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nanomaterials on different components of the reproductive system, namely the
gametes, the placental barrier, and the zygote. The side effects on the selected
models seem to be mainly linked to the chemical nature, and the toxicity generally
moderate. We conclude that the in vitro methods, alternative to in vivo experiences
in mammals, are proficient for the assessment of the reproductive toxicity of
nanomaterials, as well as for convenient testing of the possible exploitations of
newer materials.
Keywords Reproductive toxicology · Nanomaterials · Alternative models ·
Biomedical exploitations · Perfused placenta · TransWell system · Whole Embryo
· Culture · Embryonic stem cells · Zebrafish embryo test
3.1 Introduction
The impact of engineered nanomaterials on the vertebrate reproduction is doublesided: while several nanomaterials can be successful agents for theragnostics, many
of them can show harmful reproductive toxicity. They can improve the artificial
insemination, cross the chorion or the placenta to deliver drugs to the zygote, or, just
the opposite, treat the mother and avoid the exposure of the zygote. Several
nanomaterials improve the growth and self-renewal of the undifferentiated
embryonic stem cells, substitute the presence of feeder cells, help the differentiation
into specialized precursors, transfect and track the stem cells, and finally, apply to
regenerative medicine (Chen et al. 2014).
However, because many nanomaterials have reproductive toxicity, their acceptable safety level must be documented. Thus, the assessment of reproductive toxicity
of nanomaterials is very important, not only for a safe use of them in biology, veterinary and medicine, but also for a classification of environmental pollutants, products, and by-products of industry. The assessment of reproductive toxicity of
chemicals with traditional methods is, however, challenging for several reasons. It
requires at least two species, usually rat or mice and rabbit, and the first- and second-generation protocols require a long observational period, the sacrifice of several dams and their litters. Environmental, endocrine, and behavioral factors increase
the complexity of studies.
The introduction of alternative assays, eventually as a battery, permits to explore
the safety of new nanomaterials, the molecular mechanism of toxicity, and their
exploitation at lower cost, as summarized in the R3 concept, that is, reduction,
refinement, and replacement of the necessary tests in mammals. After a decade-long
period of increasing interest, these methods became accepted in the guidelines
issued by the International Council for Harmonization of technical requirements for
human use (2017), which the European Medicine Agency (2017) promptly accepted.
The guidelines recommended the use of alternative methods to reduce, refine, and
in part replace the necessary tests “in vivo,” as shown in the simplified flowchart
(Fig. 3.1). Recommended protocols include the use of stem cells, stabilized cell
A. G. Cattaneo
nanomaterials on different components of the reproductive system, namely the
gametes, the placental barrier, and the zygote. The side effects on the selected
models seem to be mainly linked to the chemical nature, and the toxicity generally
moderate. We conclude that the in vitro methods, alternative to in vivo experiences
in mammals, are proficient for the assessment of the reproductive toxicity of
nanomaterials, as well as for convenient testing of the possible exploitations of
newer materials.
Keywords Reproductive toxicology · Nanomaterials · Alternative models ·
Biomedical exploitations · Perfused placenta · TransWell system · Whole Embryo
· Culture · Embryonic stem cells · Zebrafish embryo test
3.1 Introduction
The impact of engineered nanomaterials on the vertebrate reproduction is doublesided: while several nanomaterials can be successful agents for theragnostics, many
of them can show harmful reproductive toxicity. They can improve the artificial
insemination, cross the chorion or the placenta to deliver drugs to the zygote, or, just
the opposite, treat the mother and avoid the exposure of the zygote. Several
nanomaterials improve the growth and self-renewal of the undifferentiated
embryonic stem cells, substitute the presence of feeder cells, help the differentiation
into specialized precursors, transfect and track the stem cells, and finally, apply to
regenerative medicine (Chen et al. 2014).
However, because many nanomaterials have reproductive toxicity, their acceptable safety level must be documented. Thus, the assessment of reproductive toxicity
of nanomaterials is very important, not only for a safe use of them in biology, veterinary and medicine, but also for a classification of environmental pollutants, products, and by-products of industry. The assessment of reproductive toxicity of
chemicals with traditional methods is, however, challenging for several reasons. It
requires at least two species, usually rat or mice and rabbit, and the first- and second-generation protocols require a long observational period, the sacrifice of several dams and their litters. Environmental, endocrine, and behavioral factors increase
the complexity of studies.
The introduction of alternative assays, eventually as a battery, permits to explore
the safety of new nanomaterials, the molecular mechanism of toxicity, and their
exploitation at lower cost, as summarized in the R3 concept, that is, reduction,
refinement, and replacement of the necessary tests in mammals. After a decade-long
period of increasing interest, these methods became accepted in the guidelines
issued by the International Council for Harmonization of technical requirements for
human use (2017), which the European Medicine Agency (2017) promptly accepted.
The guidelines recommended the use of alternative methods to reduce, refine, and
in part replace the necessary tests “in vivo,” as shown in the simplified flowchart
(Fig. 3.1). Recommended protocols include the use of stem cells, stabilized cell
A. G. Cattaneo