Background/Purpose: Nanotechnology has developed into a key technology of the 21^st century. Over the recent years, the number of nanotechnical products has received an enormous boost. More and more efforts are currently being done to use this technology also in rheumatology for diagnostic and therapeutic purposes (see www.nanodiara.eu). Therefore, crucial questions concern the safety aspects. Thus, the focus of our work here was to identify putative effects of nanoparticles on human immune cell function. We analysed interactions between PVA coated super paramagnetic iron oxide nanoparticles (SPIONS) and human immune cells in the presence or absence of dexamethasone.

Methods: PBMCs were isolated from blood samples obtained from healthy donors, RA and OA patients, and CD4 positive T cells were separated via MACS-Sort. Cells were incubated in fully supplemented RPMI 1640 with/without dexamethasone treatment at the clinical relevant concentration 10^-8M. Functionalised amino-PVA-SPIONS were added at varying concentrations, and cells were incubated for 24h. Apoptosis was analysed by measuring the caspase-3/7-activity via luminescence. Caspase-3 and -7 are members of the cysteine aspartic acid-specific protease family, which play a key effector role in apoptosis in mammalian cells. Furthermore, CD4 positive T cells were incubated with/without PHA, with/without 10^-8M dexamethasone and/or with/without PVA-SPIONS at different concentrations. Functionality was determined via proliferation measurements of CFSE (carboxyfluorescein diacetatesuccinimidyl ester) labeled T cells after 72h under normoxic (5% CO₂ and 18% O₂) or hypoxic (5% CO₂ and <1% O₂) conditions by flow cytometry.

Results:

Caspase measurements to investigate cellular toxicity of amino-PVA-SPIONS did not show any measurable effects on the survival of isolated CD4+ T cells (as already observed for whole blood assays) at concentrations less than 1000µg/ml. Interestingly, SPION-treatment with increasing concentrations in the presence of dexamethasone even resulted in a decrease of caspase activity indicating a diminished apoptosis of the CD4+ T cells in RA patients. Also in healthy donors a decrease of caspase activity with increasing SPION concentrations could be observed. Dexamethasone itself did not have any effects on caspase activity.

As expected, there was less proliferation under hypoxia than under normoxia; and treatment with dexamethasone decreased the percentage of divided cells for both RA patients and HD under normoxia and hypoxia. Focusing on the influence of dexamethasone on the T cell proliferation in the presence of PVA-SPIONS, we observed no difference in the impact of dexamethasone on proliferation.

Conclusion: PVA coated nanoparticles at concentrations up to 1000µg/ml do not interfere with effects of dexamethasone on proliferation and caspase-3/7-activity of human T cells. The impact of PVA-SPIONS on other human immune cells and on effects of glucocorticoids on these cells need to be further analyzed. This represents a critical need prior to the clinical use of nanoparticles in rheumatology.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/impact-of-pva-coated-nanoparticles-on-cellular-viability-and-functionality-of-immune-cells-obtained-from-healthy-donors-and-patients-with-rheumatoid-arthritis-or-osteoarthritis/