Delivery of siRNA via cationic Sterosomes to enhance osteogenic differentiation of mesenchymal stem cells

Programmable biomaterials for bone regeneration

Programmable biomaterials are distinguished by their ability to adjust properties and functions on demand, in a periodic, reversible, or sequential manner. This contrasts with traditional biomaterials, which undergo irreversible, uncontrolled changes. This review synthesizes key advances in programmable biomaterials, examining their design principles, functionalities and applications in bone regeneration. It charts the transition from traditional to programmable biomaterials, emphasizing their enhanced precision, safety and control, which are critical from clinical and biosafety standpoints. We then classify programmable biomaterials into six types: dynamic nucleic acid-based biomaterials, electrically responsive biomaterials, bioactive scaffolds with programmable properties, nanomaterials for targeted bone regeneration, surface-engineered implants for sequential regeneration and stimuli-responsive release materials. Each category is analyzed for its structural properties and its impact on bone tissue engineering. Finally, the review further concludes by highlighting the challenges faced by programmable biomaterials and suggests integrating artificial intelligence and precision medicine to enhance their application in bone regeneration and other biomedical fields.

Phospholipid Free Nano-Vesicles of Brinzolamide Biopolymer Ocular Insert; Design, In vitro and In vivo Evaluation

The aim of this work to study the feasibility of using phospholipid free vesicles with positive charge inducer in a slowly dissolving polymer ocular insert to successfully control intraocular pressure (IOP) for an extended period. Brinzolamide (BRNZ) was chosen as a model drug and a full factorial design was assembled to investigate the drug loading effect, ratio of cholesterol to fatty moiety and the type of the fatty moiety used on the vesicle size and entrapment efficiency. Linear regression models were constructed, and optimization of the formulation compositions yielded two formulae with palmitic acid as a negatively charged vesicles and cetrimide positively charged vesicles. Both formulae were studied in term of permeation efficiency through bovine corneal membranes. Positively charged vesicles although it didn't achieve the highest flux and cumulative amount permeated per unit surface area in the experiment time course, it achieved the highest retention of drug inside the corneal tissue, so it was chosen to be incorporated in a slowly dissolving polymer ocular insert. The insert was evaluated in term content, physical evaluation, and release properties. In vivo evaluation of the casted ocular inserts was conducted in male albino rabbits against market eye drop product and IOP readings were collected for 48 hours. The positively charged sterosomes containing BRNZ and formulated in polymer ocular inserts achieved extended control of IOP of the test animals compared to the market product.

A facile and smart strategy to enhance bone regeneration with efficient vitamin D3 delivery through sterosome technology

The spontaneous healing of critical-sized bone defects is often limited, posing an increased risk of complications and suboptimal outcomes. Osteogenesis, a complex process central to bone formation, relies significantly on the pivotal role of osteoblasts. Despite the well-established osteogenic properties of vitamin D3 (VD3), its lipophilic nature confines administration to oral or muscle injection routes. Therefore, a strategic therapeutic approach involves designing a multifunctional carrier to enhance efficacy, potentially incorporating it into the delivery system. Here, we introduce an innovative sterosome-based delivery system, utilizing palmitic acid (PA) and VD3, aimed at promoting osteogenic differentiation and facilitating post-defect bone regeneration. The delivery system exhibited robust physical characteristics, including excellent stability, loading efficiency, sustained drug release and high cellular uptake efficiency. Furthermore, comprehensive investigations demonstrated outstanding biocompatibility and osteogenic potential in both 2D and 3D in vitro settings. A critical-sized calvarial defect model in mice recapitulated the notable osteogenic effects of the sterosomes in vivo. Collectively, our research proposes a clinically applicable strategy for bone healing, leveraging PA/VD3 sterosomes as an efficient carrier to deliver VD3 and enhance bone regenerative effects.

Cationic Glucan Dendrimer Gel-Mediated Local Delivery of Anti-OC-STAMP-siRNA for Treatment of Pathogenic Bone Resorption

Osteoclast stimulatory transmembrane protein (OC-STAMP) plays a pivotal role in the promotion of cell fusion during osteoclast differentiation (osteoclastogenesis) in the context of pathogenic bone resorption. Thus, it is plausible that the suppression of OC-STAMP through a bioengineering approach could lead to the development of an effective treatment for inflammatory bone resorptive diseases with minimum side effects. Here, we synthesized two types of spermine-bearing (Spe) cationic glucan dendrimer (GD) gels (with or without C12) as carriers of short interfering RNA (siRNA) to silence OC-STAMP. The results showed that amphiphilic C12-GD-Spe gel was more efficient in silencing OC-STAMP than GD-Spe gel and that the mixture of anti-OC-STAMP siRNA/C12-GD-Spe significantly downregulated RANKL-induced osteoclastogenesis. Also, local injection of anti-OC-STAMP-siRNA/C12-GD-Spe could attenuate bone resorption induced in a mouse model of periodontitis. These results suggest that OC-STAMP is a promising target for the development of a novel bone regenerative therapy and that C12-GD-Spe gel provides a new nanocarrier platform of gene therapies for osteolytic disease.

Advances in RNA therapeutics for modulation of 'undruggable' targets

Over the past decades, drug discovery utilizing small pharmacological compounds, fragment-based therapeutics, and antibody therapy have significantly advanced treatment options for many human diseases. However, a major bottleneck has been that>70% of human proteins/genomic regions are 'undruggable' by the above-mentioned approaches. Many of these proteins constitute essential drug targets against complex multifactorial diseases like cancer, immunological disorders, and neurological diseases. Therefore, alternative approaches are required to target these proteins or genomic regions in human cells. RNA therapeutics is a promising approach for many of the traditionally 'undruggable' targets by utilizing methods such as antisense oligonucleotides, RNA interference, CRISPR/Cas-based genome editing, aptamers, and the development of mRNA therapeutics. In the following chapter, we will put emphasis on recent advancements utilizing these approaches against challenging drug targets, such as intranuclear proteins, intrinsically disordered proteins, untranslated genomic regions, and targets expressed in inaccessible tissues.

Bioactive materials for in vivo sweat gland regeneration

Loss of sweat glands (SwGs) commonly associated with extensive skin defects is a leading cause of hyperthermia and heat stroke. In vivo tissue engineering possesses the potential to take use of the body natural ability to regenerate SwGs, making it more conducive to clinical translation. Despite recent advances in regenerative medicine, reconstructing SwG tissue with the same structure and function as native tissue remains challenging. Elucidating the SwG generation mechanism and developing biomaterials for in vivo tissue engineering is essential for understanding and developing in vivo SwG regenerative strategies. Here, we outline the cell biology associated with functional wound healing and the characteristics of bioactive materials. We critically summarize the recent progress in bioactive material-based cell modulation approaches for in vivo SwG regeneration, including the recruitment of endogenous cells to the skin lesion for SwG regeneration and in vivo cellular reprogramming for SwG regeneration. We discussed the re-establishment of microenvironment via bioactive material-mediated regulators. Besides, we offer promising perspectives for directing in situ SwG regeneration via bioactive material-based cell-free strategy, which is a simple and effective approach to regenerate SwG tissue with both fidelity of structure and function. Finally, we discuss the opportunities and challenges of in vivo SwG regeneration in detail. The molecular mechanisms and cell fate modulation of in vivo SwG regeneration will provide further insights into the regeneration of patient-specific SwGs and the development of potential intervention strategies for gland-derived diseases.

Enhanced Osteogenic Potential of Noggin Knockout C2C12 Cells on BMP-2 Releasing Silk Scaffolds

The CRISPR/Cas9 mechanism offers promising therapeutic approaches for bone regeneration by stimulating or suppressing critical signaling pathways. In this study, we aimed to increase the activity of BMP-2 signaling through knockout of Noggin, thereby establishing a synergistic effect on the osteogenic activity of cells in the presence of BMP-2. Since Noggin is an antagonist expressed in skeletal tissues and binds to subunits of bone morphogenetic proteins (BMPs) to inhibit osteogenic differentiation, here Noggin expression was knocked out using the CRISPR/Cas9 system. In accordance with this purpose, C2C12 (mouse myoblast) cells were transfected with CRISPR/Cas9 plasmids. Transfection was achieved with Lipofectamine and confirmed with intense fluorescent signals in microscopic images and deletion in target sequence in Sanger sequencing analysis. Thus, Noggin knockout cells were identified as a new cell source for tissue engineering studies. Then, the transfected cells were seeded on highly porous silk scaffolds bearing BMP-2-loaded silk nanoparticles (30 ng BMP-2/mg silk nanoparticle) in the size of 288 ± 62 nm. BMP-2 is released from the scaffolds in a controlled manner for up to 60 days. The knockout of Noggin by CRISPR/Cas9 was found to synergistically promote osteogenic differentiation in the presence of BMP-2 through increased Coll1A1 and Ocn expression and mineralization. Gene editing of Noggin and BMP-2 increased almost 2-fold Col1A1 expression and almost 3-fold Ocn expression compared to the control group. Moreover, transfected cells produced extracellular matrix (ECM) containing collagen fibers on the scaffolds and mineral-like structures were formed on the fibers. In addition, mineralization characterized by intense Alizarin red staining was detected in transfected cells cultured in the presence of BMP-2, while the other groups did not exhibit any mineralized areas. As has been demonstrated in this study, the CRISPR/Cas9 mechanism has great potential for obtaining new cell sources to be used in tissue engineering studies.

Novel scaffold platforms for simultaneous induction osteogenesis and angiogenesis in bone tissue engineering: a cutting-edge approach

Despite the recent advances in the development of bone graft substitutes, treatment of critical size bone defects continues to be a significant challenge, especially in the elderly population. A current approach to overcome this challenge involves the creation of bone-mimicking scaffolds that can simultaneously promote osteogenesis and angiogenesis. In this context, incorporating multiple bioactive agents like growth factors, genes, and small molecules into these scaffolds has emerged as a promising strategy. To incorporate such agents, researchers have developed scaffolds incorporating nanoparticles, including nanoparticulate carriers, inorganic nanoparticles, and exosomes. Current paper provides a summary of the latest advancements in using various bioactive agents, drugs, and cells to synergistically promote osteogenesis and angiogenesis in bone-mimetic scaffolds. It also discusses scaffold design properties aimed at maximizing the synergistic effects of osteogenesis and angiogenesis, various innovative fabrication strategies, and ongoing clinical studies.

Research Progress of Design Drugs and Composite Biomaterials in Bone Tissue Engineering

Bone, like most organs, has the ability to heal naturally and can be repaired slowly when it is slightly injured. However, in the case of bone defects caused by diseases or large shocks, surgical intervention and treatment of bone substitutes are needed, and drugs are actively matched to promote osteogenesis or prevent infection. Oral administration or injection for systemic therapy is a common way of administration in clinic, although it is not suitable for the long treatment cycle of bone tissue, and the drugs cannot exert the greatest effect or even produce toxic and side effects. In order to solve this problem, the structure or carrier simulating natural bone tissue is constructed to control the loading or release of the preparation with osteogenic potential, thus accelerating the repair of bone defect. Bioactive materials provide potential advantages for bone tissue regeneration, such as physical support, cell coverage and growth factors. In this review, we discuss the application of bone scaffolds with different structural characteristics made of polymers, ceramics and other composite materials in bone regeneration engineering and drug release, and look forward to its prospect.

Intrinsic antibacterial and osteoinductive sterosomes promote infected bone healing

Open fractures and internal fixation implants are often accompanied by bacterial infection, leading to osteomyelitis, characterized by intractable bone infection and sequestrum formation, and can result in lifelong disability or fatal sepsis. As common clinical treatment strategies, high-dose antibiotic application and autologous bone transplantation face the risk of recurrence and donor site injury. Herein, we designed and prepared a novel drug delivery system by rational selection of the antibacterial single-chain amphiphile (cetylpyridinium chloride, CPC) and osteoinductive sterol (20S-hydroxycholesterol, Oxy) to formulate CPC/Oxy sterosomes. We demonstrate their excellent biocompatibility and antibacterial ability through 2D and 3D settings in vitro. In addition, the osteogenic differentiation of bone marrow mesenchymal stem cells was investigated in cell monolayers and a hydrogel environment. Moreover, a rat infected critical-sized calvarial defect model was employed to illustrate the effects of antibacterial and osteogenic CPC/Oxy sterosomes in vivo. Our results showed that CPC/Oxy sterosomes not only exterminated bacterial infections, but also enhanced calvarial healing without additional antibiotics, bone formation promoters or exogenous cells. This research provides a promising and effective multifunctional sterosomal platform for the treatment of infected bone defects, with the potential to be combined with therapeutic genes, and small molecule drugs.

Evaluation of the transdentinal capability of the intrinsic antibacterial cetylpyridinium chloride/cholesterol sterosomes in vitro and in vivo

AIM

Dentinal tubules serve as disease-causing channels for infiltration and penetration of bacteria and their by-products; which are regarded as the major driver of pathogenesis in pulpal inflammation and infection. In this study, we aimed to evaluate the transdentinal potential of nanoscale cetylpyridinium chloride/cholesterol (CPC/Chol) sterosomes, which are a recently developed type of cationic non-phospholipid liposomal nanocarrier; as well as their intrinsic and universal antibacterial activity.

METHODOLOGY

Cetylpyridinium chloride/cholesterol sterosomes were formulated, with a hydrodynamic diameter of 134 ± 4 nm, a low polydisperse index of 0.161 ± 0.007, and a positive zeta potential of 41 ± 3 mV at pH 7.4. Transdentinal diffusion ability of sterosomes was evaluated using human dentine blocks in vitro, and Wistar rat molar teeth in vivo. The intrinsic antibacterial activities of CPC/Chol sterosomes against Enterococcus faecalis, Streptococcus mutans, Fusobacterium nucleatum, and Porphyromonas gingivalis were further examined.

RESULTS

Cetylpyridinium chloride/cholesterol sterosomes successfully penetrated through the dentinal tubules, and diffused into the pulp, which could be internalized by dental pulp cells with a high efficiency. In addition, they exhibited substantial levels of intrinsic antibacterial activity against these Gram-positive and Gram-negative endodontic bacteria and their biofilms.

CONCLUSIONS

Given its high penetration and diffusion ability through the dentine and pulp, great potential for multi-drug delivery, and distinct intrinsic antibacterial activity; sterosome-based nanocarriers might serve as a promising therapeutic strategy aimed at targeting various specific pathways associated with pulpal diseases. This will help determine and characterize the most appropriate prophylactic and therapeutic targets for early intervention in our future dentistry practice.

Mussel-Inspired Polydopamine-Based Multilayered Coatings for Enhanced Bone Formation

Repairing bone defects remains a challenge in clinical practice and the application of artificial scaffolds can enhance local bone formation, but the function of unmodified scaffolds is limited. Considering different application scenarios, the scaffolds should be multifunctionalized to meet specific demands. Inspired by the superior adhesive property of mussels, polydopamine (PDA) has attracted extensive attention due to its universal capacity to assemble on all biomaterials and promote further adsorption of multiple external components to form PDA-based multilayered coatings with multifunctional property, which can induce synergistic enhancement of new bone formation, such as immunomodulation, angiogenesis, antibiosis and antitumor property. This review will summarize mussel-inspired PDA-based multilayered coatings for enhanced bone formation, including formation mechanism and biofunction of PDA coating, as well as different functional components. The synergistic enhancement of multiple functions for better bone formation will also be discussed. This review will inspire the design and fabrication of PDA-based multilayered coatings for different application scenarios and promote deeper understanding of their effect on bone formation, but more efforts should be made to achieve clinical translation. On this basis, we present a critical conclusion, and forecast the prospects of PDA-based multilayered coatings for bone regeneration.

Non-coding RNA delivery for bone tissue engineering: progress, challenges and potential solutions

More than 20 million individuals worldwide suffer from congenital or acquired bone defects annually. The development of bone scaffold materials that simulate natural bone for bone defect repair remains challenging. Recently, ncRNA-based therapies for bone defects have attracted increasing interest because of the great potential of ncRNAs in disease treatment. Various types of ncRNAs regulate gene expression in osteogenesis-related cells via multiple mechanisms. The delivery of ncRNAs to the site of bone loss through gene vectors or scaffolds is a potential therapeutic option for bone defect repair. Therefore, this study discusses and summarizes the regulatory mechanisms of miRNAs, siRNAs, and piRNAs in osteogenic signaling and reviews the widely used current RNA delivery vectors and scaffolds for bone defect repair. Additionally, current challenges and potential solutions of delivery scaffolds for bone defect repair are proposed, with the aim of providing a theoretical basis for their future clinical applications.

Enhanced osteogenic effect in reduced BMP-2 doses with siNoggin transfected pre-osteoblasts in 3D silk scaffolds

Bone morphogenetic proteins (BMPs), especially BMP-2, are being increasingly used in bone tissue engineering due to its osteo-inductive effects. Although recombinant human BMP-2 (rhBMP-2) was approved by Food and Drug Administration (FDA) to use for bone repair, its high doses cause undesired side effects. In order to reduce the BMP-2 dose for enhanced osteogenic differentiation, in this study we decided to suppress the synthesis of Noggin protein, the primary antagonist of BMP-2, on the MC3T3-E1 cells using Noggin targeted small interfering RNA (siRNA). Unlike other studies, Noggin siRNA (siNoggin) transfected cells were seeded on silk scaffolds, and osteogenic differentiation was investigated for a long-term period (21 days) with MTT, qPCR, SEM/EDS, and histological analysis. Besides, siNoggin transfected MC3T3-E1 cells were evaluated as a new cell source for tissue engineering studies. It was determined that Nog gene expression was suppressed in the siNoggin group and Ocn gene expression increased 5-fold compared to the control group (*p < 0.05). The osteogenic effect of BMP-2 was clearly observed in siNoggin transfected cells. According to the SEM/EDS analysis, the siNoggin group has mineral structures clustered on cells, which contain intense Ca and P elements. Histological staining showed that the siNoggin group has a more intense mineralized area than that of the control group. In conclusion, this study indicated that Noggin silencing by siRNA induces osteogenic differentiation in reduced BMP-2 doses for scaffold-based bone regeneration. This non-gene integration strategy has as a safe therapeutic potential to enhance tissue regeneration.

Advancements in nucleic acids-based techniques for bone regeneration

The dynamic biology of bone involving an enormous magnitude of cellular interactions and signaling transduction provides ample biomolecular targets, which can be enhanced or repressed to mediate a rapid regeneration of the impaired bone tissue. The delivery of nucleic acids such as DNA and RNA can enhance the expression of osteogenic proteins. Members of the RNA interference pathway such as miRNA and siRNA can repress negative osteoblast differentiation regulators. Advances in nanomaterials have provided researchers with a plethora of delivery modules that can ensure proper transfection. Combining the nucleic acid carrying vectors with bone scaffolds has met with tremendous success in accomplishing bone formation. Recent years have witnessed the advent of CRISPR and DNA nanostructures in regenerative medicine. This review focuses on the delivery of nucleic acids and touches upon the prospect of CRISPR and DNA nanostructures for bone tissue engineering, emphasizing their potential in treating bone defects.

Bioactive Scaffolds Integrated with Liposomal or Extracellular Vesicles for Bone Regeneration

With population aging and increased life expectancy, an increasing number of people are facing musculoskeletal health problems that necessitate therapeutic intervention at defect sites. Bone tissue engineering (BTE) has become a promising approach for bone graft substitutes as traditional treatments using autografts or allografts involve clinical complications. Significant advancements have been made in developing ideal BTE scaffolds that can integrate bioactive molecules promoting robust bone repair. Herein, we review bioactive scaffolds tuned for local bone regenerative therapy, particularly through integrating synthetic liposomal vesicles or extracellular vesicles to the scaffolds. Liposomes offer an excellent drug delivery system providing sustained release of the loaded bioactive molecules. Extracellular vesicles, with their inherent capacity to carry bioactive molecules, are emerging as an advanced substitute of synthetic nanoparticles and a novel cell-free therapy for bone regeneration. We discuss the recent advance in the use of synthetic liposomes and extracellular vesicles as bioactive materials combined with scaffolds, highlighting major challenges and opportunities for their applications in bone regeneration. We put a particular focus on strategies to integrate vesicles to various biomaterial scaffolds and introduce the latest advances in achieving sustained release of bioactive molecules from the vesicle-loaded scaffolds at the bone defect site.

Pulmonary Delivery of Anticancer Drugs via Lipid-Based Nanocarriers for the Treatment of Lung Cancer: An Update

Lung cancer (LC) is the leading cause of cancer-related deaths, responsible for approximately 18.4% of all cancer mortalities in both sexes combined. The use of systemic therapeutics remains one of the primary treatments for LC. However, the therapeutic efficacy of these agents is limited due to their associated severe adverse effects, systemic toxicity and poor selectivity. In contrast, pulmonary delivery of anticancer drugs can provide many advantages over conventional routes. The inhalation route allows the direct delivery of chemotherapeutic agents to the target LC cells with high local concertation that may enhance the antitumor activity and lead to lower dosing and fewer systemic toxicities. Nevertheless, this route faces by many physiological barriers and technological challenges that may significantly affect the lung deposition, retention, and efficacy of anticancer drugs. The use of lipid-based nanocarriers could potentially overcome these problems owing to their unique characteristics, such as the ability to entrap drugs with various physicochemical properties, and their enhanced permeability and retention (EPR) effect for passive targeting. Besides, they can be functionalized with different targeting moieties for active targeting. This article highlights the physiological, physicochemical, and technological considerations for efficient inhalable anticancer delivery using lipid-based nanocarriers and their cutting-edge role in LC treatment.

Emerging Applications of Nanotechnology in Healthcare Systems: Grand Challenges and Perspectives

Healthcare, as a basic human right, has often become the focus of the development of innovative technologies. Technological progress has significantly contributed to the provision of high-quality, on-time, acceptable, and affordable healthcare. Advancements in nanoscience have led to the emergence of a new generation of nanostructures. Each of them has a unique set of properties that account for their astonishing applications. Since its inception, nanotechnology has continuously affected healthcare and has exerted a tremendous influence on its transformation, contributing to better outcomes. In the last two decades, the world has seen nanotechnology taking steps towards its omnipresence and the process has been accelerated by extensive research in various healthcare sectors. The inclusion of nanotechnology and its allied nanocarriers/nanosystems in medicine is known as nanomedicine, a field that has brought about numerous benefits in disease prevention, diagnosis, and treatment. Various nanosystems have been found to be better candidates for theranostic purposes, in contrast to conventional ones. This review paper will shed light on medically significant nanosystems, as well as their applications and limitations in areas such as gene therapy, targeted drug delivery, and in the treatment of cancer and various genetic diseases. Although nanotechnology holds immense potential, it is yet to be exploited. More efforts need to be directed to overcome these limitations and make full use of its potential in order to revolutionize the healthcare sector in near future.

Sulfonate Hydrogel-siRNA Conjugate Facilitates Osteogenic Differentiation of Mesenchymal Stem Cells by Controlled Gene Silencing and Activation of BMP Signaling

Hydrogels have been widely used in bone tissue engineering due to their tunable characteristics that allow facile modifications with various biochemical properties to support cell growth and guide proper cell functions. Herein, we report a design of hydrogel-siRNA conjugate that facilitates osteogenesis via gene silencing and activation of bone morphogenetic protein (BMP) signaling. A sulfonate hydrogel is prepared by modifying chitosan with sulfoacetic acid to mimic a natural sulfated polysaccharide and to provide a hydrogel surface that enables BMP binding. Then, siRNA targeting noggin, an endogenous extracellular antagonist of BMP signaling, is covalently conjugated to the sulfonate hydrogel by visible blue light crosslinking. The sulfonate hydrogel-siRNA conjugate is efficient to bind BMPs and also successfully prolongs the release of siRNA for sustained noggin suppression, thereby resulting in significantly increased osteogenic differentiation. Lastly, demineralized bone matrix (DBM) is incorporated into the sulfonate hydrogel-siRNA conjugate, wherein the DBM incorporation induces noggin expression via a negative feedback mechanism that regulates BMP signaling in DBM. However, simultaneous delivery of siRNA downregulates noggin thus facilitating endogenous BMP activity and enhancing the osteogenic efficacy of DBM. These findings support a promising hydrogel RNA silencing platform for bone tissue engineering applications.

Study the lipidoid nanoparticle mediated genome editing protein delivery using 3D intestinal tissue model

Lipid nanoparticles are promising carriers for oral drug delivery. For bioactive cargos with intracellular targets, e.g. gene-editing proteins, it is essential for the cargo and carrier to remain complexed after crossing the epithelial layer of intestine in order for the delivery system to transport the cargos inside targeted cells. However, limited studies have been conducted to verify the integrity of cargo/carrier nanocomplexes and their capability in facilitating cargo delivery intracellularly after the nanocomplex crossing the epithelial barrier. Herein, we used a traditional 2D transwell system and a recently developed 3D tissue engineered intestine model and demonstrated the synthetic lipid nanoparticle (carrier) and protein (cargo) nanocomplexes are able to cross the epithelial layer and deliver the protein cargo inside the underneath cells. We found that the EC16-63 LNP efficiently encapsulated the GFP-Cre recombinase, penetrated the intestinal monolayer cells in both the 2D cell culture and 3D tissue models through temporarily interrupting the tight junctions between epithelial layer. After transporting across the intestinal epithelia, the EC16-63 and GFP-Cre recombinase nanocomplexes can enter the underneath cells to induce gene recombination. These results suggest that the in vitro 3D intestinal tissue model is useful for identifying effective lipid nanoparticles for potential oral drug delivery.

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Employed a 3D intestine model for nanodrug screening.

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Developed lipidoid nanoparticles for genome engineering protein delivery.

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Used 3D tissue model to test lipidoid nanoparticles for potential oral drug delivery.

Development of a Biomaterial Scaffold Integrated with Osteoinductive Oxysterol Liposomes to Enhance Hedgehog Signaling and Bone Repair

Bone repair requires the tightly regulated control of multiple intrinsic and extrinsic cell types and signaling pathways. One of the positive regulatory signaling pathways in membranous and endochondral bone healing is the Hedgehog (Hh) signaling family. Here, a novel therapeutic liposomal delivery vector was developed by self-assembly of an Hh-activating cholesterol analog with an emulsifier, along with the addition of Smoothened agonist (SAG) as a drug cargo, for the enhancement of Hh signaling in bone regeneration. The drug-loaded nanoparticulate agonists of Hh signaling were immobilized onto trabecular bone-mimetic apatite-coated 3D scaffolds using bioinspired polydopamine adhesives to ensure favorable microenvironments for cell growth and local therapeutic delivery. Results showed that SAG-loaded liposomes induced a significant and dose-dependent increase in Hh-mediated osteogenic differentiation, as evidenced by in vitro analysis of bone marrow stromal cells, and in vivo calvarial bone healing, as evidenced using all radiographic parameters and histomorphometric analyses. Moreover, favorable outcomes were achieved in comparison to standards of care, including collagen sponge-delivered rBMP2 or allograft bone. In summary, this study demonstrates using a nanoparticle packaged Hh small molecule as a widely applicable bone graft substitute for robust bone repair.

Lipid nanovesicles for biomedical applications: 'What is in a name'?

Vesicles, generally defined as self-assembled structures formed by single or multiple concentric bilayers that surround an aqueous core, have been widely used for biomedical applications. They can either occur naturally (e.g. exosomes) or be produced artificially and range from the micrometric scale to the nanoscale. One the most well-known vesicle is the liposome, largely employed as a drug delivery nanocarrier. Liposomes have been modified along the years to improve physicochemical and biological features, resulting in long-circulating, ligand-targeted and stimuli-responsive liposomes, among others. In this process, new nomenclatures were reported in an extensive literature. In many instances, the new names suggest the emergence of a new nanocarrier, which have caused confusion as to whether the vesicles are indeed new entities or could simply be considered modified liposomes. Herein, we discussed the extensive nomenclature of vesicles based on the suffix "some" that are employed for drug delivery and composed of various types and proportions of lipids and others amphiphilic compounds. New names have most often been selected based on changes of vesicle lipid composition, but the payload, structural complexity (e.g. multicompartment) and new/improved proprieties (e.g. elasticity) have also inspired new vesicle names. Based on this discussion, we suggested a rational classification for vesicles.

Fabrication of Non-phospholipid Liposomal Nanocarrier for Sustained-Release of the Fungicide Cymoxanil

Liposome nanocarriers can be used to solve problems of pesticide instability, rapid degradation and a short period of efficacy. Cymoxanil with antifungal activity requires an ideal drug loading system due to its degradation issues. In this paper, cholesterol and stearylamine were used to prepare non-phospholipid liposomes (sterosomes) as a pesticide nanocarrier, and were characterized with field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), Fourier-transform infrared (FT-IR) spectrometer, size distribution, and ζ-potential. The results showed sterosomes were successfully loaded with cymoxanil. The loading efficiency and the drug-to-lipid ratio were 92.6% and 0.0761, respectively. Prolonged drug release was obtained for 3 days, improving the short duration of the drug itself. The addition of cymoxanil-loaded sterosomes in culture medium effectively inhibited the growth of yeast cells, which serve as model fungal targets. Sterosomes as nanocarriers significantly improved the stability and efficacy of cymoxanil, thus introducing practical and economically desirable strategies for the preparation of novel pesticide formulations.

Nanocarrier Mediated siRNA Delivery Targeting Stem Cell Differentiation

Stem cell-based regenerative medicine holds exceptional therapeutic potential and hence the development of efficient techniques to enhance control over the rate of differentiation has been the focus of active research. One of the strategies to achieve this involves delivering siRNA into stem cells and exploiting the RNA interference (RNAi) mechanism. Transport of siRNA across the cell membrane is a challenge due to its anionic property, especially in primary human cells and stem cells. Moreover, naked siRNA incites immune responses, may cause off-target effects, exhibits low stability and is easily degraded by endonucleases in the bloodstream. Although siRNA delivery using viral vectors and electroporation has been used in stem cells, these methods demonstrate low transfection efficiency, cytotoxicity, immunogenicity, events of integration and may involve laborious customization. With the advent of nanotechnology, nanocarriers which act as novel gene delivery vehicles designed to overcome the problems associated with safety and practicality are being developed. The various nanomaterials that are currently being explored and discussed in this review include liposomes, carbon nanotubes, quantum dots, protein and peptide nanocarriers, magnetic nanoparticles, polymeric nanoparticles, etc. These nanodelivery agents exhibit advantages such as low immunogenic response, biocompatibility, design flexibility allowing for surface modification and functionalization, and control over the surface topography for achieving the desired rate of siRNA delivery and improved gene knockdown efficiency. This review also includes discussion on siRNA co-delivery with imaging agents, plasmid DNA, drugs etc. to achieve combined diagnostic and enhanced therapeutic functionality, both for in vitro and in vivo applications.

Rational design of hydrogels to enhance osteogenic potential

Bone tissue engineering (BTE) encompasses the field of biomaterials, cells, and bioactive molecules to successfully guide the growth and repair of bone tissue. Current BTE strategies rely on delivering osteogenic molecules or cells via scaffolding materials. However, growth factor- and stem cell-based treatments have several limitations, such as source restriction, low stability, difficulties in predicting long-term efficacy, and high costs, among others. These issues have promoted the development of material-based therapy with properties of accessibility, high stability, tunable efficacy, and low-cost production. Hydrogels are widely used in BTE applications because of their unique hydrophilic nature and tunable physicochemical properties to mimic the native bone environment. However, current hydrogel materials are not ideal candidates due to minimal osteogenic capability on their own. Therefore, recent studies of BTE hydrogels attempt to counterbalance these issues by modifying their biophysical properties. In this article, we review recent progress in the design of hydrogels to instruct osteogenic potential, and present strategies developed to precisely control its bone healing properties.

The Roles of Nanoparticles in Stem Cell-Based Therapy for Cardiovascular Disease

Cardiovascular disease (CVD) is currently one of the primary causes of mortality and morbidity worldwide. Nanoparticles (NPs) are playing increasingly important roles in regulating stem cell behavior because of their special features, including shape, size, aspect ratio, surface charge, and surface area. In terms of cardiac disease, NPs can facilitate gene delivery in stem cells, track the stem cells in vivo for long-term monitoring, and enhance retention after their transplantation. The advantages of applying NPs in peripheral vascular disease treatments include facilitating stem cell therapy, mimicking the extracellular matrix environment, and utilizing a safe non-viral gene delivery tool. However, the main limitation of NPs is toxicity, which is related to their size, shape, aspect ratio, and surface charge. Currently, there have been many animal models proving NPs’ potential in treating CVD, but no extensive applications of stem-cell therapy using NPs are available in clinical practice. In conclusion, NPs might have significant potential uses in clinical trials of CVD in the future, thereby meeting the changing needs of individual patients worldwide.

Delivery of RNAi-Based Therapeutics for Bone Regeneration

PURPOSE OF REVIEW

The clinical significance, target pathways, recent successes, and challenges that preclude translation of RNAi bone regenerative approaches are overviewed.

RECENT FINDINGS

RNA interference (RNAi) is a promising new therapeutic approach for bone regeneration by stimulating or inhibiting critical signaling pathways. However, RNAi suffers from significant delivery challenges. These challenges include avoiding nuclease degradation, achieving bone tissue targeting, and reaching the cytoplasm for mRNA inhibition. Many drug delivery systems have overcome stability and intracellular localization challenges but suffer from protein adsorption that results in clearance of up to 99% of injected dosages, thus severely limiting drug delivery efficacy. While RNAi has myriad promising attributes for use in bone regenerative applications, delivery challenges continue to plague translation. Thus, a focus on drug delivery system development is critical to provide greater delivery efficiency and bone targeting to reap the promise of RNAi.

A Comprehensive Review of Concentrated Growth Factors and Their Novel Applications in Facial Reconstructive and Regenerative Medicine

BACKGROUND

Concentrated growth factors (CGFs) are the latest generation of platelet concentrates. The objective of developing CGF is to increase therapeutic efficacy. However, few studies have supported the superiority of CGF in composition and efficacy. The reconstruction and regeneration process is complicated and long term, whereas bioactivity of CGF is not durable. The purpose of this review is threefold. The first is to recommend more comparative studies between CGF and other platelet concentrates. The second is to constitute a continuous drug delivery system by combining CGF with other biomaterials. Finally, the novel use of CGF in facial regenerative and reconstructive medicine will be highlighted.

METHODS

A comprehensive review of literature regarding the use of CGF in facial regenerative and reconstructive medicine was performed. Based on the inclusion and exclusion criteria, a total of 135 articles were included.

RESULTS

The use of CGF involving facial rejuvenation, cartilage grafting, facial bone defects, facial peripheral nerve injury and wounding is reviewed. The reconstructive and regenerative principles lie in firm fibrin scaffolds and continuous in situ delivery of multiple growth factors.

CONCLUSIONS

CGF represents an advance in personalized medicine concept. However, the current scientific evidences about the use of CGF are limited. More basic and clinical studies should be conducted to understand the characteristics and clinical application of CGF.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Smoothened agonist sterosome immobilized hybrid scaffold for bone regeneration

Biomaterial delivery of bioactive agents and manipulation of stem cell fate are an attractive approach to promote tissue regeneration. Here, smoothened agonist sterosome is developed using small-molecule activators [20S-hydroxycholesterol (OHC) and purmorphamine (PUR)] of the smoothened protein in the hedgehog pathway as carrier and cargo. Sterosome presents inherent osteoinductive property even without drug loading. Sterosome is covalently immobilized onto three-dimensional scaffolds via a bioinspired polydopamine intermediate to fabricate a hybrid scaffold for bone regeneration. Sterosome-immobilized hybrid scaffold not only provides a favorable substrate for cell adhesion and proliferation but also delivers bioactive agents in a sustained and spatially targeted manner. Furthermore, this scaffold significantly improves osteogenic differentiation of bone marrow stem cells through OHC/PUR-mediated synergistic activation of the hedgehog pathway and also enhances bone repair in a mouse calvarial defect model. This system serves as a versatile biomaterial platform for many applications, including therapeutic delivery and endogenous regenerative medicine.

Induction of chondrogenic or mesenchymal stem cells from human periodontal ligament cells through inhibition of Twist2 or Klf12

Periodontitis leads to destruction of periodontal ligament, cementum and alveolar bone. Regeneration of periodontal tissue is dependent on mesenchymal stem cells (MSC) present in the periodontal ligament, and transcription factors determine the direction of MSC differentiation. The present study was conducted to investigate the transcription factors that are crucial for maintaining the characteristics of the periodontal ligament. The mRNA levels of several transcription factors were measured in cultured human periodontal ligament (HPDL) cells, human gingival fibroblasts and osteoblast-like Saos2 cells. HPDL cells were transfected for 72 h with siTwist2, siKlf12, or siMix (siTwist2, siPax9, and siKlf12). The cells were then harvested and subjected to real-time PCR and Western blotting. siTwist2 suppressed the levels of Twist2, Sox2 and Col1a1 mRNAs, and increased those of Sox5 and aggrecan mRNAs. siKlf12 decreased the mRNA levels of Klf12, Runx3, Zfp521, and Stab2, and increased those of Sox2, Klf4, and the MSC markers CD90 and CD105. These results suggest that transfection with siMix and siTwist2 induced chondrogenesis, and that siKlf12 induced the differentiation of MSC in HPDL cells. Thus, inhibition of Twist2 or Klf12 induced the differentiation of chondrogenic or mesenchymal stem cells in this setting, suggesting that the characteristics of HPDL cells may be altered by inhibition of specific transcription factors.

Microporous methacrylated glycol chitosan-montmorillonite nanocomposite hydrogel for bone tissue engineering

Injectable hydrogels can fill irregular defects and promote in situ tissue regrowth and regeneration. The ability of directing stem cell differentiation in a three-dimensional microenvironment for bone regeneration remains a challenge. In this study, we successfully nanoengineer an interconnected microporous networked photocrosslinkable chitosan in situ-forming hydrogel by introducing two-dimensional nanoclay particles with intercalation chemistry. The presence of the nanosilicates increases the Young’s modulus and stalls the degradation rate of the resulting hydrogels. We demonstrate that the reinforced hydrogels promote the proliferation as well as the attachment and induced the differentiation of encapsulated mesenchymal stem cells in vitro. Furthermore, we explore the effects of nanoengineered hydrogels in vivo with the critical-sized mouse calvarial defect model. Our results confirm that chitosan-montmorillonite hydrogels are able to recruit native cells and promote calvarial healing without delivery of additional therapeutic agents or stem cells, indicating their tissue engineering potential.

Injectable hydrogels could be used to repair bone defects. Here the authors incorporate nanoclay particles into chitosan creating an interconnected microporous hydrogel and show that this hydrogel can support MSC proliferation and differentiation in vitro, and support the recruitment of native cells and bone regeneration in a mouse calvarial defect model.

Will Nanotechnology Bring New Hope for Stem Cell Therapy?

The potential of stem cell therapy has been shown in preclinical trials for the treatment of damage and replacement of organs and degenerative diseases. After many years of research, its clinical application is limited. Currently there is not a single stem cell therapy product or procedure. Nanotechnology is an emerging field in medicine and has huge potential due to its unique characteristics such as its size, surface effects, tunnel effects, and quantum size effect. The importance of application of nanotechnology in stem cell technology and cell-based therapies has been recognized. In particular, the effects of nanotopography on stem cell differentiation, proliferation, and adhesion have become an area of intense research in tissue engineering and regenerative medicine. Despite the many opportunities that nanotechnology can create to change the fate of stem cell technology and cell therapies, it poses several risks since some nanomaterials are cytotoxic and can affect the differentiation program of stem cells and their viability. Here we review some of the advances and the prospects of nanotechnology in stem cell research and cell-based therapies and discuss the issues, obstacles, applications, and approaches with the aim of opening new avenues for further research.

Comparison of osteogenic differentiation induced by siNoggin and pBMP-2 delivered by lipopolysaccharide-amine nanopolymersomes and underlying molecular mechanisms

Purpose: Gene therapies via Noggin small interfering (si)RNA (siNoggin) and bone morphogenetic protein (BMP)-2 plasmid DNA (pBMP-2) may be promising strategies for bone repair/regeneration, but their ideal delivery vectors, efficacy difference, and underlying mechanisms have not been explored, so these issues were probed here.

Methods: This study used lipopolysaccharide-amine nanopolymersomes (LNPs), an efficient cytosolic delivery vector developed by the research team, to mediate siNoggin and pBMP-2 to transfect MC3T3-E1 cells, respectively. The cytotoxicity, cell uptake, and gene knockdown efficiency of siNoggin-loaded LNPs (LNPs/siNoggin) were studied, then the osteogenic-differentiation efficacy of MC3T3-E1 cells treated by LNPs/pBMP-2 and LNPs/siNoggin, respectively, were compared by measuring the expression of osteogenesis-related genes and proteins, alkaline phosphatase (ALP) activity, and mineralization of the extracellular matrix at all osteogenic stages. Finally, the possible signaling pathways of the two treatments were explored.

Results: LNPs delivered siNoggin into cells efficiently to silence 50% of Noggin expression without obvious cytotoxicity. LNPs/siNoggin and LNPs/pBMP-2 enhanced the osteogenic differentiation of MC3T3 E1 cells, but LNPs/siNoggin was better than LNPs/pBMP-2. BMP/Mothers against decapentaplegic homolog (Smad) and glycogen synthase kinase (GSK)-3β/β-catenin signaling pathways appeared to be involved in osteogenic differentiation induced by LNPs/siNoggin, but GSK-3β/β-catenin was not stimulated upon LNPs/pBMP-2 treatment.

Conclusion: LNPs are safe and efficient delivery vectors for DNA and RNA, which may find wide applications in gene therapy. siNoggin treatment may be a more efficient strategy to enhance osteogenic differentiation than pBMP-2 treatment. LNPs loaded with siNoggin and/or pBMP-2 may provide new opportunities for the repair and regeneration of bone.

Preparation of photothermal palmitic acid/cholesterol liposomes

Indocyanine green (ICG) is the only FDA-approved near-infrared dye and it is currently used clinically for diagnostic applications. However, there is significant interest in using ICG for triggered drug delivery applications and heat ablation therapy. Unfortunately, free ICG has a short half-life in vivo and is rapidly cleared from circulation. Liposomes have been frequently used to improve ICG's stability and overall time of effectiveness in vivo, but they have limited stability due to the susceptibility of phospholipids to hydrolysis and oxidation. In this study, nonphospholipid liposomes were used to encapsulate ICG, and the resulting liposomes were characterized for size, encapsulation efficiency, stability, and photothermal response. Using the thin-film hydration method, an ICG encapsulation efficiency of 54% was achieved, and the liposomes were stable for up to 12 weeks, with detectable levels of encapsulated ICG up to week 4. Additionally, ICG-loaded liposomes were capable of rapidly producing a significant photothermal response upon exposure to near-infrared light, and this photothermal response was able to induce changes in the mechanical properties of thermally responsive hydrogels. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1384-1392, 2019.

pH-Sensitive Nanocarrier-Mediated Codelivery of Simvastatin and Noggin siRNA for Synergistic Enhancement of Osteogenesis

The inexpensive hypolipidemic drug simvastatin (SIM), which promotes bone regeneration by enhancing bone morphogenetic protein 2 (BMP-2) expression, has been regarded as an ideal alternative to BMP-2 therapy. However, SIM has low bioavailability and may induce the upregulation of the BMP-2-antagonistic noggin protein, which greatly limits the osteogenic effect. Here, a pH-sensitive copolymer, monomethoxy-poly(ethylene glycol)- b-branched polyethyleneimine- b-poly( N-( N', N'-diisopropylaminoethyl)- co-benzylamino)aspartamide (mPEG-bPEI-PAsp(DIP-BzA)) (PBP), was synthesized and self-assembled into a cationic micelle. SIM and siRNA targeting the noggin gene (N-siRNA) were loaded into the PAsp(DIP-BzA) core and the cationic bPEI interlayer of the micelle via hydrophobic and electrostatic interactions, respectively. The SIM-loaded micelle effectively delivered SIM into preosteoblast MC3T3-E1 cells and rapidly released it inside the acidic lysosome, resulting in the elevated expression of BMP-2. Meanwhile, the codelivered N-siRNA effectively suppressed the expression of noggin. Consequently, SIM and N-siRNA synergistically increased the BMP-2/noggin ratio and resulted in an obviously higher osteogenetic effect than did simvastatin or N-siRNA alone, both in vitro and in vivo.

RNA interfering molecule delivery from in situ forming biodegradable hydrogels for enhancement of bone formation in rat calvarial bone defects

RNA interference (RNAi) may be an effective and valuable tool for promoting the growth of functional tissue, as short interfering RNA (siRNA) and microRNA (miRNA) can block the expression of genes that have negative effects on tissue regeneration. Our group has recently reported that the localized and sustained presentation of siRNA against noggin (siNoggin) and miRNA-20a from in situ forming poly(ethylene glycol) (PEG) hydrogels enhanced osteogenic differentiation of encapsulated human bone marrow-derived mesenchymal stem cells (hMSCs). Here, the capacity of the hydrogel system to accelerate bone formation in a rat calvarial bone defect model is presented. After 12 weeks post-implantation, the hydrogels containing encapsulated hMSCs and miRNA-20a resulted in more bone formation in the defects than the hydrogels containing hMSCs without siRNA or with negative control siRNA. This localized and sustained RNA interfering molecule delivery system may provide an excellent platform for healing bony defects and other tissues.

STATEMENT OF SIGNIFICANCE

Delivery of RNAi molecules may be a valuable strategy to guide cell behavior for tissue engineering applications, but to date there have been no reports of a biomaterial system capable of both encapsulation of cells and controlled delivery of incorporated RNA. Here, we present PEG hydrogels that form in situ via Michael type reaction, and that permit encapsulation of hMSCs and the concomitant controlled delivery of siNoggin and/or miRNA-20a. These RNAs were chosen to suppress noggin, a BMP-2 antagonist, and/or PPAR-γ, a negative regulator of BMP-2-mediated osteogenesis, and therefore promote osteogenic differentiation of hMSCs and subsequent bone repair in critical-sized rat calvarial defects. Simultaneous delivery of hMSCs and miRNA-20a enhanced repair of these defects compared to hydrogels containing hMSCs without siRNA or with negative control siRNA. This in situ forming PEG hydrogel system offers an exciting platform for healing critical-sized bone defects by localized, controlled delivery of RNAi molecules to encapsulated hMSCs and surrounding cells.

Recent review of the effect of nanomaterials on stem cells

The field of stem-cell-therapy offers considerable promise as a means of delivering new treatments for a wide range of diseases. Recent progress in nanotechnology has stimulated the development of multifunctional nanomaterials (NMs) for stem-cell-therapy. Several clinical trials based on the use of NMs are currently underway for stem-cell-therapy purposes, such as drug/gene delivery and imaging. However, the interactions between NMs and stem cells are far from being completed, and the effects of the NMs on cellular behavior need critical evaluation. In this review, the interactions between several types of mostly used NMs and stem cells, and their associated possible mechanisms are systematically discussed, with specific emphasis on the possible differentiation effects induced by NMs. It is expected that the enhanced understanding of NM-stem cell interactions will facilitate biomaterial design for stem-cell-therapy and regenerative medicine applications.

Tripartite polyionic complex (PIC) micelles as non-viral vectors for mesenchymal stem cell siRNA transfection

In the context of regenerative medicine, the use of RNA interference mechanisms has already proven its efficiency in targeting specific gene expression with the aim of enhancing, accelerating or, more generally, directing stem cell differentiation. However, achievement of good transfection levels requires the use of a gene vector. For in vivo applications, synthetic vectors are an interesting option to avoid possible issues associated with viral vectors (safety, production costs, etc.). Herein, we report on the design of tripartite polyionic complex micelles as original non-viral polymeric vectors suited for mesenchymal stem cell transfection with siRNA. Three micelle formulations were designed to exhibit pH-triggered disassembly in an acidic pH range comparable to that of endosomes. One formulation was selected as the most promising with the highest siRNA loading capacity while clearly maintaining pH-triggered disassembly properties. A thorough investigation of the internalization pathway of micelles into cells with tagged siRNA was made before showing an efficient inhibition of Runx2 expression in primary bone marrow-derived stem cells. This work evidenced PIC micelles as promising synthetic vectors that allow efficient MSC transfection and control over their behavior, from the perspective of their clinical use.

[Osteogenic effect of collagen/bioglass composites carrying noggin siRNA]

OBJECTIVE

To investigate osteogenic effect of collagen/bioglass composites loaded with a small interfering RNA (siRNA) targeting noggin.

METHODS

The collagen/bioglass composites loaded with the negative control siRNA or noggin siRNA were prepared by freeze-drying method. CCK8 test was used to evaluate the proliferation of MC3T3 cells exposed to the aqueous extracts of collagen/bioglass composites and the siRNA-loaded collagen/bioglass composites. ALP activity assay, quantitative real-time PCR and Alizarin Red staining were used to assess the effect of the 3 composites on mineralization in MC3T3 cells.

RESULTS

MC3T3 cells cultured for 3 and 5 days in the presence of the extracts of the 3 composites all showed significantly more active proliferation than the blank control cells (P < 0.05). Compared with the cells seeded on the scaffold without siRNA, MC3T3 cells seeded on collagen/bioglass scaffold loaded with noggin siRNA showed a significantly higher ALP activity at 14 days after seeding (P < 0.05) with significantly increased expression of ALP, Runx2 and BSP mRNAs (P < 0.05). Alizarin Red staining showed that the cells seeded on the noggin siRNA-loading collagen/bioglass scaffold contained significantly more mineralized nodules than the other cells (P < 0.05).

CONCLUSIONS

The collagen/bioglass composites loaded with noggin siRNA have a good biocompatibility, and the collagen/bioglass composites and noggin siRNA show a synergistic effect in promoting osteogenesis.

Down-regulation of Noggin and miR-138 coordinately promote osteogenesis of mesenchymal stem cells

Mesenchymal stem cells (MSCs) can differentiate to osteocytes under suitable conditions. In recent years, micro-nucleotides have been progressively used to modulate gene expression in cells due to the consideration of safety. Our present study aimed to investigate whether co-delivery of Noggin-siRNA and antimiR-138 enhances the osteogenic effect of MSCs. Using a murine MSC line, C3H/10T1/2 cells, the delivery efficiency of Noggin-siRNA and antimiR-138 into MSCs was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). Cell phenotype and proliferation capacity was assessed by flow cytometry and MTT assay respectively. The osteogenesis of MSCs was tested by Alkaline Phosphatase (ALP) staining, qRT-PCR, and western blot analyses. Our results demonstrated that the expression of Noggin and miR-138 were significantly silenced in MSCs by Noggin-siRNA and/or antimiR-138 delivery, while the phenotype and proliferation capacity of MSCs were not affected. Down-regulation of Noggin and miR-138 cooperatively promoted osteogenic differentiation of MSCs. The ALP positive cells reached about 83.57 ± 10.18%. Compared with single delivery, the expression of osteogenic related genes, such as Alp, Col-1, Bmp2, Ocn and Runx2, were the highest in cells with co-delivery of the two oligonucleotides. Moreover, the protein level of RUNX2, and the ratios of pSMAD1/5/SMAD1/5 and pERK1/2/ERK1/2 were significantly increased. The activation of Smad, Erk signaling may constitute the underlying mechanism of the enhanced osteogenesis process. Taken together, our study provides a safe strategy for the clinical rehabilitation application of MSCs in skeletal deficiency.

Nanomaterials modulate stem cell differentiation: biological interaction and underlying mechanisms

Stem cells are unspecialized cells that have the potential for self-renewal and differentiation into more specialized cell types. The chemical and physical properties of surrounding microenvironment contribute to the growth and differentiation of stem cells and consequently play crucial roles in the regulation of stem cells’ fate. Nanomaterials hold great promise in biological and biomedical fields owing to their unique properties, such as controllable particle size, facile synthesis, large surface-to-volume ratio, tunable surface chemistry, and biocompatibility. Over the recent years, accumulating evidence has shown that nanomaterials can facilitate stem cell proliferation and differentiation, and great effort is undertaken to explore their possible modulating manners and mechanisms on stem cell differentiation. In present review, we summarize recent progress in the regulating potential of various nanomaterials on stem cell differentiation and discuss the possible cell uptake, biological interaction and underlying mechanisms.

Emerging potential of gene silencing approaches targeting anti-chondrogenic factors for cell-based cartilage repair

The field of cartilage repair has exponentially been growing over the past decade. Here, we discuss the possibility to achieve satisfactory regeneration of articular cartilage by means of human mesenchymal stem cells (hMSCs) depleted of anti-chondrogenic factors and implanted in the site of injury. Different types of molecules including transcription factors, transcriptional co-regulators, secreted proteins, and microRNAs have recently been identified as negative modulators of chondroprogenitor differentiation and chondrocyte function. We review the current knowledge about these molecules as potential targets for gene knockdown strategies using RNA interference (RNAi) tools that allow the specific suppression of gene function. The critical issues regarding the optimization of the gene silencing approach as well as the delivery strategies are discussed. We anticipate that further development of these techniques will lead to the generation of implantable hMSCs with enhanced potential to regenerate articular cartilage damaged by injury, disease, or aging.

Design and Characterization of a Therapeutic Non-phospholipid Liposomal Nanocarrier with Osteoinductive Characteristics To Promote Bone Formation

Sterosomes are recently developed types of non-phospholipid liposomes formed from single-chain amphiphiles and high content of sterols. Although sterosomes presented significantly increased stability compared to conventional phospholipid liposomes, current sterosome biomaterials are not truly bioactive and have no intrinsic therapeutic effects. The purpose of this study was to develop a sterosome formulation with osteoinductive properties by an effective selection of sterol, one of the sterosome components. Oxysterols are oxidized derivatives of cholesterol and are known to stimulate osteogenesis and bone formation. Thus, 20S-hydroxycholesterol (Oxy), one of the most potent oxysterols for bone regeneration, was examined as a promising candidate molecule to form fluid lamellar phases with a single-chain amphiphile, namely, stearylamine (SA). First, the optimal composition was identified by investigating the phase behavior of SA/Oxy mixtures. Next, the capacity of the optimized SA/Oxy sterosomes to promote osteogenic differentiation of bone marrow stromal cells was assessed in vitro in a hydrogel environment. Furthermore, we explored the effects of osteogenic oxysterol sterosomes in vivo with the mouse critical-sized calvarial defect model. Our results showed that SA/Oxy sterosomes induced osteogenic differentiation in vitro and enhanced calvarial healing without delivery of additional therapeutic agents, indicating their intrinsic bone-forming potential. This study suggests a promising non-phospholipid liposomal platform with osteoinductive properties for delivery of small molecular drugs and/or other therapeutic genes for enhanced bone formation.

Simultaneous delivery of hydrophobic small molecules and siRNA using Sterosomes to direct mesenchymal stem cell differentiation for bone repair

The use of small molecular drugs with gene manipulation offers synergistic therapeutic efficacy by targeting multiple signaling pathways for combined treatment. Stimulation of mesenchymal stem cells (MSCs) with osteoinductive small molecule phenamil combined with suppression of noggin is a promising therapeutic strategy that increases bone morphogenetic protein (BMP) signaling and bone repair. Our cationic Sterosome formulated with stearylamine (SA) and cholesterol (Chol) is an attractive co-delivery system that not only forms stable complexes with small interfering RNA (siRNA) molecules but also solubilizes hydrophobic small molecules in a single vehicle, for directing stem cell differentiation. Herein, we demonstrate the ability of SA/Chol Sterosomes to simultaneously deliver hydrophobic small molecule phenamil and noggin-directed siRNA to enhance osteogenic differentiation of MSCs both in in vitro two- and three-dimensional settings as well as in a mouse calvarial defect model. These results suggest a novel liposomal platform to simultaneously deliver therapeutic genes and small molecules for combined therapy.

STATEMENT OF SIGNIFICANCE

Application of phenamil, a small molecular bone morphogenetic protein (BMP) stimulator, combined with suppression of natural BMP antagonists such as noggin is a promising therapeutic strategy to enhance bone regeneration. Here, we present a novel strategy to co-deliver hydrophobic small molecule phenamil and noggin-targeted siRNA via cationic Sterosomes formed with stearylamine (SA) and high content of cholesterol (Chol) to enhance osteogenesis and bone repair. SA/Chol Sterosomes demonstrated high phenamil encapsulation efficiency, supported sustained release of encapsulated drugs, and significantly reduced drug dose requirements to induce osteogenic differentiation of mesenchymal stem cells (MSCs). Simultaneous deliver of phenamil and noggin siRNA in a single vehicle synergistically enhanced MSC osteogenesis and calvarial bone repair. This study suggests a new non-phospholipid liposomal formulation to simultaneously deliver small molecules and therapeutic genes for combined treatment.

Enhanced efficacy of anti-miR-191 delivery through stearylamine liposome formulation for the treatment of breast cancer cells

MicroRNAs are gaining rapid attention as promising targets for cancer treatment; however, efficient delivery of therapeutic miRNA or anti-miRNA into cancer cells remains a major challenge. Our previous work identified miR-191 as an oncogenic miRNA overexpressed in breast cancer that assists in progression of malignant transformation. Thus, inhibition of miR-191 using antisense miR-191 (anti-miR-191) has immense therapeutic potential. Here, we have developed a stearylamine (SA) based cationic liposome for delivery of miR-191 inhibitor (anti-miR-191), and studied its efficacy in breast cancer cells (MCF-7 and ZR-75-1) in culture. SA liposomes alone inhibited cancer cell growth with lesser IC_50s (50% inhibitory concentration) values as compared to normal mouse fibroblast cells (L929). The efficient delivery of anti-miR-191 in SA liposome complex was found to be highly effective in killing the cancer cells than a comparable dose of SA free anti-miR-191 liposome complex. The formulation also showed negligible cytotoxicity in human erythrocytes. Combined treatment of SA liposome with anti-miR-191 markedly enhanced apoptotic cell death and suppressed the migration of cancer cells in vitro. Notably, anti-miR-191 loaded SA liposome complex increased chemosensitivity of breast cancer cells to currently used anti-cancer drugs (doxorubicin or cisplatin) in free form. Our work demonstrates that anti-miR-191 loaded in SA liposome complex has promising clinical application for breast cancer therapy.