Hyaluronic acid increases motility/intracellular CA2+ concentration in human sperm in vitro

Exploring the Role of Hyaluronic Acid in Reproductive Biology and Beyond: Applications in Assisted Reproduction and Tissue Engineering

Hyaluronic acid (HA) plays a prominent role in various aspects of reproductive biology and assisted reproductive technologies (ART). This review describes the multifaceted influence of HA, ranging from primordial germ cell migration, ovarian follicle development, and ovulation in females to sperm structure, physiology, motility, and capacitation in males. In addition, HA also plays an important role in fertilization and promotes embryo implantation by mediating cellular adhesion and communication within the uterus. Against this physiological background, the review examines the current applications of HA in the context of ART. In addition, the article addresses the emerging field of reproductive tissue engineering, where HA-based hydrogels offer promising perspectives as they can support the development of mature oocytes and spermatogenesis in vitro. Overall, this review highlights the integral role of HA in the intricate mechanisms of reproductive biology and its growing importance for improving ART outcomes and the field of tissue engineering of the reproductive system.

Microfluidic devices employing chemo- and thermotaxis for sperm selection can improve sperm parameters and function in patients with high DNA fragmentation

Conventional sperm processing uses centrifugation has a negative effect on sperm parameters and DNA integrity. We designed and fabricated a novel microfluid device based on chemotaxis and thermotaxis, and compared it with the swim-up method. Twenty normal samples with high DNA fragmentation were included. Each sample was divided into four groups: Group 1, control, Group 2: sperm selection by thermotaxis, Group 3: sperm selection by chemotaxis, and Group 4: sperm selection with thermotaxis and chemotaxis. We used cumulus cells in a microfluid device to create chemotaxis, and, two warm stages to form a temperature gradient for thermotaxis. The spermatozoa were assessed based on the concentration, motility, and fine morphology using Motile Sperm Organelle Morphology Examination, mitochondrial membrane potential (MMP), acrosome reaction (AR), and sperm DNA fragmentation. Concentration (22.40 ± 5.39 vs. 66.50 ± 19.21; p < 0.001) and DNA fragmentation (12.30 ± 3.96% vs. 17.95 ± 2.89%; p < 0.001) after selection in the chemotaxis and thermotaxis microfluid device were significantly lower than control group. The progressive motility (93.75 ± 4.39% vs. 75.55 ± 5.86%, p < 0.001), normal morphology (15.45 ± 2.50% vs. 10.35 ± 3.36, p < 0.001), MMP (97.65 ± 1.81% vs. 94 ± 3.89%, p = 0.02), and AR status (79.20 ± 5.28% vs. 31.20 ± 5.24%, p < 0.001) in the chemotaxis and thermotaxis microfluid device were significantly increased compared to control group. According to these findings, spermatozoa that have penetrated the cumulus oophorus have better morphology and motility, as well as acrosome reactivity and DNA integrity.

Simulating nature in sperm selection for assisted reproduction

Sperm selection in the female reproductive tract (FRT) is sophisticated. Only about 1,000 sperm out of millions in an ejaculate reach the fallopian tube and thus have a chance of fertilizing an oocyte. In assisted reproduction techniques, sperm are usually selected using their density or motility, characteristics that do not reflect their fertilization competence and, therefore, might result in failure to fertilize the oocyte. Although sperm processing in in vitro fertilization (IVF) and intrauterine insemination (IUI) bypasses many of the selection processes in the FRT, selection by the cumulus mass and the zona pellucida remain intact. By contrast, the direct injection of a sperm into an oocyte in intracytoplasmic sperm injection (ICSI) bypasses all natural selection barriers and, therefore, increases the risk of transferring paternal defects such as fragmented DNA and genomic abnormalities in sperm to the resulting child. Research into surrogate markers of fertilization potential and into simulating the natural sperm selection processes has progressed. However, methods of sperm isolation - such as hyaluronic acid-based selection and microfluidic isolation based on sperm tactic responses - use only one or two parameters and are not comparable with the multistep sperm selection processes naturally occurring within the FRT. Fertilization-competent sperm require a panel of molecules, including zona pellucida-binding proteins and ion channel proteins, that enable them to progress through the FRT to achieve fertilization. The optimal artificial sperm selection method will, therefore, probably need to use a multiparameter tool that incorporates the molecular signature of sperm with high fertilization potential, and their responses to external cues, within a microfluidic system that can replicate the physiological processes of the FRT in vitro.

Sperm selection strategies and their impact on assisted reproductive technology outcomes

The application of assisted reproductive technologies (ART) has revolutionised the treatment of human infertility, giving hope to the patients previously considered incapable of establishing pregnancy. While semen analysis is performed to access whether a sample has an adequate number of viable, motile and morphologically normal sperm cells able to achieve fertilisation, sperm selection techniques for ART aim to isolate the most competent spermatozoon which is characterised by the highest fertilising potential. Based on the semen analysis results, the correct sperm selection technique must be chosen and applied. In this review, different sperm selection strategies for retrieving spermatozoa with the highest fertilising potential and their impact on ART outcomes are discussed. In addition, advantages and disadvantages of each method and the best suited techniques for each clinical scenario are described.

Metabolites involved in cellular communication among human cumulus-oocyte-complex and sperm during in vitro fertilization

BACKGROUND

Fertilization is a key physiological process for the preservation of the species. Consequently, different mechanisms affecting the sperm and the oocyte have been developed to ensure a successful fertilization. Thus, sperm acrosome reaction is necessary for the egg coat penetration and sperm-oolema fusion. Several molecules are able to induce the sperm acrosome reaction; however, this process should be produced coordinately in time and in the space to allow the success of fertilization between gametes. The goal of this study was to analyze the metabolites secreted by cumulus-oocyte-complex (COC) to find out new components that could contribute to the induction of the human sperm acrosome reaction and other physiological processes at the time of gamete interaction and fertilization.

METHODS

For the metabolomic analysis, eighteen aliquots of medium were used in each group, containing: a) only COC before insemination and after 3 h of incubation; b) COC and capacitated spermatozoa after insemination and incubated for 16-20 hours; c) only capacitated sperm after 16-20 h in culture and d) only fertilization medium as control. Six patients undergoing assisted reproduction whose male partners provided normozoospermic samples were included in the study. Seventy-two COC were inseminated.

RESULTS

The metabolites identified were monoacylglycerol (MAG), lysophosphatidylcholine (LPC) and phytosphingosine (PHS). Analysis by PCR and in silico of the gene expression strongly suggests that the cumulus cells contribute to the formation of the PHS and LPC.

CONCLUSIONS

LPC and PHS are secreted by cumulus cells during in vitro fertilization and they could be involved in the induction of human acrosome reaction (AR). The identification of new molecules with a paracrine effect on oocytes, cumulus cells and spermatozoa will provide a better understanding of gamete interaction.

Pharmacological investigation of voltage-dependent Ca2+ channels in human ejaculatory sperm in vitro

The types of the voltage-dependent calcium channels (VDCCs) in human ejaculatory sperm and the effects of calcium channel blocker (CCB) on human sperm motility parameters in vitro were investigated. The human sperm motility parameters in vitro in response to the pharmacological agents nifedipine (NIF, inhibitor of L-type VDCC) and co-conotoxin (GVIA, inhibitor of N-type VDCC) were compared and analyzed statistically. The results showed that NIF (1, 5, 10 micromol/L) could not only significantly affect human sperm's shape but also spermatozoa motility after incubated at least 10 min in vitro (P<0.001). GVIA (0.1, 0.5 and 1 micromol/L) could just only significantly affect human sperm's progressive motility (a %+b %) after incubated for 20 min in vitro (P<0.01), but they both could not significantly affect spermic abnormality rate. It is suggested that L-type VDCC, non L-type VDCCs and isoform of L-type VDCC exist in the cell membrane of human sperm solely or together, and they participate in the spermic physiological processes especially the spermic motility.

Preservation of beluga (Delphinapterus leucas) spermatozoa using a trehalose-based cryodiluent and directional freezing technology

A beluga (Delphinapterus leucas) sperm preservation method was developed for use in genome banking and AI. In Study 1, glycerol-based cryodiluents (modified BF5F and modified Platz Diluent Variant (PDV)) were unable to maintain adequate progressive motility using straws (fast and slow freezing rate (FR)) or pellets (slow FR). Neither freezing method nor FR affected in vitro sperm characteristics (P > 0.05), but retention of prefreeze progressive motility following thawing was greater (P < 0.05) for BF5F (21%) than PDV (15%). In Study 2, examining the effects of straw freeze–thawing using BF5F with glycerol (1 and 3%, v/v) or trehalose (46 and 91 mM) on sperm characteristics, samples cryopreserved in trehalose exhibited superior (P < 0.05) in vitro parameters compared with their glycerol-treated counterparts. In Study 3, compared with a straw method, directional freezing using 91 mM trehalose enhanced (P < 0.05) sperm characteristics, with samples retaining 38%, 75% and 61% of their prefreeze progressive motility, curvilinear velocity and viability, respectively. A higher (P < 0.05) proportion of motile spermatozoa displayed rapid velocity after directional (21 ± 1%) compared with straw (12 ± 3%) freezing. Systematic development of a cryodiluent and the use of directional freezing resulted in beluga spermatozoa exhibiting adequate post-thaw quality for genome banking and use in AI.

Cumulus cells and their extracellular matrix affect the quality of the spermatozoa penetrating the cumulus mass

OBJECTIVE

To investigate the role of the cumulus cells and the cumulus matrix in affecting the penetrability, morphology, acrosome reaction, and motility of human spermatozoa penetrating the cumulus oophorus.

DESIGN

Controlled experimental laboratory study.

SETTING

University gynecology unit.

PATIENT(S)

Women undergoing assisted reproduction treatment and men visiting the subfertility clinics.

INTERVENTION(S)

Human spermatozoa were allowed to penetrate through the cumulus oophorus and cell-depleted cumulus matrix in a capillary, and were treated with cumulus cell extract or hyaluronic acid.

MAIN OUTCOME MEASURE(S)

The morphology, acrosomal status, and motility of human spermatozoa were determined.

RESULT(S)

Fewer spermatozoa could penetrate the fresh cell-depleted matrix compared with intact cumulus oophorus. Spermatozoa that penetrated through the cumulus oophorus had higher percentages of normal morphology and acrosome reaction and had specific motility pattern. These effects were lost or reduced in the cell-depleted matrix that had been stored overnight. Hyaluronic acid, a main component of the cumulus matrix at concentration found in the cumulus oophorus, modulated sperm motility but did not affect spontaneous acrosome reaction. Cumulus cell extract did not affect sperm motility, but induced acrosome reaction.

CONCLUSION(S)

Both the cumulus matrix and the cumulus cells contribute to the effect of cumulus oophorus on spermatozoa penetrating through it.

Involvement of an unnamed protein, RDA288, in the mechanism through which progesterone mediates its antiapoptotic action in spontaneously immortalized granulosa cells

Progesterone (P4) inhibits apoptosis of rat granulosa cells and spontaneously immortalized granulosa cells (SIGCs), which were derived from rat granulosa cells. Defining the mechanism through which P4 mediates its action has been difficult because these cells do not express the classic nuclear P4 receptor. Previous studies have shown that a P4 receptor antibody, C-262, detects a 60-kDa protein that is involved in regulating P4's antiapoptotic action. Using a C-262 affinity column, this 60-kDa protein was isolated and sequenced by mass spectrometry. This analysis revealed that the C-262-detectable protein is an unnamed protein referred to as RDA288. This protein has several putative hyaluronic acid binding sites. Further hyaluronic acid antagonizes (3)H-P4 binding to SIGCs and mimics P4's action, whereas exogenous hyaluronic acid binding protein attenuates P4's actions. RT-PCR demonstrated that RDA288 mRNA was present in SIGCs, immature rat ovary, lung, and skeletal muscle but was not present in several other organs. Forced expression of RDA288 increased the capacity of SIGCs to bind and respond to P4. An antibody was also developed against RDA288. Using this antibody in a Western blot protocol, RDA288 expression was confirmed in both SIGCs and granulosa cells. An immunohistochemical study detected RDA288 in the cytoplasm and plasma membrane components of granulosa cells of antral follicles. Immunocytochemical studies on living nonpermeabilized SIGCs revealed that RDA288 was present on the extracellular surface of the plasma membrane. Finally, pretreatment with the RDA288 antibody blocked P4's antiapoptotic actions. Taken together, these data suggest that RDA288 plays a significant role in mediating P4's antiapoptotic action in granulosa cells.

Human sperm cells express CD44

OBJECTIVE

To determine whether CD44 is expressed by human sperm cells.

DESIGN

Prospective study.

SETTING

Assisted conception unit and university research laboratory.

PATIENT(S)

Fourteen normal fertile donors.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Enzyme-linked immunoassay was used to measure the concentration of CD44 in samples of human sperm cells. Immunocytochemistry using a fluorescent antibody system was used to confirm and localize the expression of CD44 on sperm membranes. Western blotting was used to identify CD44 protein in extracts of lysed sperm cells.

RESULT(S)

The presence of CD44 was identified in suspensions of pure sperm cells by ELISA. The mean sperm count was 66 million per milliliter (range, 60 million-75 million per milliliter) and the mean concentration of CD44 was 0.013 ng per 10(6) sperm (range, 0.012 ng-0.015 ng per 10(6) sperm). Use of a fluorescently labeled antibody to CD44 confirmed the presence of CD44 on sperm membranes. CD44 expression was mostly localized in the acrosome region. Western blotting using a specific monoclonal antibody to CD44 identified a variant of CD44 with an approximate molecular weight of 73 kDa.

CONCLUSION(S)

The expression of CD44 on the surface of human sperm membranes was confirmed by three independent methods.