Internalization of mesoporous silica nanoparticles induces transient but not sufficient osteogenic signals in human mesenchymal stem cells

Magnetic nanosystem a tool for targeted delivery and diagnostic application: Current challenges and recent advancement

Over the last two decades, researchers have paid more attention to magnetic nanosystems due to their wide application in diverse fields. The metal nanomaterials' antimicrobial and biocidal properties make them an essential nanosystem for biomedical applications. Moreover, the magnetic nanosystems could have also been used for diagnosis and treatment because of their magnetic, optical, and fluorescence properties. Superparamagnetic iron oxide nanoparticles (SPIONs) and quantum dots (QDs) are the most widely used magnetic nanosystems prepared by a simple process. By surface modification, researchers have recently been working on conjugating metals like silica, copper, and gold with magnetic nanosystems. This hybridization of the nanosystems modifies the structural characteristics of the nanomaterials and helps to improve their efficacy for targeted drug and gene delivery. The hybridization of metals with various nanomaterials like micelles, cubosomes, liposomes, and polymeric nanomaterials is gaining more interest due to their nanometer size range and nontoxic, biocompatible nature. Moreover, they have good injectability and higher targeting ability by accumulation at the target site by application of an external magnetic field. The present article discussed the magnetic nanosystem in more detail regarding their structure, properties, interaction with the biological system, and diagnostic applications.

Characterisation and Expression of Osteogenic and Periodontal Markers of Bone Marrow Mesenchymal Stem Cells (BM-MSCs) from Diabetic Knee Joints

Type 2 diabetes mellitus (T2DM) represents a significant health problem globally and is linked to a number of complications such as cardiovascular disease, bone fragility and periodontitis. Autologous bone marrow mesenchymal stem cells (BM-MSCs) are a promising therapeutic approach for bone and periodontal regeneration; however, the effect of T2DM on the expression of osteogenic and periodontal markers in BM-MSCs is not fully established. Furthermore, the effect of the presence of comorbidities such as diabetes and osteoarthritis on BM-MSCs is also yet to be investigated. In the present study, BM-MSCs were isolated from osteoarthritic knee joints of diabetic and nondiabetic donors. Both cell groups were compared for their clonogenicity, proliferation rates, MSC enumeration and expression of surface markers. Formation of calcified deposits and expression of osteogenic and periodontal markers were assessed after 1, 2 and 3 weeks of basal and osteogenic culture. Diabetic and nondiabetic BM-MSCs showed similar clonogenic and growth potentials along with comparable numbers of MSCs. However, diabetic BM-MSCs displayed lower expression of periostin (POSTN) and cementum protein 1 (CEMP-1) at Wk3 osteogenic and Wk1 basal cultures, respectively. BM-MSCs from T2DM patients might be suitable candidates for stem cell-based therapeutics. However, further investigations into these cells' behaviours in vitro and in vivo under inflammatory environments and hyperglycaemic conditions are still required.

Mesoporous Silica-Based Nanoplatforms Are Theranostic Agents for the Treatment of Inflammatory Disorders

Complete recovery from infection, sepsis, injury, or trauma requires a vigorous response called inflammation. Inflammatory responses are essential in balancing tissue homeostasis to protect the tissue or resolve harmful stimuli and initiate the healing process. Identifying pathologically important inflammatory stimuli is important for a better understanding of the immune pathways, mechanisms of inflammatory diseases and organ dysfunctions, and inflammatory biomarkers and for developing therapeutic targets for inflammatory diseases. Nanoparticles are an efficient medical tool for diagnosing, preventing, and treating various diseases due to their interactions with biological molecules. Nanoparticles are unique in diagnosis and therapy in that they do not affect the surroundings or show toxicity. Modern medicine has undergone further development with nanoscale materials providing advanced experimentation, clinical use, and applications. Nanoparticle use in imaging, drug delivery, and treatment is growing rapidly owing to their spectacular accuracy, bioavailability, and cellular permeability. Mesoporous silica nanoparticles (MSNs) play a significant role in nano therapy with several advantages such as easy synthesis, loading, controllability, bioavailability over various surfaces, functionalization, and biocompatibility. MSNs can be used as theranostics in immune-modulatory nano systems to diagnose and treat inflammatory diseases. The application of MSNs in the preparation of drug-delivery systems has been steadily increasing in recent decades. Several preclinical studies suggest that an MSN-mediated drug-delivery system could aid in treating inflammatory diseases. This review explains the role of nanoparticles in medicine, synthesis, and functional properties of mesoporous silica nanoparticles and their therapeutic role against various inflammatory diseases.

Combining Mg–Zn–Ca Bulk Metallic Glass with a Mesoporous Silica Nanocomposite for Bone Tissue Engineering

Mg–Zn–Ca bulk metallic glass (BMG) is a promising orthopedic fixation implant because of its biodegradable and biocompatible properties. Structural supporting bone implants with osteoinduction properties for effective bone regeneration have been highly desired in recent years. Osteogenic growth peptide (OGP) can increase the proliferation and differentiation of mesenchymal stem cells and enhance the mineralization of osteoblast cells. However, the short half-life and non-specificity to target areas limit applications of OGP. Mesoporous silica nanoparticles (MSNs) as nanocarriers possess excellent properties, such as easy surface modification, superior targeting efficiency, and high loading capacity of drugs or proteins. Accordingly, we propose a system of combining the OGP-containing MSNs with Mg–Zn–Ca BMG materials to promote bone regeneration. In this work, we conjugated cysteine-containing OGP (cgOGP, 16 a.a.) to interior walls of channels in MSNs and maintained the dispersity of MSNs via PEGylation. An in vitro study showed that metal ions released from Mg–Zn–Ca BMG promoted cell proliferation and migration and elevated alkaline phosphatase (ALP) activity and mineralization. On treating cells with both BMG ion-containing Minimum Essential Medium Eagle-alpha modification (α-MEM) and OGP-conjugated MSNs, enhanced focal adhesion turnover and promoted differentiation were observed. Hematological analyses showed the biocompatible nature of this BMG/nanocomposite system. In addition, in vivo micro-computed tomographic and histological observations revealed that our system stimulated osteogenesis and new bone formation around the implant site.

Scaffold-Free Strategy Using a PEG-Dextran Aqueous Two-Phase-System for Corneal Tissue Repair

Forming thin tissue constructs with minimal extracellular matrix surrounding them is important for tissue engineering applications. Here, we explore and optimize a strategy that enables rapid fabrication of scaffold-free corneal tissue constructs using the liquid-liquid interface of an aqueous two-phase system (ATPS) that is based on biocompatible polymers, dextran and polyethylene glycol. Intact tissue-like constructs, made of corneal epithelial or endothelial cells, can be formed on the interface between the two liquid phases of ATPS within hours and subsequently collected simply by removing the liquid phases. The formed corneal cell constructs express essential physiological markers and have preserved viability and proliferative ability in vitro. The corneal epithelial cell constructs are also able to re-epithelialize the corneal epithelial wound in vitro. The results suggest the promise of our reported strategy in corneal repair.

2D Covalent Organic Framework Direct Osteogenic Differentiation of Stem Cells

2D covalent organic frameworks (COFs) are an emerging class of crystalline porous organic polymers with a wide-range of potential applications. However, poor processability, aqueous instability, and low water dispersibility greatly limit their practical biomedical implementation. Herein, a new class of hydrolytically stable 2D COFs for sustained delivery of drugs to direct stem cell fate is reported. Specifically, a boronate-based COF (COF-5) is stabilized using amphiphilic polymer Pluronic F127 (PLU) to produce COF-PLU nanoparticles with thickness of ≈25 nm and diameter ≈200 nm. These nanoparticles are internalized via clathrin-mediated endocytosis and have high cytocompatibility (half-inhibitory concentration ≈1 mg mL^-1 ). Interestingly, the 2D COFs induce osteogenic differentiation in human mesenchymal stem cells, which is unique. In addition, an osteogenic agent-dexamethasone-is able to be loaded within the porous structure of COFs for sustained delivery which further enhances the osteoinductive ability. These results demonstrate for the first time the fabrication of hydrolytically stable 2D COFs for sustained delivery of dexamethasone and demonstrate its osteoinductive characteristics.

Silicon-Gold Nanoparticles Affect Wharton's Jelly Phenotype and Secretome during Tri-Lineage Differentiation

Multiple studies have demonstrated that various nanoparticles (NPs) stimulate osteogenic differentiation of mesenchymal stem cells (MSCs) and inhibit adipogenic ones. The mechanisms of these effects are not determined. The aim of this paper was to estimate Wharton’s Jelly MSCs phenotype and humoral factor production during tri-lineage differentiation per se and in the presence of silicon–gold NPs. Silicon (SiNPs), gold (AuNPs), and 10% Au-doped Si nanoparticles (SiAuNPs) were synthesized by laser ablation, characterized, and studied in MSC cultures before and during differentiation. Humoral factor production (n = 41) was analyzed by Luminex technology. NPs were nontoxic, did not induce ROS production, and stimulated G-CSF, GM-CSF, VEGF, CXCL1 (GRO) production in four day MSC cultures. During MSC differentiation, all NPs stimulated CD13 and CD90 expression in osteogenic cultures. MSC differentiation resulted in a decrease in multiple humoral factor production to day 14 of incubation. NPs did not significantly affect the production in chondrogenic cultures and stimulated it in both osteogenic and adipogenic ones. The major difference in the protein production between osteogenic and adipogenic MSC cultures in the presence of NPs was VEGF level, which was unaffected in osteogenic cells and 4–9 times increased in adipogenic ones. The effects of NPs decreased in a row AuNPs > SiAuNPs > SiNPs. Taken collectively, high expression of CD13 and CD90 by MSCs and critical level of VEGF production can, at least, partially explain the stimulatory effect of NPs on MSC osteogenic differentiation.

Hepatic and renal cellular cytotoxic effects of heparin-coated superparamagnetic Iron oxide nanoparticles

Background

Superparamagnetic iron oxide (SPIO) nanoparticles have been widely used in several biomedical engineering in vivo. Although various surface modifications have been made to these non-biodegradable nanoparticles to make them more biocompatible, their toxic potential still remains a major concern.

Method

In this study, we newly developed unfractionated heparin (UFH)-coated and low molecular weight heparin (LMWH)-coated SPIO nanoparticles through surface modification engineering, which was compared with commercially available dextran-coated SPIO nanoparticles. Their toxicity such as cytotoxicity, single cell gel electrophoresis (SCGE) comet assay, intracellular reactive oxygen species (ROS) content and cellular apoptosis was evaluated to hepatic HepG2 and renal HK-2 cells.

Results

When UFH-, LMWH- or dextran-coated SPIO nanoparticles were applied, they did not affect the viability of HepG2 cell. However, HK-2 cells were more sensitive to dextran-coated SPIO nanoparticles than others. In genotoxicity assay using SCGE comet, DNA tail moment values in the groups treated with dextran- and LMWH-coated SPIO nanoparticles significantly increased. However, UFH-coated SPIO nanoparticles was only significantly lowing DNA tail moment value. In addition, UFH-coated SPIO nanoparticles had lower cytotoxicity in HepG2 and HK-2 cells compared to dextran-coated SPIO nanoparticles, especially in terms of apoptosis and intracellular ROS production.

Conclusions

Collectively, it is possible that UFH- coated SPIO nanoparticles can be used as alternative negative contrast agents.

Antibacterial and osteogenic activities of clindamycin-releasing mesoporous silica/carboxymethyl chitosan composite hydrogels

Conventional treatment of jaw bone infection is often ineffective at controlling bacterial infection and enhancing bone regeneration. Biodegradable composite hydrogels comprised of carboxymethyl chitosan (CMCS) and clindamycin (CDM)-loaded mesoporous silica nanoparticles (MCM-41), possessing dual antibacterial activity and osteogenic potency, were developed in the present study. CDM was successfully loaded into both untreated and plasma-treated MCM-41 nanoparticles, denoted as (p)-MCM-41, followed by the incorporation of each of CDM-loaded (p)-MCM-41 into CMCS. The resulting CDM-loaded composite hydrogels, (p)-MCM-41-CDM-CMCS, demonstrated slow degradation rates (about 70% remaining weight after 14-day immersion), while the CDM-free composite hydrogel entirely disintegrated after 4-day immersion. The plasma treatment was found to improve drug loading capacity and slow down initial drug burst effect. The prolonged releases of CDM from both (p)-MCM-41-CDM-CMCS retained their antibacterial effect against Streptococcus sanguinis for at least 14 days in vitro. In vitro assessment of osteogenic activity showed that the CDM-incorporated composite hydrogel was cytocompatible to human mesenchymal stem cells (hMSCs) and induced hMSC mineralization via p38-dependent upregulated alkaline phosphatase activity. In conclusion, novel (p)-MCM-41-CDM-CMCS hydrogels with combined controlled release of CDM and osteogenic potency were successfully developed for the first time, suggesting their potential clinical benefit for treatment of intraoral bone infection.

Hydrophobic Mesoporous Silica Particles Modified With Nonfluorinated Alkyl Silanes

This work reports the preparation of hydrophobic mesoporous silica particles (MSPs) modified with nonfluorinated alkyl silanes. Alkyl silanes were grafted onto the surface of the MSPs as a function of the length of nonfluorinated alkyl chains such as propyltriethoxysilane (C₃), octyltriethoxysilane (C₈), dodecyltriethoxysilane (C₁₂), and octadecyltriethoxysilane (C₁₈). Moreover, the grafting of the different alkyl silanes onto the surface of MSPs to make them hydrophobic was demonstrated using different conditions such as by changing the pH (0, 4, 6, 8, and 13), solvent type (protic and aprotic), concentration of silanes (0, 0.12, 0.24, 0.36, 0.48, and 0.60 M), reaction time (1, 2, 3, and 4 days), and reaction temperature (25 and 40 °C). The contact angles of the alkyl silane-modified MSPs were increased as a function of the alkyl chain lengths in the order of C₁₈ > C₁₂ > C₈ > C₃, and the contact angle of C₁₈-modified MSPs was 4 times wider than that of unmodified MSPs. The unmodified MSPs had a contact angle of 25.3°, but C₁₈-modified MSPs had a contact angle of 102.1°. Furthermore, the hydrophobicity of the nonfluorinated alkyl silane-modified MSPs was also demonstrated by the adsorption of a hydrophobic lecithin compound, which showed the increase of lecithin adsorption as a function of the alkyl chain lengths. The cross-linking ratios of the modified silanes on the MSPs were confirmed by solid-state ²⁹Si-MAS nuclear magnetic resonance (NMR) measurement. Consequently, the hydrophobic modification on MSPs using nonfluorinated alkyl silanes was best preferred in a protic solvent, with a reaction time of ∼24 h at 25 °C and at a high concentration of silanes.

In vivo magnetic nanoparticle hyperthermia: a review on preclinical studies, low-field nano-heaters, noninvasive thermometry and computer simulations for treatment planning

Magnetic nanoparticle hyperthermia (MNH) is a promising nanotechnology-based cancer thermal therapy that has been approved for clinical use, together with radiation therapy, for treating brain tumors. Almost ten years after approval, few new clinical applications had appeared, perhaps because it cannot benefit from the gold standard noninvasive MRI thermometry technique, since static magnetic fields inhibit heat generation. This might limit its clinical use, in particular as a single therapeutic modality. In this article, we review the in vivo MNH preclinical studies, discussing results of the last two decades with emphasis on safety as a clinical criteria, the need for low-field nano-heaters and noninvasive thermal dosimetry, and the state of the art of computational modeling for treatment planning using MNH. Limitations to more effective clinical use are discussed, together with suggestions for future directions, such as the development of ultrasound-based, computed tomography-based or magnetic nanoparticle-based thermometry to achieve greater impact on clinical translation of MNH.

Nanotechnology and its challenges in the food sector: a review

Antibacterial activity of nanoparticles has received significant attention worldwide because of their great physical and chemical stability, excellent magnetic properties, and large lattice constant values. These properties are predominate in the food science for enhancing the overall quality, shelf life, taste, flavor, process-ability, etc., of the food. Nanoparticles exhibit attractive antibacterial activity due to their increased specific surface area leading to enhanced surface reactivity. When nanoparticles are suspended in the biological culture, they encounter various biological interfaces, resulting from the presence of cellular moieties like DNA, proteins, lipids, polysaccharides, etc., which helps antibacterial properties in many ways. This paper reviews different methods used for the synthesis of nanoparticles but is specially focusing on the green synthesis methods owing to its non-toxic nature towards the environment. This review highlights their antibacterial application mainly in the food sector in the form of food-nanosensors, food-packaging, and food-additives. The possible mechanism of nanoparticles for their antibacterial behavior underlying the interaction of nano-particles with bacteria, (i) excessive ROS generation including hydrogen peroxide (H₂O₂), OH^- (hydroxyl radicals), and O^- ₂ ² (peroxide); and (ii) precipitation of nano-particles on the bacterial exterior; which, disrupts the cellular activities, resulting in membranes disturbance. All these phenomena results in the inhibition of bacterial growth. Along with this, their current application and future perspectives in the food sector are also discussed. Nanoparticles help in destroying not only pathogens but also deadly fungi and viruses. Most importantly it is required to focus more on the crop processing and its containment to stop the post-harvesting loss. So, nanoparticles can act as a smart weapon towards the sustainable move.

Potential Toxicity of Iron Oxide Magnetic Nanoparticles: A Review

The noteworthy intensification in the development of nanotechnology has led to the development of various types of nanoparticles. The diverse applications of these nanoparticles make them desirable candidate for areas such as drug delivery, coasmetics, medicine, electronics, and contrast agents for magnetic resonance imaging (MRI) and so on. Iron oxide magnetic nanoparticles are a branch of nanoparticles which is specifically being considered as a contrast agent for MRI as well as targeted drug delivery vehicles, angiogenic therapy and chemotherapy as small size gives them advantage to travel intravascular or intracavity actively for drug delivery. Besides the mentioned advantages, the toxicity of the iron oxide magnetic nanoparticles is still less explored. For in vivo applications magnetic nanoparticles should be nontoxic and compatible with the body fluids. These particles tend to degrade in the body hence there is a need to understand the toxicity of the particles as whole and degraded products interacting within the body. Some nanoparticles have demonstrated toxic effects such inflammation, ulceration, and decreases in growth rate, decline in viability and triggering of neurobehavioral alterations in plants and cell lines as well as in animal models. The cause of nanoparticles' toxicity is attributed to their specific characteristics of great surface to volume ratio, chemical composition, size, and dosage, retention in body, immunogenicity, organ specific toxicity, breakdown and elimination from the body. In the current review paper, we aim to sum up the current knowledge on the toxic effects of different magnetic nanoparticles on cell lines, marine organisms and rodents. We believe that the comprehensive data can provide significant study parameters and recent developments in the field. Thereafter, collecting profound knowledge on the background of the subject matter, will contribute to drive research in this field in a new sustainable direction.

Multifunctional nanoparticles in stem cell therapy for cellular treating of kidney and liver diseases

The review gives an overview of the mechanisms of internalization and distribution of nanoparticles in stem cells this is achieved via providing analysis of the methods used in exploring the migration routes of stem cells, and their reciprocity. In addition, exploring microenvironment target in the body, and tracking the fate of exogenously transplanted stem cells by using innovative and non-invasive techniques will also be discussed. Such techniques like magnetic resonance imaging (MRI), multimodality tracking, optical imaging, and nuclear medicine imaging, which were designed to follow up stem cell migration. This review will explain the various distinctive strategies to enhance homing of labeled stem cells with nanoparticles into damaged hepatic and renal tissues, this purpose was obtained by inducing a specific gene into stem cells, various chemokines, and applying an external magnetic field. Also, this work illustrates how to improve nanoparticles uptake by using transfection agents or covalently binding an exogenous protein (i.e., Human immunodeficiency virus-Tat protein) or conjugating a receptor-specific monoclonal antibody or make modifications to iron coat. It contains stem cell labeling methods such as extracellular labeling and internalization approaches. Ultimately, our review indicates trails of researchers in nanoparticles utilization in stem cell therapy in both kidney and liver diseases.

A brief review of cytotoxicity of nanoparticles on mesenchymal stem cells in regenerative medicine

Multipotent mesenchymal stem cells have shown great promise for application in regenerative medicine owing to their particular therapeutic effects, such as significant self-renewability, low immunogenicity, and ability to differentiate into a variety of specialized cells. However, there remain certain complicated and unavoidable problems that limit their further development and application. One of the challenges is to noninvasively monitor the delivery and biodistribution of transplanted stem cells during treatment without relying on behavioral endpoints or tissue histology, and it is important to explore the potential mechanisms to clarify how stem cells work in vivo. To solve these problems, various nanoparticles (NPs) and their corresponding imaging methods have been developed recently and have made great progress. In this review, we mainly discuss NPs used to label stem cells and their toxic effects on the latter, the imaging techniques to detect such NPs, and the current existing challenges in this field.

Bioceramics: from bone substitutes to nanoparticles for drug delivery

Since the second half of the 20th century, bioceramics are used for bone repair and regeneration. Inspired by bones and teeth, and aimed at mimicking their structure and composition, several artificial bioceramics were developed for biomedical applications. And nowadays, in the 21st century, with the increasing prominence of nanoscience and nanotechnology, certain bioceramics are being used to build smart drug delivery systems, among other applications. This minireview will mainly describe both tendencies through the research work carried out by the research team of María Vallet-Regí.

Lipid surface modifications increase mesoporous silica nanoparticle labeling properties in mesenchymal stem cells

BACKGROUND

Nanoparticles have emerged as promising cell-labeling tools, as they can be precisely tailored in terms of chemical and physical properties. Mesoporous silica nanoparticles (MSNs), in particular, are easily tunable with regard to surface and core chemistry, and are able to confine dyes and drug molecules efficiently.

PURPOSE

The aim of this study was to investigate the effect of lipid and polyethylene glycol (PEG) surface modifications on MSN stem-cell-tracking abilities.

METHODS

Lipid and PEG surface functionalized MSNs were synthesized and the effect of surface functionalization on cell internalization, proliferation, differentiation and cell proteomics was investigated in patient derived mesenchymal stem cells (MSCs).

RESULTS

MSNs and lipid surface-modified MSNs were internalized by >80% of the MSC population, with the exception of nanoparticles modified with short PEG chains (molecular weight 750 [MSN-PEG750]). Lipid-modified MSNs had higher labeling efficiency with maximum uptake after 2 hours of exposure and were in addition internalized 17 times higher compared to unmodified MSNs, without negatively affecting differentiation capacity. Using a mass-spectrometry-based label-free quantitative proteomics approach, we show that MSN labeling leads to the up- and downregulation of proteins that were unique for the different surface-modified MSNs. In addition, functional enrichments were found in human MSCs labeled with MSNs, MSN-PEG750, and lipid-modified MSNs.

SUMMARY

Here we show that organic modifications with lipids and PEGylation can be used as a promising strategy to improve MSN labeling capabilities. In particular, we show that lipid modifications can optimize such probes in three distinct ways: significantly improved signal strength, a barrier for sustained release of additional probes, and improved stem-cell-labeling efficiency.

Mesoporous silica nanoparticles for therapeutic/diagnostic applications

Based on unique intrinsic properties of mesoporous silica nanoparticles (MSNs) such as high surface area, large pore size, good biocompatibility and biodegradability, stable aqueous dispersion, they have received much attention in the recent decades for their applications as a promising platform in the biomedicine field. These porous structures possess a pore size ranging from 2 to 50 nm which make them excellent candidates for various biomedical applications. Herein, at first we described the common approaches of cargo loading and release processes from MSNs. Then, the intracellular uptake, safety and cytotoxicity aspects of MSNs are discussed as well. This review also highlights the most recent advances in the biomedical applications of MSNs, including 1) MSNs-based carriers, 2) MSNs as bioimaging agents, 3) MSNs-based biosensors, 4) MSNs as therapeutic agents (photodynamic therapy), 5) MSN based quantum dots, 6) MSNs as platforms for upconverting nanoparticles, and 6) MSNs in tissue engineering.

Small GTPases: Structure, biological function and its interaction with nanoparticles

Small GTPase is a kind of GTP-binding protein commonly found in eukaryotic cells. It plays an important role in cytoskeletal reorganization, cell polarity, cell cycle progression, gene expression and many other significant events in cells, such as the interaction with foreign particles. Therefore, it is of great scientific significance to understand the biological properties of small GTPases as well as the GTPase-nano interplay, since more and more nanomedicine are supposed to be used in biomedical field. However, there is no review in this aspect. This review summarizes the small GTPases in terms of the structure, biological function and its interaction with nanoparticles. We briefly introduced the various nanoparticles such as gold/silver nanoparticles, SWCNT, polymeric micelles and other nano delivery systems that interacted with different GTPases. These current nanoparticles exhibited different pharmacological effect modes and various target design concepts in the small GTPases study. This will help to elucidate the conclusion that the therapeutic strategy targeting small GTPases might be a new research direction. It is believed that the in-depth study on the functional mechanism of GTPases can provide insights for the design and study of nanomedicines.

Gold Nanoparticles: A Powerful Tool to Visualize Proteins on Ordered Mesoporous Silica and for the Realization of Theranostic Nanobioconjugates

Ordered mesoporous silica (OMS) is a very interesting nanostructured material for the design and engineering of new target and controlled drug-delivery systems. Particularly relevant is the interaction between OMS and proteins. Large pores (6–9 nm) micrometric particles can be used for the realization of a drug depot system where therapeutic proteins are adsorbed either inside the mesopores or on the external surface. Small pores (1–2 nm) mesoporous silica nanoparticles (MSNs), can be injected in the blood stream. In the latter case, therapeutic proteins are mainly adsorbed on the MSNs’ external surface. Whenever a protein-OMS conjugate is prepared, a diagnostic method to locate the protein either on the internal or the external silica surface is of utmost importance. To visualize the fine localization of proteins adsorbed in mesoporous silica micro- and nanoparticles, we have employed specific transmission electron microscopy (TEM) analytical strategies based on the use of gold nanoparticles (GNPs) conjugates. GNPs are gaining in popularity, representing a fundamental tool to design future applications of MSNs in nanomedicine by realizing theranostic nanobioconjugates. It may be pointed out that we are at the very beginning of a new age of the nanomaterial science: the “mesoporous golden age„.

Nanoscale Electrical Potential and Roughness of a Calcium Phosphate Surface Promotes the Osteogenic Phenotype of Stromal Cells

Mesenchymal stem cells (MSCs) and osteoblasts respond to the surface electrical charge and topography of biomaterials. This work focuses on the connection between the roughness of calcium phosphate (CP) surfaces and their electrical potential (EP) at the micro- and nanoscales and the possible role of these parameters in jointly affecting human MSC osteogenic differentiation and maturation in vitro. A microarc CP coating was deposited on titanium substrates and characterized at the micro- and nanoscale. Human adult adipose-derived MSCs (hAMSCs) or prenatal stromal cells from the human lung (HLPSCs) were cultured on the CP surface to estimate MSC behavior. The roughness, nonuniform charge polarity, and EP of CP microarc coatings on a titanium substrate were shown to affect the osteogenic differentiation and maturation of hAMSCs and HLPSCs in vitro. The surface EP induced by the negative charge increased with increasing surface roughness at the microscale. The surface relief at the nanoscale had an impact on the sign of the EP. Negative electrical charges were mainly located within the micro- and nanosockets of the coating surface, whereas positive charges were detected predominantly at the nanorelief peaks. HLPSCs located in the sockets of the CP surface expressed the osteoblastic markers osteocalcin and alkaline phosphatase. The CP multilevel topography induced charge polarity and an EP and overall promoted the osteoblast phenotype of HLPSCs. The negative sign of the EP and its magnitude at the micro- and nanosockets might be sensitive factors that can trigger osteoblastic differentiation and maturation of human stromal cells.

Mesoporous silica nanoparticles in nanomedicine applications

In the last few years mesoporous silica nanoparticles (MSNs) have gained the attention of the nanomedicine research community, especially for the potential treatment of cancer. Although this topic has been reviewed before, periodic updates on such a hot topic are necessary due to the dynamic character of this field. The reasons that make MSNs so attractive for designing controlled drug delivery systems lie beneath their physico-chemical stability, easy functionalisation, low toxicity and their great loading capacity of many different types of therapeutic agents. The present brief overview tries to cover some of the recent findings on stimuli-responsive mesoporous silica nanocarriers together with the efforts to design targeted nanosystems using that platform. The versatility of those smart nanocarriers has promoted them as very promising candidates to be used in the clinic in the near future to overcome some of the pitfalls of conventional medicine.

Magnetic nanoparticles for drug targeting: from design to insights into systemic toxicity. Preclinical evaluation of hematological, vascular and neurobehavioral toxicology

A simple two-step drug encapsulation method was developed to obtain biocompatible magnetic nanocarriers for the potential targeted treatment of diverse diseases. The nanodevice consists of a magnetite core coated with chitosan (Chit@MNPs) as a platform for diclofenac (Dic) loading as a model drug (Dic-Chit@MNPs). Mechanistic and experimental conditions related to drug incorporation and quantification are further addressed. This multi-disciplinary study aims to elucidate the toxicological impact of the MNPs at hematological, vascular, neurological and behavioral levels. Blood compatibility assays revealed that MNPs did not affect either erythrosedimentation rates or erythrocyte integrity at the evaluated doses (1, 10 and 100 μg mL^-1). A microscopic evaluation of blood smears indicated that MNPs did not induce morphological changes in blood cells. Platelet aggregation was not affected by MNPs either and just a slight diminution was observed with Dic-Chit@MNPs, an effect possibly due to diclofenac. The examined formulations did not exert cytotoxicity on rat aortic endothelial cells and no changes in cell viability or their capacity to synthesize NO were observed. Behavioral and functional nervous system parameters in a functional observational battery were assessed after a subacute treatment of mice with Chit@MNPs. The urine pools of the exposed group were decreased. Nephritis and an increased number of megakaryocytes in the spleen were observed in the histopathological studies. Sub-acute exposure to Chit@MNPs did not produce significant changes in the parameters used to evaluate neurobehavioral toxicity. The aspects focused on within this manuscript are relevant at the pre-clinical level providing new and novel knowledge concerning the biocompatibility of magnetic nanodevices for biomedical applications.

Synthesis, Characterization, and in Vitro Biological Evaluation of Copper-Containing Magnetic Bioactive Glasses for Hyperthermia in Bone Defect Treatment

Hyperthermia treatment induced by magnetic mesoporous glasses has been applied as a potential therapeutic approach for bone defects due to malignant tumors. The objective of this study was to synthesize and characterize the structural and biological properties of magnetic bioactive glasses (BGs) for producing multifunctional materials. The effect of the addition of copper (Cu) to the bioactive glass composition was also evaluated. Fe BG and FeCu BG as magnetic mesoporous BGs, and Cu BG as mesoporous BG were synthesized and dried by template sol-gel method. Then the synthesized bioglasses were characterized and analyzed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive electron disperse spectroscopy (EDS), Brunauer-Emmett-Teller (BET), and vibrating sample magnetometer (VSM). In addition, the antibacterial behavior, cytotoxicity assay (MTT test), proliferation assay of HUVEC cell assay, and bioactivity (ALP activity test) of the synthesized BGs were evaluated. The characterization results exhibited that the synthesized powders formed mesoporous glasses with nanoparticle morphology, good surface area, and magnetic properties. The synthesized BGs also demonstrated suitable biological behavior. The magnetic saturation of bioactive glasses was increased by the addition of copper oxide. A two-phase structure was observed for the magnetic glasses compared to the copper-containing glasses, thus making them suitable for drug delivery systems. The antibacterial behavior was found to be better for the Cu BG and Fe BG compared to the FeCu BG. However, the least amount of cytotoxicity was observed for the Fe BG and FeCu BG, compared to the Cu BG. In addition, the Fe-containing BGs compared with the control group showed a lack of HUVEC cell proliferation and angiogenesis motivation. From the ALP assay, higher bioactivity for the magnetic bioglasses in the presence of mesenchymal cells was found. From the results of this in vitro study, the Cu-containing magnetic bioglass (FeCu BG) could be considered as a new generation of magnetic glasses for inducing hyperthermia in treatment of bone defects due to malignant tumors. However, further in vitro and in vivo studies are required to confirm their applications in healing of bone defects and tissue engineering.

Effects of silica-gentamicin nanohybrids on osteogenic differentiation of human osteoblast-like SaOS-2 cells

INTRODUCTION

In recent years, there has been an increasing interest in silica (SiO2) nanoparticles (NPs) as drug delivery systems. This interest is mainly attributed to the ease of their surface functionalization for drug loading. In orthopedic applications, gentamicin-loaded SiO2 NPs (nanohybrids) are frequently utilized for their prolonged antibacterial effects. Therefore, the possible adverse effects of SiO2-gentamicin nanohybrids on osteogenesis of bone-related cells should be thoroughly investigated to ensure safe applications.

MATERIALS AND METHODS

The effects of SiO2-gentamicin nanohybrids on the cell viability and osteogenic differentiation of human osteoblast-like SaOS-2 cells were investigated, together with native SiO2 NPs and free gentamicin.

RESULTS

The results of Cell Count Kit-8 (CCK-8) assay show that both SiO2-gentamicin nanohybrids and native SiO2 NPs reduce cell viability of SaOS-2 cells in a dose-dependent manner. Regarding osteogenesis, SiO2-gentamicin nanohybrids and native SiO2 NPs at the concentration range of 31.25-125 μg/mL do not influence the osteogenic differentiation capacity of SaOS-2 cells. At a high concentration (250 μg/mL), both materials induce a lower expression of alkaline phosphatase (ALP) but an enhanced mineralization. Free gentamicin at concentrations of 6.26 and 9.65 μg/mL does not significantly influence the cell viability and osteogenic differentiation capacity of SaOS-2 cells.

CONCLUSIONS

The results of this study suggest that both SiO2-gentamicin nanohybrids and SiO2 NPs show cytotoxic effects to SaOS-2 cells. Further investigation on the effects of SiO2-gentamicin nanohybrids on the behaviors of stem cells or other regular osteoblasts should be conducted to make a full evaluation of the safety of SiO2-gentamicin nanohybrids in orthopedic applications.

In vitro osteogenesis by intracellular uptake of strontium containing bioactive glass nanoparticles

Monodispersed strontium containing bioactive glass nanoparticles (Sr-BGNPs) with two compositions were synthesised, through a modified sol-gel Stöber process, wherein silica nanoparticles (SiO₂-NPs) were formed prior to incorporation of calcium and strontium, with diameters of 90 ± 10 nm. The osteogenic response of a murine preosteoblast cell line, MC3T3-E1, was investigated in vitro for a nanoparticle concentration of 250 µg/mL with compositions of 87 mol% SiO₂, 7 mol% CaO, 6 mol% SrO and 83 mol% SiO₂, 3 mol% CaO, 14 mol% SrO. Dissolution studies in minimum essential media (α-MEM) at pH 7.4 and artificial lysosomal fluid (ALF) at pH 4.5 showed that the particles dissolved and that Sr²⁺ ions were released from Sr-BGNPs in both environments. Both particle compositions and their ionic dissolution products enhanced the alkaline phosphatase (ALP) activity of the cells and calcium deposition. Immunohistochemistry (IHC) staining of Col1a1, osteocalcin (OSC) and osteopontin (OSP) showed that these proteins were expressed in the MC3T3-E1 cells following three weeks of culture. In the basal condition, the late osteogenic differentiation markers, OSC and OSP, were more overtly expressed by cells cultured with Sr-BGNPs with 14 mol% SrO and their ionic release products than in the control condition. Col1a1 expression was only slightly enhanced in the basal condition, but was enhanced further by the osteogenic supplements. These data demonstrate that Sr-BGNPs accelerate mineralisation without osteogenic supplements. Sr-BGNPs were internalised into MC3T3-E1 cells by endocytosis and stimulated osteogenic differentiation of the pre-osteoblast cell line. Sr-BGNPs are likely to be beneficial for bone regeneration and the observed osteogenic effects of these particles can be attributed to their ionic release products.

STATEMENT OF SIGNIFICANCE

We report, for the first time, that monodispersed bioactive glass nanoparticles (∼90 nm) are internalised into preosteoblast cells by endocytosis but by unspecific mechanisms. The bioactive nanoparticles and their dissolution products (without the particles present) stimulated the expression of osteogenic markers from preosteoblast cells without the addition of other osteogenic supplements. Incorporating Sr into the bioactive glass nanoparticle composition, in addition to Ca, increased the total cation content (and therefore dissolution rate) of the nanoparticles, even though nominal total cation addition was constant, without changing size or morphology. Increasing Sr content in the nanoparticles and in their dissolution products enhanced osteogenesis in vitro. The particles therefore have great potential as an injectable therapeutic for bone regeneration, particularly in patients with osteoporosis, for which Sr is known to be therapeutic agent.

Mesoporous Silica Nanoparticles for Drug Delivery: Current Insights

This manuscript reviews the recent progress on mesoporous silica nanoparticles as drug delivery systems. Their intrinsic structural, textural and chemical features permit to design versatile multifunctional nanosystems with the capability to target the diseased tissue and release the cargo on demand upon exposition to internal or external stimuli. The degradation rate of these nanocarriers in diverse physiological fluids is overviewed obeying their significance for their potential translation towards clinical applications. To conclude, the balance between the benefits and downsides of this revolutionary nanotechnological tool is also discussed.

Dual functions of silver nanoparticles in F9 teratocarcinoma stem cells, a suitable model for evaluating cytotoxicity- and differentiation-mediated cancer therapy

Background

Silver nanoparticles (AgNPs) exhibit strong antibacterial and anticancer activity owing to their large surface-to-volume ratios and crystallographic surface structure. Owing to their various applications, understanding the mechanisms of action, biological interactions, potential toxicity, and beneficial effects of AgNPs is important. Here, we investigated the toxicity and differentiation-inducing effects of AgNPs in teratocarcinoma stem cells.

Materials and methods

AgNPs were synthesized and characterized using various analytical techniques such as UV–visible spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. The cellular responses of AgNPs were analyzed by a series of cellular and biochemical assays. Gene and protein expressions were analyzed by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively.

Results

The AgNPs showed typical crystalline structures and spherical shapes (average size =20 nm). High concentration of AgNPs induced cytotoxicity in a dose-dependent manner by increasing lactate dehydrogenase leakage and reactive oxygen species. Furthermore, AgNPs caused mitochondrial dysfunction, DNA fragmentation, increased expression of apoptotic genes, and decreased expression of antiapoptotic genes. Lower concentrations of AgNPs induced neuronal differentiation by increasing the expression of differentiation markers and decreasing the expression of stem cell markers. Cisplatin reduced the viability of F9 cells that underwent AgNPs-induced differentiation.

Conclusion

The results showed that AgNPs caused differentially regulated cytotoxicity and induced neuronal differentiation of F9 cells in a concentration-dependent manner. Therefore, AgNPs can be used for differentiation therapy, along with chemotherapeutic agents, for improving cancer treatment by targeting specific chemotherapy-resistant cells within a tumor. Furthermore, understanding the molecular mechanisms of apoptosis and differentiation in stem cells could also help in developing new strategies for cancer stem cell (CSC) therapies. The findings of this study could significantly contribute to the nanomedicine because this study is the first of its kind, and our results will lead to new strategies for cancer and CSC therapies.

Detailed toxicity evaluation of β-cyclodextrin coated iron oxide nanoparticles for biomedical applications

The application of iron oxide nanoparticles [IONPs] in biomedical research is progressively increasing, leading to the rapid development of biocompatible and surface modified IONPs. However, there is still a need of information pertaining to its cellular and acute toxicity profile. This work reports the synthesis of β-cyclodextrin coated iron oxide nanoparticles (βCD-IONPs) and their characterization using spectroscopic (FT-IR), thermal (TGA) and surface analysis (TEM, SEM, BET and Zeta potential). All the characterization techniques displayed the synthesis of well dispersed, rod shaped βCD-IONPs of 45nm. Time dependent cellular uptake of these nanoparticles was also evaluated using Prussian blue staining. Further, cytocompatibility analysis was executed in mouse fibroblast cell line (NIH 3T3) using MTT and LDH assays, respectively which did not show any cytotoxic indications of βCD-IONPs. Finally, acute toxicity analysis was carried out in female Wistar rats according to OECD guidelines 420. Rats were exposed to the highest dose (2000mg/kg) of βCD-IONPs along with control and observed for 14days. After two weeks of administration, tissues and blood were collected and subjected to histopathological and biochemical analysis (SGOT, SGPT and ALP). Animals were sacrificed and gross necropsy was carried out. It has been shown that βCD-IONPs does not have any significant toxic effect at the cellular level. Thus, this study provides new perspectives for future biomedical applications.

The negative effect of silica nanoparticles on adipogenic differentiation of human mesenchymal stem cells

Nanoparticles have drawn much attention for a wide variety of applications in biomedical and bioengineering fields. The combined use of nanoparticles and human mesenchymal stem cells (hMSCs) in tissue engineering and regenerative medicine requires more knowledge of the influence of nanoparticles on cell viability and differentiation potential of hMSCs. The objective of this study is to investigate the in vitro uptake of silica nanoparticles (silica NPs) and their effect on adipogenic differentiation of hMSCs. After exposure of hMSCs to silica NPs, the uptake and localization of silica NPs were assessed using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). The adipogenic differentiation potential of hMSCs was examined by analyzing the formation and accumulation of lipids droplets, triglyceride (TG) content and the expression of adipogenic marker genes/proteins. The results showed that silica NPs did not affect the cell viability but significantly decreased the differentiation of hMSCs to adipocytes. These findings improve the understanding of the influence of silica NPs on adipogenic differentiation of hMSCs and will provide a reference for the applications of silica NPs in biomedical and bioengineering fields.

Nanostructured scaffold as a determinant of stem cell fate

The functionality of stem cells is tightly regulated by cues from the niche, comprising both intrinsic and extrinsic cell signals. Besides chemical and growth factors, biophysical signals are important components of extrinsic signals that dictate the stem cell properties. The materials used in the fabrication of scaffolds provide the chemical cues whereas the shape of the scaffolds provides the biophysical cues. The effect of the chemical composition of the scaffolds on stem cell fate is well researched. Biophysical signals such as nanotopography, mechanical forces, stiffness of the matrix, and roughness of the biomaterial influence the fate of stem cells. However, not much is known about their role in signaling crosstalk, stem cell maintenance, and directed differentiation. Among the various techniques for scaffold design, nanotechnology has special significance. The role of nanoscale topography in scaffold design for the regulation of stem cell behavior has gained importance in regenerative medicine. Nanotechnology allows manipulation of highly advanced surfaces/scaffolds for optimal regulation of cellular behavior. Techniques such as electrospinning, soft lithography, microfluidics, carbon nanotubes, and nanostructured hydrogel are described in this review, along with their potential usage in regenerative medicine. We have also provided a brief insight into the potential signaling crosstalk that is triggered by nanomaterials that dictate a specific outcome of stem cells. This concise review compiles recent developments in nanoscale architecture and its importance in directing stem cell differentiation for prospective therapeutic applications.

The stimulatory effect of silica nanoparticles on osteogenic differentiation of human mesenchymal stem cells

Silica-based materials with favourable biocompatibility are generally considered as excellent candidates for applications in biomedical fields. However, previous researches mainly focused on the safety of silica-based materials, their effects on osteogenic differentiation of human mesenchymal stem cells (hMSCs) still need further investigations. In this study, core-shell fluorescent silica nanoparticles (silica NPs) with three different sizes (S1 ~ 50 nm, S2 ~ 200 nm, S3 ~ 400 nm, respectively) were prepared according to the Stöber method. The silica NPs with different sizes did not affect the cell viability (even up to a concentration of 500 µg ml^-1), showing size- and dose-independent cytocompatibility of silica NPs on hMSCs. Uptake of silica NPs significantly enhanced the activity of alkaline phosphatase (ALP) and the formation of bone-like nodules of hMSCs after osteogenic induction. At the concentration of 10 µg ml^-1, after treating hMSCs with larger sized silica NPs (S2 and S3), higher ALP activity of hMSCs was measured and larger sized bone-like nodules were formed by hMSCs compared with that treated with smaller sized silica NPs (S1).The enhanced osteogenic potential of hMSCs treated with silica NPs may be attributed to the Si released from silica NPs due to the lysosomal degradation inside hMSCs. These results demonstrate the stimulatory effect of silica NPs on osteogenic differentiation of hMSCs and the application potential of silica NPs in bone tissue engineering.

Biofabrication and spectral characterization of silver nanoparticles and their cytotoxic studies on human CD34 +ve stem cells

Biosynthesis of plant-mediated silver nanoparticles is gaining significant importance due to environmentally safe ‘green method’ and it is an efficient alternative method. In the present study, silver nanoparticles were synthesized by using root extract of Glycyrrhiza glabra an important medicinal plant. The AgNPs are characterized by spectral analysis; the surface plasmon resonance (SPR) peak of AgNPs showed maximum absorption at 445 nm. Fourier-transform infrared spectroscopy (FT-IR) data show that the O–H hydroxyl groups, carboxylic acids, ester and ether groups and C–O stretching of alcohols have been utilized in the formation of AgNPs. The X-ray powder diffraction (XRD) data reveal that the AgNPs are face-centered cubic (fcc) in structure. The size was determined by particle size analyzer and atomic force microscope (AFM); the results reveal that AgNPs were spherical in shape and the average grain size is determined as 41.5–46.5 nm. Transmission electron microscopy (TEM) micrographs obtained show that AgNPs were roughly spherical and well dispersed with the sizes ranging from 10 to 45 nm ± 5 nm. The biofabricated AgNPs are extremely stable due to its high negative zeta potential −34.1 mV which indicates that the nanoparticles are polydispered in nature. The cytotoxic studies of AgNPs on human CD34 +ve stem cells in microcarrier culture reveal excellent growth at different concentrations of biosynthesized AgNPs. This is the first report of microcarrier culture of CD34 +ve stem cells on biosynthesized AgNPs.

Nanomedicine in Central Nervous System (CNS) Disorders: A Present and Future Prospective

Purpose: For the past few decades central nervous system disorders were considered as a major strike on human health and social system of developing countries. The natural therapeutic methods for CNS disorders limited for many patients. Moreover, nanotechnology-based drug delivery to the brain may an exciting and promising platform to overcome the problem of BBB crossing. In this review, first we focused on the role of the blood-brain barrier in drug delivery; and second, we summarized synthesis methods of nanomedicine and their role in different CNS disorder. Method: We reviewed the PubMed databases and extracted several kinds of literature on neuro nanomedicines using keywords, CNS disorders, nanomedicine, and nanotechnology. The inclusion criteria included chemical and green synthesis methods for synthesis of nanoparticles encapsulated drugs and, their in-vivo and in-vitro studies. We excluded nanomedicine gene therapy and nanomaterial in brain imaging. Results: In this review, we tried to identify a highly efficient method for nanomedicine synthesis and their efficacy in neuronal disorders. SLN and PNP encapsulated drugs reported highly efficient by easily crossing BBB. Although, these neuro-nanomedicine play significant role in therapeutics but some metallic nanoparticles reported the adverse effect on developing the brain. Conclusion: Although impressive advancement has made via innovative potential drug development, but their efficacy is still moderate due to limited brain permeability. To overcome this constraint,powerful tool in CNS therapeutic intervention provided by nanotechnology-based drug delivery methods. Due to its small and biofunctionalization characteristics, nanomedicine can easily penetrate and facilitate the drug through the barrier. But still, understanding of their toxicity level, optimization and standardization are a long way to go.

Oxidative stress response in neural stem cells exposed to different superparamagnetic iron oxide nanoparticles

Biocompatibility, safety, and risk assessments of superparamagnetic iron oxide nanoparticles (SPIONs) are of the highest priority in researching their application in biomedicine. One improvement in the biological properties of SPIONs may be achieved by different functionalization and surface modifications. This study aims to investigate how a different surface functionalization of SPIONs – uncoated, coated with d-mannose, or coated with poly-l-lysine – affects biocompatibility. We sought to investigate murine neural stem cells (NSCs) as important model system for regenerative medicine. To reveal the possible mechanism of toxicity of SPIONs on NSCs, levels of reactive oxygen species, intracellular glutathione, mitochondrial membrane potential, cell-membrane potential, DNA damage, and activities of SOD and GPx were examined. Even in cases where reactive oxygen species levels were significantly lowered in NSCs exposed to SPIONs, we found depleted intracellular glutathione levels, altered activities of SOD and GPx, hyperpolarization of the mitochondrial membrane, dissipated cell-membrane potential, and increased DNA damage, irrespective of the surface coating applied for SPION stabilization. Although surface coating should prevent the toxic effects of SPIONs, our results showed that all of the tested SPION types affected the NSCs similarly, indicating that mitochondrial homeostasis is their major cellular target. Despite the claimed biomedical benefits of SPIONs, the refined determination of their effects on various cellular functions presented in this work highlights the need for further safety evaluations. This investigation helps to fill the knowledge gaps on the criteria that should be considered in evaluating the biocompatibility and safety of novel nanoparticles.

Recent advances in mesoporous silica nanoparticles for antitumor therapy: our contribution

Since 2001, when our research group proposed for the first time MCM-41 as a drug release system, the scientific community has demonstrated a growing interest in mesoporous silica nanoparticles (MSNs) for their revolutionary potential in nanomedicine. Among the diverse pathologies that can be treated with MSNs, cancer has received increasing attention. MSNs can be loaded with large amounts of therapeutic cargoes and once intravenously administrated preferentially accumulate in solid tumours via the enhanced permeation and retention (EPR) effect. Herein we report the recent developments achieved by our research group as a pioneer in this field, highlighting: the design of sophisticated MSNs as stimuli-responsive drug delivery systems to release the entrapped cargo upon exposure to a given stimulus while preventing the premature release of highly cytotoxic drugs before reaching the target; transporting non-toxic prodrugs and the enzyme responsible for its conversion into cytotoxic agents into the same MSNs; improving the selectivity and cellular uptake by cancer cells by active targeting of MSNs; increasing the penetration of MSNs within the tumour mass, which is one of the major challenges in the use of NPs to treat solid tumours.

Bioactive SiO2@Ru nanoparticles for osteogenic differentiation of mesenchymal stem cells via activation of Akt signaling pathways

The surface chemistry of materials has an interactive influence on cell behavior.

Copper-doped mesoporous silica nanospheres, a promising immunomodulatory agent for inducing osteogenesis

The application of mesoporous silica nanospheres (MSNs) loaded with drugs/growth factors to induce osteogenic differentiation of stem cells has been trialed by a number of researchers recently. However, limitations such as high cost, complex fabrication and unintended side effects from supraphysiological concentrations of the drugs/growth factors represent major obstacles to any potential clinical application in the near term. In this study we reported an in situ one-pot synthesis strategy of MSNs doped with hypoxia-inducing copper ions and systematically evaluated the nanospheres by in vitro biological assessments. The Cu-containing mesoporous silica nanospheres (Cu-MSNs) had uniform spherical morphology (∼100nm), ordered mesoporous channels (∼2nm) and homogeneous Cu distribution. Cu-MSNs demonstrated sustained release of both silicon (Si) and Cu ions and controlled degradability. The Cu-MSNs were phagocytized by immune cells and appeared to modulate a favorable immune environment by initiating proper pro-inflammatory cytokines, inducing osteogenic/angiogenic factors and suppressing osteoclastogenic factors by the immune cells. The immune microenvironment induced by the Cu-MSNs led to robust osteogenic differentiation of bone mesenchymal stem cells (BMSCs) via the activation of Oncostation M (OSM) pathway. These results suggest that the novel Cu-MSNs could be used as an immunomodulatory agent with osteostimulatory capacity for bone regeneration/therapy application.

STATEMENT OF SIGNIFICANCE

In order to stimulate both osteogenesis and angiogenesis of stem cells for further bone regeneration, a new kind of hypoxia-inducing copper doped mesoporous silica nanospheres (Cu-MSNs) were prepared via one-pot synthesis. Biological assessments under immune environment which better reflect the in vivo response revealed that the nanospheres possessed osteostimulatory capacity and had potential as immunomodulatory agent for bone regeneration/therapy application. The strategy of introducing controllable amount of therapeutic ions instead of loading expensive drugs/growth factors in mesoporous silica nanosphere provides new options for bioactive nanomaterial functionalization.

Stem Cell Tracking with Nanoparticles for Regenerative Medicine Purposes: An Overview

Accurate and noninvasive stem cell tracking is one of the most important needs in regenerative medicine to determine both stem cell destinations and final differentiation fates, thus allowing a more detailed picture of the mechanisms involved in these therapies. Given the great importance and advances in the field of nanotechnology for stem cell imaging, currently, several nanoparticles have become standardized products and have been undergoing fast commercialization. This review has been intended to summarize the current use of different engineered nanoparticles in stem cell tracking for regenerative medicine purposes, in particular by detailing their main features and exploring their biosafety aspects, the first step for clinical application. Moreover, this review has summarized the advantages and applications of stem cell tracking with nanoparticles in experimental and preclinical studies and investigated present limitations for their employment in the clinical setting.

Nanoparticles Biosynthesized by Fungi and Yeast: A Review of Their Preparation, Properties, and Medical Applications

In the field of nanotechnology, the use of various biological units instead of toxic chemicals for the reduction and stabilization of nanoparticles, has received extensive attention. Among the many possible bio resources, biologically active products from fungi and yeast represent excellent scaffolds for this purpose. Since fungi and yeast are very effective secretors of extracellular enzymes and number of species grow fast and therefore culturing and keeping them in the laboratory are very simple. They are able to produce metal nanoparticles and nanostructure via reducing enzyme intracellularly or extracellularly. The focus of this review is the application of fungi and yeast in the green synthesis of inorganic nanoparticles. Meanwhile the domain of biosynthesized nanoparticles is somewhat novel; the innovative uses in nano medicine in different areas including the delivery of drug, cancer therapy, antibacterial, biosensors, and MRI and medical imaging are reviewed. The proposed signaling pathways of nanoparticles induced apoptosis in cancerous cells and anti-angiogenesis effects also are reviewed. In this article, we provide a short summary of the present study universally on the utilization of eukaryotes like yeast and fungi in the biosynthesis of nanoparticles (NPs) and their uses.

Stimulation of osteogenesis and angiogenesis of hBMSCs by delivering Si ions and functional drug from mesoporous silica nanospheres

Multifunctional bioactive materials with the ability to stimulate osteogenesis and angiogenesis of stem cells play an important role in the regeneration of bone defects. However, how to develop such biomaterials remains a significant challenge. In this study, we prepared mesoporous silica nanospheres (MSNs) with uniform sphere size (∼90 nm) and mesopores (∼2.7 nm), which could release silicon ions (Si) to stimulate the osteogenic differentiation of human bone marrow stromal cells (hBMSCs) via activating their ALP activity, bone-related gene and protein (OCN, RUNX2 and OPN) expression. Hypoxia-inducing therapeutic drug, dimethyloxaloylglycine (DMOG), was effectively loaded in the mesopores of MSNs (D-MSNs). The sustained release of DMOG from D-MSNs could stabilize HIF-1α and further stimulated the angiogenic differentiation of hBMSCs as indicated by the enhanced VEGF secretion and protein expression. Our study revealed that D-MSNs could combine the stimulatory effect on both osteogenic and angiogenic activity of hBMSCs. The potential mechanism of D-MSN-stimulated osteogenesis and angiogenesis was further elucidated by the supplementation of cell culture medium with pure Si ions and DMOG. Considering the easy handling characteristics of nanospheres, the prepared D-MSNs may be applied in the forms of injectable spheres for minimally invasive surgery, or MSNs/polymer composite scaffolds for bone defect repair. The concept of delivering both stimulatory ions and functional drugs may offer a new strategy to construct a multifunctional biomaterial system for bone tissue regeneration.

Autologous serum improves bone formation in a primary stable silica-embedded nanohydroxyapatite bone substitute in combination with mesenchymal stem cells and rhBMP-2 in the sheep model

New therapeutic strategies are required for critical size bone defects, because the gold standard of transplanting autologous bone from an unharmed area of the body often leads to several severe side effects and disadvantages for the patient. For years, tissue engineering approaches have been seeking a stable, axially vascularized transplantable bone replacement suitable for transplantation into the recipient bed with pre-existing insufficient conditions. For this reason, the arteriovenous loop model was developed and various bone substitutes have been vascularized. However, it has not been possible thus far to engineer a primary stable and axially vascularized transplantable bone substitute. For that purpose, a primary stable silica-embedded nanohydroxyapatite (HA) bone substitute in combination with blood, bone marrow, expanded, or directly retransplanted mesenchymal stem cells, recombinant human bone morphogenetic protein 2 (rhBMP-2), and different carrier materials (fibrin, cell culture medium, autologous serum) was tested subcutaneously for 4 or 12 weeks in the sheep model. Autologous serum lead to an early matrix change during degradation of the bone substitute and formation of new bone tissue. The best results were achieved in the group combining mesenchymal stem cells expanded with 60 μg/mL rhBMP-2 in autologous serum. Better ingrowth of fibrovascular tissue could be detected in the autologous serum group compared with the control (fibrin). Osteoclastic activity indicating an active bone remodeling process was observed after 4 weeks, particularly in the group with autologous serum and after 12 weeks in every experimental group. This study clearly demonstrates the positive effects of autologous serum in combination with mesenchymal stem cells and rhBMP-2 on bone formation in a primary stable silica-embedded nano-HA bone grafting material in the sheep model. In further experiments, the results will be transferred to the sheep arteriovenous loop model in order to engineer an axially vascularized primary stable bone replacement in clinically relevant size for free transplantation.

A comprehensive review on the role of various materials in the osteogenic differentiation of mesenchymal stem cells with a special focus on the association of heat shock proteins and nanoparticles

Mesenchymal stem cells (MSCs) have important roles in the area of regenerative medicine and clinical applications due to their pluripotent nature. Osteogenic differentiation of MSCs has been studied extensively using various stimulants to develop models of bone repair. There are several factors that enhance the differentiation of MSCs into bone tissues. This review focuses on the effects of various inducers on the osteoblast differentiation of MSCs at different stages of cellular development. We discuss the various growth factors, hormones, vitamins, cytokines, chemical stimulants, and mechanical forces applied in bioreactors that play an essential role in the proliferation, differentiation, and matrix mineralization of stem cells during osteogenesis. Various nanoparticles have also been used recently for the same purpose and the results are promising. Moreover, we review the role of various stresses, including thermal stress, and the subsequent involvement of heat shock proteins as inducers of the proliferation and differentiation of osteoblasts. We also report how various proteasome inhibitors have been shown to induce proliferation and osteogenic differentiation of MSCs in a number of cases. In this communication, the role of peptide-based scaffolds in osteoblast proliferation and differentiation is also reviewed. Based on the reviewed information, this article proposes novel possibilities for the enhancement of proliferation, differentiation, and migration of osteoblasts from MSCs. © 2014 S. Karger AG, Basel.

In vivo delivery of bovine viral diahorrea virus, E2 protein using hollow mesoporous silica nanoparticles

Our work focuses on the application of mesoporous silica nanoparticles as a combined delivery vehicle and adjuvant for vaccine applications. Here we present results using the viral protein, E2, from bovine viral diarrhoea virus (BVDV). BVDV infection occurs in the target species of cattle and sheep herds worldwide and is therefore of economic importance. E2 is a major immunogenic determinant of BVDV and is an ideal candidate for the development of a subunit based nanovaccine using mesoporous silica nanoparticles. Hollow type mesoporous silica nanoparticles with surface amino functionalisation (termed HMSA) were characterised and assessed for adsorption and desorption of E2. A codon-optimised version of the E2 protein (termed Opti-E2) was produced in Escherichia coli. HMSA (120 nm) had an adsorption capacity of 80 μg Opti-E2 per mg HMSA and once bound E2 did not dissociate from the HMSA. Immunisation studies in mice with a 20 μg dose of E2 adsorbed to 250 μg HMSA was compared to immunisation with Opti-E2 (50 μg) together with the traditional adjuvant Quillaja saponaria Molina tree saponins (QuilA, 10 μg). The humoral responses with the Opti-E2/HMSA nanovaccine although slightly lower than those obtained for the Opti-E2 + QuilA group demonstrated that HMSA particles are an effective adjuvant that stimulated E2-specific antibody responses. Importantly the cell-mediated immune responses were consistently high in all mice immunised with Opti-E2/HMSA nanovaccine formulation. Therefore we have shown the Opti-E2/HMSA nanoformulation acts as an excellent adjuvant that gives both T-helper 1 and T-helper 2 mediated responses in a small animal model. This study has provided proof-of-concept towards the development of an E2 subunit nanoparticle based vaccine.

Hyaluronic acid/poly-l-lysine bilayered silica nanoparticles enhance the osteogenic differentiation of human mesenchymal stem cells

The coating of silica nanoparticles with a bilayer of poly-l-lysine and hyaluronic acid enhances the osteogenic differentiation of human bone marrow stem cells at low nanoparticle concentrations (25 μg mL⁻¹ and 12.5 μg mL⁻¹).