Caspase activity in preimplantation human embryos is not associated with apoptosis.
BACKGROUND
Previous studies on mammalian preimplantation embryos have suggested an association between caspase activation, blastomere fragmentation and apoptosis. However, some reports on human embryos questioned the causal relationship between blastomere fragmentation and apoptosis, and information about the presence and activity of caspases in human embryos is lacking.


METHODS
A fluorochrome-labelled universal caspase inhibitor was used to visualize active caspases in blastomeres and fragments of preimplantation human embryos.


RESULTS
Caspase activity was detected only after fertilization, and was rare in blastomeres but frequent in fragments. The incidence of caspase activity in blastomeres and fragments was stable between the 2-cell and 12-cell stages. Caspase-positive blastomeres were only seen in poor-morphology embryos. The percentage of caspase-positive fragments was increased in embryos with multinucleated blastomeres but was unrelated to embryo morphology. Moreover, caspase-positive fragments detached from healthy blastomeres that were isolated by embryo biopsy and subsequently underwent mitotic division in culture.


CONCLUSIONS
These data suggest that caspases in preimplantation human embryos are involved in developmental processes unrelated to cell death.
Martinez
Francisco
F
University of Granada, Campus Universitario Fuentenueva, Granada, Spain.
Rienzi
Laura
L
Iacobelli
Marcello
M
Ubaldi
Filippo
F
Mendoza
Carmen
C
Greco
Ermanno
E
Tesarik
Jan
J
D017209:Apoptosis / Q000502:physiology*; D001755:Blastocyst / Q000166:cytology* / Q000201:enzymology*; D001757:Blastomeres / Q000201:enzymology; D020169:Caspases / Q000378:metabolism*; D002467:Cell Nucleus / Q000648:ultrastructure; D002469:Cell Separation; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques
D020169:Caspases