Bioprinted superparamagnetic nanoparticles for tissue engineering applications: synthesis, cytotoxicity assessment, novel hybrid printing system

Novel technologies are required in tissue engineering to manufacture three-dimensional organs with complex architecture. While superparamagnetic nanoparticles have been widely used in medicine for magnetic resonance imaging and targeted drug delivery, they have not been extensively applied in tissue engineering. These nanoparticles would allow active patterning and non-destructive imaging during tissue growth and development. However, no inexpensive method exists for synthesis of commercial amounts of these nanoparticles with controlled morphology, chemistry and size. Furthermore, superparamagnetic nanoparticle cytotoxicity mechanisms are not well understood, which makes it difficult to control or block adverse nanoparticle effects on human health.In this dissertation, superparamagnetic iron oxide nanoparticles were produced by flame synthesis using a coflow diffusion flame. Nanoparticle flame synthesis has significant advantages, including improved nanoparticle property control and commercial production rate capability with minimal post-processing. Final iron oxide nanoparticle morphology, elemental composition, and particle size was controlled by changing flame configuration, flame temperature, and additive loading, and morphology, elemental composition, and particle size of the synthesized nanoparticles were analyzed by electron microscopy (TEM, ESEM, EDS), and Raman Spectroscopy. Then flame synthesized iron oxide nanoparticle interaction with endothelial cells was compared to commercially available iron oxide nanoparticles. Flame synthesized particles showed no statistically significant toxicity difference from commercially available nanoparticles, as measured by Live/Dead assay, Alamar blue, and lactase dehydrogenase release. Both synthesized and purchased nanoparticles localized inside the cell cytoplasm as shown by TEM images. Iron oxide nanoparticles resulted in an increase in reactive oxygen species (ROS) formation in cells within the first three hours after nanoparticle uptake, and this ROS formation contributed to actin cytoskeleton disruption. Finally, a new hybrid nano-bioprinting technique that facilitates manipulation and tracking of cells and bioactive factors within a three-dimensional tissue construct was developed. This technique combined the initial patterning capabilities of syringe-based cell deposition with the active patterning capabilities of superparamagnetic nanoparticles. Superparamagnetic iron oxide nanoparticles, either in the alginate biopolymer or loaded inside endothelial cells, were bioprinted using the hybrid solid freeform fabrication direct cell writing system and they were manipulated using an external magnet and imaged by MicroCT.Ph.D., Mechanical Engineering -- Drexel University, 200

The relationship between oxidative stress and coronary artery ectasia

Background: Whereas coronary artery ectasia (CAE) is a rare abnormality of the coronary arteries, co-existent coronary artery disease (CAD) is commonly seen in CAE patients. Since a causative relationship has been shown to exist between oxidative stress and CAD, we sought to determine whether any relationship exists between oxidative stress and CAE. Methods: Fourty four patients with CAE (without CAD) and 86 controls (without any coronary disease) were recruited from among 1,520 patients undergoing coronary angiography. CAE subgroups were determined in accordance with the Markis classification system. Mean values for serum total oxidant status (TOS), total antioxidant status (TAS) and the oxidative stress index (OSI) were statistically compared between these two study groups and among CAE subgroups, with p = 0.05 set as the threshold for statistical significance. Results: TOS and OSI were significantly increased (p = 0.018 and 0.0002) and TAS decreased (p = 0.031) in the CAE versus control group. TOS and TAS were independently related to CAE (p = 0.037 and 0.039), with an r2 of 0.127. Interestingly, however, among CAE subgroups, no differences were observed. Conclusions: Oxidative stress might be implicated in the pathogenesis of CAE. Clinically-defined CAE subgroups did not differ in terms of oxidative stress status. However, the clinical implications of these findings are unclear and warrant further investigation. (Cardiol J 2010; 17, 5: 488-494

Dextran and Polymer Polyethylene Glycol (PEG) Coating Reduce Both 5 and 30 nm Iron Oxide Nanoparticle Cytotoxicity in 2D and 3D Cell Culture

Superparamagnetic iron oxide nanoparticles are widely used in biomedical applications, yet questions remain regarding the effect of nanoparticle size and coating on nanoparticle cytotoxicity. In this study, porcine aortic endothelial cells were exposed to 5 and 30 nm diameter iron oxide nanoparticles coated with either the polysaccharide, dextran, or the polymer polyethylene glycol (PEG). Nanoparticle uptake, cytotoxicity, reactive oxygen species (ROS) formation, and cell morphology changes were measured. Endothelial cells took up nanoparticles of all sizes and coatings in a dose dependent manner, and intracellular nanoparticles remained clustered in cytoplasmic vacuoles. Bare nanoparticles in both sizes induced a more than 6 fold increase in cell death at the highest concentration (0.5 mg/mL) and led to significant cell elongation, whereas cell viability and morphology remained constant with coated nanoparticles. While bare 30 nm nanoparticles induced significant ROS formation, neither 5 nm nanoparticles (bare or coated) nor 30 nm coated nanoparticles changed ROS levels. Furthermore, nanoparticles were more toxic at lower concentrations when cells were cultured within 3D gels. These results indicate that both dextran and PEG coatings reduce nanoparticle cytotoxicity, however different mechanisms may be important for different size nanoparticles

Evaluación de parámetros de estrés oxidativo y actividades metabólicas de enfermeras trabajando en turnos diurnos y nocturnos

Se objetivó evaluar estrés oxidativo y actividades metabólicas de enfermeras en turnos diurnos y nocturnos. Participaron enfermeras de Unidad de Terapia Intensiva (UTI, n=70) y del servicio común (SC, n=70). Se obtuvieron muestras sanguíneas al inicio y al final de los turnos para medir parámetros de estrés oxidativo. Las actividades metabólicas también fueron analizadas utilizando brazaletes SenseWear. Los parámetros de estrés oxidativo aumentaron hacia el final de los turnos de todas las enfermeras SC y UTI, comparados con la medida de inicio. Los niveles de TAS, TOS y OSI no eran significativamente diferentes entre enfermeras SC y UTI al cierre de los turnos diurnos y nocturnos. Las actividades metabólicas de enfermeras SC y UTI se mostraron similares. Consecuentemente, los parámetros de estrés oxidativo y las actividades metabólicas de enfermeras SC y UTI no resultaron diferentes, y todas las enfermeras sufren efectos semejantes en sus turnos, tanto diurnos como nocturnos.O objetivo deste estudo foi avaliar o estresse oxidativo e as atividades metabólicas das enfermeiras em turnos diurnos e noturnos. Enfermeiras da Unidade de Tratamento Intensivo (UTI) (n=70) e do serviço comum (SC) (n=70) participaram do estudo. Logo no início e ao final dos turnos, amostras de sangue foram obtidas para medir parâmetros de estresse oxidativo. Atividades metabólicas também foram analisadas com o uso da braçadeira SenseWear. Parâmetros de estresse oxidativo aumentaram no fim dos turnos de todas as enfermeiras SC e UTI quando comparados ao início dos turnos. Comparados às enfermeiras SC, os níveis de TAS, TOS e OSI das enfermeiras de UTI não eram significativamente diferentes no final dos turnos diurnos e noturnos. Além disso, as atividades metabólicas das enfermeiras de SC e UTI se revelaram como sendo similares. Assim, os parâmetros de estresse oxidativo e as atividades metabólicas das enfermeiras SC e UTI não eram diferentes, e todas as enfermeiras sofrem efeitos semelhantes dos turnos, tanto no dia quanto na noite.The aim of this study was to evaluate the oxidative stress and metabolic activities of nurses working day and night shifts. Intensive care unit (ICU) (n=70) and ordinary service (OS) nurses (n=70) were enrolled in the study. Just before and the end of the shifts, blood samples were obtained to measure the participants' oxidative stress parameters. Metabolic activities were analyzed using the SenseWear Armband. Oxidative stress parameters were increased at the end of the shifts for all OS and ICU nurses compared to the beginning of the shifts. Compared to the OS nurses, the ICU nurses' TAS, TOS, and OSI levels were not significantly different at the end of the day and night shifts. The metabolic activities of the OS and ICU nurses were found to be similar. As a result, the OS and ICU nurses' oxidative stress parameters and metabolic activities were not different, and all of the nurses experienced similar effects from both the day and night shifts

Evaluation of oxidative stress parameters and metabolic activities of nurses working day and night shifts

The aim of this study was to evaluate the oxidative stress and metabolic activities of nurses working day and night shifts. Intensive care unit (ICU) (n=70) and ordinary service (OS) nurses (n=70) were enrolled in the study. Just before and the end of the shifts, blood samples were obtained to measure the participants' oxidative stress parameters. Metabolic activities were analyzed using the SenseWear Armband. Oxidative stress parameters were increased at the end of the shifts for all OS and ICU nurses compared to the beginning of the shifts. Compared to the OS nurses, the ICU nurses' TAS, TOS, and OSI levels were not significantly different at the end of the day and night shifts. The metabolic activities of the OS and ICU nurses were found to be similar. As a result, the OS and ICU nurses' oxidative stress parameters and metabolic activities were not different, and all of the nurses experienced similar effects from both the day and night shifts

Establishment of a Transgenic Mouse Model Specifically Expressing Human Serum Amyloid A in Adipose Tissue

Obesity and obesity co-morbidities are associated with a low grade inflammation and elevated serum levels of acute phase proteins, including serum amyloid A (SAA). In the non-acute phase in humans, adipocytes are major producers of SAA but the function of adipocyte-derived SAA is unknown. To clarify the role of adipocyte-derived SAA, a transgenic mouse model expressing human SAA1 (hSAA) in adipocytes was established. hSAA expression was analysed using real-time PCR analysis. Male animals were challenged with a high fat (HF) diet. Plasma samples were subjected to fast protein liquid chromatography (FPLC) separation. hSAA, cholesterol and triglyceride content were measured in plasma and in FPLC fractions. Real-time PCR analysis confirmed an adipose tissue-specific hSAA gene expression. Moreover, the hSAA gene expression was not influenced by HF diet. However, hSAA plasma levels in HF fed animals (37.7±4.0 µg/mL, n = 7) were increased compared to those in normal chow fed animals (4.8±0.5 µg/mL, n = 10; p<0.001), and plasma levels in the two groups were in the same ranges as in obese and lean human subjects, respectively. In FPLC separated plasma samples, the concentration of hSAA peaked in high-density lipoprotein (HDL) containing fractions. In addition, cholesterol distribution over the different lipoprotein subfractions as assessed by FPLC analysis was similar within the two experimental groups. The established transgenic mouse model demonstrates that adipose tissue produced hSAA enters the circulation, resulting in elevated plasma levels of hSAA. This new model will enable further studies of metabolic effects of adipose tissue-derived SAA

Application of Magnetic Nanoparticles to Gene Delivery

Nanoparticle technology is being incorporated into many areas of molecular science and biomedicine. Because nanoparticles are small enough to enter almost all areas of the body, including the circulatory system and cells, they have been and continue to be exploited for basic biomedical research as well as clinical diagnostic and therapeutic applications. For example, nanoparticles hold great promise for enabling gene therapy to reach its full potential by facilitating targeted delivery of DNA into tissues and cells. Substantial progress has been made in binding DNA to nanoparticles and controlling the behavior of these complexes. In this article, we review research on binding DNAs to nanoparticles as well as our latest study on non-viral gene delivery using polyethylenimine-coated magnetic nanoparticles

Choose your cell model wisely: The in vitro nanoneurotoxicity of differentially coated iron oxide nanoparticles for neural cell labeling

Currently, there is a large interest in the labeling of neural stem cells (NSCs) with iron oxide nanoparticles (IONPs) to allow MRI-guided detection after transplantation in regenerative medicine. For such biomedical applications, excluding nanotoxicity is key. Nanosafety is primarily evaluated in vitro where an immortalized or cancer cell line of murine origin is often applied, which is not necessarily an ideal cell model. Previous work revealed clear neurotoxic effects of PMA-coated IONPs in distinct cell types that could potentially be applied for nanosafety studies regarding neural cell labeling. Here, we aimed to assess if DMSA-coated IONPs could be regarded as a safer alternative for this purpose and how the cell model impacted our nanosafety optimization study. Hereto, we evaluated cytotoxicity, ROS production, calcium levels, mitochondrial homeostasis and cell morphology in six related neural cell types, namely neural stem cells, an immortalized cell line and a cancer cell line from human and murine origin. The cell lines mostly showed similar responses to both IONPs, which were frequently more pronounced for the PMA-IONPs. Of note, ROS and calcium levels showed opposite trends in the human and murine NSCs, indicating the importance of the species. Indeed, the human cell models were overall more sensitive than their murine counterpart. Despite the clear cell type-specific nanotoxicity profiles, our multiparametric approach revealed that the DMSA-IONPs outperformed the PMA-IONPs in terms of biocompatibility in each cell type. However, major cell type-dependent variations in the observed effects additionally warrant the use of relevant human cell models.status: publishe