Cytoskeletal organization defects and abortive activation in human oocytes after IVF and ICSI failure

Purpose Sperm-borne PLCζ protein induces Ca 2+ oscillations in the oocyte and is believed to play a major role during oocyte activation. However, its implication in fertilization failure following ICSI is still debated. We analyzed PLCζ gene sequence, protein expression level, and localization in both patients with previous failed fertilization by ICSI and sperm donors with proven fertility in order to assess the association of PLCζ with both sperm characteristics and ability to fertilize. Methods Semen from 15 patients and 13 sperm donors with proven fertility was included in the study. Analysis of the PLCζ gene sequence, protein expression through Western blot, and protein localization by immunofluorescence were performed. Results Two patients with total fertilization failure presented mutations in heterozygosis in the PLCζ gene. Comparison with donor sample sequences displayed comparable SNP allele frequency. Distribution pattern of PLCζ did not vary significantly between donor and patient samples. Levels of PLCζ protein in sperm cells showed an interindividual variability both in patient and donor samples. Several SNPs previously reported in infertile patients were also present in fertile men. ConclusionFailed fertilization occurs even when levels and distribution of PLCζ protein are within normal range. PLCζ seems to be a necessary but not sufficient factor in determining the molecular pathway involved in oocyte activation.

Section: Introductionmentioning

confidence: 99%

PLCζ sequence, protein levels, and distribution in human sperm do not correlate with semen characteristics and fertilization rates after ICSI

Ferrer-Vaquer¹,

Barragán²,

Fréour

et al. 2016

“…Intracytoplasmic sperm injection (ICSI) is widely used to achieve fertilization in the presence of severe male factor, resulting in high fertilization rates. Nevertheless, 1-3 % of couples experience complete fertilization failure after ICSI [2], mostly caused by an activation failure [3][4][5]. Assisted oocyte activation (AOA) with a Ca 2+ ionophore (A213187 or ionomycin), or strontium chloride (SrCl 2 ), direct microinjection of calcium, or electrical stimuli, have been shown to overcome fertilization failure after ICSI [6].…”

Section: Introductionmentioning

confidence: 99%

PLCζ disruption with complete fertilization failure in normozoospermia

Durbán¹,

Barragán²,

Colodrón³

et al. 2015

Purpose Intracytoplasmic sperm injection (ICSI) is widely used to achieve fertilization in the presence of severe male factor, resulting in high fertilization rates. Nevertheless, 1-3 % of couples experience complete fertilization failure after ICSI. When a male factor is identified, assisted oocyte activation (AOA) can help overcome fertilization failures. The objective of this study is to describe a case of repeated complete fertilization failures after ICSI with donor oocytes, and to investigate the molecular and functional aspects of phospholipase C zeta (PLCζ) protein in the patient semen. Methods The patient was a normozoospermic male who had previously fathered, through natural conception, four children by a different partner. Molecular and functional analysis of sperm-specific PLCζ in the patient and control samples by means of gene sequencing, immunocytochemistry, Western blot, mouse oocyte activation test (MOAT), and mouse oocyte calcium analysis (MOCA) were used.Results PLCζ expression levels and distribution were significantly disrupted, although MOAT and MOCA did not indicate a decrease in activation ability. Conclusions Normozoospermic males can have disrupted expression and distribution of PLCζ, and reduced activation ability after ICSI in human oocytes, despite their normal activation potential in functional testing using mouse oocytes. Discrepancy among molecular and functional data might exist, as mutations in the gene sequence may not be the only cause of alteration in PLCζ protein related to activation failures.

“…Fertilization failure after IVF can be caused by failure of sperm penetration, failure of oocyte activation, and defects in pronuclei apposition (9). Also, there could be a problem of timing in the visualization of the pronuclei that they have already disappeared or the formation is retarded.…”

Section: Discussionmentioning

confidence: 99%

Embryonic Chromosomal Abnormalities Obtained After Rescue Intracytoplasmic Sperm Injection of 1-Day-Old Unfertilized Oocytes

Pehlivan

Rubio

Ruı́z

et al. 2004

Purpose : To study if second day intracytoplasmic sperm injection (ICSI) results in chromosomal abnormalities in the embryos. Methods : Rescue ICSI was performed on 14 metaphase II (MII) oocytes after unsuccessful conventional IVF, four were fertilized. Fluorescent in situ hybridization (FISH) was performed on these four embryos and was informative for three. Results : There were two tetraploid embryos, one mosaic embryo with trisomy 21, tetrasomy 18, and tetrasomy for sex chromosomes in one cell and trisomy 22 in another cell. Conclusions : We discourage the use of second day ICSI due to the observed increase in chromosomal abnormalities in these embryos.