Biomedical Engineering Reference
In-Depth Information
TABLE 17.1
Summary of the Different Genotoxicity Assays Used in the 102 Papers Analyzed
Number of Papers
a
In vitro
81
Comet assay
52
Micronucleus test
30
Ames test
9
Chromosome aberration test
9
Detection of γ-H2AX by immunostaining
9
Standard DNA gel electrophoresis
4
In vivo
16
Comet assay
6
Micronucleus test
11
5
In vitro
+
in vivo
Note:
In vitro
assays used in a marginal number of studies: sister chromatid exchange, alkaline unwinding
assay, eukaryotic gene mutation assays, and chemical detection of different DNA lesions.
In vivo
assays used in a marginal number of studies: chromosome aberration test (bone marrow), detection of
γ-H2AX by immunostaining (bone marrow), and DNA fragmentation (liver).
a
The same study can use different assays.
summarizes some of the results of the analysis; there is a clear lack of
in vivo
studies in the charac-
terization of the genotoxic effects of NPs.
The detection of 8-oxo-gua was performed in 22% of the
in vitro
studies, mainly by the comet
assay in combination with formamidopyrimidine DNA glycosylase (FPG) or 8-oxoguanine DNA
glycosylase (OGG1), and in 31% of the
in vivo
studies. In this case, the lesion was detected by dif-
ferent techniques and in different specimens (liver, lung, colon, bone marrow, and urine).
The
in vivo
micronucleus (MN) test was performed in the blood or bone marrow of rodents (rats
and mice) and the comet assay in the liver, lung, brain, bone marrow, and blood.
The nuclear uptake of NPs, important in interpreting the results, was assessed in approximately
50% of the papers that use
in vitro
approaches; 65% of these studies localize the NPs in different
cellular compartments. The presence of the NPs in different tissues was checked in 31% of
in vivo
studies, but a proper bioavailability study was not carried.
The generation of ROS and inflammatory markers were assayed in 25% of
in vivo
studies.
The most frequent NPs studied in the analyzed papers were TiO
2
-, silver-, zinc-, and fullerenes,
followed by gold-, silica-, and ferric NPs.
17.5 TESTS USED IN NANOGENOTOXICOLOGY
A Working Party on Manufactured Nanomaterials was established by the OECD in 2006. One of
the aims of this organization is to review the OECD guidelines for testing the genotoxicity of chemi-
cals in order to decide their applicability to testing NPs. In a preliminary review (Test Guidelines
for their Applicability to Manufactured Nanomaterials, 2009), the working party recommended the
bacterial reverse mutation test (OECD TG 471), mammalian chromosome aberration test (OECD
TG 473), and mammalian cell gene mutation test (OECD TG 476) for
in vitro
testing; and the mam-
malian bone marrow chromosome aberration test (OECD TG 475), mammalian erythrocyte micro-
nucleus test (OECD TG 474), and unscheduled DNA synthesis (UDS) test with mammalian liver
cells for
in vivo
testing. Nevertheless, according to the literature, these are not the most widely used
tests to check the genotoxicity of nanomaterials. Instead, the comet assay and the MN test, both in
in vitro
and in
in vivo
, are the most used techniques. Both assays are well-established methods for
