Effects of Metal Micro and Nano-Particles on hASCs: An In Vitro Model

Abstract

As the knowledge about the interferences of nanomaterials on human staminal cells are scarce and contradictory, we undertook a comparative multidisciplinary study based on the size effect of zero-valent iron, cobalt, and nickel microparticles (MPs) and nanoparticles (NPs) using human adipose stem cells (hASCs) as a model, and evaluating cytotoxicity, morphology, cellular uptake, and gene expression. Our results suggested that the medium did not influence the cell sensitivity but, surprisingly, the iron microparticles (FeMPs) resulted in being toxic. These data were supported by modifications in mRNA expression of some genes implicated in the inflammatory response. Microscopic analysis confirmed that NPs, mainly internalized by endocytosis, persist in the vesicles without any apparent cell damage. Conversely, MPs are not internalized, and the effects on hASCs have to be ascribed to the release of ions in the culture medium, or to the reduced oxygen and nutrient exchange efficiency due to the presence of MP agglomerating around the cells. Notwithstanding the results depicting a heterogeneous scene that does not allow drawing a general conclusion, this work reiterates the importance of comparative investigations on MPs, NPs, and corresponding ions, and the need to continue the thorough verification of NP and MP innocuousness to ensure unaffected stem cell physiology and differentiation.

Recovery Ability of Human Adipose Stem Cells Exposed to Cobalt Nanoparticles: Outcome of Dissolution

“…Most of these observations were confirmed by TEM analysis; in fact, as depicted in Figure 5A-D, the morphology of unexposed cells is that expected for hASCs embedded for TEM observation. The cell body was rounded, the nucleus was large, indented and eccentric, with abundant euchromatin and a prominent nucleolus; lysosomes, lipid droplets and vacuoles of different sizes were present in the cytoplasm and the cell membrane was characterized by some pseudopodia-like protrusions [10]. Notwithstanding the low cell mortality, the EC20 used in these experiments provoked some ultrastructural modifications, even causing severe cellular damage that, probably, depended on NPs.…”

“…Characterization of the NPs used in this research was reported in our previous publications: Palombella et al [10] for zCoNPs and Papis et al [9] for Co 3 O 4 -NPs.…”

“…For transmission electron microscopy (TEM) analysis, 100,000 cells were cultured in a T25 flask and treated as previously described. At the end of the experiment the cells were harvested, fixed and embedded as previously described [10], and finally observed by using a Morgagni electron microscope (Philips, Eindhoven, The Netherlands) operating at 80 kV.…”

“…In this scenario, an issue that should be considered is the exponential growth of production, use and discharge of Co nanoparticles (Co-NPs). Consequently, the human body is very likely to come into contact, intentionally or not, with Co-NPs that may easily enter the body in different ways [7][8][9], encounter cells of different tissues and then act on them by perturbing their physiology [10]. In this perspective, special attention should be paid to the presence of multipotent stem cells, a population residing in almost all human tissues that fulfills important functions, including renewal, repair and remodeling [11].…”

“…Among the different stem cell populations, mesenchymal stem cells (MSCs) are very interesting due to their great potential in many medical applications, such as regenerative medicine, bone marrow transplantation and orthopedic injuries. Unfortunately, MSCs are more sensitive to NP exposure than are differentiated cells [10,[12][13][14]; thus, it is important to evaluate the effects of the Co-NPs on MSCs and to determine a Nanomedicine (Lond.) (2020) 15(5), 453-465…”