Evaluation of the Efficiency of Two Different Freezing Media and Two Different Protocols to Preserve Human Spermatozoa from Cryoinjury

Technical pitfalls when collecting, cryopreserving, thawing, and stimulating human T-cells

The collection, cryopreservation, thawing, and culture of peripheral blood mononuclear cells (PBMCs) can profoundly influence T cell viability and immunogenicity. Gold-standard PBMC processing protocols have been developed by the Office of HIV/AIDS Network Coordination (HANC); however, these protocols are not universally observed. Herein, we have explored the current literature assessing how technical variation during PBMC processing can influence cellular viability and T cell immunogenicity, noting inconsistent findings between many of these studies. Amid the mounting concerns over scientific replicability, there is growing acknowledgement that improved methodological rigour and transparent reporting is required to facilitate independent reproducibility. This review highlights that in human T cell studies, this entails adopting stringent standardised operating procedures (SOPs) for PBMC processing. We specifically propose the use of HANC's Cross-Network PBMC Processing SOP, when collecting and cryopreserving PBMCs, and the HANC member network International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) PBMC Thawing SOP when thawing PBMCs. These stringent and detailed protocols include comprehensive reporting procedures to document unavoidable technical variations, such as delayed processing times. Additionally, we make further standardisation and reporting recommendations to minimise and document variability during this critical experimental period. This review provides a detailed overview of the challenges inherent to a procedure often considered routine, highlighting the importance of carefully considering each aspect of SOPs for PBMC collection, cryopreservation, thawing, and culture to ensure accurate interpretation and comparison between studies.

Timing of semen cryopreservation: before or after processing?

Objective

Seminal cryopreservation causes significant damage to the sperm; therefore, different methods of cryopreservation have been studied. The aim of the study was to compare the effects of density gradient processing and washing/centrifugation with seminal plasma removal for cryopreservation in semen parameters.

Methods

Seminal samples of 26 normozoospermic patients were divided into 3 parts: with seminal plasma; after washing/centrifugation; and after selection through density gradient. The samples were cryopreserved for at least two weeks. Motility, sperm count, morphology and viability were evaluated before cryopreservation and after thawing.

Results

Density gradient processing selected motile and viable sperm with normal morphology in fresh samples (p<0.05). Cryopreservation negatively affected all sperm parameters regardless of the processing performed, and even if the sperm recovery was lower in the density gradient after the thawing, progressive motility, total motility, viability and morphology remained higher (p<0.05).

Conclusion

Cryopreservation significantly compromises sperm parameters (motility, morphology, viability). In normozoospermic patients, the density gradients select better quality spermatozoa compared to other processing methods; this benefit was kept after thawing.

Comparative Effect of Photobiomodulation on Human Semen Samples Pre- and Post-Cryopreservation

The primary objective of this study is to evaluate and to compare the effects of photobiomodulation (PBM) on sperm parameters both before and after cryopreservation. In this regard, 24 freshly ejaculated semen samples from normozoospermic men were included in this study. Each semen sample was randomly divided into three groups (1 ml aliquot for each group): the control group (group one) underwent conventional sperm cryopreservation (n = 24), group two underwent pre-freezing PBM exposure (810 nm, diode laser, and 0.6 J/cm²) (n = 24), and group three underwent post freezing and thawing PBM exposure (n = 24). Indicators of sperm quality, including total sperm motility (TSM), progressive sperm motility (PSM), DNA fragmentation, lipid peroxidation levels, apoptosis-like changes, and gene expression levels of protamine (PRM) 1, PRM2, and adducin 1 alpha (ADD1), were investigated in a blinded style. Due to the beneficial effect of pre-freezing PBM therapy, group 2 exhibited the highest TSM and PSM levels compared to groups 1 and 3. At the same time, DNA fragmentation and lipid peroxidation were significantly reduced in the group 2 compared to the group 1 (p = 0.024 p = 0.016, respectively). Evaluation of apoptotic/necrotic changes revealed that parameters including early apoptosis, dead, and necrotic cells decreased in the group 2 compared to the either groups 1 (p = 0. 008, p = 0. 032, p = 0. 02, respectively) or group 3 (p = 0.037, p = 0.108, p = 0.083). There were no significant differences in the expression levels of PRM1, PRM2, and ADD1 among the study groups. Based on our results, PBM therapy prior to cryopreservation, even in the normal semen samples, plays a significant protective role against cryo-damage by preserving the functional parameters of spermatozoa.

Development and validation of HPLC method for simultaneous quantification of alpha-tocopherol (free or encapsulated) and cholesterol in semen cryopreservation media

The HPLC method was developed and validated for assaying alpha-tocopherol and cholesterol in cryopreservation media. Chromatographic separation was performed on an isocratic system, using a C-18 column. The mobile phase was composed of a mixture of methanol:acetonitrile:water 68:28:4 (v/v/v), using a flow rate of 1.5 mL/min and 20 μL injection volume, at a wavelength of 208 nm. The method was validated according to International Conference on Harmonization guidelines. The method proved to be specific, accurate, precise, and linear with correlation coefficients greater than 0.996 over a wide concentration range of both analytes. Vitamin E and cholesterol presented limits of detection of 0.002 mg/mL, 0.026 mg/mL and limits of quantitation of 0.006 mg/mL, 0.086 mg/mL, respectively. This method is simple and rapid, shows high precision and accuracy, and offers the advantage of simultaneous assaying of vitamin E and cholesterol (alone, in cyclodextrins complexes or in liposome loaded) on semen cryopreservation media.

Cryopreservation media differentially affect sperm motility, morphology and DNA integrity

INTRODUCTION

Human sperm freezing is very widely used for male fertility preservation. This procedure consists in adding cryoprotectants to the spermatozoa followed by cooling and storing the spermatozoa at a subzero temperature. Many standardized cryopreservation media are available on the market. However, these media differ in their chemical composition and there are no sufficient data to optimize their classification. Therefore, the aim of this study was to compare five commercially available sperm cryopreservation media, which have not been compared together, in terms of motility, morphology and DNA integrity.

MATERIALS AND METHODS

One-hundred semen samples were obtained from 10 fertile participants and 90 infertile men. Each sample was evaluated before freezing for motility, morphology and DNA fragmentation index (DFI). Then, it was equally divided into five aliquots. Each aliquot was cryopreserved using one of the five media (A, B, C, D, and E). The same parameters were re-evaluated after the addition of the cryopreservation media in the fertile group, and after sperm thawing in fertile and infertile groups.

RESULTS

The results showed that the five selected cryopreservation media had negative effects on sperm motility and morphology per se. In the infertile group, the cryosurvival factor was significantly lower in cryomedium A when compared to the four other media (p < 0.001). In addition, a significantly higher percentage of sperm with coiled tail was detected in cryomedium E compared to cryomedium A (p < 0.05) and to cryomedium B (p < 0.001) after thawing, in the infertile group. Furthermore, the sperm DFI was significantly higher in cryomedia A (p < 0.001), B (p < 0.001), C (p < 0.01), D (p < 0.01) and E (p < 0.05) compared to that of the fresh semen derived from infertile participants.

CONCLUSION

This study indicates that the recovery rate of competent spermatozoa, after cryopreservation, is still critical in infertile men. Therefore, frozen semen sample should be used only when necessary.

Dynamic assessment of human sperm DNA damage I: the effect of seminal plasma-sperm co-incubation after ejaculation

AIM

The purpose of the study was to evaluate the impact of seminal plasma in human ejaculates on the sperm DNA quality and DNA longevity.

METHODS

Semen samples for this study were obtained from 20 donors with a normal spermiogram. Following centrifugation, the sperm pellet was resuspended either in the seminal plasma proceeding from its respective donor, or in an equal amount of PBS, adjusting the concentration to 50 × 10⁶/ml. Each set of samples was incubated at 37 °C for 24 h and the sperm DNA damage was assessed using the chromatin-dispersion test following 0, 2, 6, and 24 h of incubation.

RESULTS

Sperm DNA fragmentation (SDF) did not differ between the two experimental conditions at T0; however, Kaplan-Meier estimates to test for survival showed an statistical significant increase of SDF in the seminal plasma group when compared to the PBS group following all timeframes (p 0.000). With respect to sperm DNA longevity, the most dramatic loss of sperm DNA quality occurred during the first 2 h of incubation, with the rate of SDF (rSDF) in the seminal plasma being 2.1 more intense than in PBS. Interestingly, the rSDF was found to vary significantly between individuals, which was confirmed with significant correlations in all rSDF timeframes (rSDF T0-2, p 0.049; rSDF T2-6, p 0.000; rSDF T6-24: p 0.000).

CONCLUSIONS

Co-incubation of semen samples in seminal plasma after ejaculation increases iatrogenic sperm damage. This effect is statistically significant after 2 h of co-incubation. Subsequently, for ART purposes seminal plasma must be quickly removed after ejaculation-liquefaction, to avoid a higher susceptibility of sperm DNA towards fragmentation.