Protective effect of L-carnitine on apoptosis, DNA fragmentation, membrane integrity and Lipid peroxidation of spermatozoa in the asthenoteratospermic men

Sperm DNA damage and disturbed chromatin condensation indexes (DFI and CMA3) in normozoospermic men with unexplained infertility problem

PURPOSE

The quantitatively measured sperm DNA damage and disturbed chromatin condensation indexes (%DNA fragmentation index [DFI%] and %high DNA staining index [%HDS]) and their relationships with sperm quality in normospermic men with unexplained infertility were investigated. The aim was also highlighting the impact of age on both DFI and CMA3 staining and on sperm quality, and their associations with male infertility.

METHODS

In this retrospective study, conventional semen tests, including sperm motility and morphological evaluations and DFI and disturbed chromatin condensation indexes (DFI, CMA3) were performed according to the World Health Organization (WHO) 2021 criteria. DFI and CMA3 were evaluated using sperm chromatin dispersion (SCD) and chromomycin A3 (CMA3) staining assays and then correlation and regression analysis were done.

RESULTS

By analyzing SCD and CMA3 results, notable differences were found in sperm parameters among different DFI and CMA3 groups (all p < 0.05). It was found that in the male fertility quality sperm concentration, progressive (PR)/non-progressive (NP) motility, immobility, and morphology were significantly associated with sperm DFI and CMA3, but not with age (p < 0.05).

CONCLUSIONS

Sperm molecular index DFI and CMA3 negatively affect male fertility quality through semen parameters (sperm concentration, motility, and morphology). SCD and CMA3 indexes show a significant negative correlation with sperm quality in normospermic males, which highlights its role in the assessment of male fertility potential and molecular evaluation of infertility treatment.

The effects of L-carnitine and fructose in improved Ham's F10 on sperm culture in idiopathic severe asthenospermia within 24h

To study the effects of L-carnitine and fructose on semen parameters of severe asthenospermia patients by sperm culturing in vitro within 24h. We optimized the energy composition and antioxidant substances of sperm culture medium in vitro (based on Ham's F10 culture medium) by orthogonal test for preparing high quality culture medium. Sperms of 60 patients with idiopathic severe asthenospermia were collected, and cultured in vitro within 24h, by Ham's F10 culture medium added to different concentrations of L-carnitine and fructose and culture temperature, whose effects on sperm motility were observed to determine which is the most appropriate concentration and temperature. For determining the appropriate concentration of L-carnitine and fructose and the suitable culture temperature in Ham's F10 culture medium, the orthogonal experiments were carried out to optimize above three factors, which had great influence on sperm viability, survival rate, deformity rate and DNA fragmentation index (DFI). The final concentration of L-carnitine and fructose was determined in terms of initial tests to assess the effects of different concentrations (4, 8, 12, and 16 mg/ml L-carnitine and 0.125, 0.250, 0.375, and 0.50 mg/ml fructose) on sperm viability and motility in culture. During the operation of processing and culturing sperms in vitro within 24h, orthogonal test showed that sperm viability was better at the final concentration of 8 mg/ml L-carnitine and 0.375 mg/ml fructose in improved Ham's F10 culture medium at 36.5°C. Idiopathic severe asthenospermia sperm can be effectively improved by the modified Ham's F10 culture medium of the final concentration of 8 mg/ml L-carnitine and 0.375 mg/ml fructose at 36.5°C within 24h, which has shown better culture effect and is superior to Ham's F10 basic medium.

Effects of L-carnitine and pentoxifylline on long-term preservation of the human sperms: An experimental study

Background

In infertility clinics, long-time preserving high-quality spermatozoa is a challenging problem.

Objective

The present study aimed to prolong preserving of the human spermatozoa by adding pentoxifylline (PT) and L-carnitine (LC) without using high-cost freezing techniques.

Materials and Methods

In this experimental study, semen samples of 26 normozoospermia men aged between 28-34 yr, were firstly prepared using the swim-up technique, and each sample was divided into the following 3 aliquots: untreated control group, the LC, and PT-treated groups. The samples were stored for up to 12 days at 4-6 C, and sperm motility was assessed. The percentages of the sperms with double-stranded DNA, apoptotic, and acrosomal interacted sperms were evaluated by sperm chromatin structure assay, AnnexinV-PI staining, and peanut agglutinin, respectively.

Results

On day 7, 26.83% ± 4.26 of sperms were motile in the PT group which was significantly more than LC (6.67% ± 0.61) and control (0.83 ± 0.17) groups (p < 0.001). At day 12, while all sperms lost their motility in LC and control groups, adding PT led to 3.17% ± 0.47 sperms remaining motile (p < 0.001). Moreover, on day 12, the percent of apoptotic sperms in the PT-treated group (8% ± 0.20) was significantly lower than in LC-treated group (5.9% ± 0.28, p = 0.03). None of the additives positively affected the number of sperms with double-stranded DNA (p > 0.05). LC could also maintain acrosomal integrity over a storage time of up to 12 days.

Conclusion

Despite PT's improved sperm motility, LC was more efficient in preventing apoptosis and acrosomal reactions. However, DNA was resistant to denaturation regardless of the treatments.

Restoring Sperm Quality Post-Cryopreservation Using Mitochondrial-Targeted Compounds

While critical for male fertility preservation, cryopreservation damage reduces sperm quality and fertilization potential. This study investigated whether the addition of mitochondrial-targeted, antioxidant compounds, also known as Mitochondrial activators, to the cryopreservation medium could protect sperm quality during cryopreservation. For this, semen samples from men undergoing IVF/ICSI treatment, which were donated for research, underwent cryopreservation in the absence or presence of BGP-15, MitoQ and L-carnitine. Fresh semen and thawed sperm samples from the same participant were analyzed for indicators of sperm quality: sperm viability, kinetics, mitochondrial reactive oxygen species (ROS) levels, Mitochondrial Membrane Potential (MMP) and DNA damage. Cryopreservation significantly reduced sperm viability and motility and predicted mucous penetration. BGP-15, MitoQ and L-carnitine improved sperm motility, whilst the addition of L-Carnitine prevented the loss of sperm viability during cryopreservation. Both BGP-15 and L-carnitine reduced sperm DNA oxidative damage, but only BGP-15 significantly reduced DNA fragmentation. More importantly, BGP-15 increased sperm predictive mucous penetration and MMP and reduced DNA oxidation. Our results show that the addition of BGP-15 or L-carnitine to the cryopreservation medium improves sperm quality post-thawing, highlighting the potential of mitochondrial antioxidants to improve long-term fertility preservation in males.

Beneficial effect of L-Proline supplementation on the quality of human spermatozoa

L-Proline is a natural anti-oxidative and osmoprotectant agent, playing a versatile role in cell metabolism and physiology. The present study aimed to explore the antioxidant effects of L-Proline on human sperm function during incubation. Thirty healthy, normozoospermic men (27-40 years) were enrolled. Sperm samples were incubated in an unsupplemented sperm medium (control group), or supplemented with L-Proline (1, 2 and 4 mmol/L) to evaluate its effect during 0, 1, 4 and 24 h of incubation. Sperm were assessed in terms of motility, viability, morphology, chromatin and DNA integrity. Moreover, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and total antioxidant capacity (TAC) were determined in the sperm medium. The results indicated that 2 mmol/L of L-Proline significantly improved the maintenance of sperm motility, viability, normal morphology, chromatin and DNA integrity, and TAC levels compared to the control group during 24 h of incubation (p < 0.05). However, 1 and 4 mmol/L of L-Proline could not significantly preserve sperm parameters, chromatin quality, and antioxidant status during different incubation times compared to the control group (p > 0.05). Collectively, the inclusion of L-Proline (2 mmol/L) in the human sperm medium maintains sperm parameters and chromatin quality probably by modulating the oxidative status.

Necrozoospermia: The tree that hides the forest

BACKGROUND

Necrozoospermia is a condition found in 0.2 to 0.4 % of male infertility cases. The causes of necrozoospermia are multiple: they can be related to testicular and/or post-testicular damage. Additionally, these causes most often involve the production of reactive oxygen species (ROS) and/or sperm DNA fragmentation (SDF) which can reduce the chances of spontaneous pregnancy or affect the outcome of assisted reproductive technologies.

OBJECTIVE

To focus on potential etiologies of necrozoospermia, its diagnosis and its therapeutic management especially before the employment of ICSI.

METHODS

Authors searched PubMed/Medline, Web of Science, Cochrane Library, Google and Institutional websites for medical subheading terms and free text words referred to "necrozoospermia", "sperm vitality", "sperm viability", "sperm DNA fragmentation" and "ICSI".

RESULTS

We identified twelve main etiologies of necrozoospermia responsible for either a decrease of sperm vitality, a mild a moderate or a severe necrozoospermia. In case of a confirmed decreased vitality, a thorough check-up should be conducted and if available, etiological treatment should be proposed. Therapeutic management could also include repeated ejaculations, drug treatments, the use of ICSI with ejaculated or surgically extracted spermatozoa in case of a non-treatable necrozoospermia.

DISCUSSION AND CONCLUSION

The potential causes of necrozoospermia should be investigated because many of them could be corrected, thus avoiding the use of ICSI. Moreover, if ICSI procedure remains necessary, the therapeutic management of necrozoospermia could also improve the chances of success by reducing oxidative stress and/or sperm DNA fragmentation. This article is protected by copyright. All rights reserved.

Metabolomic fingerprinting of pig seminal plasma identifies in vivo fertility biomarkers

Background

Metabolomic approaches, which include the study of low molecular weight molecules, are an emerging -omics technology useful for identification of biomarkers. In this field, nuclear magnetic resonance (NMR) spectroscopy has already been used to uncover (in) fertility biomarkers in the seminal plasma (SP) of several mammalian species. However, NMR studies profiling the porcine SP metabolome to uncover in vivo fertility biomarkers are yet to be carried out. Thus, this study aimed to evaluate the putative relationship between SP-metabolites and in vivo fertility outcomes. To this end, 24 entire ejaculates (three ejaculates per boar) were collected from artificial insemination (AI)-boars throughout a year (one ejaculate every 4 months). Immediately after collection, ejaculates were centrifuged to obtain SP-samples, which were stored for subsequent metabolomic analysis by NMR spectroscopy. Fertility outcomes from 1525 inseminations were recorded over a year, including farrowing rate, litter size, stillbirths per litter and the duration of pregnancy.

Results

A total of 24 metabolites were identified and quantified in all SP-samples. Receiver operating characteristic (ROC) curve analysis showed that lactate levels in SP had discriminative capacity for farrowing rate (area under the curve [AUC] = 0.764) while carnitine (AUC = 0.847), hypotaurine (AUC = 0.819), sn-glycero-3-phosphocholine (AUC = 0.833), glutamate (AUC = 0.799) and glucose (AUC = 0.750) showed it for litter size. Similarly, citrate (AUC = 0.743), creatine (AUC = 0.812), phenylalanine (AUC = 0.750), tyrosine (AUC = 0.753) and malonate (AUC = 0.868) levels had discriminative capacity for stillbirths per litter; and malonate (AUC = 0.767) and fumarate (AUC = 0.868) levels for gestation length.

Conclusions

The assessment of selected SP-metabolites in ejaculates through NMR spectroscopy could be considered as a promising non-invasive tool to predict in vivo fertility outcomes in pigs. Moreover, supplementing AI-doses with specific metabolites should also be envisaged as a way to improve their fertility potential.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-021-00636-5.