X-Message-Number: 25502
Date: Sun, 9 Jan 2005 09:40:28 -0800 (PST)
From: Doug Skrecky <>
Subject: Cerium Oxide Nanoparticles Extend Cell Longevity and Act as Free

D. Bailey1, L.Chow2, S. Merchant1, S.C. Kuiry2, S. Patil2, S. Seal2, and
University of Central Florida, 1Dept. of Molecular Biology &
Microbiology; Advanced Materials Processing Center (AMPAC).

Introduction: Nanobiology implies application of the engineering concepts
of nanotechnology to biological systems, providing novel opportunities to
intervene in the pathology of disease. Here, we have merged nanoscale
engineering with cell biology to intervene in a common biomedical
pathology, that being aging and free radical-induced cell dysfunction.
Methods: Engineered nanoparticles of cerium oxide, 2-10 nm, were
administered to organotypic rat brain cortical cultures, containing
astrocytes, neurons, oligodendrocytes, and microglia, using a single 10nM
dose on day 10 in vitro. Culture lifespan was assessed by cell lysis or
Propidium Iodide staining and intracellular free calcium ([Ca2+]i) was
measured with Fura-2 spectrophotometry.
Results: The average lifespan of organotypic cultures ranges from 28-32
days in vitro (DIV). In nanoparticle-treated cultures, lifespan was
increased to a minimum of 68 DIV, with some cultures attaining 123+ DIV.
Electron microscopy of nanoparticle-treated cells revealed nanoparticles
associated with mitochondria, inclusion bodies, and cell boundaries.
Importantly, neuronal function was preserved in neurons from nano-treated
cultures, as shown in Fig. 1 (representative of 4 separate experiments).
In neurons from control cultures, the average basal [Ca2+]i was 91 nM.
Basal [Ca2+]i increased to 262 nM as these neurons approached the end of
their lifespan in culture, at 28-31 days in vitro (top tracing),
consistent with neuronal demise. However neurons from nanoparticle
treated cultures maintained normal basal [Ca2+]i levels through 68 DIV.
Neurons in organotypic cultures normally form abundant synapses and
develop calcium oscillations as the cultures mature. In 28 day old
control cultures, calcium oscillations no longer occurred and basal
[Ca2+]i was elevated (top tracing). However in 28 and 68 day old
nanoparticle-treated cultures, spontaneous calcium oscillations were
preserved. Additionally, nanoparticle-treated cultures responded to a
glutamate stimulus with a robust elevation in [Ca2+]i, wereas control
cultures did not. Since cell aging is associated with increased free
radical production, we examined the effect of nanoparticles on
free-radical induced cell damage using UV light. As shown,
nanoparticle-treated cultures had an increased survival, 1 hr after a 15
min exposure to UV light. The protective effects of a single dose of
nanoparticles was maintained through 68 DIV.
Conclusions: We hypothesize that the unique valence structure of cerium
oxide, in the nanoparticle form, promotes cell longevity and protects
against free radical-mediated injury by acting as a regenerative free
radical scavenger.

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