Peptide-laden mesoporous silica nanoparticles with promoted bioactivity and osteo-differentiation ability for bone tissue engineering

Nanoengineered Silica-Based Biomaterials for Regenerative Medicine

The paradigm of regenerative medicine is undergoing a transformative shift with the emergence of nanoengineered silica-based biomaterials. Their unique confluence of biocompatibility, precisely tunable porosity, and the ability to modulate cellular behavior at the molecular level makes them highly desirable for diverse tissue repair and regeneration applications. Advancements in nanoengineered silica synthesis and functionalization techniques have yielded a new generation of versatile biomaterials with tailored functionalities for targeted drug delivery, biomimetic scaffolds, and integration with stem cell therapy. These functionalities hold the potential to optimize therapeutic efficacy, promote enhanced regeneration, and modulate stem cell behavior for improved regenerative outcomes. Furthermore, the unique properties of silica facilitate non-invasive diagnostics and treatment monitoring through advanced biomedical imaging techniques, enabling a more holistic approach to regenerative medicine. This review comprehensively examines the utilization of nanoengineered silica biomaterials for diverse applications in regenerative medicine. By critically appraising the fabrication and design strategies that govern engineered silica biomaterials, this review underscores their groundbreaking potential to bridge the gap between the vision of regenerative medicine and clinical reality.

Potential of bone morphogenetic protein-7 in treatment of lupus nephritis: addressing the hurdles to implementation

Up to 50% of systemic lupus erythematosus (SLE) patients world-wide develop lupus nephritis (LN). In low to middle income countries and in particular in sub-Saharan Africa, where SLE is prevalent with a more aggressive course, LN and end stage renal disease is a major cause of mortality. While developed countries have the funding to invest in SLE and LN research, patients of African descent are often underrepresented in clinical trials. Thus, the complex influence of ethnicity and genetic background on outcome of LN and SLE as a whole, is not fully understood. Several pathophysiological mechanisms including major role players driving LN have been identified. A large body of literature suggest that prevention of fibrosis-which contributes to chronicity of LN-may significantly improve long-term prognosis. Bone morphogenetic protein-7 (BMP-7) was first identified as a therapeutic option in this context decades ago and evidence of its benefit in various conditions, including LN, is ever-increasing. Despite these facts, BMP-7 is not being implemented as therapy in the context of renal disease. With this review, we briefly summarise current understanding of LN pathology and discuss the evidence in support of therapeutic potential of BMP-7 in this context. Lastly, we address the obstacles that need to be overcome, before BMP-7 may become available as LN treatment.

Particle carriers for controlled release of peptides

There has been growing discovery and use of therapeutic peptides in drug delivery and tissue engineering. Peptides are smaller than proteins and can be formulated into drug delivery systems without significant loss of their bioactivity, which remains a concern with proteins. However, the smaller size of peptides has made the controlled release of these bioactive molecules from carriers challenging. Thus, there has been increasing development of carriers to improve the controlled release of peptides by leveraging hydrophobic and electrostatic interactions between the peptide and the carrier. The focus of this review paper is to critically discuss synthetic and natural nanoparticles and microparticles that have been investigated for the controlled delivery of peptides with emphasis on the underlying interactions.

Thiol-Functionalized, Antioxidant, and Osteogenic Mesoporous Silica Nanoparticles for Osteoporosis

Osteoporosis is a chronic bone disorder characterized by decreased bone mass, leading to brittle bones and fractures. Oxidative stress has been identified as the most profound trigger for the initiation and progression of osteoporosis. Current treatment strategies do not induce new bone formation and fail to address a high level of reactive oxygen species (ROS). Mesoporous silica nanoparticles (MSNs) have been explored in bone tissue regeneration owing to their inherent osteogenic property, but they lack antioxidant and cell adhesion properties, required in such applications. We have developed thiolated, bioactive mesoporous silica nanoparticles (MSN-SH) to address this challenge. MSNs were fabricated using the Stöber method, and 11% of the surface was functionalized post-synthesis with thiol groups using MPTMS to obtain MSN-SH. The particle size measured by the dynamic light scattering technique was found to be around 300 nm. The surface morphology was investigated using HR-TEM, and their physical and chemical properties were characterized using various spectroscopic techniques. They exhibited more than 90% antioxidant activity, neutralized ROS formed in cells, and provided protection against ROS-induced cell damage. The cell viability assay in murine osteoblast precursor cells (MC3T3) showed that MSN-SH is cell-proliferative in nature with 140% cell viability. Osteogenic potential was evaluated by measuring the ALP activities, calcium deposition, and gene expression levels of osteogenic markers, such as RUNX2, ALP, OCN, and OPN, and results revealed that MSN-SH increases calcium deposition and induces osteogenesis through upregulation of osteogenic genes and markers without the involvement of any osteogenic supplements. Besides promoting osteogenesis, MSN-SH was found to inhibit osteoclastogenesis. The nanomaterial was found to be regenerative in nature, and it stimulated migration of osteoblast cells and caused a complete wound closure within 48 h. We were able to achieve a multifunctional nanomaterial by simply modifying the surface. MSNs have been explored for bone tissue engineering/osteoporosis as a composite system incorporating metals, like gold and cerium, or as a nanocarrier loaded with growth factors or active drugs. This study offers a simple and economical method to enhance the existing properties of MSNs and impart new activities by a single-step surface modification. It can be concluded that MSN-SH holds promise as a complementary and alternate treatment for osteoporosis along with the standardized therapy.

Bioactive peptides for boosting stem cell culture platform: Methods and applications

Peptides, short protein fragments, can emulate the functions of their full-length native counterparts. Peptides are considered potent recombinant protein alternatives due to their specificity, high stability, low production cost, and ability to be easily tailored and immobilized. Stem cell proliferation and differentiation processes are orchestrated by an intricate interaction between numerous growth factors and proteins and their target receptors and ligands. Various growth factors, functional proteins, and cellular matrix-derived peptides efficiently enhance stem cell adhesion, proliferation, and directed differentiation. For that, peptides can be immobilized on a culture plate or conjugated to scaffolds, such as hydrogels or synthetic matrices. In this review, we assess the applications of a variety of peptides in stem cell adhesion, culture, organoid assembly, proliferation, and differentiation, describing the shortcomings of recombinant proteins and their full-length counterparts. Furthermore, we discuss the challenges of peptide applications in stem cell culture and materials design, as well as provide a brief outlook on future directions to advance peptide applications in boosting stem cell quality and scalability for clinical applications in tissue regeneration.

Surface Characteristics and Bone Biocompatibility of Cold-Sprayed Porous Titanium on Polydimethylsiloxane Substrates

A variant of the cold spray (CS) technique was applied for the functionalization of polymer-based materials such as polydimethylsiloxane (PDMS) to improve the extent of mammalian cell interactions with these substrates. This was demonstrated by the embedment of porous titanium (pTi) into PDMS substrates using a single-step CS technique. CS processing parameters such as gas pressure and temperature were optimized to achieve the mechanical interlocking of pTi in the compressed PDMS to fabricate a unique hierarchical morphology possessing micro-roughness. As evidenced by the preserved porous structure, the pTi particles did not undergo any significant plastic deformation upon impact with the polymer substrate. The thickness of the particle embedment layer was determined, by cross-sectional analysis, ranging from 120 μm to over 200 μm. The behavior of osteoblast-like cells MG63 coming into contact with the pTi-embedded PDMS was examined. The results showed that the pTi-embedded PDMS samples promoted 80-96% of cell adhesion and proliferation during the early stages of incubation. The low cytotoxicity of the pTi-embedded PDMS was confirmed, with cell viability of the MG63 cells being above 90%. Furthermore, the pTi-embedded PDMS facilitated the production of alkaline phosphatase and calcium deposition in the MG63 cells, as demonstrated by the higher amount of alkaline phosphatase (2.6 times) and calcium (10.6 times) on the pTi-embedded PDMS sample fabricated at 250 °C, 3 MPa. Overall, the work demonstrated that the CS process provided flexibility in the parameters used for the production of the modified PDMS substrates and is highly efficient for the fabrication of coated polymer products. The results obtained in this study suggest that a tailorable porous and rough architecture could be achieved that promoted osteoblast function, indicating that the method has promise in the design of titanium-polymer composite materials applied to biomaterials used in musculoskeletal applications.

The application of mesoporous silica nanoparticles as a drug delivery vehicle in oral disease treatment

Mesoporous silica nanoparticles (MSNs) hold promise as safer and more effective medication delivery vehicles for treating oral disorders. As the drug's delivery system, MSNs adapt to effectively combine with a variety of medications to get over systemic toxicity and low solubility issues. MSNs, which operate as a common nanoplatform for the co-delivery of several compounds, increase therapy effectiveness and show promise in the fight against antibiotic resistance. MSNs offer a noninvasive and biocompatible platform for delivery that produces long-acting release by responding to minute stimuli in the cellular environmen. MSN-based drug delivery systems for the treatment of periodontitis, cancer, dentin hypersensitivity, and dental cavities have recently been developed as a result of recent unparalleled advancements. The applications of MSNs to be embellished by oral therapeutic agents in stomatology are discussed in this paper.

Functionalized Microscaffold-Hydrogel Composites Accelerating Osteochondral Repair through Endochondral Ossification

Osteochondral regeneration remains a key challenge because of the limited self-healing ability of the bone and its complex structure and composition. Biomaterials based on endochondral ossification (ECO) are considered an attractive candidate to promote bone repair because they can effectively address the difficulties in establishing vascularization and poor bone regeneration via intramembranous ossification (IMO). However, its clinical application is limited by the complex cellular behavior of ECO and the long time required for induction of the cell cycle. Herein, functionalized microscaffold-hydrogel composites are developed to accelerate the developmental bone growth process via recapitulating ECO. The design comprises arginine-glycine-aspartic acid (RGD)-peptide-modified microscaffolds loaded with kartogenin (KGN) and wrapped with a layer of RGD- and QK-peptide-comodified alginate hydrogel. These microscaffolds enhance the proliferation and aggregation behavior of the human bone marrow mesenchymal stem cells (hBMSCs); the controlled release of kartogenin induces the differentiation of hBMSCs into chondrocytes; and the hydrogel grafted with RGD and QK peptide facilitates chondrocyte hypertrophy, which creates a vascularized niche for osteogenesis and finally accelerates osteochondral repair in vivo. The findings provide an efficient bioengineering approach by sequentially modulating cellular ECO behavior for osteochondral defect repair.

Synthesis and Characterization of Porous Forsterite Ceramics with Prospective Tissue Engineering Applications

Due to the urgent need to develop and improve biomaterials, the present article proposes a new strategy to obtain porous scaffolds based on forsterite (Mg₂SiO₄) for bone tissue regeneration. The main objective is to restore and improve bone function, providing a stable environment for regeneration. The usage of magnesium silicate relies on its mechanical properties being superior to hydroxyapatite and, in general, to calcium phosphates, as well as its high biocompatibility, and antibacterial properties. Mg₂SiO₄ powder was obtained using the sol-gel method, which was calcinated at 800 °C for 2 h; then, part of the powder was further used to make porous ceramics by mixing it with a porogenic agent (e.g., sucrose). The raw ceramic bodies were subjected to two sintering treatments, at 1250 or 1320 °C, and the characterization results were discussed comparatively. The porogenic agent did not influence the identified phases or the samples' crystallinity and was efficiently removed during the heat treatment. Moreover, the effect of the porogenic agent no longer seems significant after sintering at 1250 °C; the difference in porosity between the two ceramics was negligible. When analysing the in vitro cytotoxicity of the samples, the ones that were porous and treated at 1320 °C showed slightly better cell viability, with the cells appearing to adhere more easily to their surface.

Engineering mesoporous silica nanoparticles for drug delivery: where are we after two decades?

The present review details a chronological description of the events that took place during the development of mesoporous materials, their different synthetic routes and their use as drug delivery systems. The outstanding textural properties of these materials quickly inspired their translation to the nanoscale dimension leading to mesoporous silica nanoparticles (MSNs). The different aspects of introducing pharmaceutical agents into the pores of these nanocarriers, together with their possible biodistribution and clearance routes, would be described here. The development of smart nanocarriers that are able to release a high local concentration of the therapeutic cargo on-demand after the application of certain stimuli would be reviewed here, together with their ability to deliver the therapeutic cargo to precise locations in the body. The huge progress in the design and development of MSNs for biomedical applications, including the potential treatment of different diseases, during the last 20 years will be collated here, together with the required work that still needs to be done to achieve the clinical translation of these materials. This review was conceived to stand out from past reports since it aims to tell the story of the development of mesoporous materials and their use as drug delivery systems by some of the story makers, who could be considered to be among the pioneers in this area.

Strontium- and peptide-modified silicate nanostructures for dual osteogenic and antimicrobial activity

Developing multifunctional nanostructures that promote bone repair while fighting infection is highly desirable in bone regenerative therapies. Previous efforts have focused on achieving one property or another by altering the chemical makeup of nanostructures or using growth factors or antibiotics. We present nanostructures with several simultaneous functional attributes including positive effects of strontium on bone formation and prevention of osteoclast differentiation along with incorporation of antimicrobial peptides (AMP) to prevent infection. To form these multifunctional nanostructures, mesoporous calcium silicate (CaMSN) was modified with high levels of strontium. For this, CaMSNs were either partially substituted (20 wt% Ca) or completely replaced with strontium (Sr) to form Sr-CaMSN or SrMSN. The mesoporous nature of these bioactive silicate nanostructures rendered a configuration for substantial AMP loading as well as their effective delivery. The physico-chemical and structural characterization of synthesized MSNs confirmed the mesoporous nature of the synthesized MSNs and their total surface area, pore size, pore volume and SBF-mediated bioactivity remained unaltered with the incorporation of Sr. However, biological evaluation confirmed that synthesized SrMSN upregulated osteogenic differentiation of mesenchymal stromal cells and significantly downregulated osteoclast differentiation. Also, the AMP-loaded MSNs prevented formation and growth of methicillin resistant Staphylococcus aureus (MRSA) biofilms. Thus, high Sr-containing AMP-loaded SrMSNs may combat MRSA-associated infection while promoting bone regeneration. The controlled availability of therapeutic Sr and AMP release as SrMSN degrade enables its potential application in bone tissue regeneration.

Adsorption of Recombinant Human β-Defensin 2 and Two Mutants on Mesoporous Silica Nanoparticles and Its Effect against Clavibacter michiganensis subsp. michiganensis

Solanum lycopersicum L. is affected among other pests and diseases, by the actinomycete Clavibacter michiganensis subsp. michiganensis (Cmm), causing important economic losses worldwide. Antimicrobial peptides (AMPs) are amphipathic cationic oligopeptides with which the development of pathogenic microorganisms has been inhibited. Therefore, in this study, we evaluate antimicrobial activity of mesoporous silica nanoparticles (MSN5.4) loaded with human β-defensin-2 (hβD2) and two mutants (TRX-hβD2-M and hβD2-M) against Cmm. hβD2, TRX-hβD2-M and hβD2-M presented a half-maximum inhibitory concentration (IC₅₀) of 3.64, 1.56 and 6.17 μg/mL, respectively. MSNs had average particle sizes of 140 nm (SEM) and a tunable pore diameter of 4.8 up to 5.4 nm (BJH). AMPs were adsorbed more than 99% into MSN and a first release after 24 h was observed. The MSN loaded with the AMPs inhibited the growth of Cmm in solid and liquid media. It was also determined that MSNs protect AMPs from enzymatic degradation when the MSN/AMPs complexes were exposed to a pepsin treatment. An improved AMP performance was registered when it was adsorbed in the mesoporous matrix. The present study could expand the applications of MSNs loaded with AMPs as a biological control and provide new tools for the management of phytopathogenic microorganisms.

An Update on Mesoporous Silica Nanoparticle Applications in Nanomedicine

The efficient and safe delivery of therapeutic drugs, proteins, and nucleic acids are essential for meaningful therapeutic benefits. The field of nanomedicine shows promising implications in the development of therapeutics by delivering diagnostic and therapeutic compounds. Nanomedicine development has led to significant advances in the design and engineering of nanocarrier systems with supra-molecular structures. Smart mesoporous silica nanoparticles (MSNs), with excellent biocompatibility, tunable physicochemical properties, and site-specific functionalization, offer efficient and high loading capacity as well as robust and targeted delivery of a variety of payloads in a controlled fashion. Such unique nanocarriers should have great potential for challenging biomedical applications, such as tissue engineering, bioimaging techniques, stem cell research, and cancer therapies. However, in vivo applications of these nanocarriers should be further validated before clinical translation. To this end, this review begins with a brief introduction of MSNs properties, targeted drug delivery, and controlled release with a particular emphasis on their most recent diagnostic and therapeutic applications.

Sustained Release Systems for Delivery of Therapeutic Peptide/Protein

Peptide/protein therapeutics have been significantly applied in the clinical treatment of various diseases such as cancer, diabetes, etc. owing to their high biocompatibility, specificity, and therapeutic efficacy. However, due to their immunogenicity, instability stemming from its complex tertiary and quaternary structure, vulnerability to enzyme degradation, and rapid renal clearance, the clinical application of protein/peptide therapeutics is significantly confined. Though nanotechnology has been demonstrated to prevent enzyme degradation of the protein therapeutics and thus enhance the half-life, issues such as initial burst release and uncontrollable release kinetics are still unsolved. Moreover, the traditional administration method results in poor patient compliance, limiting the clinical application of protein/peptide therapeutics. Exploiting the sustained-release formulations for more controllable delivery of protein/peptide therapeutics to decrease the frequency of injection and enhance patient compliance is thus greatly meaningful. In this review, we comprehensively summarize the substantial advancements of protein/peptide sustained-release systems in the past decades. In addition, the advantages and disadvantages of all these sustained-release systems in clinical application together with their future challenges are also discussed in this review.

Development of methods for detecting the fate of mesenchymal stem cells regulated by bone bioactive materials

The fate of mesenchymal stem cells (MSCs) is regulated by biological, physical and chemical signals. Developments in biotechnology and materials science promoted the occurrence of bioactive materials which can provide physical and chemical signals for MSCs to regulate their fate. In order to design and synthesize materials that can precisely regulate the fate of MSCs, the relationship between the properties of materials and the fate of mesenchymal stem cells need to be clarified, in which the detection of the fate of mesenchymal stem cells plays an important role. In the past 30 years, a series of detection technologies have been developed to detect the fate of MSCs regulated by bioactive materials, among which high-throughput technology has shown great advantages due to its ability to detect large amounts of data at one time. In this review, the latest research progresses of detecting the fate of MSCs regulated by bone bioactive materials (BBMs) are systematically reviewed from traditional technology to high-throughput technology which is emphasized especially. Moreover, current problems and the future development direction of detection technologies of the MSCs fate regulated by BBMs are prospected. The aim of this review is to provide a detection technical framework for researchers to establish the relationship between the properties of BMMs and the fate of MSCs, so as to help researchers to design and synthesize BBMs better which can precisely regulate the fate of MSCs.

Bioactive glasses and glass-ceramics for hyperthermia treatment of cancer: state-of-art, challenges, and future perspectives

Bioactive glasses and glass-ceramics are well-proven potential biomaterials for bone-tissue engineering applications because of their compositional flexibility. Many research groups have been focused to explore the utility of bioactive glass-ceramics beyond bone engineering to hyperthermia treatment of cancer. Hyperthermia refers to raising the temperature of tumor close to 44°C at which malignant cells perish with negligible harm to normal cells. Hyperthermia can be employed by many means such as by ultrasonic waves, electromagnetic waves, infrared radiations, alternating magnetic fields, etc. Magnetic bioactive glass-ceramics are advantageous over other potential candidates for thermoseeds such as nanofluids, superparamagnetic nanoparticles because they can bond not only to the natural bone but also with soft tissues in few cases, which helps regenerating the affected part due to its bioactive nature. Strict restrictions on clinical settings ( H × f < 5 × 10 9 ) force the research activities to be more focused on material characteristics to raise the implant temperature to required ranges. Lots of efforts have been made in past years to tackle these challenges and design best-suited glass-ceramics for hyperthermia treatment. This review aims to provide essential information on the concept of hyperthermia treatment of cancer and recent developments in the field of bioactive glass-ceramics for cancer treatment. The advantages and disadvantages of magnetic glass-ceramics over other potential thermoseed materials are highlighted. In this field, the major challenges are to develop magnetic glasses, which have fast and bulk crystallization with optimized magnetic phases with lower Curie and Neel temperatures.

Biodegradable nanofibrous temperature-responsive gelling microspheres for heart regeneration

Myocardial infarction (heart attack) is the number one killer of heart patients. Existing treatments for heart attack do not address the underlying problem of cardiomyocyte (CM) loss and cannot regenerate the myocardium. Introducing exogenous cardiac cells is required for heart regeneration due to the lack of resident progenitor cells and very limited proliferative potential of adult CMs. Poor retention of transplanted cells is the critical bottleneck of heart regeneration. Here, we report the invention of a poly(l-lactic acid)-b-poly(ethylene glycol)-b-poly(N-Isopropylacrylamide) copolymer and its self-assembly into nanofibrous gelling microspheres (NF-GMS). The NF-GMS undergo thermally responsive transition to form not only a 3D hydrogel after injection in vivo, but also exhibit architectural and structural characteristics mimicking the native extracellular matrix (ECM) of nanofibrous proteins and gelling proteoglycans or polysaccharides. By integrating the ECM-mimicking features, injectable form, and the capability of maintaining 3D geometry after injection, the transplantation of hESC-derived CMs carried by NF-GMS led to a striking 10-fold graft size increase over direct CM injection in an infarcted rat model, which is the highest reported engraftment to date. Furthermore, NF-GMS carried CM transplantation dramatically reduced infarct size, enhanced integration of transplanted CMs, stimulated vascularization in the infarct zone, and led to a substantial recovery of cardiac function. The NF-GMS may also serve as advanced injectable and integrative biomaterials for cell/biomolecule delivery in a variety of biomedical applications.

Poly-l-lactic acid scaffold incorporated chitosan-coated mesoporous silica nanoparticles as pH-sensitive composite for enhanced osteogenic differentiation of human adipose tissue stem cells by dexamethasone delivery

Nowadays, the development of drug-loaded electrospun organic-inorganic composite scaffolds for tissue engineering application is an attractive approach. In this study, a composite scaffold of Poly-l-lactic acid (PLLA) incorporated dexamethasone (Dexa) loaded Mesoporous Silica Nanoparticles (MSN) coated with Chitosan (CS) were fabricated by electrospinning for bone tissue engineering application. The MSN was prepared by precipitation method. After that, Dexamethasone (Dexa) was loaded into MSNs (MSN-Dexa). In the following, CS was coated over the prepared nanoparticles to form MSN-Dexa@CS and then, were mixed to PLLA solution to form MSN-Dexa@CS/PLLA composite for electrospinning. The surface morphology, hydrophilicity, tensile strength and the bioactivity of the scaffolds were characterized. The osteogenic proliferation and differentiation potential were evaluated by MTT assay and by measuring the basic osteogenic markers: the activity of the enzyme alkaline phosphatase and the level of calcium deposition. The composite scaffolds prepared here have conductive surface property and have a better osteogenic potential than pure PLLA scaffolds. Hence, the controlled release of nanoparticle containing Dexa from composite scaffold supported the osteogenesis and made the composite scaffolds ideal candidates for bone tissue engineering application and pH-sensitive delivery of drugs at the site of implantation in tissue regeneration.

Nanomaterials for bone tissue regeneration: updates and future perspectives

Joint replacement and bone reconstructive surgeries are on the rise globally. Current strategies for implants and bone regeneration are associated with poor integration and healing resulting in repeated surgeries. A multidisciplinary approach involving basic biological sciences, tissue engineering, regenerative medicine and clinical research is required to overcome this problem. Considering the nanostructured nature of bone, expertise and resources available through recent advancements in nanobiotechnology enable researchers to design and fabricate devices and drug delivery systems at the nanoscale to be more compatible with the bone tissue environment. The focus of this review is to present the recent progress made in the rationale and design of nanomaterials for tissue engineering and drug delivery relevant to bone regeneration.

Naturally Occurring and Synthetic Mesoporous Nanosilica: Multimodal Applications in Frontier Areas of Science

Mesoporous silica nanoparticles (MSNs) have gained attention worldwide due to their structural versatility for diverse applications in a number of frontier areas of sciences. The intrinsic chemical, textural and structural features of MSNs allow fabricating versatile multifunctional nanosystems. The present review provides an overview of the research progress in artificial and biological production of MSNs, their properties and various applications in cutting edge areas of sciences.

Silica nanoparticle surface chemistry: An important trait affecting cellular biocompatibility in two and three dimensional culture systems

Great advantages bestowed by mesoporous silica nanoparticles (MSNs) including high surface area, tailorable pore diameter and surface chemistry, and large pore volume render them as efficient tools in biomedical applications. Herein, MSNs with different surface chemistries were synthesized and investigated in terms of biocompatibility and their impact on the morphology of bone marrow-derived mesenchymal stem cells both in 2D and 3D culture systems. Bare MSNs (BMSNs) were synthesized by template removing method using tetraethylorthosilicate (TEOS) as a precursor. The as-prepared BMSNs were then used to prepare amine-functionalized (AMSNs), carboxyl-functionalized (CMSNs) and polymeric amine-functionalized (PMSNs) samples, consecutively. These nanoparticles were characterized by scanning electron microscopy, zeta potential measurement, dynamic light scattering, BET (Brunauer, Emmett, Teller) analysis, and FTIR technique. In a 3D culture system, stem cells were encapsulated in alginate hydrogel in which MSNs of different functionalities were incorporated. The results showed good biocompatibility for both BMSNs and AMSNs in 2D and 3D culture systems. For these samples, the viability of about 80% was acquired after 2 weeks of 3D culture. When compared to the control, CMSNs caused higher cell proliferation in the 2D culture; while they showed cytotoxic effects in the 3D culture system. Interestingly, polymeric amine-functionalized silica nanoparticles (PMSNs) resulted in disrupted morphology and very low viability in the 2D cell culture and even less viability in 3D environment in comparison to BMSNs and AMSNs. This significant decrease in cell viability was attributed to the higher uptake values of highly positively charged PMSNs by cells as compared to other MSNs. This up-regulated uptake was evaluated by using an inductively coupled plasma optical emission spectroscopy instrument (ICP-OES). These results uncover different interactions between cell and nanoparticles with various surface chemistries. Building on these results, new windows are opened for employing biocompatible nanoparticles such as BMSNs and AMSNs, even at high concentrations, as potential cargos for carrying required growth and/or differentiation factors for tissue engineering applications.

Versatile Nanocarrier Based on Functionalized Mesoporous Silica Nanoparticles to Codeliver Osteogenic Gene and Drug for Enhanced Osteodifferentiation

To achieve enhanced stimulatory effects on the osteogenic differentiation of stem cells, the combination of dual factors with synergistic bioactivity has been regarded as the most effective and powerful strategy. In this study, polylysine-modified polyethylenimine (PEI-PLL) copolymers with various molecular weight PEI blocks were first synthesized and evaluated focusing on their cytotoxicity and gene transfection efficiency, and the results demonstrated that the synthesized copolymer PEI-PLL-25k (synthesized using 25 kDa PEI) exhibited lower cytotoxicity and higher in vitro transfection efficiency than commercial PEI-25k (M_w = 25 kDa). In order to effectively load and deliver plasmid DNA and osteogenic drug dexamethasone (DEX), PEI-PLL-25k copolymer and arginine-glycine-aspartate (RGD) peptide were successively anchored onto the surface of mesoporous silica nanoparticles (MSNs) to construct the dual-factor delivery system, which allows the surface adsorption of DNA and DEX loading in the mesopores of MSNs. The modification of PEI-PLL-25k copolymer and RGD on nanoparticles was successfully characterized by various techniques. The functionalized MSNs with RGD conjugation on the surface showed good cytocompatibility as evidenced by in vitro cell viability assays and cytoskeleton observation. The dual-factor delivery system could quickly release plasmid DNA (pDNA), while releasing DEX in a sustained manner. When cultured with the vector bearing bone morphogenetic protein-2 (BMP-2) pDNA, the transfected bone mesenchymal stem cells (BMSCs) were capable of expressing BMP-2 protein. With the simultaneous delivery of DEX and the BMP-2 gene, this dual-factor delivery system could significantly enhance the level of osteogenic differentiation of BMSCs, as demonstrated by in vitro results of alkaline phosphatase (ALP) activity, expression of osteo-related genes, and calcium deposition. Therefore, the versatile functionalized MSNs nanocarrier for codelivery of osteogenic gene and drug may be considered as a promising dual-delivery system to synergistically enhance the osteogenic outcomes of stem cells.

Nanomaterials as potential and versatile platform for next generation tissue engineering applications

Tissue engineering (TE) is an emerging field where alternate/artificial tissues or organ substitutes are implanted to mimic the functionality of damaged or injured tissues. Earlier efforts were made to develop natural, synthetic, or semisynthetic materials for skin equivalents to treat burns or skin wounds. Nowadays, many more tissues like bone, cardiac, cartilage, heart, liver, cornea, blood vessels, and so forth are being engineered using 3-D biomaterial constructs or scaffolds that could deliver active molecules such as peptides or growth factors. Nanomaterials (NMs) due to their unique mechanical, electrical, and optical properties possess significant opportunities in TE applications. Traditional TE scaffolds were based on hydrolytically degradable macroporous materials, whereas current approaches emphasize on controlling cell behaviors and tissue formation by nano-scale topography that closely mimics the natural extracellular matrix. This review article gives a comprehensive outlook of different organ specific NMs which are being used for diversified TE applications. Varieties of NMs are known to serve as biological alternatives to repair or replace a portion or whole of the nonfunctional or damaged tissue. NMs may promote greater amounts of specific interactions stimulated at the cellular level, ultimately leading to more efficient new tissue formation. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2433-2449, 2019.

3D printable SiO2 nanoparticle ink for patient specific bone regeneration

3D printing of a complex and irregular virtual defect using SiO₂ nanoparticle and hydrogel composite ink for patient specific defect fabrication.

Polysaccharide Based Scaffolds for Soft Tissue Engineering Applications

Soft tissue reconstructs require materials that form three-dimensional (3-D) structures supportive to cell proliferation and regenerative processes. Polysaccharides, due to their hydrophilicity, biocompatibility, biodegradability, abundance, and presence of derivatizable functional groups, are distinctive scaffold materials. Superior mechanical properties, physiological signaling, and tunable tissue response have been achieved through chemical modification of polysaccharides. Moreover, an appropriate formulation strategy enables spatial placement of the scaffold to a targeted site. With the advent of newer technologies, these preparations can be tailor-made for responding to alterations in temperature, pH, or other physiological stimuli. In this review, we discuss the developmental and biological aspects of scaffolds prepared from four polysaccharides, viz. alginic acid (ALG), chitosan (CHI), hyaluronic acid (HA), and dextran (DEX). Clinical studies on these scaffolds are also discussed.

Nanoparticles as Carriers of Proteins, Peptides and Other Therapeutic Molecules

Nanoparticles have many applications both in industry and medicine. Depending upon their physical and chemical properties, they can be used as carriers of therapeutic molecules or as therapeutics. Nanoparticles are made of synthetic or natural polymers, lipids or metals. Their use allows for faster transport to the place of action, thus prolonging its presence in the body and limiting side effects. In addition, the use of such a drug delivery system protects the drug from rapid disintegration and elimination from the body. In recent years, the use of proteins and peptides as therapeutic molecules has grown significantly. Unfortunately, proteins are subject to enzymatic digestion and can cause unwanted immune response beyond therapeutic action. The use of drug carriers can minimize undesirable side effects and reduce the dose of medication needed to achieve the therapeutic effect. The current study presents the use of several selected drug delivery systems for the delivery of proteins, peptides and other therapeutic molecules.

Mesoporous Silica Nanoparticles: A Comprehensive Review on Synthesis and Recent Advances

Recent advancements in drug delivery technologies utilizing a variety of carriers have resulted in a path-breaking revolution in the approach towards diagnosis and therapy alike in the current times. Need for materials with high thermal, chemical and mechanical properties have led to the development of mesoporous silica nanoparticles (MSNs). These ordered porous materials have garnered immense attention as drug carriers owing to their distinctive features over the others. They can be synthesized using a relatively simple process, thus making it cost effective. Moreover, by controlling the parameters during the synthesis; the morphology, pore size and volume and particle size can be transformed accordingly. Over the last few years, a rapid increase in research on MSNs as drug carriers for the treatment of various diseases has been observed indicating its potential benefits in drug delivery. Their widespread application for the loading of small molecules as well as macromolecules such as proteins, siRNA and so forth, has made it a versatile carrier. In the recent times, researchers have sorted to several modifications in the framework of MSNs to explore its potential in drug resistant chemotherapy, antimicrobial therapy. In this review, we have discussed the synthesis of these multitalented nanoparticles and the factors influencing the size and morphology of this wonder carrier. The second part of this review emphasizes on the applications and the advances made in the MSNs to broaden the spectrum of its use especially in the field of biomedicine. We have also touched upon the lacunae in the thorough understanding of its interaction with a biological system which poses a major hurdle in the passage of this carrier to the clinical level. In the final part of this review, we have discussed some of the major patents filed in the field of MSNs for therapeutic purpose.

Osteostimulation scaffolds of stem cells: BMP-7-derived peptide-decorated alginate porous scaffolds promote the aggregation and osteo-differentiation of human mesenchymal stem cells

The scaffolds for stem cell-based bone tissue engineering should hold the ability to guide stem cells osteo-differentiating. Otherwise, stem cells will differentiate into unwanted cell types or will form tumors in vivo. Alginate, a natural polysaccharide with great biocompatibility, was widely used in biomedical applications. However, the limited bioactivity and poor osteogenesis capability of pristine alginate hampered its further application in tissue engineering. In this work, a bone forming peptide-1 (BFP-1), derived from bone morphogenetic protein-7, was grafted to alginate polymer chains to prepare peptide-decorated alginate porous scaffolds (pep-APS) for promoting osteo-differentiation of human mesenchymal stem cells (hMSCs). SEM images of pep-APS exhibited porous structure with about 90% porosity (pore size 100-300 μm), which was appropriate for hMSCs ingrowth. The adhesion, proliferation and aggregation of hMSCs grown on pep-APS were enhanced in vitro. Moreover, pep-APS promoted the alkaline phosphatase (ALP) activity of hMSCs, and the osteo-related genes expression was obviously up-regulated. The immunochemical staining and western blot analysis results showed high expression level of OCN and Col1a1 in the hMSCs grown on pep-APS. This work provided a facile and valid strategy to endow the alginate polymers themselves with specific bioactivity and prepare osteopromoting scaffold with enhanced osteogenesis ability, possessing potential applications in stem cell therapy and regenerative medicine.

Time-responsive osteogenic niche of stem cells: A sequentially triggered, dual-peptide loaded, alginate hybrid system for promoting cell activity and osteo-differentiation

The efficacy of stem cell-based bone tissue engineering has been hampered by cell death and limited fate control. A smart cell culture system with the capability of sequentially delivering multiple factors in specific growth stages, like the mechanism of the natural extracellular matrix modulating tissue formation, is attractive for enhancing cell activity and controlling cell fate. Here, a bone forming peptide-1 (BFP-1)-laden mesoporous silica nanoparticles (pep@MSNs) incorporated adhesion peptide, containing the arginine-glycine-aspartic acid (RGD) domain, modified alginate hydrogel (RA) system (pep@MSNs-RA) was developed to promote the activity and stimulate osteo-differentiation of human mesenchymal stem cells (hMSCs) in sequence. The survivability and proliferation of hMSCs were enhanced in the adhesion peptide modified hydrogel. Next, BFP-1 released from pep@MSNs induced hMSCs osteo-differentiation after the proliferation stage. Moreover, BFP-1 near the cells was self-captured by the additional cell-peptide cross-linked networks formed by the ligands (RGD) binding to receptors on the cell surface, leading to long-term sustained osteo-stimulation of hMSCs. The results suggest that independent and sequential stimulation in proliferation and osteo-differentiation stages could synergistically enhance the survivability, expansion, and osteogenesis of hMSCs, as compared to stimulating alone or simultaneously. Overall, this study provided a new and valid strategy for stem cell expansion and osteo-differentiation in 2D or 3D culture systems, possessing potential applications in 3D bio-printing and tissue regeneration.

Polymer coated mesoporous ceramic for drug delivery in bone tissue engineering

Treatment strategy for various bone fracture and defects the researchers are focusing to develop a new carrier for delivering the drug into injured area with controlled and sustained manner using biomaterials with dynamic architecture orientation. Ceramic materials are resembled with bone compositional architecture and better bioactivity, degradability as well as antimicrobial activity made its enormous application in bone tissue engineering (BTE). Current focus in regenerative medicine were orchestration of biomaterials with the capacity of loading the drugs, growth factors, ionic components to promote better healing of bone tissue. Mesoporous type materials owed a great look towards the delivery of drugs, growth factors, etc in BTE because of its unique geometry. So the guest molecules loaded with geometrically organized ceramics would deliver onto the site of injury in controlled manner also the guiding and regulation of delivery of molecules have been controlled with the polymers response to different stimulation or biochemical factors as either scaffold or encapsulated particles for bone regeneration. Hence the review aims to describing the recent progress in bone tissue engineering using the ceramic based mesoporous materials encapsulated with polymers respond to different physiochemical stimulation for the efficient and controlled delivery of drug/growth factors for better bone healing.

Nanomedicine for safe healing of bone trauma: Opportunities and challenges

Historically, high-energy extremity injuries resulting in significant soft-tissue trauma and bone loss were often deemed unsalvageable and treated with primary amputation. With improved soft-tissue coverage and nerve repair techniques, these injuries now present new challenges in limb-salvage surgery. High-energy extremity trauma is pre-disposed to delayed or unpredictable bony healing and high rates of infection, depending on the integrity of the soft-tissue envelope. Furthermore, orthopedic trauma surgeons are often faced with the challenge of stabilizing and repairing large bony defects while promoting an optimal environment to prevent infection and aid bony healing. During the last decade, nanomedicine has demonstrated substantial potential in addressing the two major issues intrinsic to orthopedic traumas (i.e., high infection risk and low bony reconstruction) through combatting bacterial infection and accelerating/increasing the effectiveness of the bone-healing process. This review presents an overview and discusses recent challenges and opportunities to address major orthopedic trauma through nanomedical approaches.

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.

Porous Inorganic Drug Delivery Systems-a Review

Innovative methods and materials have been developed to overcome limitations associated with current drug delivery systems. Significant developments have led to the use of a variety of materials (as excipients) such as inorganic and metallic structures, marking a transition from conventional polymers. Inorganic materials, especially those possessing significant porosity, are emerging as good candidates for the delivery of a range of drugs (antibiotics, anticancer and anti-inflammatories), providing several advantages in formulation and engineering (encapsulation of drug in amorphous form, controlled delivery and improved targeting). This review focuses on key selected developments in porous drug delivery systems. The review provides a short broad overview of porous polymeric materials for drug delivery before focusing on porous inorganic materials (e.g. Santa Barbara Amorphous (SBA) and Mobil Composition of Matter (MCM)) and their utilisation in drug dosage form development. Methods for their preparation and drug loading thereafter are detailed. Several examples of porous inorganic materials, drugs used and outcomes are discussed providing the reader with an understanding of advances in the field and realistic opportunities.

Recent advances in nano scaffolds for bone repair

Biomedical applications of nanomaterials are exponentially increasing every year due to analogy to various cell receptors, ligands, structural proteins, and genetic materials (that is, DNA). In bone tissue, nanoscale materials can provide scaffold for excellent tissue repair via mechanical stimulation, releasing of various loaded drugs and mediators, 3D scaffold for cell growth and differentiation of bone marrow stem cells to osteocytes. This review will therefore highlight recent advancements on tissue and nanoscale materials interaction.

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.

Synthesis of novel quaternary silica hybrid bioactive microspheres

PURPOSE

To survey the preparation of novel hybrid microspheres of quaternary silicate glassy composition (SiO₂ P₂ O₅ CaONa₂ O) and the prospect of using them as an osteogenic system with enhanced bioactive properties for the development of hydroxyapatite.

METHOD

In line with our previous synthetic procedure a two-step process was followed, wherein polystyrene (PS) microspheres were prepared by the emulsifier free-emulsion polymerization method and constituted the core for the sol-gel coating of the silicate inorganic shell. The development of the hybrid microspheres was based on silane and phosphate precursors and was assesses at different ratio of ethanol/water (of 9/1, 4/1, and 2/1, in mL) and at varied ammonia concentration of 4.8-1.0 mL.

RESULTS

The hybrid microspheres had an average size ranged between 350 and 550 nm according to SEM, depending on the ethanol/water solution rate and ammonia content. The final microspheres probably exhibited a porous-like structure through the formation of diffused voids along with the low carbon content of the EDX analysis, which could be regulated by the catalyst content. The hybrid microspheres exhibited effective in vitro bioactivity assessed in simulated body fluids (SBF).

CONCLUSION

Quaternary hybrid silica microspheres were effectively synthesized. The bioassay evaluation of the final microspheres revealed the rapid in vitro formation of a bone-like apatite layer. The results verify the bioactivity of the microspheres and promote further research of their suitability on regenerative treatment of bone abnormalities. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 112-120, 2018.

Nanotherapeutics of PTEN Inhibitor with Mesoporous Silica Nanocarrier Effective for Axonal Outgrowth of Adult Neurons

Development of therapeutic strategies such as effective drug delivery is an urgent and yet unmet need for repair of damaged nervous systems. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) regulates axonal regrowth of central and peripheral nervous systems; its inhibition, meanwhile, facilitates axonal outgrowth of injured neurons. Here we show that nanotherapeutics based on mesoporous silica nanoparticles loading PTEN-inhibitor bisperoxovanadium (BpV) are effective for delivery of drug molecules and consequent improvement of axonal outgrowth. Mesoporous nanocarriers loaded BpV drug at large amount (27 μg per 1 mg of carrier), and released sustainably over 10 d. Nanocarrier-BpV treatment of primary neurons from the dorsal root ganglions (DRGs) of rats and mice at various concentrations induced them to actively take up the nanocomplexes with an uptake efficiency as high as 85%. The nanocomplex-administered neurons exhibited significantly enhanced axonal outgrowth compared with those treated with free-BpV drug. The expression of a series of proteins involved in PTEN inhibition and downstream signaling was substantially up-/down-regulated by the nanocarrier-BpV system. Injection of the nanocarriers into neural tissues (DRG, brain cortex, and spinal cord), moreover, demonstrated successful integration into neurons, glial cells, oligodendrocytes, and macrophages, suggesting the possible nanotherapeutics applications in vivo. Together, PTEN-inhibitor delivery via mesoporous nanocarriers can be considered a promising strategy for stimulating axonal regeneration in central and peripheral nervous systems.

Biocompatibility of artificial bone based on vancomycin loaded mesoporous silica nanoparticles and calcium sulfate composites

The aim of this study was to evaluate the in vitro and in vivo biocompatibility of artificial bone based on vancomycin loaded mesoporous silica nanoparticles and calcium sulfate composites. In vitro cytotoxicity tests by cholecystokinin octapeptide (CCK-8) assay showed that the 5%Van-MSN-CaSO4 and Van-CaSO4 bone cements were cytocompatible for mouse osteoblastic cell line MC3T3-E1. The microscopic observation confirmed that MC3T3-E1cells incubated with Van-CaSO4 group and 5%Van-MSN-CaSO4 group exhibited clear spindle-shaped changes, volume increase and maturation, showing that these cements supported adhesion of osteoblastic cells on their surfaces. In addition, the measurement of alkaline phosphatase activity revealed the osteoconductive property of these biomaterials. In order to assess in vivo biocompatibility, synthesized cements were implanted into the distal femur of twelve adult male and female New Zealand rabbits. After implantation in artificial defects of the distal femur, 5%Van-MSN-CaSO4 and Van-CaSO4 bone cements did not damage the function of main organs of rabbits. In addition, the Van-MSN-CaSO4 composite allowed complete repair of bone defects with new bone formation 3 months after implantation. These results show potential application of Van-MSN-CaSO4 composites as bone graft materials for the treatment of open fracture in human due to its mechanical, osteoconductive and potential sustained drug release characteristics and the absence of adverse effects on the body.

Mesoporous silica nanoparticles in tissue engineering – a perspective

In this review, we summarize the latest developments and give a perspective on future applications of mesoporous silica nanoparticles (MSNs) in regenerative medicine. MSNs constitute a flexible platform for controlled delivery of drugs and imaging agents in tissue engineering and stem cell therapy. We highlight the recent advances in applying MSNs for controlled drug delivery and stem cell tracking. We touch upon novel functions of MSNs in real time imaging of drug release and biological function, and as tools to control the chemical and mechanical environment of stem cells. We discuss the need for novel model systems for studying biofunctionality and biocompatibility of MSNs, and how the interdisciplinary activities within the field will advance biotechnology research.

Controlled release of drugs in electrosprayed nanoparticles for bone tissue engineering

Generating porous topographic substrates, by mimicking the native extracellular matrix (ECM) to promote the regeneration of damaged bone tissues, is a challenging process. Generally, scaffolds developed for bone tissue regeneration support bone cell growth and induce bone-forming cells by natural proteins and growth factors. Limitations are often associated with these approaches such as improper scaffold stability, and insufficient cell adhesion, proliferation, differentiation, and mineralization with less growth factor expression. Therefore, the use of engineered nanoparticles has been rapidly increasing in bone tissue engineering (BTE) applications. The electrospray technique is advantageous over other conventional methods as it generates nanomaterials of particle sizes in the micro/nanoscale range. The size and charge of the particles are controlled by regulating the polymer solution flow rate and electric voltage. The unique properties of nanoparticles such as large surface area-to-volume ratio, small size, and higher reactivity make them promising candidates in the field of biomedical engineering. These nanomaterials are extensively used as therapeutic agents and for drug delivery, mimicking ECM, and restoring and improving the functions of damaged organs. The controlled and sustained release of encapsulated drugs, proteins, vaccines, growth factors, cells, and nucleotides from nanoparticles has been well developed in nanomedicine. This review provides an insight into the preparation of nanoparticles by electrospraying technique and illustrates the use of nanoparticles in drug delivery for promoting bone tissue regeneration.