Biologically produced silver chloride nanoparticles from B. megaterium modulate interleukin secretion by human adipose stem cell spheroids

Abstract

Stem cell tissue constructs are likely to come into contact with silver-based nanoparticlessuch as silver chloride nanoparticles (AgCl-NPs)used as microbicidals at the implant site or in cosmetics. However, the effect of silver-based nanoparticles on 3D cell cultures with potential for tissue engineering has received little attention. Here, we examined the effect of sub-lethal doses (5, 10 and 25 lg/mL, for 1, 7 and 21 days) of AgCl-NPs produced by 'green' bacterial-based synthesis on spheroid 3D cultures of human adipose tissue stem cells (ASCs). Light microscopy analysis revealed that the shape and diameter of ASC spheroids remained largely unchanged after AgCl-NP treatment. Flow cytometry analysis with 7-AAD and 2 0 ,7 0-dichlorofluorescein diacetate revealed no statistically significant differences in cell death but showed an increase of ROS levels for the untreated group and significant differences for the groups treated with 5 and 10 lg/mL at day 7 (p = 0.0395, p = 0.0266, respectively). Electron microscopy analysis showed limited cell damage in the periphery of AgCl-NP-treated spheroids. However, treatment with AgCl-NP had statistically Letícia E. Charelli and Nathalia Müller have contributed equally to this work.

Assessing the antiproliferative effect of biogenic silver chloride nanoparticles on glioblastoma cell lines by quantitative image‐based analysis

“…Groups with significant differences relative to the control group are indicated by * for p < 0.05, ** for p < 0.01 and *** for p < 0.001 automatically using digital fluorescent images. The AgCl-NPs biosynthesis-from B. megaterium and their characterisation by spectroscopy and electron microscopy-was previously reported by our group [19]. Automated image-based analysis has been used in the field of cancer biology for years, and its main area of application has been drug discovery.…”

“…The biosynthesis of AgCl‐NPs used in this work and their characterisation by spectroscopic and electron microscopy approaches were previously reported by our group [ 19 ]. In summary, AgCl‐NPs were produced from Gram‐positive bacterium Bacillus megaterium cultures.…”

“…However, between days 1 and 7 of AgCl‐NP treatment, increased ROS levels, as well as changes in the secretory profiles of interleukins (pro‐inflammatory interleukins IL‐6, IL‐1b and IL‐8 and anti‐inflammatory interleukin IL‐10) and TGF‐β, were observed in the supernatants of the ASC spheroids. The possibility of modulation of the microenvironment and remodelling of the extracellular matrix suggests the need for further studies [ 19 ].…”

“…B. megaterium ATCC 14,581 was grown in modified nutrient broth (1% peptone, 0.5% meat extract and 0.5% yeast extract) for 24 h. The production of AgCl‐NPs was conducted as reported previously by our group [ 19 ]. Briefly, the culture was maintained in the presence of 3.5 mM silver nitrate (AgNO 3 ) for 7 days at 37°C with agitation at 150 rpm in the absence of light.…”

“…The production of silver‐based nanoparticles by members of the genus Bacillus has been described. [ 17 ] e [ 18 ] reported the production of AgNPs using Bacillus megaterium , and our group demonstrated the production of AgCl‐NPs by the same bacteria [ 17 , 18 , 19 ].…”