Predictive value of oocyte morphology in human IVF: a systematic review of the literature

BACKGROUND: Non-invasive selection of developmentally competent human oocytes may increase the overall efficiency of human assisted reproduction and is regarded as crucial in countries where legal, social or religious factors restrict the production of supernumerary embryos. The purpose of this study was to summarize the predictive value for IVF success of morphological features of the oocyte that can be obtained by light or polarized microscopic investigations. METHODS: Studies about oocyte morphology and IVF/ICSI outcomes were identified by using a systematic literature search. RESULTS: Fifty relevant articles were identified: 33 analysed a single feature, 9 observed multiple features and investigated the effect of these features individually, 8 summarized the effect of individual features. Investigated structures were the following: meiotic spindle (15 papers), zona pellucida (15 papers), vacuoles or refractile bodies (14 papers), polar body shape (12 papers), oocyte shape (10 papers), dark cytoplasm or diffuse granulation (12 papers), perivitelline space (11 papers), central cytoplasmic granulation (8 papers), cumulus–oocyte complex (6 papers) and cytoplasm viscosity and membrane resistance characteristics (2 papers). None of these features were unanimously evaluated to have prognostic value for further developmental competence of oocytes. CONCLUSIONS: No clear tendency in recent publications to a general increase in predictive value of morphological features was found. These contradicting data underline the importance of more intensive and coordinated research to reach a consensus and fully exploit the predictive potential of morphological examination of human oocytes

Evaluation of zona pellucida birefringence intensity during in vitro maturation of oocytes from stimulated cycles

Background: This study evaluated whether there is a relationship between the zona pellucida birefringence (ZP-BF) intensity and the nuclear (NM) and cytoplasmic (CM) in vitro maturation of human oocytes from stimulated cycles.Results: The ZP-BF was evaluated under an inverted microscope with a polarizing optical system and was scored as high/positive (when the ZP image presented a uniform and intense birefringence) or low/negative (when the image presented moderate and heterogeneous birefringence). CM was analyzed by evaluating the distribution of cortical granules (CGs) throughout the ooplasm by immunofluorescence staining. CM was classified as: complete, when CG was localized in the periphery; incomplete, when oocytes presented a cluster of CGs in the center; or in transition, when oocytes had both in clusters throughout cytoplasm and distributed in a layer in the cytoplasm periphery Nuclear maturation: From a total of 83 germinal vesicle (GV) stage oocytes, 58 of oocytes (69.9%) reached NM at the metaphase II stage. From these 58 oocytes matured in vitro, the high/positively scoring ZP-BF was presented in 82.7% of oocytes at the GV stage, in 75.8% of oocytes when at the metaphase I, and in 82.7% when oocytes reached MII. No relationship was observed between NM and ZP-BF positive/negative scores (P = 0.55). These variables had a low Pearson's correlation coefficient (r = 0.081). Cytoplasmic maturation: A total of 85 in vitro-matured MII oocytes were fixed for CM evaluation. Forty-nine oocytes of them (57.6%) showed the complete CM, 30 (61.2%) presented a high/positively scoring ZP-BF and 19 (38.8%) had a low/negatively scoring ZP-BF. From 36 oocytes (42.3%) with incomplete CM, 18 (50%) presented a high/positively scoring ZPBF and 18 (50%) had a low/negatively scoring ZP-BF. No relationship was observed between CM and ZP-BF positive/negative scores (P = 0.42). These variables had a low Pearson's correlation coefficient (r = 0.11).Conclusions: The current study demonstrated an absence of relationship between ZP-BF high/positive or low/negative score and nuclear and cytoplasmic in vitro maturation of oocytes from stimulation cycles

Viability-Dependent Promoting Action of Adult Neural Precursors in Spinal Cord Injury

The aim of the study was the assessment of the effects of adult neural stem cell (NSC) transplantation in a mouse model of spinal cord injury (SCI). The contusion injury was performed by means of the Infinite Horizon Device to allow the generation of reproducible traumatic lesion to the cord. We administered green fluorescent-labeled (GFP-)NSCs either by intravenous (i.v.) injection or by direct transplantation into the spinal cord (intraspinal route).We report that NSCs significantly improved recovery of hind limb function and greatly attenuated secondary degeneration. The i.v. route of NSC administration yielded better recovery than the intraspinal route of administration. About 2% of total i.v.-administered NSCs homed to the spinal cord injury site, and survived almost undifferentiated; thus the positive effect of NSC treatment cannot be ascribed to damaged tissue substitution. The NSCs homing to the injury site triggered, within 48 h, a large increase of the expression of neurotrophic factors and chemokines. One wk after transplantation, exogenous GFP-NSCs still retained their proliferation potential and produced neurospheres when recovered from the lesion site and cultured in vitro. At a later time, GFP-NSC were phagocytated by macrophages. We suggest that the process of triggering the recovery of function might be strongly related to the viability of GFP-NSC, still capable ex vivo of producing neurospheres, and their ability to modify the lesion environment in a positive fashion

The Use of Poly(N-[2-Hydroxypropyl]-Methacrylamide) Hydrogel to Repair a T10 Spinal Cord Hemisection in Rat: A Behavioural, Electrophysiological and Anatomical Examination

There have been considerable interests in attempting to reverse the deficit because of an SCI (spinal cord injury) by restoring neural pathways through the lesion and by rebuilding the tissue network. In order to provide an appropriate micro-environment for regrowing axotomized neurons and proliferating and migrating cells, we have implanted a small block of pHPMA [poly N-(2-hydroxypropyl)-methacrylamide] hydrogel into the hemisected T10 rat spinal cord. Locomotor activity was evaluated once a week during 14 weeks with the BBB rating scale in an open field. At the 14th week after SCI, the reflexivity of the sub-lesional region was measured. We also monitored the ventilatory frequency during an electrically induced muscle fatigue known to elicit the muscle metaboreflex and increase the respiratory rate. Spinal cords were then collected, fixed and stained with anti-ED-1 and anti-NF-H antibodies and FluoroMyelin. We show in this study that hydrogel-implanted animals exhibit: (i) an improved locomotor BBB score, (ii) an improved breathing adjustment to electrically evoked isometric contractions and (iii) an H-reflex recovery close to control animals. Qualitative histological results put in evidence higher accumulation of ED-1 positive cells (macrophages/monocytes) at the lesion border, a large number of NF-H positive axons penetrating the applied matrix, and myelin preservation both rostrally and caudally to the lesion. Our data confirm that pHPMA hydrogel is a potent biomaterial that can be used for improving neuromuscular adaptive mechanisms and H-reflex responses after SCI

The Association between α-Synuclein and α-Tubulin in Brain Synapses

α-synuclein is a small protein that is mainly expressed in the synaptic terminals of nervous tissue. Although its implication in neurodegeneration is well established, the physiological role of α-synuclein remains elusive. Given its involvement in the modulation of synaptic transmission and the emerging role of microtubules at the synapse, the current study aimed at investigating whether α-synuclein becomes involved with this cytoskeletal component at the presynapse. We first analyzed the expression of α-synuclein and its colocalization with α-tubulin in murine brain. Differences were found between cortical and striatal/midbrain areas, with substantia nigra pars compacta and corpus striatum showing the lowest levels of colocalization. Using a proximity ligation assay, we revealed the direct interaction of α-synuclein with α-tubulin in murine and in human brain. Finally, the previously unexplored interaction of the two proteins in vivo at the synapse was disclosed in murine striatal presynaptic boutons through multiple approaches, from confocal spinning disk to electron microscopy. Collectively, our data strongly suggest that the association with tubulin/microtubules might actually be an important physiological function for α-synuclein in the synapse, thus suggesting its potential role in a neuropathological context

The interactions of fullerene C60 and Benzo(α)pyrene influence their bioavailability and toxicity to zebrafish embryos

This study aimed to assess the toxicological consequences related to the interaction of fullerene nanoparticles (C60) and Benzo(α)pyrene (B(α)P) on zebrafish embryos, which were exposed to C60and B(α)P alone and to C60doped with B(α)P. The uptake of pollutants into their tissues and intra-cellular localization were investigated by immunofluorescence and electron microscopy. A set of biomarkers of genotoxicity and oxidative stress, as well as functional proteomics analysis were applied to assess the toxic effects due to C60interaction with B(α)P. The carrier role of C60for B(α)P was observed, however adsorption on C60did not affect the accumulation and localization of B(α)P in the embryos. Instead, C60doped with B(α)P resulted more prone to sedimentation and less bioavailable for the embryos compared to C60alone. As for toxicity, our results suggested that C60alone elicited oxidative stress in embryos and a down-regulation of proteins involved in energetic metabolism. The C60+ B(α)P induced cellular response mechanisms similar to B(α)P alone, but generating greater cellular damages in the exposed embryos. Once C60nanoparticles and B(α)P meet in water, they reciprocally affect their bioavailability and, by consequence, their toxicity to organisms