Entry-Prohibited Effect of kHz Pulsed Magnetic Field Upon Interaction Between SPIO Nanoparticles and Mesenchymal Stem Cells

Preparing the functional biomaterial with osteogenic bioactivities by incorporating annealing pretreated silk fiber and iron oxide nanoparticles

Silk fiber (SF), a kind of bio-fiber from biomass protein fibers with biocompatibility and mechanical properties, has been widely utilized in biomedical engineering. However, SF-based bio-scaffolds often encounter challenges in promoting osteogenesis within bone tissue engineering (BTE) applications. In this study, SF-based composites were constructed via the solution casting method in the presence of IONPs (SFFC-IONPs), followed by annealing-induced self-assembly to form magnetic SF annealing films (SFFCA-IONPs). Three types of IONPs loaded SF films (SFFCA-50, SFFCA-100, and SFFCA-200) were prepared by altering the feeding IONPs (50 μg/mL, 100 μg/mL, and 200 μg/mL). Results demonstrated that SFFC films primarily exhibited random coil structures and were water-soluble, while SFFCA films demonstrated the formation of silk II structures and became water-insoluble. The incorporation of IONPs significantly enhanced the porosity, mechanical strength, and thermal stability of the SFFCA films. Furthermore, the SFFCA-IONPs films not only exhibited excellent biocompatibility but also demonstrated enhanced osteo-inductive properties, as evidenced by increased alkaline phosphatase (ALP) activity, enhanced mineralized nodule formation, and upregulation of osteogenic gene expression. This study presents a promising bio-based material with significant potential for use as a scaffold in BTE applications.

The Story of Ferumoxytol: Synthesis Production, Current Clinical Applications, and Therapeutic Potential

Ferumoxytol, approved by the U.S. Food and Drug Administration in 2009, is one of the intravenous iron oxide nanoparticles authorized for the treatment of iron deficiency in chronic kidney disease and end-stage renal disease. With its exceptional magnetic properties, catalytic activity, and immune activity, as well as good biocompatibility and safety, ferumoxytol has gained significant recognition in various biomedical diagnoses and treatments. Unlike most existing reviews on this topic, this review primarily focuses on the recent clinical and preclinical advances of ferumoxytol in disease treatment, spanning anemia, cancer, infectious inflammatory diseases, regenerative medicine application, magnetic stimulation for neural modulation, etc. Additionally, the newly discovered mechanisms associated with the biological effects of ferumoxytol are discussed, including its magnetic, catalytic, and immunomodulatory properties. Finally, the summary and future prospects concerning the treatment and application of ferumoxytol-based nanotherapeutics are presented.

Endowing improved osteogenic activities with collagen membrane by incorporating biocompatible iron oxide nanoparticles

Introduction: Collagen-based scaffolds, renowned for their exceptional biocompatibility, have garnered attention as promising scaffolds for advancing bone tissue regeneration. Nevertheless, these scaffolds possess inherent limitations, such as notably compromised osteo-conductivity and osteo-inductivity. Methods: Our study focused on enhancing the mechanical properties and osteogenic bioactivities of bovine-derived collagen membranes (CMs) from the Achilles tendon by incorporating FDA-approved iron oxide nanoparticles (IONPs), termed as IONP-CM. Three types of IONP-CMs (IONP-CM-0.5, IONP-CM-1, and IONPCM-1.5) were constructed by altering the amounts of feeding IONPs. Results: Surface topography analysis demonstrated comparable characteristics between the IONP-CM and neat CM, with the former exhibiting augmented mechanical properties. In vitro evaluations revealed the remarkable biocompatibility of IONP-CMs toward mouse calvarial pre-osteoblast MC3T3-E1 cells, concurrently stimulating osteogenic differentiation. Mechanistic investigations unveiled that the osteogenic differentiation induced by IONP-CMs stemmed from the activation of the Wnt/β-catenin signaling pathway. Furthermore, in vivo bone regeneration assessment was performed by implanting IONP-CMs into the radial defect in rabbits. Results derived from micro-computed tomography and histological analyses unequivocally substantiated the capacity of IONP-CMs to expedite bone repair processes. Discussion: IONP-CMs emerged as scaffolds boasting exceptional biocompatibility and enhanced osteogenic properties, positioning them as promising candidates for facilitating bone tissue regeneration.

Extracellular magnetic labeling of biomimetic hydrogel-induced human mesenchymal stem cell spheroids with ferumoxytol for MRI tracking

Labeling of mesenchymal stem cells (MSCs) with superparamagnetic iron oxide nanoparticles (SPIONs) has emerged as a potential method for magnetic resonance imaging (MRI) tracking of transplanted cells in tissue repair studies and clinical trials. Labeling of MSCs using clinically approved SPIONs (ferumoxytol) requires the use of transfection reagents or magnetic field, which largely limits their clinical application. To overcome this obstacle, we established a novel and highly effective method for magnetic labeling of MSC spheroids using ferumoxytol. Unlike conventional methods, ferumoxytol labeling was done in the formation of a mechanically tunable biomimetic hydrogel-induced MSC spheroids. Moreover, the labeled MSC spheroids exhibited strong MRI T2 signals and good biosafety. Strikingly, the encapsulated ferumoxytol was localized in the extracellular matrix (ECM) of the spheroids instead of the cytoplasm, minimizing the cytotoxicity of ferumoxytol and maintaining the viability and stemness properties of biomimetic hydrogel-induced MSC spheroids. This demonstrates the potential of this method for post-transplantation MRI tracking in the clinic.

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An extracellular magnetic labeling method was developed for MSC spheroids using ferumoxytol.

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Ferumoxytol encapsulated into abundant ECM proteins network of MSC spheroids ensured this method is stable and durable.

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Uniformly sized magnetic spheroids induced by mechanically tunable biomimetic hydrogels promoted MSCs stemness properties.

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Magnetically labeled MSC spheroids exhibited superior MRI imaging both in vitro and in vivo.

Osteogenesis of Iron Oxide Nanoparticles-Labeled Human Precartilaginous Stem Cells in Interpenetrating Network Printable Hydrogel

Smart biomaterials combined with stem cell-based therapeutic strategies have brought innovation in the field of bone tissue regeneration. However, little is known about precartilaginous stem cells (PCSCs), which can be used as seed cells and incorporated with bioactive scaffolds for reconstructive tissue therapy of bone defects. Herein, iron oxide nanoparticles (IONPs) were employed to modulate the fate of PCSCs, resulting in the enhanced osteogenic differentiation potential both in vitro and in vivo. PCSCs were isolated from the ring of La-Croix extracted from polydactylism patient and identified through immunohistochemically staining using anti-FGFR-3 antibodies. Potential toxicity of IONPs toward PCSCs was assessed through cell viability, proliferation, and attachment assay, and the results demonstrated that IONPs exhibited excellent biocompatibility. After that, the effects of IONPs on osteogenic differentiation of PCSCs were evaluated and enhanced ALP activity, formation of mineralized nodule, and osteogenic-related genes expressions could be observed upon IONPs treatment. Moreover, in vivo bone regeneration assessment was performed using rabbit femur defects as a model. A novel methacrylated alginate and 4-arm poly (ethylene glycol)-acrylate (4A-PEGAcr)-based interpenetrating polymeric printable network (IPN) hydrogel was prepared for incorporation of IONPs-labeled PCSCs, where 4A-PEGAcr was the common component for three-dimensional (3D) printing. The implantation of IONPs-labeled PCSCs significantly accelerated the bone formation process, indicating that IONPs-labeled PCSCs could endow current scaffolds with excellent osteogenic ability. Together with the fact that the IONPs-labeled PCSCs-incorporated IPN hydrogel (PCSCs-hydrogels) was biosafety and printable, we believed that PCSCs-hydrogels with enhanced osteogenic bioactivity could enrich the stem cell-based therapeutic strategies for bone tissue regeneration.

Superparamagnetic Iron Oxide Nanoparticles Protect Human Gingival Fibroblasts from Porphyromonas gingivalis Invasion and Inflammatory Stimulation

Introduction

Modulating the inflammatory response of human gingival fibroblasts (hGFs) is important for the control of periodontal inflammation because it is a key event in the pathogenesis of periodontitis. Here, we aimed to determine whether polyglucose sorbitol carboxymethyl ether (PSC)-coated superparamagnetic iron oxide nanoparticles (SPIONs) protect hGFs against invasion and inflammatory stimulation by Porphyromonas gingivalis (P. gingivalis).

Methods

First, we determined the cytotoxicity and antimicrobial activity of PSC-SPIONs. Then, their effects on invasion of hGFs by P. gingivalis were evaluated by counting invading P. gingivalis, fluorescence staining, and transmission electron microscopy. The effect of PSC-SPIONs on inflammation in hGFs induced by P. gingivalis lipopolysaccharide was evaluated by measurement of reactive oxygen species (ROS), and enzyme-linked immunosorbent assays, quantitative reverse transcription-polymerase chain reaction, and Western blotting of key indicator molecules. The effects of dimercaptosuccinic acid (DMSA)-coated SPIONs and the free form of PSC alone were also tested and compared with those of PSC-SPIONs.

Results

PSC-SPIONs (25 μg/mL) are cytocompatible with hGFs and exhibit no antimicrobial effects on P. gingivalis. However, they inhibit invasion of hGFs by P. gingivalis at 15 μg/mL. They also decrease ROS production and inflammatory cytokine secretion by hGFs at 5, 15, and 25 μg/mL, by downregulating activation of the nuclear factor-kappa B signaling pathway. Furthermore, PSC alone does not inhibit inflammation, while DMSA-SPIONs do. This indicates that the nanosize effects of PSC-SPIONs, rather than their coating material, play the dominant role in their anti-inflammatory activity.

Conclusion

PSC-SPIONs protect hGFs against P. gingivalis invasion and inflammatory stimulation. Thus, they have potential for clinical application in control of periodontal inflammation.

Neurite Extension and Orientation of Spiral Ganglion Neurons Can Be Directed by Superparamagnetic Iron Oxide Nanoparticles in a Magnetic Field

Introduction

Neuroregeneration is a major challenge in neuroscience for treating degenerative diseases and for repairing injured nerves. Numerous studies have shown the importance of physical stimulation for neuronal growth and development, and here we report an approach for the physical guidance of neuron orientation and neurite growth using superparamagnetic iron oxide (SPIO) nanoparticles and magnetic fields (MFs).

Methods

SPIO nanoparticles were synthesized by classic chemical co-precipitation methods and then characterized by transmission electron microscope, dynamic light scattering, and vibrating sample magnetometer. The cytotoxicity of the prepared SPIO nanoparticles and MF was determined using CCK-8 assay and LIVE/DEAD assay. The immunofluorescence images were captured by a laser scanning confocal microscopy. Cell migration was evaluated using the wound healing assay.

Results

The prepared SPIO nanoparticles showed a narrow size distribution, low cytotoxicity, and superparamagnetism. SPIO nanoparticles coated with poly-L-lysine could be internalized by spiral ganglion neurons (SGNs) and showed no cytotoxicity at concentrations less than 300 µg/mL. The neurite extension of SGNs was promoted after internalizing SPIO nanoparticles with or without an external MF, and this might be due to the promotion of growth cone development. It was also confirmed that SPIO can regulate cell migration and can direct neurite outgrowth in SGNs preferentially along the direction imposed by an external MF.

Conclusion

Our results provide a fundamental understanding of the regulation of cell behaviors under physical cues and suggest alternative treatments for sensorineural hearing loss caused by the degeneration of SGNs.

Citrate-Stabilized Gold Nanorods-Directed Osteogenic Differentiation of Multiple Cells

Objective

Gold nanorods (AuNRs) show great potential for versatile biomedical applications, such as stem cell therapy and bone tissue engineering. However, as an indispensable shape-directing agent for the growth of AuNRs, cetyltrimethylammonium bromide (CTAB) is not optimal for biological studies because it forms a cytotoxic bilayer on the AuNR surface, which interferes with the interactions with biological cells.

Methods

Citrate-stabilized AuNRs with various aspect-ratios (Cit-NRI, Cit-NRII, and Cit-NRIII) were prepared by the combination of end-selective etching and poly(sodium 4-styrenesulfonate)-assisted ligand exchange method. Their effects on osteogenic differentiation of the pre-osteoblastic cell line (MC3T3-E1), rat bone marrow mesenchymal stem cells (rBMSCs), and human periodontal ligament progenitor cells (PDLPs) have been investigated. Potential signaling pathway of citrate-stabilized AuNRs-induced osteogenic effects was also investigated.

Results

The experimental results showed that citrate-stabilized AuNRs have superior biocompatibility and undergo aspect-ratio-dependent osteogenic differentiation via expression of osteogenic marker genes, alkaline phosphatase (ALP) activity and formation of mineralized nodule. Furthermore, Wnt/β-catenin signaling pathway might provide a potential explanation for the citrate-stabilized AuNRs-mediated osteogenic differentiation.

Conclusion

These findings revealed that citrate-stabilized AuNRs with great biocompatibility could regulate the osteogenic differentiation of multiple cell types through Wnt/β-catenin signaling pathway, which promote innovative AuNRs in the field of tissue engineering and other biomedical applications.

Magnetic PLGA microspheres loaded with SPIONs promoted the reconstruction of bone defects through regulating the bone mesenchymal stem cells under an external magnetic field

Superparamagnetic iron oxide nanoparticles (SPIONs) have been presented to regulate the migration and osteogenic differentiation of bone mesenchymal stem cells (BMSCs) under magnetic field (MF). However, the toxicity and short residence for the massively exposed SPIONs at bone defects compromises their practical application. Herein, SPIONs were encapsulated into PLGA microspheres to overcome these shortcomings. Three types of PLGA microspheres (PFe-I, PFe-II and PFe-III) were prepared by adjusting the feeding amount of SPIONs, in which the practical SPIONs loading amounts was 1.83%, 1.38% and 1.16%, respectively. The average diameter of the fabricated microspheres ranged from 160 μm to 200 μm, having the porous and rough surfaces displayed by SEM. Moreover, they displayed the magnetic property with a saturation magnetization of 0.16 emu/g. In vitro cell studies showed that most of BMSCs were adhered on the surface of PFe-II microspheres after 2 days of co-culture. Moreover, the osteoblasts differentiation of BMSCs was significantly promoted by PFe-II microspheres after 2 weeks of co-culture, as shown by detecting osteogenesis-related proteins expressions of ALP, COLI, OPN and OCN. Afterward, PFe-II microspheres were surgically implanted into the defect zone of rat femoral bone, followed by exposure to an external MF, to evaluate their bone repairing effect in vivo. At 6th week after treatment with PFe-II + MF, the bone mineral density (BMD, 263.97 ± 25.99 mg/cm³), trabecular thickness (TB.TH, 0.58 ± 0.08 mm), and bone tissue volume/total tissue volume (BV/TV, 78.28 ± 5.01%) at the defect zone were markedly higher than that of the PFe-II microspheres alone (BMD, 194.34 ± 26.71 mg/cm³; TB.TH, 0.41 ± 0.07 mm; BV/TV, 50.49 ± 6.41%). Moreover, the higher expressions of ALP, COLI, OPN and OCN in PFe-II + MF group were displayed in the repairing bone. Collectively, magnetic PLGA microspheres together with MF may be a promising strategy for repairing bone defects.

Moderate cooling coprecipitation for extremely small iron oxide as a pH dependent T1-MRI contrast agent

Iron based nanomedicine (IBNM) has been one powerful diagnostic tool as a magnetic resonance imaging (MRI) contrast agent (CA) in the clinic for years. Conventional IBNMs are generally employed as T₂-MRI CAs, but most of them are constrained in clinical indication expansion by magnetic susceptibility artifacts. In comparison, extremely small iron oxide (ESIO) with a core size less than 5 nm has demonstrated the T₁-MRI effect, which provides prospects for a Gd-based agent alternative. Nevertheless, currently developed ESIOs for T₁-MRI CAs always require harsh conditions such as a high temperature and high boiling point reagent. Moreover, very few of the currently developed ESIOs meet the stringent pharmaceutical standard. Herein, on the basis of a crystal nuclear precipitation-dissolution equilibrium mechanism and outer/inner sphere T₁-MRI theory, monodisperse ESIOs with an average size of 3.43 nm (polydispersity index of 0.104) are fabricated using a moderate cooling procedure with mild coprecipitation reaction conditions. The as-synthesized ESIOs display around 3-fold higher T₁ MRI signal intensity than that of commercial Ferumoxytol (FMT), comparable to that of Gd-based CAs in vitro. Additionally, the T₁-MRI performance of the ESIOs is pH dependent and delivers bright signal augmentation. Eventually, the internalization into mesenchymal stem cells of the ESIO is realized in the absence of a transferring agent. Considering the identical structure and composition of the ESIOs as compared to that of FMT, they could meet the pharmaceutical criteria, thus providing great potential as T₁-MRI Cas, for instance as stem cell tracers.