Human neurospheres as three-dimensional cellular systems for developmental neurotoxicity testing.
BACKGROUND
Developmental neurotoxicity (DNT) of environmental chemicals is a serious threat to human health. Current DNT testing guidelines propose investigations in rodents, which require large numbers of animals. With regard to the "3 Rs" (reduction, replacement, and refinement) of animal testing and the European regulation of chemicals [Registration, Evaluation, and Authorisation of Chemicals (REACH)], alternative testing strategies are needed in order to refine and reduce animal experiments and allow faster and less expensive screening.


OBJECTIVE
The goal of this study was to establish a three-dimensional test system for DNT screening based on human fetal brain cells.


METHODS
We established assays suitable for detecting disturbances in basic processes of brain development by employing human neural progenitor cells (hNPCs), which grow as neurospheres. Furthermore, we assessed effects of mercury and oxidative stress on these cells.


RESULTS
We found that human neurospheres imitate proliferation, differentiation, and migration in vitro. Exposure to the proapoptotic agent staurosporine further suggests that human neurospheres possess functioning apoptosis machinery. The developmental neurotoxicants methylmercury chloride and mercury chloride decreased migration distance and number of neuronal-like cells in differentiated hNPCs. Furthermore, hNPCs undergo caspase-independent apoptosis when exposed toward high amounts of oxidative stress.


CONCLUSIONS
Human neurospheres are likely to imitate basic processes of brain development, and these processes can be modulated by developmental neurotoxicants. Thus, this three-dimensional cell system is a promising approach for DNT testing.
Moors
Michaela
M
Institut für Umweltmedizinische Forschung gGmbH an der Heinrich Heine-Universität, Toxicology, Düsseldorf, Germany.
Rockel
Thomas Dino
TD
Abel
Josef
J
Cline
Jason E
JE
Gassmann
Kathrin
K
Schreiber
Timm
T
Schuwald
Janette
J
Weinmann
Nicole
N
Fritsche
Ellen
E
D017209:Apoptosis / Q000187:drug effects; D001921:Brain / Q000166:cytology / Q000196:embryology; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D005333:Fetus / Q000166:cytology / Q000196:embryology; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008628:Mercury / Q000633:toxicity; D008767:Methylmercury Compounds / Q000633:toxicity; D055495:Neurogenesis / Q000187:drug effects*
D008767:Methylmercury Compounds; D008628:Mercury; C004925:methylmercuric chloride