Pro-osteogenic role of interleukin-22 in calcific aortic valve disease

BACKGROUND AND AIMS

Although calcific aortic valve disease (CAVD) is a common valvular disease among elderly populations and its incidence has markedly increased in recent decades, the pathogenesis of CAVD remains unclear. In this study, we explored the potential role of interleukin (IL)-22 and the underlying molecular mechanism in CAVD.

METHODS AND RESULTS

Our results showed that IL-22 was upregulated in calcific aortic valves from CAVD patients, and its main sources were CD3+ T cells and CD68+ macrophages. Human aortic valve interstitial cells (VICs) expressed the IL-22-specific receptor IL-22R1, and IL-22R1 expression also was elevated in calcified valves. Treatment of cultured human VICs with recombinant human IL-22 resulted in markedly increased expression of osteogenic proteins Runt-related transcription factor 2 (RUNX2) and alkaline phosphatase (ALP), as well as increased matrix calcium deposition. Moreover, siRNA silencing of IL-22R1 blocked the pro-osteogenic effect of IL-22 in VICs. In IL-22-treated VICs, we also observed increased phosphorylation of JAK3 and STAT3 and nuclear translocation of STAT3. Pretreatment with a specific JAK3 inhibitor, WHIP-154, or siRNA knockout of STAT3 effectively mitigated the IL-22-induced osteoblastic trans-differentiation of human VICs.

CONCLUSIONS

Together, these data indicate that IL-22 promotes osteogenic differentiation of VICs by activating JAK3/STAT3 signaling. Based on our results demonstrating a pro-osteogenic role of IL-22 in human aortic valves, pharmacological inhibition of IL-22 signaling may represent a potential strategy for alleviating CAVD.

Enhancing Osteoblastic Cell Cultures with Gelatin Methacryloyl, Bovine Lactoferrin, and Bioactive Mesoporous Glass Scaffolds Loaded with Distinct Parsley Extracts

The increasing interest in innovative solutions for addressing bone defects has driven research into the use of Bioactive Mesoporous Glasses (MBGs). These materials, distinguished by their well-ordered mesoporous structure, possess the capability to accommodate plant extracts with well-established osteogenic properties, including bovine lactoferrin (bLF), as part of their 3D scaffold composition. This harmonizes seamlessly with the ongoing advancements in the field of biomedicine. In this study, we fabricated 3D scaffolds utilizing MBGs loaded with extracts from parsley leaves (PL) and embryogenic cultures (EC), rich in bioactive compounds such as apigenin and kaempferol, which hold potential benefits for bone metabolism. Gelatin Methacryloyl (GelMa) served as the polymer, and bLF was included in the formulation. Cytocompatibility, Runx2 gene expression, ALP enzyme activity, and biomineralization were assessed in preosteoblastic MC3T3-E1 cell cultures. MBGs effectively integrated PL and EC extracts with loadings between 22.6 ± 0.1 and 43.6 ± 0.3 µM for PL and 26.3 ± 0.3 and 46.8 ± 0.4 µM for EC, ensuring cell viability through a release percentage between 28.3% and 59.9%. The incorporation of bLF in the 3D scaffold formulation showed significant differences compared to the control in all assays, even at concentrations below 0.2 µM. Combinations, especially PL + bLF at 0.19 µM, demonstrated additive potential, with superior biomineralization compared to EC. In summary, this study highlights the effectiveness of MBGs in incorporating PL and EC extracts, along with bLF, into 3D scaffolds. The results underscore cytocompatibility, osteogenic activity, and biomineralization, offering exciting potential for future in vivo applications.

Self-Calibrating Lanthanide Infinite Coordination Polymer Constructs Fluorescent Probes: A Sensitive Approach for Early Diagnosis of Hepatocellular Carcinoma and Environmental Analysis

The development of a self-calibrating ratio fluorescence probe without the need for additional substrates is a major advancement in biosensing. In this study, at room temperature, a self-calibrating infinite coordination polymer (SSA-Tb-ATP ICPs) has been proposed by self-assembling adenosine triphosphate (ATP) with 5-sulfosalicylic acid (SSA) and Tb3+. Due to the antenna effect, SSA-Tb-ATP ICPs exhibited strong green fluorescence emission of Tb3+ (at 547 nm) and blue fluorescence emission of SSA (at 407 nm). This material offers several advantages over existing detection methods, including simplicity of synthesis and exceptional sensitivity. Our self-calibrating SSA-Tb-ATP ICPs demonstrated excellent performance in detecting alkaline phosphatase (ALP) and phosphate (Pi) in both serum and environmental samples with detection limits of 0.076 U/L and 0.025 μM, respectively. Moreover, we successfully employed the SSA-Tb-ATP ICPs to perform cellular imaging of ALP in both hepatocellular carcinoma cells (HepG2) and normal liver cells (LO2), representing a significant advancement in ALP detection and imaging. The simplicity of the synthesis and high sensitivity make this probe a promising tool for early diagnosis of hepatocellular carcinoma in clinical settings and environment analysis.

Calcium phosphate cement with minocycline hydrochloride-loaded gelatine microspheres for peri-implantitis treatment

OBJECTIVES

This study aimed to fabricate an antibacterial calcium phosphate cement (CPC) with minocycline hydrochloride (MINO)-loaded gelatine microspheres (GMs) as a local drug delivery system for the treatment of peri‑implantitis.

METHODS

CPC/GMs(MINO), incorporating MINO-loaded GMs into CPC, was developed and characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD), and drug release profiling. The antibacterial activity against Porphyromonas gingivalis and Fusobacterium nucleatum was evaluated. Bone mesenchymal stem cells (BMSCs) were cultured in the extracts of the developed cements to evaluate osteoinductivity in vitro. Furthermore, a rabbit femoral model was established to evaluate osteogenic ability in vivo.

RESULTS

SEM and XRD confirmed the porous structure and chemical stability of CPC/GMs(MINO). The release profile showed a sustained release of MINO from CPC/GMs(MINO), reaching an equilibrium state on the 14th day with a cumulative release ratio of approximately 84%. For antibacterial assays, the inhibition zone of CPC/GMs(MINO) was 3.67 ± 0.31 cm for P. gingivalis and 7.47 ± 0.50 cm for F. nucleatum. Most bacteria seeded on CPC/GMs(MINO) died after 24 h of culture. In addition, CPC/GMs(MINO) significantly enhanced alkaline phosphatase activity, osteogenic gene expression, and BMSC mineralisation compared with CPC/GMs and the control group (P < 0.05). The in vivo results showed that CPC/GMs(MINO) possessed a higher quality and quantity of bone formation and maturation than CPC/GMs and CPC.

CONCLUSIONS

CPC/GMs(MINO) showed excellent antibacterial activity against pathogens associated with peri‑implantitis and demonstrated good osteoinductivity and osteogenic ability.

CLINICAL SIGNIFICANCE

Peri-implantitis is among the most common and challenging biological complications associated with dental implants. In this study, MINO-loaded GMs were incorporated into CPC, which endowed the composite cement with excellent antibacterial and osteogenic abilities, demonstrating its potential as a bone graft substitute for treating peri‑implantitis.

An osteogenic magnesium alloy with improved corrosion resistance, antibacterial, and mechanical properties for orthopedic applications

The aim of this study was to develop a novel biodegradable magnesium (Mg) alloy for bone implant applications. We used scandium (Sc; 2 wt %) and strontium (Sr; 2 wt %) as alloying elements due to their high biocompatibility, antibacterial efficacy, osteogenesis, and protective effects against corrosion. In the present work, we also examined the effect of a heat treatment process on the properties of the Mg-Sc-Sr alloy. Alloys were manufactured using a metal casting process followed by heat treatment. The microstructure, corrosion, mechanical properties, antibacterial activity, and osteogenic activity of the alloy were assessed in vitro. The results showed that the incorporation of Sc and Sr elements controlled the corrosion, reduced the hydrogen generation, and enhanced mechanical properties. Furthermore, alloying with Sc and Sr demonstrated a significantly enhanced antibacterial activity and decreased biofilm formation compared to control Mg. Also, culturing Mg-Sc-Sr alloy with human bone marrow-derived mesenchymal stromal cells showed a high degree of biocompatibility (>90% live cells) and a significant increase in osteoblastic differentiation in vitro shown by Alizarin red staining and alkaline phosphatase activity. Based on these results, the Mg-Sc-Sr alloy heat-treated at 400°C displayed optimal mechanical properties, corrosion rate, antibacterial efficacy, and osteoinductivity. These characteristics make the Mg-Sc-Sr alloy a promising candidate for biodegradable orthopedic implants in the fixation of bone fractures such as bone plate-screws or intramedullary nails.

Recent Advancements in Developments of Novel Fluorescent Probes: In Cellulo Recognitions of Alkaline Phosphatases

Alkaline phosphatase (ALP) is one of the vital phospho-ester bond cleaving biocatalysts that has inevitable significance in cellular systems, viz., early-stage osteoblast differentiation, cell integrity in tissues, bone mineralization, cancer biomarker, liver dysfunction, cellular osmotic pressure, protein folding and many more. Variation from optimal levels of ALP in intra and extracellular fluids can cause severe diseases, including death. Due to these reasons, ALP is considered as a vital biomarker for various preclinical and medical diagnosis. Fluorescence image-based diagnosis is the most widely used method, owing to its simplicity, robustness, non-invasive properties and excellent spatio-temporal resolution (up to the nM/pM level), as compared to conventional analytical techniques, such as the electroanalytical method, nuclear magnetic resonance (NMR) and high-performance liquid chromatography (HPLC). Most of the reviews reported for ALP’s recognition in the literature scarcely explain the structurally related, photophysical and biophysical parameters; and the sub-cellular localizations. Considering these facts, in order to enhance the opto-analytical parameters of fluorescence-based diagnostic materials at the cellular level, herein we have systematically documented recent developments in the opto-analytical capabilities of quencher-free probes for ALP, used in in vitro (biological buffers) to in cellulo conditions, along with in vivo models.

Brightness Analysis per Moving Particle: In Situ Analysis of Alkaline Phosphatase in Living Cells

In situ quantitative analysis of enzymes such as phosphatase is important to understand a number of involved biological processes ranging from various metabolisms to signal transduction and cellular regulation. In this paper, a novel in situ measurement strategy was proposed to detect alkaline phosphatase (ALP) activity in different locations within single living cells. The principle is based on the measurement of the resonance light scattering brightness ratio (SBR) per moving nanoparticle that forms in an ALP-related chemical reaction. In the method, a novel resonance light scattering correlation spectroscopy (RLSCS) system was developed using two lasers for illumination or two detection channels. Using the gold nanoparticles (AuNPs) as probes, the Au@Ag nanoparticles (Au@Ag NPs) formed due to the ALP-catalyzed hydrolysis of ascorbic acid 2-phosphate (AAP) and the subsequent reduction-deposition reaction of Ag ions that occurred on the AuNPs. The SBR value per moving particle was determined based on the obtained RLS intensity traces and RLSCS curves. The SBR value was found to be not influenced by the intracellular viscosity and size that was confirmed in the experiments. The linear relation between the SBR and ALP activity was established and applied to detect ALP activity and evaluate the inhibition of different drugs. Finally, the method was successfully used to in situ measure ALP activity within living cells. The method overcomes the shortcoming of conventional methods that lack quantitative analysis and are susceptible to intracellular viscosity.

Selective Detection of an Infection Biomarker by an Osteo-Friend Scaffold: Development of a Multifunctional Artificial Bone Substitute

Developments in three-dimensional (3D) printing technologies have led to many potential applications in various biomedical fields, especially artificial bone substitutes (ABSs). However, due to the characteristics of artificial materials, biocompatibility and infection remain issues. Here, multifunctional ABSs have been designed to overcome these issues by the inclusion of a biochemical modality that allows simultaneous detection of an infection biomarker by osteo-friend 3D scaffolds. The developed multifunctional scaffolds consist of calcium-deficient hydroxyapatite (CDHA), which has a similar geometric structure and chemical composition to human bone, and gold nanoparticles (Au NPs), which assists osteogenesis and modulates the fluorescence of labels in their microenvironment. The Au NPs were subsequently conjugated with fluorescent dye-labeled probe DNA, which allowed selective interaction with a specific target biomarker, and the fluorescent signal of the dye was temporally quenched by the Au NP-derived Förster resonance energy transfer (FRET). When the probe DNA unfolded to bind to the target biomarker, the fluorescence signal was recovered due to the increased distance between the dye and Au NPs. To demonstrate this sensing mechanism, a microbial oligonucleotide was selected as a target biomarker. Consequently, the multifunctional scaffold simultaneously facilitated osteogenic proliferation and the detection of the infection biomarker.

Effect of ethanol consumption during pregnancy and lactation on bone histomorphometry and in vitro osteogenic differentiation of bone marrow mesenchymal stem cells in maternal rats

This study aimed to evaluate the effect of maternal ethanol consumption during gestation and lactation on bone mass and osteogenic differentiation of mesenchymal stem cells of the bone marrow (BMMSCs) in rats. Thirteen adult Wistar rats were used. The rats were mated, and after confirmation of gestation, (day 0) they were distributed in two groups: the control group and the ethanol-treated group. From the ninth day of gestation, the rats of the ethanol and control groups were administered 40% alcoholic solution (4 g ethanol/kg) and distilled water, respectively, daily via gavage until the thirtieth day of lactation. The BMMSCs were extracted from the right femurs and tibiae and cultured using an osteogenic medium for 7, 14, and 21 days. The conversion of MTT to formazan crystals, alkaline phosphatase activity, and percentages of cells per field were analyzed. The number of mineralized nodules per field was examined, and quantification of the gene transcripts for osteopontin, osteocalcin, and BMP-2 was evaluated on day 21 by real-time RT-PCR. Morphometric evaluations of the percentage of trabecular bone and cortical thickness in the left femur and tibia were performed. The means were compared by the Student's t-test, and the differences were considered significant if p < 0.05. The BMMSCs of the rats that consumed ethanol during gestation and lactation, when subjected to osteogenic differentiation in vitro, demonstrated higher conversion of MTT to formazan, higher alkaline phosphatase activity, a higher percentage of cells per field, higher expression of BMP-2, and higher synthesis of mineralized nodules when compared to those of control rat cells. However, there was no significant difference in the percentage of trabecular bone or cortical thickness between both groups. Hence, the consumption of ethanol during pregnancy and lactation did not alter the trabecular and cortical bone tissues of the femur and tibia compared with that of pregnant and lactating control rats that did not consume alcohol, despite BMMSCs showing higher osteogenic differentiation under in vitro conditions.

Timosaponin BII improved osteoporosis caused by hyperglycemia through promoting autophagy of osteoblasts via suppressing the mTOR/NFκB signaling pathway

Defective autophagy occurred in osteoblasts under stress induced by high glucose and played an essential role in the development of diabetic osteoporosis. Timosaponin BII, a steroidal saponin isolated from the rhizomes of Anemarrhena asphodeloides Bunge, possessed anti-osteoporosis properties. In this study, we investigated the efficacy and mechanism of timosaponin BII on diabetic osteoporosis. Timosaponin BII attenuated the deterioration in the microarchitecture of the tibias in diabetic rats. Furthermore, treatment with timosaponin BII dose-dependently reduced hyperglycemia-induced cell apoptosis in primary osteoblasts from rat calvaria. High glucose-exposed osteoblasts exhibited increased mitochondrial superoxide level, decreased mitochondrial membrane potential and impaired autophagic flux, which was attenuated by timosaponin BII, as evidenced by the upregulation of autophagosome numbers, LC3B puncta formation and Beclin1 expression. The antiapoptotic and antioxidative effect of timosaponin BII were repressed by the autophagy inhibitor 3-methyladenine and enhanced by the autophagy inducer rapamycin. Further studies showed that timosaponin BII suppressed the phosphorylation of mTOR and S6K, as well as the downstream factors NFκB and IκB, consequently activating autophagy and decreasing apoptosis. Of note, coincubation of timosaponin BII with MHY1485, a pharmacological activator of mTOR, diminished the protein expression of Bcl2 induced by timosaponin BII, which was in parallel with decreased autophagy and increased phosphorylation of NFκB and IκB. Overexpression of NFκB reduced timosaponin BII-evoked autophagy and promoted apoptosis. The in vivo results showed that oral administration of timosaponin BII downregulated the phosphorylation of mTOR and NFκB and upregulated Beclin1 expression in the proximal tibias of diabetic rats. These results suggested that timosaponin BII attenuated high glucose-induced oxidative stress and apoptosis through activating autophagy by inhibiting mTOR/NFκB signalling in osteoblasts.

Surface topography and free energy regulate osteogenesis of stem cells: effects of shape-controlled gold nanoparticles

The surface free energy of a biomaterial plays an important role in the early stages of cell-biomaterial interactions, profoundly influencing protein adsorption, interfacial water accessibility, and cell attachment on the biomaterial surface. Although multiple approaches have been developed to engineer the surface free energy of biomaterials, systematically tuning their surface free energy without altering other physicochemical properties remains challenging. In this study, we constructed an array of chemically-equivalent surfaces with comparable apparent roughness through assembly of gold nanoparticles adopting various geometrically-distinct shapes but all capped with the same surface ligand, (1-hexadecyl)trimethylammonium chloride, on cell culture substrates. We found that bone marrow stem cells exhibited distinct osteogenic differentiation behaviours when interacting with different types of substrates comprising shape-controlled gold nanoparticles. Our results reveal that bone marrow stem cells are capable of sensing differences in the nanoscale topographical features, which underscores the role of the surface free energy of nanostructured biomaterials in regulating cell responses. The study was approved by Institutional Animal Care and Use Committee, School of Medicine, University of South Carolina.

A colorimetric alkaline phosphatase biosensor based on p-aminophenol-mediated growth of silver nanoparticles

Alkaline phosphatase (ALP) is an enzyme that catalyzes the dephosphorylation of proteins, nucleic acids, and biomolecules. It is a potential biomarker for diverse diseases such as breast cancer, osteopenia, and hepatobiliary. Herein, we developed a colorimetric sensor for the ALP assay based on its enzymatic activity to dephosphorylate the p-aminophenol phosphate (pAPP) into pAP. In a solution containing silver nanoparticles (AgNPs) and Ag⁺ ions prepared using a low concentration of NaBH₄, pAP mediates the growth of AgNPs by reducing the concentration of Ag⁺ ions to enhance the intensity of localized surface plasmon resonance as the pAPP cannot induce a reduction of the remaining Ag⁺ due to the masking of the hydroxyl with phosphate. The quantitative assay of the ALP was demonstrated via the colorimetric detection of the pAP-mediated growth of AgNPs in the presence of an ALP. The highly sensitive enzymatic growth of AgNPs provided a wider dynamic linear range of 0.5-225 U/L with a lower limit of detection of 0.24 U/L than that previously reported. The use of pAP resulted in excellent selectivity of the sensor for the ALP assay in human serum, yielding a high recovery rate and a high precision of 99.2 ± 1.5 % for the standard addition method.

Effects of Different Doses of Calcium on the Mitochondrial Apoptotic Pathway and Rho/ROCK Signaling Pathway in the Bone of Fluorosis Rats

For this study, we investigate more deeply the effect calcium (Ca) develops on the mechanism underlying fluoride-triggered osteocyte apoptosis. We detected the morphology of osteocytes by HE staining, mitochondrial microstructure by using the transmission electron microscope, and the biochemical indexes related to bone metabolism and the expression of apoptosis-related genes. These results showed that NaF brought out the reduced osteocytes and ruptured mitochondrial outer membrane, with a significantly increased StrACP activity by 10.414 IU/L at the 4th week (P < 0.05), markedly upregulating the mRNA expression of Bax, Cyto-C, Apaf-1, caspase-7, ROCK-1, BMP-2, and BGP (P < 0.01), as well as caspase-6 (P < 0.05), while downregulating Bcl-2 by 61.3% (P < 0.01). Through immunohistochemical analysis, we also found that NaF notably increased the protein expression of ROCK-1 (P < 0.05) and Cyto-C, BMP-2, and BGP (P < 0.01), suggesting that NaF triggered the activation of the mitochondrial apoptotic pathway and Rho/ROCK signaling pathway. Nevertheless, 1% Ca supplementation in diet notably enhanced the mRNA expression of Bcl-2 by 39.3% (P < 0.01), thus blocking the increment of the expression of mitochondrial apoptotic pathway-related genes and ROCK-1. Meanwhile, Ca could attenuate the StrACP activity by 10.741 IU/L at the 4th week (P < 0.05) and protect the integrity of the mitochondrial outer membrane. These findings strongly suggest that 1% Ca abated the mitochondrial apoptosis pathway by increasing the anti-apoptotic gene Bcl-2 expression, and effectively inhibited the hyper-activation of ROCK-1, dually protecting the structural integrity of the mitochondrial outer membrane and maintaining normal cellular metabolic function.

Solid-Supported Amplification of Aggregation Emission: A Tetraphenylethylene-Cucurbit[6]uril@Hydroxyapatite-Based Supramolecular Sensing Assembly for the Detection of Spermine and Spermidine in Human Urine and Blood

The development of sensitive and selective tools for the detection and quantification of biomarkers is important in the diagnosis and treatment of clinical diseases. Spermine (SP) and spermidine (SPD) act as biomarkers for early-stage diagnosis of cancer in humans as their increased levels in urine are indicative of abnormal biological processes associated with this fatal disease. In this study, we introduced a strategy for solid-supported amplification of the effective aggregation-induced-emission (AIE) effect of a water-soluble tetraphenylethylene (TPE)-based probe in developing a supramolecular sensing platform for the rapid, sensitive, and selective detection of SP and SPD in water. The nonemissive TPE derivative (TPEHP) forms a less emissive conjugate with hydroxyl cucurbit[6]uril (CB[6]OH) in water, which undergoes several-fold enhancement of effective emission upon electrostatic interaction with the solid surface of hydroxyapatite nanoparticles (HAp NPs), dispersed in the aqueous media. The corresponding three-component supramolecular assembly disrupts by the intrusion of SP and SPD in the CB[6] portal because of the stronger binding ability with CB[6], resulting in a turn-off fluorescence sensor for SP and SPD with enhanced sensitivity. The assembly-disassembly-based sensing mechanism was thoroughly demonstrated by carrying out isothermal titration calorimetry (ITC), spectroscopic, and microscopic experiments. The sensing system showed low limits of detection (LODs) of 1.4 × 10^-8 and 3.6 × 10^-8 M for SP and SPD, respectively, which are well below the required range for the early diagnosis of cancer. Besides, a good linear relationship was obtained for both SP and SPD. Nominal interference from various metal ions, anions, common chemicals, amino acids, and other biogenic amines makes this sensing platform suitable for the real-time, low-level measurement of spermine (and spermidine) in human urinary and blood samples.

Bifunctional MIL-53(Fe) with pyrophosphate-mediated peroxidase-like activity and oxidation-stimulated fluorescence switching for alkaline phosphatase detection

Alkaline phosphatase (ALP) is extensively used as a clinical biomarker because of its close relevance with a variety of diseases. Thus, exploring reliable and practical methods for ALP analysis is of great significance. In the present work, we explored MIL-53(Fe) as a bifunctional platform with pyrophosphate (PPi)-mediated peroxidase-like activity and oxidation-stimulated fluorescence switching for ALP sensing. The proposed MIL-53(Fe) could exhibit favorable peroxidase-mimicking activity to catalytically decompose H2O2 to hydroxyl radicals, which had strong oxidizing ability to oxidize the terephthalic acid bridging ligand, resulting in the oxidation-stimulated turn-on fluorescence of MIL-53(Fe) itself. Due to the strong coordination interaction between PPi and Fe3+, the former with a relatively large molecular structure was able to inhibit the catalytic activity of MIL-53(Fe) via capping active Fe3+ sites, leading to the suppression of its self-fluorescence response. When ALP was present, it could hydrolyze the PPi inhibitor and restore the dual functions of MIL-53(Fe) to provide fluorescence again. With the above principle, highly sensitive and selective determination of ALP with a linear scope of 2-80 U L-1 and a detection limit down to 0.7 U L-1 was achieved. The MIL-53(Fe) was also demonstrated to be very reliable in measuring the target in human serum, indicating its great promise as an integrated tool for ALP detection in clinical practice.

Effects of novel non-thermal atmospheric plasma treatment of titanium on physical and biological improvements and in vivo osseointegration in rats

Titanium (Ti) has achieved extensive applications due to its excellent biocompatibility and mechanical properties. Plasma can enhance surface hydrophilia of Ti with decreased carbon contamination. The traditional conditions using a single gas plasma was for longer treatment time and more prone to being contaminated. We designed and developed novel and universal apparatus and methods with a special clamping device of non-thermal atmospheric plasma (NTAP) treatment using mixed gas for Ti surface activation. We systematically and quantitatively investigated the effective effects of NTAP-Ti. The surface water contact angle decreased by 100%, the carbon content decreased by 80% and oxygen content increased by 50% in the novel NTAP-Ti surfaces. NTAP treatment accelerated the attachment, spread, proliferation, osteogenic differentiation and mineralization of MC3T3-E1 mouse preosteoblasts in vitro. The percentage of bone-to-implant contact increased by 25–40%, and the osteoclasts and bone resorption were suppressed by 50% in NTAP-Ti in vivo. In conclusion, NTAP-Ti substantially enhanced the physical and biological effects and integration with bone. The novel and universal apparatus and methods with a special clamping device using gas mixtures are promising for implant activation by swiftly and effectively changing the Ti surface to a hydrophilic one to enhance dental and orthopedic applications.

Smart Surface-Enhanced Resonance Raman Scattering Nanoprobe for Monitoring Cellular Alkaline Phosphatase Activity during Osteogenic Differentiation

High-efficiency induction of bone marrow mesenchymal stem cells (BMSCs) to osteogenic differentiation in vitro can help solve a series of bone diseases such as bone injury, fracture repair, and osteoporosis. In order to explore the optimal conditions for different chemical inducers to promote BMSCs differentiation and the possible differentiation mechanisms, we developed a smart nanoprobe that can achieve in situ alkaline phosphatase (ALP) activity detection during osteogenic differentiation in cells. The smart nanoprobe (Au@BCIP) was designed as the surface decoration of gold nanoparticles (AuNPs) with 5-bromo-4-chloro-3-indolyl phosphate (BCIP). The nanoprobe was co-cultured with differentiated BMSCs at different stages to monitor ALP activity based on an ALP-catalyzed hydrolysis reaction with BCIP as a substrate. The product can be quickly oxidized by dissolved oxygen to obtain a Raman-active species (5,5'-dibromo-4,4'-dichloro-1H,1H-[2,2'] biindolylidene-3,3'-dione). The SERS sensitivity was greatly improved by resonating the excitation wavelength of 632.8 nm. It is a new strategy for tracing bone disease-related ALP activity in an in vivo model with high sensitivity and selectivity and non-invasion. By using this nanoprobe, osteogenic differentiation of cells under osteogenic supplements was assessed and the p38 MAPK signaling pathway for osteogenic differentiation was experimentally evidenced, which are of significance for understanding BMSCs and regulating their osteogenic differentiation process.

Zingerone Promotes Osteoblast Differentiation Via MiR-200c-3p/smad7 Regulatory Axis in Human Bone Mesenchymal Stem Cells

BACKGROUND Osteoblast differentiation is a critical process to maintain the stability of the bone homeostasis. Zingerone, 4-(4-hydroxy-3-methoxyphenyl)-2-butanone (ZG), isolated from ginger, performs a wide range of biological functions in human diseases. The objective of this paper was to clarify the role of ZG in human bone mesenchymal stem cells (hBMSCs) and associated mechanisms of ZG promoting osteoblast differentiation. MATERIAL AND METHODS The cytotoxicity of ZG was detected by MTT assay. The expression levels of miR-200c-3p, smad7, and osteoblast differentiation markers (alkaline phosphatase [ALP], osteocalcin [OC], osterix [OSX] and runt-related transcription factor 2 [RUNX2]) were assessed by quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of smad7, ALP, OC, OSX, and RUNX2 were quantified by western blot analysis. The target mRNAs were predicted by bioinformatics tools TargetScan. The interaction between miR-200c-3p and smad7 was verified by luciferase reporter assay and RIP assay. RESULTS ZG was nontoxic to hBMSCs, and it accelerated osteoblast differentiation by inducing the expression of ALP, OC, OSX, and RUNX2. MiR-200c-3p was upregulated, but smad7 was downregulated in hBMSCs treated with ZG at different concentrations at different periods. Besides, miR-200c-3p positively regulated the expression of ALP, OC, OSX, and RUNX2 in ZG-induced hBMSCs. Moreover, miR-200c-3p targeted smad7 and strengthened the expression of ALP, OC, OSX, and RUNX2 in ZG-induced hBMSCs by downregulating smad7. CONCLUSIONS ZG contributed to osteoblast differentiation via miR-200c-3p/smad7 regulatory axis by promoting the expression of ALP, OC, OSX, and RUNX2 in hBMSCs.

A signal amplification strategy for prostate specific antigen detection via releasing oxidase-mimics from coordination nanoparticles by alkaline phosphatase

A novel signal amplification method for prostate specific antigen (PSA) is developed by freeing fluorescein with photoinduced oxidase-like activity from coordination nanoparticles (CNPs) in the presence of alkaline phosphatase (ALP). CNPs loaded with fluorescein (F@CNPs) are obtained in aqueous solution by self-assembly using Tb³⁺ as metal ion, guanosine monophosphate (5'-GMP) as ligand, and fluorescein as signal molecule. The F@CNPs display outstanding properties of simple synthesis, low cost, good water solubility, negligible leakage and satisfactory load capacity. Fluorescein is quantitatively encapsulated in CNPs with a binding ratio of 92.72%. Meanwhile, ALP can specifically hydrolyze the phosphate group of 5'-GMP ligand, triggering the destruction of F@CNPs and leakage of fluorescein. Fluorescein, a photoinduced oxidase mimic, can catalyze the oxidation of non-fluorescent Amplex UltraRed (AUR) into fluorescent resorufin under LED lamp. This strategy exhibits good sensitivity for ALP detection. In addition, a new immunoassay for PSA is validated by labelling ALP on PSA antibody. The low detection limit of 0.04 ng mL^-1 in detecting PSA is appropriate for PSA detection in real samples. Therefore, the work not only establishes a new strategy for ALP and PSA determination, but also provides a new conception for putting photoinduced oxidase-like fluorescein in practical application.

The effect of phospho-peptide on the stability of gold nanoparticles and drug delivery

BACKGROUND

Gold nanoparticles (AuNPs) have been proposed for many applications in medicine and bioanalysis. For use in all these applications, maintaining the stability of AuNPs in solution by suppressing aggregation is paramount. Herein, the effects of amino acids were investigated in stabilizing AuNPs by rationally designed peptide scaffolds.

RESULTS

Compared to other tested amino acids, phosphotyrosine (pY) significantly stabilized AuNPs. Our results indicated that pY modified AuNPs presented a high level of stability in various solutions, and had good biocompatibility. When a pY-peptide was used in stabilizing AuNPs, the phosphate group could be removed by phosphatases, which subsequently caused the aggregation and the cargo release of AuNPs. In vitro study showed that AuNPs formed aggregation in a phosphatase concentration depending manner. The aggregation of AuNPs was well correlated with the enzymatic activity (R² = 0.994). In many types of cancer, a significant increase in phosphatases has been observed. Herein, we demonstrated that cancer cells treated with pY modified AuNPs in conjunction with doxorubicin killed SGC-7901 cells with high efficiency, indicating that the pY peptide stabilized AuNPs could be used as carriers for targeted drug delivery.

CONCLUSION

In summary, pY peptides can act to stabilize AuNPs in various solutions. In addition, the aggregation of pY-AuNPs could be tuned by phosphatase. These results provide a basis for pY-AuNPs acting as potential drug carriers and anticancer efficacy.

A review on emerging principles and strategies for colorimetric and fluorescent detection of alkaline phosphatase activity

Alkaline phosphatase (ALP) is a natural enzyme that is able to catalyze the dephosphorylation of phosphate esters. It participates in a great number of biological processes ranging from various metabolisms to signal transduction and cellular regulation. Since the abnormality of ALP activity in body is closely associated with many diseases, it has become an important biomarker for clinical diagnosis and treatment. Besides, it is often utilized in enzyme-linked immunosorbent assays. Given these demands, in the last few years considerable interest has been focused on exploring new materials and methods for ALP activity detection. In this review, we first made a clear classification on the principles that could be used for ALP activity determination. After that, emerging colorimetric and fluorescent strategies designed on the basis of these principles were systematically summarized. Finally, some perspectives on ALP activity analysis were discussed, hoping to inspire future efforts in the field.

Tanshinone IIA exerts beneficial effects on fracture healing in vitro and in vivo

BACKGROUND

Fracture healing is a very important process after fracture. Tanshinone IIA (Tan IIA) has been reported to possess beneficial impact on osteoblasts growth. Our study investigated the effects of Tan IIA on fracture healing.

METHODS

In vitro, mouse pre-osteoblast MC3T3-E1 cells were treated with Tan IIA. Then, the protein levels of Runx2, Osx, Collagen I, JNK and c-Jun, alkaline phosphatase (ALP) activity and calcium deposition were detected, respectively. Furthermore, the roles of microRNA-424 (miR-424) and Bone morphogenetic protein 2 (BMP-2) in Tan IIA-caused MC3T3-E1 cell differentiation were probed. In vivo, mice open osteotomy at femur diaphysis model was established. The callus area, callus intensity, low-density bone volume/callus total volume (BV1/TV), tissue mineral density (TMD) and bone mineral density (BMD) were tested.

RESULTS

In vitro, Tan IIA promoted MC3T3-E1 cell differentiation via increasing the Runx2, Osx and collagen I expression, along with enhancing ALP activity and calcium deposition. In addition, Tan IIA activated JNK pathway in MC3T3-E1 cells, while inhibition of JNK pathway mitigated the Tan IIA-caused MC3T3-E1 cell differentiation. Moreover, Tan IIA declined the miR-424 expression in MC3T3-E1 cells. Overexpression of miR-424 also weakened the Tan IIA-caused MC3T3-E1 cell differentiation. BMP-2 was a target gene of miR-424. BMP-2 silence reversed the Tan IIA-caused activation of JNK pathway. In vivo, Tan IIA increased the callus area, callus intensity, BV1/TV, TMD and BMD.

CONCLUSION

Tan IIA could promote fracture healing. In vitro, Tan IIA promoted MC3T3-E1 cell differentiation might be via down-regulating miR-424, up-regulating BMP-2 and then activating JNK pathway.

Genotype-phenotype relationship in a large cohort of osteogenesis imperfecta patients with COL1A1 mutations revealed by a new scoring system

BACKGROUND

Osteogenesis imperfecta (OI), a heritable bone fragility disorder, is mainly caused by mutations in COL1A1 gene encoding α1 chain of type I collagen. This study aimed to investigate the COL1A1 mutation spectrum and quantitatively assess the genotype-phenotype relationship in a large cohort of Chinese patients with OI.

METHODS

A total of 161 patients who were diagnosed as OI in Department of Endocrinology of Peking Union Medical College Hospital from January 2010 to December 2017 were included in the study. The COL1A1 mutation spectrum was identified by next generation sequencing and confirmed by Sanger sequencing. A new clinical scoring system was developed to quantitatively assess the clinical severity of OI and the genotype-phenotype relationship was analyzed. The independent sample t-test, analysis of variance, Mann-Whitney U-test, Chi-squared test, Pearson correlation, and multiple linear regression were applied for statistical analyses.

RESULTS

Among 161 patients with OI, 32.9% missense mutations, 16.8% non-sense mutations, 24.2% splice-site mutations, 24.8% frameshift mutations, and 1.2% whole-gene deletions were identified, of which 38 variations were novel. These mutations led to 53 patients carrying qualitative defects and 67 patients carrying quantitative defects in type I collagen. Compared to patients with quantitative mutations, patients with qualitative mutations had lower alkaline phosphatase level (296 [132, 346] U/L vs. 218 [136, 284] U/L, P = 0.009) and higher clinical score (12.2 ± 5.3 vs. 7.4 ± 2.4, P < 0.001), denoting more severe phenotypes including shorter stature, lower bone mineral density, higher fracture frequency, more bone deformity, vertebral compressive fractures, limited movement, and dentinogenesis imperfecta (DI). Patients would not present with DI if the glycine substitutions happened before the 79th amino acid in triple helix of α1 chains.

CONCLUSIONS

This presented distinctive COL1A1 mutation spectrum in a large cohort of Chinese patients with OI. This new quantitative analysis of genotype-phenotype correlation would be helpful to predict the prognosis of OI and genetic counseling.

An ALP-activatable and mitochondria-targeted probe for prostate cancer-specific bimodal imaging and aggregation-enhanced photothermal therapy

Tumor-derived alkaline phosphatase (ALP) is over-expressed in metastatic prostate cancer. The development of selective probes for ALP detection is therefore critical for early diagnosis and therapy of metastatic prostate cancer. Herein, we develop a mitochondria-targeted near-infrared activatable fluorescent/photoacoustic (NIR FL/PA) probe for the selective detection of prostate cancer-derived ALP and aggregation-enhanced photothermal therapy. Upon dephosphorylation, the probes are activated and they provide a red-shifted strong absorption and emission in the NIR window and thus enable NIR FL and PA imaging of ALP activity in tumor tissues. Particularly, the activated probes self-assemble in situ into a supramolecular network structure which induces cell apoptosis and significantly enhances the photothermal therapy efficacy.

Photoelectrochemical determination of alkaline phosphatase activity based on a photo-excited electron transfer strategy

A sensitive photoelectrochemical (PEC) biosensor for determination of alkaline phosphatase (ALP) activity was constructed based on a photo-excited electron transfer strategy. Immobilization of CdTe quantum dots (QDs) on TiO₂ nanotube arrays (TNAs), addition of iron (III) and adenosine triphosphate (ATP) in turn can effectively adjust the photocurrent response of TNAs under visible light irradiation due to a photo-excited electron transfer process, and alkaline phosphatase (ALP) activity can be determined for its catalysis toward dephosphorylation of ATP. The preparation of CdTe QDs, construction of TNA/QD PEC biosensor and the mechanism of photo-excited electron transfer are investigated in the present work. Under the optimal experimental conditions, the TNA/QD PEC biosensor shows a low limits of detection (LODs) (0.05 U L^-1) and limits of quantification detection (LOQs) (0.15 U L^-1), wide linear range from 0.2 to 15 U L^-1, and good selectivity towards ALP determination, which has been successfully applied for human serum analysis with good precision (RSD ≤ 5.4%) and high accuracy (recovery rate, 91-112%).

Multifunctional melanin-like nanoparticles for bone-targeted chemo-photothermal therapy of malignant bone tumors and osteolysis

Malignant bone tumors associated with aggressive osteolysis are currently hard to be cured by the clinical strategies. Nevertheless, nanomedicine might provide a promising therapeutic opportunity. Here, we developed a multifunctional melanin-like nanoparticle for bone-targeted chemo-photothermal treatment of malignant bone tumors. The particle was originally fabricated from alendronate-conjugated polydopamine nanoparticle (PDA-ALN) that exhibited excellent photothermal effect and high affinity to hydroxyapatite. PDA/Fe-ALN significantly enhanced the magnetic resonance contrast of the bone tumors in vivo, suggesting that more PDA-ALN accumulated at the osteolytic bone lesions in the tumors compared with the non-targeting PDA. Chemodrug SN38 was efficiently loaded on PDA-ALN, and the drug release could be triggered by near-infrared irradiation and acidic stimulus. Finally, the combined chemo-photothermal therapy efficiently suppressed the growth of bone tumors and reduced the osteolytic damage of bones at a mild temperature around 43 °C. This study provides an efficient and robust nanotherapeutics for the treatment of malignant bone tumors.

iPhone-imaged and cell-powered electrophoresis titration chip for the alkaline phosphatase assay in serum by the moving reaction boundary

As a vital enzyme, alkaline phosphatase (ALP) has great clinical significance in diagnoses of bone or liver cancer, bone metastases, rickets, and extrahepatic biliary obstruction. However, there is still no really portable chip for the ALP assay in blood. Herein, a simple electrophoresis titration (ET) model was developed for ALP detection via a moving reaction boundary (MRB). In the model, ALP catalyzed the dephosphorylation of a 4-methylumbelliferyl phosphate disodium salt (4-MUP) substrate in the cathode well to 4-methylumbelliferone ([4-MU]-) with a negative charge and blue fluorescence under UV excitation. After the catalysis, an electric field was used between the cathode and the anode. Under the electric field, [4-MU]- moved into the channel and neutralized the acidic Tris-HCl buffer, resulting in the quenching of [4-MU]- and creating a MRB. The ET system just had an ET chip, a lithium cell, a UV LED and an iPhone used as a recorder, having no traditional expensive power supply and fluorescence detector. The relevant method was developed, and a series of experiments were conducted via the ET chip. The experiments showed: (i) a MRB could be formed between the [4-MU]- base and the acidic buffer, and the MRB motion had a linear relationship with the ALP activity, validating the ET model; (ii) the ET run was not impacted by many interferences, implying good selectivity; and (iii) the ET chip could be used for portable detection within 10 min, implying an on-site and rapid analysis. In addition, the ET method had a relatively good sensitivity (0.1 U L-1), linearity (V = 0.033A + 3.87, R2 = 0.9980), stability (RSD 2.4-6.8%) and recoveries (101-105%). Finally, the ET method was successfully used for ALP assays in real serum samples. All the results implied that the developed method was simple, rapid and low-cost, and had potential for POCT clinical ALP assays.

Eu/Tb luminescence for alkaline phosphatase and β-galactosidase assay in hydrogels and on paper devices

Simple technologies for efficient detection of important (bio)molecules are always in great demand. We now report the detection and assay of two biologically important enzymes, alkaline phosphatase and β-galactosidase, in Eu- or Tb-based cholate hydrogels, respectively, and on filter paper discs coated with such hydrogels. Pro-sensitizers derived from 1-hydroxypyrene and 2,3-dihydroxynaphthalene were incorporated into Eu or Tb cholate hydrogels, respectively. Upon enzyme action, these artificial substrates liberate free sensitizers both in the gel and on gel-coated discs, resulting in turn-on luminescence, red/magenta for Eu, and green for Tb. The detection of enzymes was also demonstrated in natural/biological samples using low-cost systems.

Fast and sensitive near-infrared fluorescent probes for ALP detection and 3d printed calcium phosphate scaffold imaging in vivo

Alkaline phosphatase (ALP) is a critical biological marker for osteoblast activity during early osteoblast differentiation, but few biologically compatible methods are available for its detection. Here, we describe the discovery of highly sensitive and rapidly responsive novel near-infrared (NIR) fluorescent probes (NIR-Phos-1, NIR-Phos-2) for the fluorescent detection of ALP. ALP cleaves the phosphate group from the NIR skeleton and substantially alters its photophysical properties, therefore generating a large "turn-on" fluorescent signal resulted from the catalytic hydrolysis on fluorogenic moiety. Our assay quantified ALP activity from 0 to 1.0UmL^-1 with a 10^-5-10^-3UmL^-1 limit of detection (LOD), showing a response rate completed within 1.5min. A potentially powerful approach to probe ALP activity in biological systems demonstrated real-time monitoring using both concentration- and time-dependent variations of endogenous ALP in live cells and animals. Based on high binding affinity to bone tissue of phosphate moiety, bone-like scaffold-based ALP detection in vivo was accessed using NIR probe-labeled three-dimensional (3D) calcium deficient hydroxyapatite (CDHA) scaffolds. They were subcutaneously implanted into mice and monitored ALP signal changes using a confocal imaging system. Our results suggest the possibility of early-stage ALP detection during neo-bone formation inside a bone defect, by in vivo fluorescent evaluation using 3D CDHA scaffolds.

Exploring the tunable excitation of QDs to maximize the overlap with the absorber for inner filter effect-based phosphorescence sensing of alkaline phosphatase

The inner filter effect (IFE) is an effective way for fluorescence modulation and thus has been extensively explored for the development of fluorescence assays. Theoretically, the key to maximize the sensitivity of IFE-based fluorescence assays is to enlarge the overlap between the absorption of the absorber and the excitation/emission of the fluorophore. Therefore, in this work, the tunable excitation of quantum dots (QDs) was explored for screening of the IFE pair having the best IFE-based assay sensitivity. A series of QDs, including CdTe QDs with different sizes, carbon dots, Cu-doped CdS QDs, and Mn-doped ZnS QDs, were investigated. PNPP (p-nitrophenylphosphate) was chosen as the absorber since its absorption overlapped with the above QDs. Besides, it can be catalytically converted to p-nitrophenol (PNP) by alkaline phosphatase (ALP) together with an absorption spectrum change (red-shift). Interestingly, it was found that the IFE efficiency of different PNPP-QD pairs increased almost linearly with the corresponding spectral overlap, and Mn-doped ZnS QDs were eventually chosen for the IFE assay of ALP because of the maximum spectral overlap and thus the best sensitivity. A simple and sensitive turn-on phosphorescence ALP assay was developed, with a detection limit of 4 × 10^-4 U L^-1. Because of the high sensitivity, we also found that ALP of different origins possessed different enzymatic activities. The developed ALP phosphorescence assay was successfully employed for the analysis of ALP in serum samples.

Reaction-Based Off-On Near-infrared Fluorescent Probe for Imaging Alkaline Phosphatase Activity in Living Cells and Mice

Alkaline phosphatases are a group of enzymes that play important roles in regulating diverse cellular functions and disease pathogenesis. Hence, developing fluorescent probes for in vivo detection of alkaline phosphatase activity is highly desirable for studying the dynamic phosphorylation in living organisms. Here, we developed the very first reaction-based near-infrared (NIR) probe (DHXP) for sensitive detection of alkaline phosphatase activity both in vitro and in vivo. Our studies demonstrated that the probe displayed an up to 66-fold fluorescence increment upon incubation with alkaline phosphatases, and the detection limit of our probe was determined to be 0.07 U/L, which is lower than that of most of alkaline phosphatase probes reported in literature. Furthermore, we demonstrated that the probe can be applied to detecting alkaline phosphatase activity in cells and mice. In addition, our probe possesses excellent biocompatibility and rapid cell-internalization ability. In light of these prominent properties, we envision that DHXP will add useful tools for investigating alkaline phosphatase activity in biomedical research.

Defect-Related Luminescent Hydroxyapatite-Enhanced Osteogenic Differentiation of Bone Mesenchymal Stem Cells Via an ATP-Induced cAMP/PKA Pathway

Novel defect-related hydroxyapatite (DHAP), which combines the advantages of HAP and defect-related luminescence, has the potential application in tissue engineering and biomedical area, because of its excellent capability of monitoring the osteogenic differentiation and material biodegradation. Although the extracellular mechanism of DHAP minerals and PO4(3-) functioning in osteogenic differentiation has been widely studied, the intracellular molecular mechanism through which PO4(3-) mediates osteogenesis of bone mesenchymal stem cells (BMSCs) is not clear. We examined a previously unknown molecular mechanism through which PO4(3-) promoted osteogenesis of BMSCs with an emphasis on adenosine-triphosphate (ATP)-induced cAMP/PKA pathway. Our studies showed that DHAP could be uptaken into lysosome, in which PO4(3-) was released from DHAP, because of the acid environment of lysosome. The released PO4(3-) interacted with ADP to form ATP, and then degraded into adenosine, an ATP metabolite, which interacted with A2b adenosine receptor to activate the cAMP/PKA pathway, resulting in the high expression of osteogenesis-related genes, such as Runx2, BMP-2, and OCN. These findings first revealed the function of ATP-metabolism in bone physiological homeostasis, which may be developed to cure bone metabolic diseases.

A smart fluorescence nanoprobe for the detection of cellular alkaline phosphatase activity and early osteogenic differentiation

In the past decades, biomaterials were designed to induce stem cell toward osteogenic differentiation. However, conventional methods for evaluation osteogenic differentiation all required a process of cell fixation or lysis, which induce waste of a large number of cells. In this study, a fluorescence nanoprobe was synthesized by combining phosphorylated fluoresceinamine isomer I (FLA) on the surface of mesoporous silica-coated superparamagnetic iron oxide (Fe3O4@mSiO2) nanoparticles. In the presence of alkaline phosphatase (ALP), the phosphorylated FLA on the nanoprobe would be hydrolyzed, resulting in a fluorescence recovery of FLA. During early osteogenic differentiation, a high-level expression of cellular ALP was induced, which accelerated the hydrolysis of phosphorylated FLA, resulting in an enhancement of cellular fluorescence intensity. This fluorescence nanoprobe provides us a rapid and non-toxic method for the detection of cellular ALP activity and early osteogenic differentiation.

Fluorescence light-up AIE probe for monitoring cellular alkaline phosphatase activity and detecting osteogenic differentiation

Three phosphorylated tetraphenylethylene (TPE) probes were synthesized for monitoring ALP activity in living stem cells and detecting osteogenic differentiation.