Effect of HSA coated iron oxide labeling on human umbilical cord derived mesenchymal stem cells.

Human umbilical cord derived mesenchymal stem cells (hUC-MSCs) are known for self-renewal and differentiation into cells of various lineages like bone, cartilage and fat. They have been used in biomedical applications to treat degenerative disorders. However, to exploit the therapeutic potential of stem cells, there is a requirement of sensitive non-invasive imaging techniques which will offer the ability to track transplanted cells, bio-distribution, proliferation and differentiation. In this study, we have analyzed the efficacy of human serum albumin coated iron oxide nanoparticles (HSA-IONPs) on the differentiation of hUC-MSCs. The colloidal stability of the HSA-IONPs was tested over a long period of time (≥20 months) and the optimized concentration of HSA-IONPs for labeling the stem cells was 60 µg ml(-1). Detailed in vitro assays have been performed to ascertain the effect of the nanoparticles (NPs) on stem cells. Lactate dehydrogenase (LDH) assay showed minimum release of LDH depicting the least disruptions in cellular membrane. At the same time, mitochondrial impairment of the cells was also not observed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry analysis revealed lesser generation of reactive oxygen species in HSA-IONPs labeled hUC-MSCs in comparison to bare and commercial IONPs. Transmission electron microscopy showed endocytic engulfment of the NPs by the hUC-MSCs. During the process, the gross morphologies of the actin cytoskeleton were found to be intact as shown by immunofluorescence microscopy. Also, the engulfment of the HSA-IONPs did not show any detrimental effect on the differentiation potential of the stem cells into adipocytes, osteocytes and chondrocytes, thereby confirming that the inherent properties of stem cells were maintained.

Cellular internalization and detailed toxicity analysis of protein-immobilized iron oxide nanoparticles.

Iron oxide nanoparticles (IONPs) have been extensively used for biomedical applications like in the diagnosis and treatment of various diseases, as contrast agents in magnetic resonance imaging, and in targeted drug delivery. Despite several attempts, there is a dearth of information with respect to the cellular response and in-depth toxicity analysis of the nanoparticles. Considering the potential benefits of IONPs, there is a need to study the potential cellular damage associated with IONPs. The size and surface of the particles are some critical factors that should be analyzed when evaluating cytotoxicity. Therefore, in this study, we synthesized and characterized bare (7-9 nm) and protein-coated IONPs of diameter 50-70 nm, and evaluated their toxicity on membrane integrity, intracellular accumulation of reactive oxygen species, and mitochondrial activity in mouse fibroblast cell line by lactate dehydrogenase, 2',7'-dichlorofluorescein diacetate, and [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (MTT) assays, respectively. Our extensive cytotoxicity analysis demonstrated that the size of the IONPs and their surface coating are the critical determinants of cellular response and potential mechanism toward cytotoxicity. The study of the interactions and assessment of potential toxicity of the nanoparticles with cells/tissues is a key determinant when considering their translation in biomedical applications.