendronate-methotrexate nanoparticle (HA-ALN-MTX NPs) with a dual-tumor-targeted drug loaded system was designed and synthesized with an average particle size of 265.6 ± 13.3 nm. The advantage of this nanosystem is that the anticancer drug MTX can be used as a tumor-targeted ligand for folate acid receptors (FA), and hyaluronic acid (HA) can be used as another tumor targeted ligand for CD44 receptors. In vitro experiments confirmed that HA-ALN-MTX NPs has lower toxic effect on normal tissue cells HUVECs and has relatively high proliferation inhibition effect on tumor cells A549. Moreover, the inhibition effect could be adjusted by altering the dose of given drugs. All these results revealed that the prepared HA-ALN-MTX NPs could be selectively taken up by tumor cells by FA and CD44 receptor-mediated endocytosis. Therefore, self-assembled HA-ALN-MTX NPs targeted by these FA/CD44 receptors for anticancer drugs could act as effective antitumor drugs.

TREM-1-targeting LP17 attenuates cerebral ischemia-induced neuronal injury by inhibiting oxidative stress and pyroptosis.

Stroke ranks as the second leading cause of disability and death globally. Trigger receptors expressed on myeloid cells (TREM) -1 are responsible for the activation of the innate immune response and also play a critical role in inflammation. In this study, we reported the contribution of TREM-1 after ischemic damage in a rat middle cerebral artery occlusion (MCAO) model. This study also demonstrated that TREM-1 expression was upregulated following cerebral infarction in rats. TREM-1 inhibition was determined using its selective inhibitor, LP17, which indicated a neuroprotective effect on cerebral infarction damage. The findings revealed that inhibition of TREM-1 by administering LP17 improved cerebral damage and decreased ischemic areas and brain water contents. Moreover, LP17 decreased MCAO-induced microglial activation and neurodegeneration, evidenced by a reduction in the expression of microglial Iba-1 and FJ-B positive cells, and reversed neuronal loss. Besides, the contribution of LP17 to ischemic neuronal damage may be associated with a decrease in the production of pro-inflammatory cytokines, and enhanced production of anti-inflammatory cytokine IL-10. Both in vivo and in vitro studies showed that inhibiting TREM-1 attenuated ROS accumulation, lipid per-oxidation (LPO) contents such as malondialdehyde (MDA) and enhanced the superoxide dismutase (SOD) activity after ischemia. Inhibiting TREM-1 alleviated inflammation and pyroptosis found in MCAO rats. This was achieved through the inhibition of the levels of NLRP3, caspase-1, ASC (an apoptosis-associated speck-like protein containing a CARD) and gasdermin D. These results confirmed that inhibiting TREM-1 protects against ischemia-induced neuronal damage and alleviates microglial mediated neuro-inflammation by reducing oxidative stress and pyroptosis. Therefore, blocking TREM-1 expression provides an effective intervention for improving ischemic stroke.

Memantine ameliorates tau protein deposition and secondary damage in the ipsilateral thalamus and sensory decline following focal cortical infarction in rats.

Previous studies have reported that memantine presents evidence of therapeutic benefits in several animal models of ischemic stroke and neurodegenerative diseases. However, the effect of memantine on secondary damage in the ipsilateral thalamus after focal cortical infarction remains undefined. Present study investigated whether memantine has a protective effect on secondary damage in the ipsilateral thalamus after focal cerebral infarction in rats. At 24 h after distal middle cerebral artery occlusion (MCAO), rats in the memantine and vehicle groups were intraperitoneal injected with memantine and isopycnic vehicle, respectively, was once daily administered for consecutive 7 days. Infarct size was evaluated through Nissl staining and sensory decline determined using adhesive removal test. Secondary thalamic damage was assessed using Nissl staining and immunofluorescence 8 days after MCAO. Immunoboltting was used to identify tau and apoptosis-associated proteins in the ipsilateral thalamus after MCAO. Results revealed that memantine ameliorated sensory decline compared to the vehicle controls. Subsequently, tau phosphorylated at threonine 231 (p-tau-231), glycogen synthase kinase3ßpY216 (GSK3ßpY216) and protein phosphatase 2A (PP2ApY307) were reduced by memantine, causing greater reduction in neuronal loss and inhibition of reactive astrogliosis in the ipsilateral ventroposterior thalamic nucleus (VPN) compared with the vehicle groups. In addition, increase in secondary damage-induced TUNEL-positive cells was blunted by memantine, as demonstrated by the significant reduction in expression of apoptosis-associated proteins. Our results suggest that memantine has a neuro-protective effect on secondary damage in the ipsilateral thalamus following MCAO by inhibiting the activity of GSK3ßpY216/PP2ApY307 and down regulating the levels of p-tau-231 protein.

Loss of BMP signaling mediated by BMPR1A in osteoblasts leads to differential bone phenotypes in mice depending on anatomical location of the bones.

Bone morphogenetic protein (BMP) signaling in osteoblasts plays critical roles in skeletal development and bone homeostasis. Our previous studies showed loss of function of BMPR1A, one of the type 1 receptors for BMPs, in osteoblasts results in increased trabecular bone mass in long bones due to an imbalance between bone formation and bone resorption. Decreased bone resorption was associated with an increased mature-to-immature collagen cross-link ratio and mineral-matrix ratios in the trabecular compartments, and increased tissue-level biomechanical properties. Here, we investigated the bone mass, bone composition and biomechanical properties of ribs and spines in the same genetically altered mouse line to compare outcomes by loss of BMPR1A functions in bones from different anatomic sites and developmental origins. Bone mass was significantly increased in both cortical and trabecular compartments of ribs with minimal to modest changes in compositions. While tissue-levels of biomechanical properties were not changed between control and mutant animals, whole bone levels of biomechanical properties were significantly increased in association with increased bone mass in the mutant ribs. For spines, mutant bones showed increased bone mass in both cortical and trabecular compartments with an increase of mineral content. These results emphasize the differential role of BMP signaling in osteoblasts in bones depending on their anatomical locations, functional loading requirements and developmental origin.

Analysis of bisphosphonate using ultraviolet-visible spectroscopy based on modified phosphorus determination reagent.

An improved phosphorous determination was developed using ethanol, phosphorus determination reagent (PDR) and Ultraviolet-visible spectroscopy (UV-Vis) for analyzing the bisphosphonates (BPs). The method was carried out under mild conditions without digestion, high temperature, high pressure, and other extreme conditions. Alcohols played an important role in this method. Without alcohol, this reaction system did not have a color reaction. Alendronate (ALN) and risedronate (RIS) were used to demonstrate the reliability of the improved phosphorous determination under different reaction conditions. The absorbance had an equal ratio of increase as well as a good trend line when the content of BPs increased. The improved phosphorous determination could be a new method to measure the drug content of BPs.

Inhibition of Caspase-1 Ameliorates Ischemia-Associated Blood-Brain Barrier Dysfunction and Integrity by Suppressing Pyroptosis Activation.

Ischemic cerebral infarction represents a significant cause of disability and death worldwide. Caspase-1 is activated by the NLRP3/ASC pathway and inflammasomes, thus triggering pyroptosis, a programmed cell death. In particular, this death is mediated by gasdermin D (GSDMD), which induces secretion of interleukin (IL)-1ß and IL-18. Accordingly, inhibition of caspase-1 prevents the development and worsening of multiple neurodegenerative diseases. However, it is not clear whether inhibition of caspase-1 can preserve blood-brain barrier (BBB) integrity following cerebral infarction. This study therefore aimed at understanding the effect of caspase-1 on BBB dysfunction and its underlying mechanisms in permanent middle cerebral artery occlusion (MCAO). Our findings in rat models revealed that expression of caspase-1 was upregulated following MCAO-induced injury in rats. Consequently, pharmacologic inhibition of caspase-1 using vx-765 ameliorated ischemia-induced infarction, neurological deficits, and neuronal injury. Furthermore, inhibition of caspase-1 enhanced the encapsulation rate of pericytes at the ischemic edge, decreased leakage of both Evans Blue (EB) and matrix metalloproteinase (MMP) proteins, and upregulated the levels of tight junctions (TJs) and tissue inhibitors of metalloproteinases (TIMPs) in MCAO-injured rats. This in turn improved the permeability of the BBB. Meanwhile, vx-765 blocked the activation of ischemia-induced pyroptosis and reduced the expression level of inflammatory factors such as caspase-1, NLRP3, ASC, GSDMD, IL-1ß, and IL-18. Similarly, vx-765 treatment significantly reduced the expression levels of inflammation-related receptor for advanced glycation end products (RAGE), high-mobility family box 1 (HMGB1), mitogen-activated protein kinase (MAPK), and nuclear factor-κB (NF-κB). Evidently, inhibition of caspase-1 significantly improves ischemia-associated BBB permeability and integrity by suppressing pyroptosis activation and the RAGE/MAPK pathway.

3D printed porous PLA/nHA composite scaffolds with enhanced osteogenesis and osteoconductivity in vivo for bone regeneration.

Repair and regeneration of large bone defects is still a challenge, especially for defects which are the irregular and complex. Three-dimension (3D) printing, as an advanced fabrication technology, has been received considerable attentions due to its high precision, customized geometry and personalization. In this study, 3D porous polylactic acid/nano hydroxyapatite (PLA/nHA) composite scaffolds with enhanced osteogenesis and osteoconductivity were successfully fabricated by desktop fused deposition modeling technology. Morphological, composition and structural analysis revealed that nHA was successfully introduced into the PLA system and homogeneously dispersed in the printed PLA/nHA scaffolds. In vitro antibacterial experiment confirmed that the printed porous PLA/nHA scaffolds have good ability for loading and releasing vancomycin and levofloxacin. Meanwhile, MG-63 cells were used to evaluate the cytocompatibility of printed porous PLA/nHA scaffolds by proliferation and cellular morphological analysis. In addition, rabbit model was established to evaluate the osteogenesis and osteoconductivity of printed PLA/nHA scaffolds. All these results suggested that the 3D printed PLA/nHA scaffolds have great potential for repairing and regeneration of large bone defects.

The association between vascular endothelial growth factor gene polymorphisms and stroke: A PRISMA-compliant meta-analysis.

BACKGROUND: Numerous studies showed that vascular endothelial growth factor (VEGF) gene polymorphisms were linked with the regularity of stroke, but the results remained controversial. The aim of this meta-analysis was to determine the associations between VEGF gene polymorphisms and the risk of stroke. METHODS: A systematic literature search of PubMed, Embase, Wed of Science, The Cochrane Library, Elsevier, China National Knowledge Infrastructure, China Biology Medicine disc, WanFang Data, VIP Database for Chinese Technical Periodicals, and Science paper Online was conducted. Two authors independently assessed trial quality and extracted data. The pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of associations. Begger funnel plot and Egger test were used to estimate the publication bias of included studies. Heterogeneity assumption was assessed by Cochran Chi-squared-based Q-statistic test and I test. RESULTS: Thirteen publications including 23 trails with a total of 3794 stroke patients and 3094 control subjects were enrolled. About 3747 cases and 2868 controls for +936C/T, 2134 cases and 1424 controls for -2578C/A, and 2187 cases and 1650 controls for -1154G/A were examined, respectively. The results indicated that VEGF +936C/T (T vs C, OR = 1.19, 95% CI = 1.01-1.40) or -2578C/A (A vs C, OR = 1.13, 95% CI = 1.02-1.27) was positively associated with the risk of stroke, whereas there was no association between -1154G/A (A vs G, OR = 0.99, 95% CI = 0.87-1.11) polymorphism and stroke risk in our study. Among the subgroup analyses on ethnicity, the results showed that VEGF +936C/T was an increased risk of stroke in Asian population (T vs C, OR = 1.21, 95% CI = 1.01-1.44), but not -1154G/A. CONCLUSION: Our findings suggest that VEGF +936C/T and -2578C/A might be related to the risk of stroke, especially in the Asian population, but not -1154G/A.

Preparation and Characterization of Biomimetic Hydroxyapatite Nanocrystals by Using Partially Hydrolyzed Keratin as Template Agent.

Hydroxyapatite (HA), a typical inorganic component of bone, is a widely utilized biomaterial for bone tissue repair and regeneration due to its excellent properties. Inspired by the recent findings on the important roles of protein in biomineralization and natural structure of fish scales, keratin was chosen as a template for modulating the assembly of HA nanocrystals. A series of HA nanocrystals with different sizes were synthesized by adjusting the concentration of partially hydrolyzed keratin. The structure and compositions of the prepared HA were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectrum, and Transmission electron microscopy (TEM). Results revealed that the size of the synthesized HA nanocrystals can be controlled by adjusting the concentration of partially hydrolyzed keratin. Specifically, the size of synthesized HA decreased from 63 ± 1.5 nm to 27 ± 0.9 nm with the increasing concentration of partially hydrolyzed keratin from 0 to 0.6g. In addition, in vitro cytocompatibility of synthesized HA nanocrystals were evaluated using the MG-63 cells.

Bone-targeted methotrexate-alendronate conjugate inhibits osteoclastogenesis in vitro and prevents bone loss and inflammation of collagen-induced arthritis in vivo.

Rheumatoid arthritis (RA), a disease that causes joint destruction and bone erosion, is related to osteoclast activity. RA is generally treated with methotrexate (MTX). In this study, a MTX-Alendronate (ALN) conjugate was synthesized and characterized. The conjugate dramatically inhibited osteoclast formation and bone resorption compared with MTX and ALN used alone or in combination. Due to the characteristics of ALN, the MTX-ALN conjugate can adhere to the exposed bone surface and enhance drug accumulation in the pathological region for targeted therapy against osteoclastogenesis. Additionally, MTX was rapidly released in the presence of lysozyme under mildly acidic conditions, similar to inflammatory tissue and osteoclast-surviving conditions, which contributes to inflammatory inhibition; this was confirmed by the presence of pro-inflammatory cytokines. Our study highlights the use of the MTX-ALN conjugate as a potential therapeutic approach for RA by targeting osteoclastogenesis.

Fabrication of strontium/calcium containing poly(γ-glutamic acid) - organosiloxane fibrous hybrid materials for osteoporotic bone regeneration.

Recent researches have proved that combination of several therapeutic metal ions, such as silicate (Si), calcium (Ca), strontium (Sr) and so on, with biomaterials may have promising effects for stimulating bone regeneration. In the present study, the Sr/Ca containing silicate hybrid materials (Sr/Ca-γ-PGA-silica) with a mimetic native extracellular matrix (ECM) structure have been developed by electrospinning. With the aim to promote the solubility of γ-PGA in aqueous-based solution and introduce Sr/Ca elements into the prepared hybrid materials, SrCO3 and CaCO3 were employed due to their nontoxicity and no by-products during chemical reaction between γ-PGA and SrCO3/CaCO3. Results of SEM, EDX and elemental mapping images showed that Sr and Ca have been successfully incorporated into the prepared fibrous hybrid materials with homogeneous dispersion. Results of ICP-AES revealed that there was continuous Si, Sr and Ca ion release behavior of Sr/Ca-γ-PGA-silica hybrid materials in Tris-HCl buffer solution and the Si ions release rate can be tailored by adjusting the molar ratio of Sr to Ca. Immersion of Sr/Ca-γ-PGA-silica hybrid materials in a simulated body fluid (SBF) resulted in the formation of an apatite-like surface layer within 3 days, indicating their excellent bioactivity. In addition, the prepared Sr/Ca-γ-PGA-silica hybrid materials supported the proliferation and alkaline phosphatase (ALP) activity of osteoblast in vitro, showing their good biocompatibility. Altogether, the results indicated that the prepared Sr/Ca-γ-PGA-silica hybrid materials with an adjusted ionic release behavior have great potential for providing an excellent ECM for osteoporotic bone regeneration.

Periosteum Extracellular-Matrix-Mediated Acellular Mineralization during Bone Formation.

Cell-mediated mineralization is essential for bone formation and regeneration. In this study, it is proven that extracellular matrix (ECM) of decellularized periosteum can play an initiative and independent role in bone-like apatite formation. Using decellularized periosteum scaffold, it is revealed that ECM scaffold itself can promote critical bone defect regeneration and nude mouse ectopic ossification. The natural collagen matrix of decellularized periosteum can serve as a 3D structural template for Ca-P nuclei initiation, controlling the size and orientation of bone-like mineral crystals. The naturally cross-linked and highly ordered 3D fibrillar network of decellularized periosteum not only provides a model for mimicking mineralization in vitro and in vivo to elucidate the important functions of ECM in bone formation and regeneration, but also can be a promising biomaterial for bone tissue engineering and clinical application.

Anti-tumor Study of Chondroitin Sulfate-Methotrexate Nanogels.

Self-assembly nanogels (NGs) were formed by bioconjugating methotrexate (MTX) with chondroitin sulfate (CS). MTX-CS NGs can greatly enhance the solubility and improve the delivery efficacy of MTX due to the CD44 binding property of CS. Vivo experiments revealed that MTX-CS NGs showed less toxicity than MTX. MTX-CS NGs can improve the anti-tumor effect while reducing the side effects of MTX. Due to their CD44 binding property, chondroitin sulfate-drug conjugates could be a promising and efficient platform for improving the solubility of sparingly soluble drug molecules as well as targeted delivery to cancer cells and tumor tissues.

Time-Resolved Study of Nanomorphology and Nanomechanic Change of Early-Stage Mineralized Electrospun Poly(lactic acid) Fiber by Scanning Electron Microscopy, Raman Spectroscopy and Atomic Force Microscopy.

In this study, scanning electron microscopy (SEM), Raman spectroscopy and high-resolution atomic force microscopy (AFM) were used to reveal the early-stage change of nanomorphology and nanomechanical properties of poly(lactic acid) (PLA) fibers in a time-resolved manner during the mineralization process. Electrospun PLA nanofibers were soaked in simulated body fluid (SBF) for different periods of time (0, 1, 3, 5, 7 and 21 days) at 10 °C, much lower than the conventional 37 °C, to simulate the slow biomineralization process. Time-resolved Raman spectroscopy analysis can confirm that apatites were deposited on PLA nanofibers after 21 days of mineralization. However, there is no significant signal change among several Raman spectra before 21 days. SEM images can reveal the mineral deposit on PLA nanofibers during the process of mineralization. In this work, for the first time, time-resolved AFM was used to monitor early-stage nanomorphology and nanomechanical changes of PLA nanofibers. The Surface Roughness and Young's Modulus of the PLA nanofiber quantitatively increased with the time of mineralization. The electrospun PLA nanofibers with delicate porous structure could mimic the extracellular matrix (ECM) and serve as a model to study the early-stage mineralization. Tested by the mode of PLA nanofibers, we demonstrated that AFM technique could be developed as a potential diagnostic tool to monitor the early onset of pathologic mineralization of soft tissues.