Buccal application of microneedles coated with an optimized hydrogel containing naproxen and dexamethasone

Inflammation and impaired bone regeneration are major challenges in oral and maxillofacial surgery, necessitating the development of effective drug delivery systems. This study aimed to develop a hydrogel-based microneedle (MN) system for the controlled release of anti-inflammatory and osteogenic drugs. A hydrogel loaded with naproxen sodium (NAS) and dexamethasone sodium phosphate (DEX) using poloxamer 407 (NDgel) was prepared using a low-temperature method and optimized via the Box-Behnken design. The optimized hydrogel exhibited a gelation temperature of 30.87 ± 0.64℃, pH 7.92 ± 0.12, and viscosity 87.47 ± 5.66 cP. Physicochemical evaluations, including differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR), confirmed that NAS and DEX were incorporated in an amorphous form. The hydrogel was coated onto microneedles (NDgMN) via a dip-coating method and dried. In vitro drug release studies in artificial saliva showed NAS and DEX release rates of 21.7 ± 5.8% and 19.0 ± 1.8%, respectively, after 5 min. The NDgMN exhibited significantly enhanced permeability, with 48.5% and 48.7% permeability for NAS and DEX after 48 h, compared to 31.0% and 28.8% for the hydrogel alone. The IC50 values of the drug solution and drug-containing gel were 123 µg/mL and 203.2 µg/mL, respectively. NDgel demonstrated concentration-dependent inhibition of nitrogen oxide (NO) production at 1-1000 µg/mL, and alkaline phosphatase (ALP) activity assays revealed a 1.2-fold increase at concentrations above 50 µg/mL. These findings suggest that hydrogel-coated MNs have potential as a novel drug delivery system for reducing inflammation and promoting osteocyte differentiation due to their enhanced permeability and bioactivity.

Injectable microgel and micro-granular hydrogels for bone tissue engineering

Injectable microgels, made from both natural and synthetic materials, are promising platforms for the encapsulation of cells or bioactive agents, such as drugs and growth factors, for delivery to injury sites. They can also serve as effective micro-scaffolds in bone tissue engineering (BTE), offering a supportive environment for cell proliferation or differentiation into osteoblasts. Microgels can be injected in the injury sites individually or in the form of aggregated/jammed ones named micro-granular hydrogels. This review focuses on common materials and fabrication techniques for preparing injectable microgels, as well as their characteristics and applications in BTE. These applications include their use as cell carriers, delivery systems for bioactive molecules, micro-granular hydrogels, bio-inks for bioprinting, three-dimensional microarrays, and the formation of microtissues. Furthermore, we discuss the current and potential future applications of microgels in bone tissue regeneration.

Nanoengineered Endocytic Biomaterials for Stem Cell Therapy

Stem cells, ideal for the tissue repair and regeneration, possess extraordinary capabilities of multidirectional differentiation and self‐renewal. However, the limited spontaneous differentiation potential makes it challenging to harness them for tissue repair without external intervention. Although conventional approaches using biomolecules, small organic molecules, and ions have shown specific and effective functions, they face challenges such as in vivo diffusion and degradation, poor internalization, and side effects on adjacent cells. Nanoengineered biomaterials offer a solution by solidifying and nanosizing these soluble regulating molecules and ions, facilitating their uptake by stem cells. Once inside lysosomes, these nanoparticles release their contents in a controlled “molecule or ion storm,” efficiently altering the intracellular biological and chemical microenvironment to tune the differentiation of stem cells. This newly emerged approach for regulating stem cell fate has attracted much attention in recent years. This method has shown promising results and is poised to enhance clinical stem cell therapy. This review provides an overview of the design principles for nanoengineered biomaterials, discusses the categories and characteristics of nanoparticles, summarizes the application of nanoparticles in tissue repair and regeneration, and discusses the direction of nanoparticle‐enhanced stem cell therapy and prospects for its clinical application in regenerative medicine.

Grafting biomaterials associated to topical glucocorticoid: effects on pre-osteoblastic cells (MC3T3-E1)

The topical glucocorticoid budesonide has been prescribed before and after sinus lift surgery as adjuvant drug treatment for maxillary sinus membrane inflammation. However, there is no study on the effects of budesonide on the regenerative process of bone grafting biomaterials. We investigated the effect of the association of budesonide with some biomaterials on the growth and differentiation capacity of pre-osteoblastic cells (MC3T3-E1 subclone 4). Xenogeneic (Bio-Oss and Bio-Gen) and synthetic hydroxyapatites (Osteogen, Bonesynth, and HAP-91) were tested in conditioned medium (1% w/v). The conditioned medium was then supplemented with budesonide (0.5% v/v). Cell viability was assessed using the MTT assay (48, 96, and 144 h), and mineralized nodules were quantified after 14 days of culture using the Alizarin Red Staining. Alkaline phosphatase activity was assessed through the release of thymolphthalein at day seven. All biomaterials showed little or no cytotoxicity. The Bio-Gen allowed significantly less growth than the control group regardless of the experimental time. Regarding differentiation potential of MC3T3-E1, the HAP-91-conditioned medium showed remarkable osteoinductive properties. In osteodifferentiation, the addition of budesonide favored the formation of mineral nodules when cells were cultured in medium conditioned with synthetic materials, whereas it weakened the mineralization potential of cells cultured in xenogeneic medium. Regardless of whether budesonide was added or not, Osteogen and Bio-Oss showed higher alkaline phosphatase activity than the other groups. Budesonide may improve bone formation when associated with synthetic biomaterials. Conversely, the presence of this glucocorticoid weakens the mineralization potential of pre-osteoblastic cells cultured with xenogeneic hydroxyapatites.

Dexamethasone: Insights into Pharmacological Aspects, Therapeutic Mechanisms, and Delivery Systems

Dexamethasone (DEX) has been widely used to treat a variety of diseases, including autoimmune diseases, allergies, ocular disorders, cancer, and, more recently, COVID-19. However, DEX usage is often restricted in the clinic due to its poor water solubility. When administered through a systemic route, it can elicit severe side effects, such as hypertension, peptic ulcers, hyperglycemia, and hydro-electrolytic disorders. There is currently much interest in developing efficient DEX-loaded nanoformulations that ameliorate adverse disease effects inhibiting advancements in scientific research. Various nanoparticles have been developed to selectively deliver drugs without destroying healthy cells or organs in recent years. In the present review, we have summarized some of the most attractive applications of DEX-loaded delivery systems, including liposomes, polymers, hydrogels, nanofibers, silica, calcium phosphate, and hydroxyapatite. This review provides our readers with a broad spectrum of nanomedicine approaches to deliver DEX safely.

Integration of a fiber-based cell culture and biosensing system for monitoring of multiple protein markers secreted from stem cells

We propose a new platform that can integrate three-dimensional cell culture scaffold and a surface-enhanced Raman spectroscopy (SERS)-based biosensor by stacking them to form a multilayer system, which would allow monitoring of the protein markers secreted from cultured stem cells without periodic cell and/or media collection. The cell culture scaffold supported the proliferation and osteogenic differentiation of adipose-derived mesenchymal stem cells (ADSCs). The SERS capture substrate detected protein markers in combination with SERS tag made with Au-Ag alloy nanoboxes. Incorporating the different Raman reporters into the SERS tag allowed easy identification of target proteins for multiplex assays. The resultant SERS-based immunoassay could detect the pg/mL levels of protein markers without crosstalk and interference. When one ADSC culture scaffold and multiple SERS capture substrates were integrated and incubated in differentiation culture media, our system was sufficiently sensitive to monitor time-dependent secretion of three different osteogenic protein markers from ADSCs during their osteogenic differentiation. Since the sensor and cell culture scaffold can be manipulated independently, various cell and biomarker combinations are possible to obtain relevant information regarding the actual state of the different types of cells.

Fabrication and Characterization of Biodegradable Gelatin Methacrylate/Biphasic Calcium Phosphate Composite Hydrogel for Bone Tissue Engineering

In the field of bone tissue, maintaining adequate mechanical strength and tissue volume is an important part. Recently, biphasic calcium phosphate (BCP) was fabricated to solve the shortcomings of hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP), and it is widely studied in the field of bone-tissue engineering. In this study, a composite hydrogel was fabricated by applying BCP to gelatin methacrylate (GelMA). It was tested by using a mechanical tester, to characterize the mechanical properties of the prepared composite hydrogel. The fabricated BCP was analyzed through FTIR and XRD. As a result, a different characteristic pattern from hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP) was observed, and it was confirmed that it was successfully bound to the hydrogel. Then, the proliferation and differentiation of preosteoblasts were checked to evaluate cell viability. The analysis results showed high cell viability and relatively high bone differentiation ability in the composite hydrogel to which BCP was applied. These features have been shown to be beneficial for bone regeneration by maintaining the volume and shape of the hydrogel. In addition, hydrogels can be advantageous for clinical use, as they can shape the structure of the material for custom applications.

Controlled Osteogenic Differentiation of Human Mesenchymal Stem Cells Using Dexamethasone-Loaded Light-Responsive Microgels

Human mesenchymal stem cells (hMSCs), which have the ability to differentiate into osteoblasts, show promise for bone tissue engineering and bone defect treatment. While there are a number of approaches currently available to accomplish this, e.g., utilizing biodegradable materials loaded with the synthetic glucocorticoid osteogenic inducer dexamethasone (DEX), there are still many disadvantages with the current technologies. Here, we generated light-responsive microgels that we showed are capable of loading and releasing DEX in a light-triggered fashion, with the released DEX being able to induce hMSC differentiation into osteoblasts. Specifically, light-responsive poly(N-isopropylacrylamide-co-nitrobenzyl methacrylate) (pNIPAm-co-NBMA) microgels were synthesized via free radical precipitation polymerization and their size, morphology, and chemical composition were characterized. We then went on to show that the microgels could be loaded with DEX (via what we think are hydrophobic interactions) and released upon exposure to UV light. We went on to show that the DEX released from the microgels was still capable of inducing osteogenic differentiation of hMSCs using an alamarBlue assay and normalized alkaline phosphatase (ALP) activity assay. We also investigated how hMSC differentiation was impacted by intermittent DEX released from UV-exposed microgels. Finally, we confirmed that the microgels themselves were not cytotoxic to hMSCs. Taken together, the DEX-loaded light-responsive microgels reported here may find a use for niche clinical applications, e.g., bone tissue repair.

Biodegradable calcium phosphate nanoparticles for cancer therapy

Calcium phosphate is the inorganic mineral of hard tissues such as bone and teeth. Due to their similarities to the natural bone, calcium phosphates are highly biocompatible and biodegradable materials that have found numerous applications in dental and orthopedic implants and bone tissue engineering. In the form of nanoparticles, calcium phosphate nanoparticles (CaP's) can also be used as effective delivery vehicles to transfer therapeutic agents such as nucleic acids, drugs, proteins and enzymes into tumor cells. In addition, facile preparation and functionalization of CaP's, together with their inherent properties such as pH-dependent solubility provide advantages in delivery and release of these bioactive agents using CaP's as nanocarriers. In this review, the challenges and achievements in the intracellular delivery of these agents to tumor cells are discussed. Also, the most important issues in the design and potential applications of CaP-based biominerals are addressed with more focus on their biodegradability in tumor microenvironment.

Culture and differentiation of purified human adipose-derived stem cells by membrane filtration via nylon mesh filters

Human adipose derived stem cells purified by the membrane migration method through filter membranes coated with vitronectin showed high osteogenic differentiation.

Interaction of Immune Cells and Tumor Cells in Gold Nanorod-Gelatin Composite Porous Scaffolds

Composite porous scaffolds prepared by immobilization of photothermal nano-agents into porous scaffold have been used for both cancer therapy and tissue regeneration. However, it is not clear how the host immune cells and ablated tumor cells interact and stimulate each other in the composite scaffolds. In this research, a gold nanorod-incorporated gelatin composite scaffold with controlled spherical large pores and well interconnected small pores was fabricated by using ice particulates as a porogen. The composite porous scaffold was used for investigating the interaction between dendritic cells and photothermally ablated breast tumor cells. The composite scaffold demonstrated excellent photothermal property and the temperature change value could be adjusted by irradiation time and laser power density. The composite scaffold showed excellent photothermal ablation ability towards breast tumor cells. The photothermally ablated tumor cells induced activation of dendritic cells when immature dendritic cells were co-cultured in the composite scaffold. Consequently, the gold nanorod-incorporated gelatin composite porous scaffold should provide a useful platform for simultaneous photothermal-immune ablation of breast tumor.

Guiding mesenchymal stem cell differentiation using mesoporous silica nanoparticle-based films

The development of smart interfaces that can guide tissue formation is of great importance in the field of regenerative medicine. Nanoparticles represent an interesting class of materials that can be used to enhance regenerative treatments by enabling close control over surface properties and directing cellular responses. Moreover, nanoparticles can be used to provide temporally controlled delivery of (multiple) biochemical compounds. Here, we exploited the cargo loading and surface functionalization properties of mesoporous silica nanoparticles (MSNs) to design films that can guide human mesenchymal stem cell (hMSC) differentiation towards the osteogenic lineage. We developed biocompatible MSN-based films that support stem cell adhesion and proliferation and demonstrated that these MSN films simultaneously allowed efficient local delivery of biomolecules without effecting film integrity. Films loaded with the osteogenesis-stimulating drug dexamethasone (Dex) were able to induce osteogenic differentiation of hMSCs in vitro. Dex delivery from the films led to increased alkaline phosphatase levels and matrix mineralization compared to directly supplementing Dex to the medium. Furthermore, we demonstrated that Dex release kinetics can be modulated using surface modifications with supported lipid bilayers. Together, these data demonstrate that MSN films represent an interesting approach to create biomaterial interfaces with controllable biomolecule release and surface properties to improve the bioactivity of biomaterials. STATEMENT OF SIGNIFICANCE: Engineering surfaces that can control cell and tissue responses is one of the major challenges in biomaterials-based regenerative therapies. Here, we demonstrate the potential of mesoporous silica nanoparticles (MSNs) as drug-delivering surface coatings. First, we show differentiation of mesenchymal stem cells towards the bone lineage when in contact with MSN films loaded with dexamethasone. Furthermore, we demonstrate that modification of MSNs with supported lipid bilayer allows control over drug release dynamics and cell shape. Given the range of loadable cargos and the tunability of release kinetics, MSN coatings can be used to mimic the sequential appearance of bioactive factors during tissue regeneration, which will ultimately lead to biomaterials with improved bioactivity.

Photothermal Ablation of Cancer Cells by Albumin-Modified Gold Nanorods and Activation of Dendritic Cells

Nanoparticle-mediated photothermal therapy has been widely studied for cancer treatment. It is important to disclose how photothermally ablated tumor cells trigger immune responses. In this study, bovine serum albumin (BSA)-coated gold nanorods (BSA-coated AuNRs) were prepared and used for photothermal ablation of breast tumor cells. The BSA-coated AuNRs showed high photothermal conversion efficiency and good photothermal ablation effect towards tumor cells. The ablated tumor cells were co-cultured with immature dendritic cells (DCs) through a direct cell contacting model and diffusion model to confirm the stimulatory effects of cell⁻cell interaction and soluble factors released from ablated tumor cells. The results indicated that photothermally ablated tumor cells induced immune-stimulatory responses of DCs through both cell⁻cell interaction and soluble factors. The results should be useful for synergistic photothermal-immunotherapy of primary and metastatic cancer.

Bifunctional scaffolds for the photothermal therapy of breast tumor cells and adipose tissue regeneration

Breast cancer is a major public health issue, whose morbidity and mortality are increasing across the world. It is still a challenge to completely ablate breast tumor cells and reconstruct tumor-initiated breast defects after surgical resection. Porous scaffolds with hyperthermal and tissue regeneration functions are a desirable option to achieve these effects. In this study, bifunctional composite porous scaffolds of gold nanorods (AuNRs) and gelatin with well controlled pore structures were prepared by introducing AuNRs into the porous matrices of gelatin and using ice particulates as a porogen material. The AuNRs-gelatin composite scaffolds exhibited a high photothermal conversion effect, whose photothermal temperature could be modulated by the amount of incorporated AuNRs, NIR laser power intensity and irradiation time. The AuNRs-gelatin composite scaffolds exhibited an excellent photothermal ablation capacity toward breast tumor cells in vitro and in vivo. Furthermore, the AuNRs-gelatin porous scaffolds supported cell adhesion and promoted the proliferation and adipogenic differentiation of human bone-marrow derived mesenchymal stem cells (hMSCs). Consequently, the AuNRs-gelatin scaffolds could not only provide photothermal therapy for breast tumors but also promote the adipogenic differentiation of stem cells for adipose tissue regeneration.

Promoted Angiogenesis and Osteogenesis by Dexamethasone-loaded Calcium Phosphate Nanoparticles/Collagen Composite Scaffolds with Microgroove Networks

Reconstruction of large bone defects remains a clinical challenge because current approaches involving surgery and bone grafting often do not yield satisfactory outcomes. For artificial bone substitutes, angiogenesis plays a pivotal role to achieve the final success of newly regenerated bone. In this study, dexamethasone-loaded biphasic calcium phosphate nanoparticles/collagen composite scaffolds with several types of concave microgrooves were prepared for simultaneous promotion of angiogenesis and osteogenesis. Microgrooves in the scaffolds were supposed to guide the assembly of human umbilical vascular endothelial cells (HUVECs) into well aligned tubular structures, thus promoting rapid angiogenesis. The scaffolds were used for co-culture of HUVECs and human bone marrow-derived mesenchymal stem cells. Subcutaneous implantation in mice showed that more blood vessels and newly formed bone were observed in the microgrooved composite scaffolds than in the control scaffold. Scaffold bearing parallel microgrooves with a concave width of 290 µm and a convex ridge width of 352 µm showed the highest promotion effect on angiogenesis and osteogenesis among the parallelly microgrooved composite scaffolds. The scaffolds bearing a grid network had further superior promotion effect to the scaffolds bearing parallel microgrooves. The results indicated that microgrooves in the composite scaffolds facilitated angiogenesis and stimulated new bone formation. The microgrooved composite scaffolds should be useful for repairing of large bone defects.

Preparation of dexamethasone-loaded biphasic calcium phosphate nanoparticles/collagen porous composite scaffolds for bone tissue engineering

Although bone is regenerative, its regeneration capacity is limited. For bone defects beyond a critical size, further intervention is required. As an attractive strategy, bone tissue engineering (bone TE) has been widely investigated to repair bone defects. However, the rapid and effective bone regeneration of large non-healing defects is still a great challenge. Multifunctional scaffolds having osteoinductivity and osteoconductivity are desirable to fasten functional bone tissue regeneration. In the present study, biomimetic composite scaffolds of collagen and biphasic calcium phosphate nanoparticles (BCP NPs) with a controlled release of dexamethasone (DEX) and the controlled pore structures were prepared for bone TE. DEX was introduced in the BCP NPs during preparation of the BCP NPs and hybridized with collagen scaffolds, which pore structures were controlled by using pre-prepared ice particulates as a porogen material. The composite scaffolds had well controlled and interconnected pore structures, high mechanical strength and a sustained release of DEX. The composite scaffolds showed good biocompatibility and promoted osteogenic differentiation of hMSCs when used for three-dimensional culture of human bone marrow-derived mesenchymal stem cells. Subcutaneous implantation of the composite scaffolds at the dorsa of athymic nude mice demonstrated that they facilitated the ectopic bone tissue regeneration. The results indicated the DEX-loaded BCP NPs/collagen composite scaffolds had high potential for bone TE.

STATEMENT OF SIGNIFICANCE

Scaffolds play a crucial role for regeneration of large bone defects. Biomimetic scaffolds having the same composition of natural bone and a controlled release of osteoinductive factors are desirable for promotion of bone regeneration. In this study, composite scaffolds of collagen and biphasic CaP nanoparticles (BCP NPs) with a controlled release nature of dexamethasone (DEX) were prepared and their porous structures were controlled by using ice particulates. In vitro cell culture and in vivo implantation experiments demonstrated the composite scaffolds exerted synergistic effects on the osteogenic differentiation of hMSCs and bone regeneration. The composite scaffolds also showed promotive effect on the formation of capillary blood vessels in the regenerated bone. This study is the first research to prepare DEX-loaded BCP NPs/collagen porous composite scaffolds. The superior performance of the composite scaffolds indicates the composite scaffolds should be useful for bone tissue engineering.