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.

Magnetic nanoparticle loaded human adipose derived mesenchymal cells spheroids in levitated culture

Magnetic nanoparticles (MNP) are intensely scrutinized for biomedical applications due to their excellent biocompatibility and adjustable magnetic field (MF) responsiveness. Three-dimensional spheroid culture of ADSC improves stem cell proliferation and differentiation, increasing their potential for clinical applications. In this study we aimed to detect if MF levitated culture of ADSC loaded with proprietary MNP maintain the properties of ADSC and improve their performances. Levitated ADSC-MNP formed aggregates with increased volume and reduced number compared to nonlevitated ones. ADSC-MNP from levitated spheroid displayed higher viability, proliferation and mobility compared to nonlevitated and 2D culture. Levitated and nonlevitated ADSC-MNP spheroids underwent three lineage differentiation, demonstrating preserved ADSC stemness. Quantitative osteogenesis showed similar values in MNP-loaded levitated and nonlevitated spheroids. Significant increases in adipogenic conversion was observed for all 3D formulation. Chondrogenic conversion in levitated and nonlevitated spheroids produced comparable ratio glucosaminoglycan (GAG)/DNA. Increased chondrogenesis could be observed for ADSC-MNP in both levitated and nonlevitated condition. Taken together, ADSC-MNP levitated spheroids retain stemness and display superior cell viability and migratory capabilities. Furthermore, the method consistently increases spheroid maneuverability, potentially facilitating large scale manufacturing and automation. Levitated spheroid culture of ADSC-MNP can be further tested for various application in regenerative medicine and organ modeling.

Human Adipose Derived Stem Cells and Osteoblasts Interaction with Fe-Cr-Nb-B Magnetic Nanoparticles

The use of materials at nanoscale is currently of increasing interest for life sciences and medicine. Magnetic nanoparticles (MNPs) are under scrutiny for a large array of applications in nanomedicine as diagnostic and therapeutic tools. Proprietary Fe-Cr-Nb-B MNPs display heating properties that recommends them as potent agents for delivery of local hyperthermia for the treatment of solid tumours. Stem cell mediated delivery represents a safe and accurate modality to target remote or metastatic tumour sites. In this study we investigated the interaction of Fe-Cr-Nb-B nanoparticles with human adipose derived mesenchymal stem cells and human primary osteoblasts. We found that: (a) bare and chitosan coated Fe-Cr-Nb-B are internalized by both cell types, (b) they can be detected up to 28 days inside the cells without signs of membrane disruption and (c) they do not display in vitro toxicity. MNPs are uploaded by cells in a time dependent manner with maximum uptake after 7-8 days cell-particle incubation. Particle internalization do not interfere with proliferative and differentiation potential (osteogenesis and adipogenesis) demonstrating an unaltered cellular phenotype. Further investigation of the potential effect of MNPs internalization on cytoskeleton dynamics and in inducing oxidative stress will be required as it is of interest for predicting cell migration and survival after transplantation. Present results are encouraging for designing a stemcell mediated delivery of Fe-Cr-Nb-B magnetic nanoparticles to solid tumour sites for hyperthermia applications.

Comparative effects of magnetic and water-based hyperthermia treatments on human osteosarcoma cells

INTRODUCTION

Hyperthermia (HT) based on magnetic nanoparticles (MNPs) represents a promising approach to induce the apoptosis/necrosis of tumor cells through the heat generated by MNPs submitted to alternating magnetic fields. However, the effects of temperature distribution on the cancer cells' viability as well as heat resistance of various tumor cell types warrant further investigation.

METHODS

In this work, the effects induced by magnetic hyperthermia (MHT) and conventional water-based hyperthermia (WHT) on the viability of human osteosarcoma cells at different temperatures (37°C-47°C) was comparatively investigated. Fe-Cr-Nb-B magnetic nanoparticles were submitted either to alternating magnetic fields or to infrared radiation generated by a water-heated incubator.

RESULTS

In terms of cell viability, significant differences could be observed after applying the two HT treatment methods. At about equal equilibrium temperatures, MHT was on average 16% more efficient in inducing cytotoxicity effects compared to WHT, as assessed by MTT cytotoxicity assay.

CONCLUSION

We propose the phenomena can be explained by the significantly higher cytotoxic effects initiated during MHT treatment in the vicinity of the heat-generating MNPs compared to the effects triggered by the homogeneously distributed temperature during WHT. These in vitro results confirm other previous findings regarding the superior efficiency of MHT over WHT and explain the cytotoxicity differences observed between the two antitumor HT methods.