Metabolic and structural integrity of magnetic nanoparticle-loaded primary endothelial cells for targeted cell therapy

Vitrification of Mammalian Oocytes: Recent Studies on Mitochondrial Dysfunction

Vitrification of reproductive cells is definitely essential and integral in animal breeding, as well as in assisted reproduction. However, issues accompanied with this technology such as decreased oocyte competency and relatively low embryo survival rates appear to be a tough conundrum that has long perplexed us. As significant organelles in cell metabolism, mitochondria play pivotal roles in numerous pathways. Nonetheless, extensive evidence has demonstrated that vitrification can seriously impair mitochondrial function in mammalian oocytes. Thus, in this article, we summarize the current progress in oocyte vitrification and particularly outline the common mitochondrial abnormalities alongside subsequent injury cascades seen in mammalian oocytes following vitrification. Based on existing literature, we tentatively come up with the potential mechanisms related to mitochondrial dysfunction and generalize efficacious ways which have been recommended to restore mitochondrial function.

Toxicity and magnetometry evaluation of the uptake of core-shell maghemite-silica nanoparticles by neuroblastoma cells

Nanoparticle uptake by cells is a key parameter in their performance in biomedical applications. However, the use of quantitative, non-destructive techniques to obtain the amount of nanoparticles internalized by cells is still uncommon. We have studied the cellular uptake and the toxicity of core-shell maghemite-silica magnetic nanoparticles (MNPs), with a core diameter of 9 nm and a shell thickness of 3 nm. The internalization of the nanoparticles by mouse neuroblastoma 2a cells was evaluated by sensitive and non-destructive Superconducting Quantum Interference Device (SQUID) magnetometry and corroborated by graphite furnace atomic absorption spectroscopy. We were thus able to study the toxicity of the nanoparticles for well-quantified MNP uptake in terms of nanoparticle density within the cell. No significant variation in cell viability or growth rate was detected for any tested exposure. Yet, an increase in both the amount of mitochondrial superoxide and in the lysosomal activity was detected for the highest concentration (100 μg ml-1) and incubation time (24 h), suggesting the onset of a disruption in ROS homeostasis, which may lead to an impairment in antioxidant responses. Our results validate SQUID magnetometry as a sensitive technique to quantify MNP uptake and demonstrate the non-toxic nature of these core-shell MNPs under our culture conditions.

Magneto-Mechanical Actuation Induces Endothelial Permeability

Cancer treatment is one of the major health problems that burden our society. According to the American Cancer Society, over 1.9 million new cancer cases and ∼0.6 million deaths from cancer are expected in the US in 2023. Therapeutic targeting is considered to be the gold standard in cancer treatment. However, when a tumor grows beyond a critical size, its vascular system differentiates abnormally and erratically, creating a heterogeneous endothelial barrier that further restricts drug delivery into tumors. While several methods exist, these prompt tumor migration and the appearance of new metastatic sites. Herein, we propose an innovative method based on magneto-mechanical actuation (MMA) to induce endothelial permeability. This method employs FDA-approved PEGylated superparamagnetic iron oxide nanoparticles (PEG-SPIONs) and alternating nonheating magnetic fields. MMA lies in the translation of magnetic forces into mechanical agitation. As a proof of concept, we developed a 2D cell culture model based on human umbilical vein endothelial cells (HUVEC), which were incubated with PEG-SPIONs and then exposed to different magnetic doses. After adjusting the particle concentration, incubation times, and parameters (amplitude, frequency, and exposure time) of the magnetic field generator, we induced actin filament remodeling and subsequent vascular endothelial-cadherin junction disruption. This led to transient gaps in cell monolayers, through which fluorescein isothiocyanate-dextran was translocated. We observed no cell viability reduction for 3 h of particle incubation up to a concentration of 100 μg/mL in the presence and absence of magnetic fields. For optimal permeability studies, the magnetic field parameters were adjusted to 100 mT, 65 Hz, and 30 min in a pulse mode with 5 min OFF intervals. We found that the endothelial permeability reached the highest value (33%) when 2 h postmagnetic field treatment was used. To explain these findings, a magneto-mechanical transduced stress mechanism mediated by intracellular forces was proposed. This method can open new avenues for targeted drug delivery into anatomic regions within the body for a broad range of disease interventions.

Magnetic Nanoparticles and Magnetic Field Exposure Enhances Chondrogenesis of Human Adipose Derived Mesenchymal Stem Cells But Not of Wharton Jelly Mesenchymal Stem Cells

Purpose: Iron oxide based magnetic nanoparticles (MNP) are versatile tools in biology and medicine. Adipose derived mesenchymal stem cells (ADSC) and Wharton Jelly mesenchymal stem cells (WJMSC) are currently tested in different strategies for regenerative regenerative medicine (RM) purposes. Their superiority compared to other mesenchymal stem cell consists in larger availability, and superior proliferative and differentiation potential. Magnetic field (MF) exposure of MNP-loaded ADSC has been proposed as a method to deliver mechanical stimulation for increasing conversion to musculoskeletal lineages. In this study, we investigated comparatively chondrogenic conversion of ADSC-MNP and WJMSC with or without MF exposure in order to identify the most appropriate cell source and differentiation protocol for future cartilage engineering strategies. Methods: Human primary ADSC and WJMSC from various donors were loaded with proprietary uncoated MNP. The in vitro effect on proliferation and cellular senescence (beta galactosidase assay) in long term culture was assessed. In vitro chondrogenic differentiation in pellet culture system, with or without MF exposure, was assessed using pellet histology (Safranin O staining) as well as quantitative evaluation of glycosaminoglycan (GAG) deposition per cell. Results: ADSC-MNP complexes displayed superior proliferative capability and decreased senescence after long term (28 days) culture in vitro compared to non-loaded ADSC and to WJMSC-MNP. Significant increase in chondrogenesis conversion in terms of GAG/cell ratio could be observed in ADSC-MNP. MF exposure increased glycosaminoglycan deposition in MNP-loaded ADSC, but not in WJMSC. Conclusion: ADSC-MNP display decreased cellular senescence and superior chondrogenic capability in vitro compared to non-loaded cells as well as to WJMSC-MNP. MF exposure further increases ADSC-MNP chondrogenesis in ADSC, but not in WJMSC. Loading ADSC with MNP can derive a successful procedure for obtaining improved chondrogenesis in ADSC. Further in vivo studies are needed to confirm the utility of ADSC-MNP complexes for cartilage engineering.

Advantages and Disadvantages of Using Magnetic Nanoparticles for the Treatment of Complicated Ocular Disorders

Nanomaterials provide enormous opportunities to overcome the limitations of conventional ocular delivery systems, such as low therapeutic efficacy, side effects due to the systemic exposure, or invasive surgery. Apart from the more common ocular disorders, there are some genetic diseases, such as cystic fibrosis, that develop ocular disorders as secondary effects as long as the disease progresses. These patients are more difficult to be pharmacologically treated using conventional drug routes (topically, systemic), since specific pharmacological formulations can be incompatible, display increased toxicity, or their therapeutic efficacy decreases with the administration of different kind of chemical molecules. Magnetic nanoparticles can be used as potent drug carriers and magnetic hyperthermia agents due to their response to an external magnetic field. Drugs can be concentrated in the target point, limiting the damage to other tissues. The other advantage of these magnetic nanoparticles is that they can act as magnetic resonance imaging agents, allowing the detection of the exact location of the disease. However, there are some drawbacks related to their use in drug delivery, such as the limitation to maintain efficacy in the target organ once the magnetic field is removed from outside. Another disadvantage is the difficulty in maintaining the therapeutic action in three dimensions inside the human body. This review summarizes all the application possibilities related to magnetic nanoparticles in ocular diseases.

Fe3O4 magnetic nanoparticles improve the vitrification of mouse immature oocytes and modulate the pluripotent genes expression in derived pronuclear-stage embryos

The vitrification of Germinal Vesicle (immature) oocytes is beneficial for preservation of fertility in cases involving reproductive problems. The use of nanoparticles (NP(s)) as vitrification aid is a novel approach towards improving vitrification efficiency. The efficacy of use of iron oxide (Fe₃O₄) nanoparticles as vitrification aid is reported in this paper. Immature oocytes from NMRI mice were collected and divided into non-vitrified (nVit), Vitrified (Vit) and Vitrified + NP (Vit^+NP) groups. In the Vit^+NP group, solutions containing Fe₃O₄ nanoparticles at three different concentrations (0.004%, 0.008% and 0.016% w/v) were separately added to the vitrification solution and their effects on the vitrification of the oocytes were compared. The concentration that was found to be best performing (0.004% w/v) was used in vitrification studies in subsequent experiments. Mitochondrial function, apoptosis incidence, ultrastructure alteration, nuclear maturity, embryo formation and genes expression (Nanog, Oct4, Cdx2, and Sox2) were evaluated in response to the addition of the nanoparticle solution during vitrification. Nuclear maturity of oocyte and embryo formation increased significantly (P ≤ 0.05) in the vitrified + NP group. Expression of Sox2 also increased significantly in both vitrified and vitrified + NP groups. While there was a significant increase in Oct4 expression in the vitrified group as compared to control, there was no significant difference between vitrified and Vit^+NP groups. The expression of Cdx2 decreased significantly (P ≤ 0.05) in the Vit^+NP group. From these observations, Fe₃O₄ nanoparticles could protect immature oocytes from cryodamages, positively affect vitrification and modulate the pluripotency of derived pronuclear-stage embryos.

Experimental Single-Platform Approach to Enhance the Functionalization of Magnetically Targetable Cells

Magnetic guidance shows promise as a strategy for improving the delivery and performance of cell therapeutics. However, clinical translation of magnetically guided cell therapy requires cell functionalization protocols that provide adequate magnetic properties in balance with unaltered cell viability and biological function. Existing methodologies for characterizing cells functionalized with magnetic nanoparticles (MNP) produce aggregate results, both distorted and unable to reflect variability in either magnetic or biological properties within a preparation. In the present study, we developed an inverted-plate assay allowing determination of these characteristics using a single-platform approach, and applied this method for a comparative analysis of two loading protocols providing highly uniform vs. uneven MNP distribution across cells. MNP uptake patterns remarkably different between the two protocols were first shown by fluorimetry carried out in a well-scan mode on endothelial cells (EC) loaded with BODIPY558/568-labeled MNP. Using the inverted-plate assay we next demonstrated that, in stark contrast to unevenly loaded cells, more than 50% of uniformly functionalized EC were captured within 5 min over a broad range of MNP doses. Furthermore, magnetically captured cells exhibited unaltered viability, substrate attachment, and proliferation rates. Conducted in parallel, magnetophoretic mobility studies corroborated the markedly superior guidance capacity of uniformly functionalized cells, confirming substantially faster cell capture kinetics on a clinically relevant time scale. Taken together, these results emphasize the importance of optimizing cell preparation protocols with regard to loading uniformity as key to efficient site-specific delivery, engraftment, and expansion of the functionalized cells, essential for both improving performance and facilitating translation of targeted cell therapeutics.

Osteotropic Radiolabeled Nanophotosensitizer for Imaging and Treating Multiple Myeloma

Rapid liver and spleen opsonization of systemically administered nanoparticles (NPs) for in vivo applications remains the Achilles' heel of nanomedicine, allowing only a small fraction of the materials to reach the intended target tissue. Although focusing on diseases that reside in the natural disposal organs for nanoparticles is a viable option, it limits the plurality of lesions that could benefit from nanomedical interventions. Here we designed a theranostic nanoplatform consisting of reactive oxygen (ROS)-generating titanium dioxide (TiO2) NPs, coated with a tumor-targeting agent, transferrin (Tf), and radiolabeled with a radionuclide (89Zr) for targeting bone marrow, imaging the distribution of the NPs, and stimulating ROS generation for cell killing. Radiolabeling of TiO2 NPs with 89Zr afforded thermodynamically and kinetically stable chelate-free 89Zr-TiO2-Tf NPs without altering the NP morphology. Treatment of multiple myeloma (MM) cells, a disease of plasma cells originating in the bone marrow, with 89Zr-TiO2-Tf generated cytotoxic ROS to induce cancer cell killing via the apoptosis pathway. Positron emission tomography/X-ray computed tomography (PET/CT) imaging and tissue biodistribution studies revealed that in vivo administration of 89Zr-TiO2-Tf in mice leveraged the osteotropic effect of 89Zr to selectively localize about 70% of the injected radioactivity in mouse bone tissue. A combination of small-animal PET/CT imaging of NP distribution and bioluminescence imaging of cancer progression showed that a single-dose 89Zr-TiO2-Tf treatment in a disseminated MM mouse model completely inhibited cancer growth at euthanasia of untreated mice and at least doubled the survival of treated mice. Treatment of the mice with cold Zr-TiO2-Tf, 89Zr-oxalate, or 89Zr-Tf had no therapeutic benefit compared to untreated controls. This study reveals an effective radionuclide sensitizing nanophototherapy paradigm for the treatment of MM and possibly other bone-associated malignancies.

Polymer-coated nanoparticles and their effects on mitochondrial function in brain endothelial cells

Laser tissue soldering is a novel treatment method for injuries of hollow organs such as cerebrovascular aneurysms. Nanomaterials contained in the solder are foreign to the body. Hence, it is indispensable to carefully examine possible adverse effects prior to introducing this technique. The aim of this study was to characterize the impact of different concentrations of polymer-coated silica nanoparticles (NPs) on mitochondrial function and integrity of brain endothelial cells using the rat brain capillary endothelial cell line rBCEC4. At maximal capacity, NP exposure resulted in a decrease in the oxygen consumption rate whereas glycolysis was not affected. In combination with a stressor, i.e. lack of glucose in the medium, NP exposure interfered primarily with glycolytic ATP generation rather than oxidative phosphorylation. Furthermore, NPs caused a metabolic shift towards a stressed phenotype, exhibiting increased levels of the oxygen consumption rate and the extracellular acidification rate compared to untreated controls. Overall, mitochondrial mass, distribution and morphology as well as intracellular ATP content were not altered. The mitochondrial membrane potential was increased after exposure to the highest NP concentration and the content of proteins involved in mitochondrial dynamics was changed slightly, indicating possible modifications of the fusion / fission balance. In conclusion, PCL-NP exposure changed mitochondrial respiration, especially under glucose deprivation, but did not affect mitochondrial morphology and distribution. Further studies are needed to investigate whether the functional effects are transient or long-term as this will be crucial for the use of these NPs in laser tissue soldering.

Dual Suppression Effect of Magnetic Induction Heating and Microencapsulation on Ice Crystallization Enables Low-Cryoprotectant Vitrification of Stem Cell-Alginate Hydrogel Constructs

Stem cells microencapsulated in hydrogel as stem cell-hydrogel constructs have wide applications in the burgeoning cell-based medicine. Due to their short shelf life at ambient temperature, long-term storage or banking of the constructs is essential to the "off-the-shelf" ready availability needed for their widespread applications. As a high-efficiency, easy-to-operate, low-toxicity, and low-cost method for long-term storage of the constructs, low-cryoprotectant (CPA) vitrification has attracted tremendous attention recently. However, we found many cells in the stem cell-alginate constructs (∼500 μm in diameter) could not attach to the substrate post low-CPA vitrification with ∼2 M penetrating CPAs. To address this problem, we introduced nanowarming via magnetic induction heating (MIH) of Fe3O4 nanoparticles to minimize recrystallization and devitrification during the warming step of the low-CPA vitrification procedure. Our results indicate that high-quality stem cell-alginate hydrogel constructs with an intact microstructure, high immediate cell survival (>80%), and greatly improved attachment efficiency (by nearly three times, 68% versus 24%) of the encapsulated cells could be obtained post-cryopreservation with nanowarming. Moreover, the cells encapsulated in the cell-hydrogel constructs post-cryopreservation maintained normal proliferation under 3D culture and retained intact biological function of multilineage differentiation. This novel low-CPA vitrification approach for cell cryopreservation enabled by the combined use of alginate hydrogel microencapsulation and Fe3O4 nanoparticles-mediated nanowarming may be valuable in facilitating the widespread application of stem cells in the clinic.

Fabrication and Cytotoxicity of Gemcitabine-Functionalized Magnetite Nanoparticles

Nanotechnology has been successfully used for the fabrication of targeted anti-cancer drug carriers. This study aimed to obtain Fe₃O₄ nanoparticles functionalized with Gemcitabine to improve the cytotoxic effects of the chemotherapeutic substance on cancer cells. The (un) functionalized magnetite nanoparticles were synthesized using a modified co-precipitation method. The nanoconjugate characterization was performed by XRD, SEM, SAED and HRTEM; the functionalizing of magnetite with anti-tumor substances has been highlighted through TGA. The interaction with biologic media has been studied by means of stability and agglomeration tendency (using DLS and Zeta Potential); also, the release kinetics of the drug in culture media was evaluated. Cytotoxicity of free-Gemcitabine and the obtained nanoconjugate were evaluated on human BT 474 breast ductal carcinoma, HepG2 hepatocellular carcinoma and MG 63 osteosarcoma cells by MTS. In parallel, cellular morphology of these cells were examined through fluorescence microscopy and SEM. The localization of the nanoparticles related to the cells was studied using SEM, EDX and TEM. Hemolysis assay showed no damage of erythrocytes. Additionally, an in vivo biodistribution study was made for tracking where Fe₃O₄@Gemcitabine traveled in the body of mice. Our results showed that the transport of the drug improves the cytotoxic effects in comparison with the one produced by free Gemcitabine for the BT474 and HepG2 cells. The in vivo biodistribution test proved nanoparticle accumulation in the vital organs, with the exception of spleen, where black-brown deposits have been found. These results indicate that our Gemcitabine-functionalized nanoparticles are a promising targeted system for applications in cancer therapy.

Magnetic Nanoparticle-Mediated Targeting of Cell Therapy Reduces In-Stent Stenosis in Injured Arteries

Although drug-eluting stents have dramatically reduced the recurrence of restenosis after vascular interventions, the nonselective antiproliferative drugs released from these devices significantly delay reendothelialization and vascular healing, increasing the risk of short- and long-term stent failure. Efficient repopulation of endothelial cells in the vessel wall following injury may limit complications, such as thrombosis, neoatherosclerosis, and restenosis, through reconstitution of a luminal barrier and cellular secretion of paracrine factors. We assessed the potential of magnetically mediated delivery of endothelial cells (ECs) to inhibit in-stent stenosis induced by mechanical injury in a rat carotid artery stent angioplasty model. ECs loaded with biodegradable superparamagnetic nanoparticles (MNPs) were administered at the distal end of the stented artery and localized to the stent using a brief exposure to a uniform magnetic field. After two months, magnetic localization of ECs demonstrated significant protection from stenosis at the distal part of the stent in the cell therapy group compared to both the proximal part of stent in the cell therapy group and the control (stented, nontreated) group: 1.7-fold (p < 0.001) less reduction in lumen diameter as measured by B-mode and color Doppler ultrasound, 2.3-fold (p < 0.001) less reduction in the ratios of peak systolic velocities as measured by pulsed wave Doppler ultrasound, and 2.1-fold (p < 0.001) attenuation of stenosis as determined through end point morphometric analysis. The study thus demonstrates that magnetically assisted delivery of ECs is a promising strategy for prevention of vessel lumen narrowing after stent angioplasty procedure.

Magnetically actuated tissue engineered scaffold: insights into mechanism of physical stimulation

Providing the right stimulatory conditions resulting in efficient tissue promoting microenvironment in vitro and in vivo is one of the ultimate goals in tissue development for regenerative medicine. It has been shown that in addition to molecular signals (e.g. growth factors) physical cues are also required for generation of functional cell constructs. These cues are particularly relevant to engineering of biological tissues, within which mechanical stress activates mechano-sensitive receptors, initiating biochemical pathways which lead to the production of functionally mature tissue. Uniform magnetic fields coupled with magnetizable nanoparticles embedded within three dimensional (3D) scaffold structures remotely create transient physical forces that can be transferrable to cells present in close proximity to the nanoparticles. This study investigated the hypothesis that magnetically responsive alginate scaffold can undergo reversible shape deformation due to alignment of scaffold's walls in a uniform magnetic field. Using custom made Helmholtz coil setup adapted to an Atomic Force Microscope we monitored changes in matrix dimensions in situ as a function of applied magnetic field, concentration of magnetic particles within the scaffold wall structure and rigidity of the matrix. Our results show that magnetically responsive scaffolds exposed to an externally applied time-varying uniform magnetic field undergo a reversible shape deformation. This indicates on possibility of generating bending/stretching forces that may exert a mechanical effect on cells due to alternating pattern of scaffold wall alignment and relaxation. We suggest that the matrix structure deformation is produced by immobilized magnetic nanoparticles within the matrix walls resulting in a collective alignment of scaffold walls upon magnetization. The estimated mechanical force that can be imparted on cells grown on the scaffold wall at experimental conditions is in the order of 1 pN, which correlates well with reported threshold to induce mechanotransduction effects on cellular level. This work is our next step in understanding of how to accurately create proper stimulatory microenvironment for promotion of cellular organization to form mature tissue engineered constructs.

Magnetically enhanced cell delivery for accelerating recovery of the endothelium in injured arteries

Arterial injury and disruption of the endothelial layer are an inevitable consequence of interventional procedures used for treating obstructive vascular disease. The slow and often incomplete endothelium regrowth after injury is the primary cause of serious short- and long-term complications, including thrombosis, restenosis and neoatherosclerosis. Rapid endothelium restoration has the potential to prevent these sequelae, providing a rationale for developing strategies aimed at accelerating the reendothelialization process. The present studies focused on magnetically guided delivery of endothelial cells (EC) functionalized with biodegradable magnetic nanoparticles (MNP) as an experimental approach for achieving rapid and stable cell homing and expansion in stented arteries. EC laden with polylactide-based MNP exhibited strong magnetic responsiveness, capacity for cryopreservation and rapid expansion, and the ability to disintegrate internalized MNP in both proliferating and contact-inhibited states. Intracellular decomposition of BODIPY558/568-labeled MNP monitored non-invasively based on assembly state-dependent changes in the emission spectrum demonstrated cell proliferation rate-dependent kinetics (average disassembly rates: 6.6±0.8% and 3.6±0.4% per day in dividing and contact-inhibited EC, respectively). With magnetic guidance using a transient exposure to a uniform 1-kOe field, stable localization and subsequent propagation of MNP-functionalized EC, markedly enhanced in comparison to non-magnetic delivery conditions, were observed in stented rat carotid arteries. In conclusion, magnetically guided delivery is a promising experimental strategy for accelerating endothelial cell repopulation of stented blood vessels after angioplasty.