Effects of blastomere biopsy on post-natal growth and behavior in mice

Abstract

Study question: Does blastomere biopsy (BB) of preimplantation embryos induce long-term effects on their growth and post-natal behavior?

Summary answer: BB induces long-term effects on body weight and behavior in male mice.

What is known already: BB is an essential technique for performing preimplantation genetic diagnosis (PGD), a screening test that can detect genetic abnormalities of embryos before their transfer in utero. There is limited understanding of the post-natal consequences and safety of BB.

Study design, size, duration: Offspring who had a BB performed as embryos, as well as control offspring, were examined for body and neurological development and subjected to a screening battery of behavioral tests, designed to model symptoms of psychiatric disorders. At least 12 mice were used for each test over the course of 16 weeks.

Participants/materials, setting, methods: Embryos were subjected to a single BB at the 8-cell stage and then cultured in vitro until the blastocyst stage (BB group). Two control groups were created, one consisting of embryos cultured in vitro without any manipulation (in vitro control (IVC) group) and one of embryos developed entirely in vivo (in vivo group). Embryos from in vitro groups (BB and IVC) were transferred to pseudo-pregnant female mice at the blastocyst stage. Body growth parameters and developmental landmarks of the resulting offspring were observed during their entire lifespan. Furthermore, validated behavioral tests were used to assess early communicative functions, startle reflex, and anxiety- and depression-like behaviors.

Main results and the role of chance: We found that male mice derived from BB exhibited peculiar behavioral alterations and changes in body weight. BB-derived male mice showed increased body weight with respect to both controls as early as the second week of life. Adult males displayed decreased times of immobility in the tail suspension test (P < 0.05) and deficits in habituation to, and pre-pulse inhibition of, the startle reflex (P < 0.05). BB did not affect communicative skills and anxiety-like responses.

Limitations, reasons for caution: Extrapolation of these results to humans requires caution as the culture protocols used in human clinics could be better established than in mice research. Furthermore species-specific neurodevelopmental features could be a source of differences between mice and humans in the effects of BB.

Wider implications of the findings: Our data demonstrate that BB affects long-term programming of post-natal development and behavior in mice, suggesting that PGD procedures could be a risk factor for late-onset, neurodevelopmental and metabolic disease predisposition. Thus, in light of our observations, long-term follow-up in humans or other primates generated after BB is needed.

Study funding/competing interests: This work was supported by the European Research Council (FP7/2007-2013)/Programme IDEAS GA no. 210103 to G.E.P. European Research Council - Programme FP7-KBBE-2012.1.3-04, GA no. 312097 Acronym: FECUND to G.E.P.; MIUR/CNR, Programme FIRB. GA n. B81J12002520001 Acronym: GenHome to P.L. The authors are participating in the COST action FA 1201 'Epiconcept' Epigenetic and Periconception Environment. No competing interests are declared.

Keywords: blastomere biopsy; in vitro embryo culture; mouse behavior; preimplantation genetic diagnosis.