Cryopreservation of biological materials: applications and economic perspectives

Cryopreservation is a transformative technology that allows for the long-term storage of biological materials by cooling them to extremely low temperatures at which metabolic and biochemical processes are effectively slowed or halted. Cryopreservation utilizes various techniques to minimize ice crystal formation and cellular damage during freezing and thawing processes. This technology has broad applications in the fields of medicine, agriculture, and conservation, spanning across stem cell research, reproductive and regenerative medicine, organ transplantation, and cell-based therapies, each with significant economic implications. While current techniques and their associated costs present certain challenges, ongoing research advancements related to cryoprotectants, cooling methods, and automation promise to enhance efficiency and accessibility, potentially broadening the technology's impact across various sectors. This review focuses on the applications of cryopreservation, research advancements, and economic implications, emphasizing the importance of continued research to overcome the current limitations.

The Influence of Three Commercial Soy Lecithin-Based Semen Extenders and Two Spermatozoa Concentrations on the Quality of Pre-Freeze and Post-Thaw Ram Epididymal Spermatozoa

There are limited studies on the factors affecting the success of ram epididymal spermatozoa (REPS) cryopreservation. On this note, the current study assessed the influence of three commercial soy lecithin-based semen extenders, AndroMed® (AND), BioXcell® (BIO), and OviXcell® (OVI), and two concentrations (400 × 106 vs. 200 × 106 spermatozoa/mL) on the pre-freeze and post-thaw quality of REPS. The REPS were retrieved from nine adult rams' testes and diluted with each of the three extenders to both concentrations. Straws were frozen manually. Standard motility (SMP) and kinematic parameters (KPs) were assessed via a CASA, while spermatozoa viability, morphology, and acrosomal integrity were assessed via the Kovács-Foote staining technique. The concentration did not significantly affect the pre-freeze and post-thaw SMP and KPs of REPS. BIO and OVI had significantly higher pre-freeze and post-thaw BCFs, post-thaw VAP, and the percentage of all intact heads than AND. In contrast, AND had a significantly lower percentage of REPS with tail defects than BIO and OVI. The 400 × 106 spermatozoa/mL concentration resulted in a significantly higher percentage of all intact heads than the 200 × 106 spermatozoa/mL concentration. Freezing significantly increased tail defects and decreased the percentage of REPS with distal cytoplasmic droplets. The cryopreservation of REPS at the 400 × 106 spermatozoa/mL concentration is recommended. All three extenders must be optimized to preserve the viability, membrane integrity, and better normal morphology of REPS; the reason for increased tail abnormality after the freezing/thawing process needs to be studied.

Post-Thaw Parameters of Buck Semen Quality after Soy Lecithin Extender Supplementation with Fumaric Acid

The supplementation of cryopreservation media with antioxidants improves the post-thaw quality and fertilizing ability of spermatozoa. To maximize the fertility of frozen-thawed buck spermatozoa, further research is required to overcome obstacles that have yielded controversial results and standardize protocols. In the present work, the effect of adding fumaric acid (a well-described antioxidant) to a soy lecithin semen extender on certain quality parameters of spermatozoa following freezing and thawing was examined for the first time. Five sexually mature Skopelos bucks were used, and ejaculates were collected with an artificial vagina. The semen samples (98 samples, five replicates) were diluted (400 × 106 spermatozoa/mL) with OviXcell®, supplemented with fumaric acid (0 mM, 2.15 mM, 10 mM or 30 mM), equilibrated (5 °C; 3 h), packed (0.5 mL straws), frozen and stored (-196 °C) until further processing. After thawing, the spermatozoa total and progressive motility (CASA), viability (eosin-nigrosin), membrane functional integrity (HOST), acrosome integrity (SpermBlue®) and mitochondrial function (Rhodamine-123/SYBR-14/PI) were evaluated. Statistical analysis was performed with one-way ANOVA, followed by Duncan's test; significance was set at 0.05. The addition of 2.15 mM fumaric acid improved (p < 0.05) spermatozoa viability, membrane functional integrity, acrosome integrity and mitochondrial function compared to all other concentrations. The addition of 30 mM fumaric acid decreased (p < 0.05) spermatozoa viability and mitochondrial function compared to all other concentrations. These results indicate a beneficial effect of a 2.15 mM fumaric acid addition to a soy lecithin extender on post-thaw buck spermatozoa quality. Further research is required to evaluate the in vivo fertility of frozen-thawed buck spermatozoa treated with fumaric acid, as well as to elucidate the mechanism of action of fumaric acid in spermatozoa.

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.

Effect of Bovine Serum Albumin Supplementation in Tris-Soybean Lecithin-Based Extender on Quality of Chilled Ram Epididymal Spermatozoa

Objective: This study was designed to assess the effects of using tris-soybean lecithin (TSL)-based extender supplemented with bovine serum albumin (BSA) on the quality of ram epididymal spermatozoa during refrigerated storage. Method: Epididymal sperm were collected from 22 Zandi rams, diluted in TSL-based extender at different concentrations (0%, 2.5%, 5%, 7.5%, and 10%) of BSA, and stored for 5 days at 4°C. Sperm parameters including motility, viability, plasma membrane integrity, chromatin protamination, and malondialdehyde (MDA) content were evaluated at 0, 24, 72, and 120 hours of refrigeration. Results: The addition of 10% BSA to the extender significantly improved sperm viability at 24 and 120 hours of refrigerated liquid storage (p < 0.05). An enhancement in plasma membrane integrity was observed along with a decrease in MDA level by increasing the concentration of BSA from 0% to 10% (p > 0.05). Sperm motion characteristics were higher in the BSA-free group at 120 hours of preservation (p < 0.05). No statistical difference was found for nuclear protamination between experimental groups (p > 0.05). Conclusion: BSA supplementation in TSL-based extender can preserve the viability of epididymal ram spermatozoa during liquid storage at 4°C.

Ultra-rapid cooling of ibex sperm by spheres method does not induce a vitreous extracellular state and increases the membrane damages

Sperm cryopreservation by ultra-rapid cooling based on dropping small volumes of sperm suspension directly into liquid nitrogen, has been successful in some wild ruminant species, including the Iberian ibex (Capra pyrenaica). In ultra-rapid cooling, the contents of these droplets are expected to enter a stable, glass-like state, but to the best of our knowledge no information exists regarding the presence or absence of ice formation in the extracellular milieu when using this technique. Different modifications to the extracellular milieu likely inflict different types of damage on the plasmalemma, the acrosome and mitochondrial membranes. The aims of the present work were: 1) to examine the physical state of the extracellular milieu after cryopreservation at slow and ultra-rapid cooling rates—and thus determine whether ultra-rapid cooling vitrifies the extracellular milieu; and 2) to compare, using conventional sperm analysis techniques and scanning and transmission electron microscopy, the damage to sperm caused by these two methods. Sperm samples were obtained by the transrectal ultrasound-guided massage method (TUMASG) from anesthetized Iberian ibexes, and cryopreserved using slow and ultra-rapid cooling techniques. Sperm motility (22.95 ± 3.22% vs 4.42 ± 0.86%), viability (25.64 ± 3.71% vs 12.8 ± 2.50%), acrosome integrity (41.45± 3.73% vs 27.00 ± 1.84%) and mitochondrial membrane integrity (16.52 ± 3.75% vs 4.00 ± 0.65%) were better after slow cooling (P<0.001) than after ultra-rapid technique. Cryo-scanning electron microscopy (Cryo-SEM) suggested that the vitrified state was not achieved by ultra-rapid cooling, and that the ice crystals formed were smaller and had more stretchmarks (P<0.001) than after slow cooling. Scanning electron microscopy revealed no differences in the types of damage caused by the examined techniques, although transmission electron microscopy showed the damage to the plasmalemma and mitochondrial membrane to be worse after ultra-rapid cooling. In conclusion ultra-rapid cooling provoked more membrane damage than slow cooling, perhaps due to the extracellular ice crystals formed.

Changes in seminal parameters and hormonal profile with use of aromatase inhibitor in management of aging broiler breeder roosters

An excessive amount of aromatase enzyme reduces reproductive performance in aging roosters. Testosterone metabolism by aromatase enzyme is one of the reasons for reduced testosterone and lower fertility of aging roosters. The purpose of this study was to determine the effects of Exemestane (EX), as a steroidal aromatase inhibitor, on the seminal parameters and reproductive hormones of aging roosters. A total of 20 roosters (45 wk of age) were housed in individual cages and received a standard basal diet and oral EX capsules for 60 D at the daily doses per rooster (mg/rooster) in the following experimental groups: 0 mg (CTRL), 0.25 mg (Ex-0.25), 0.5 mg (Ex-0.5), and 1.5 mg (Ex-1.5). Sperm samples were obtained on days 1, 20, 40, and 60 of experiment. Blood samples were taken on days 1 and 60. The results indicated that different EX dosages affected semen parameters (P < 0.05) other than semen volume, morphology, apoptosis, and acrosome integrity. Various semen characteristics were significant (P < 0.05) during different times of the experiment, with the exception of semen volume, total motility, membrane integrity, morphology, apoptosis, and acrosome integrity. Roosters that received 0.5 mg of EX had higher percentages of sperm concentration, total motility, progressive motility, membrane integrity, viability, and mitochondrial activity (P < 0.05). There were lower concentrations of malondialdehyde in the CTRL (0 mg) and Ex-0.25 groups (P < 0.05). Although there was no significant difference in hormones at day 0 of the experiment (P > 0.05), roosters in the Ex-0.5 had higher concentration of testosterone as well as lower of aromatase activity at day 60 (P < 0.05). It can be concluded that EX improved semen parameters and testosterone, which ultimately can increase fertility in the aging broiler breeder roosters.

Effects of CoQ10 on the quality of ram sperm during cryopreservation in plant and animal based extenders

The purpose of this study was to evaluate the effect of different concentrations of CoQ10 in soybean lecithin (SL) or egg yolk (EY) extenders on ram semen cryopreservation. Semen samples were collected from five rams, twice a week, then diluted in the extenders (SL and EY) containing different concentrations of CoQ10 as follows: extender containing SL: 0 μM (control, SL/Q0), 1 μM (SL/Q1), 2 μM (SL/Q2), 5 μM (SL/Q5) and 10 μM (SL/Q10) CoQ10; extender containing EY: 0 μM (control, EY/Q0), 1 μM (EY/Q1), 2 μM (EY/Q2), 5 μM (EY/Q5) and 10 μM (EY/Q10) CoQ10. Sperm motion characteristics, membrane integrity, abnormal morphology, viability, apoptotic-like changes, mitochondria active potential, acrosome integrity and lipid peroxidation were evaluated after freeze-thaw process. The SL/Q1, SL/Q2, EY/Q1 and EY/Q2 resulted in greater (P ≤ 0.05) sperm total motility, progressive motility, membrane integrity and mitochondria active potential compared to the other groups. Acrosome integrity in the SL/Q0, SL/Q1, SL/Q2, EY/Q0, EY/Q1 and EY/Q2 groups was greater (P ≤ 0.05) than in the SL/Q5, SL/Q10, EY/Q5 and EY/Q10 groups. The SL/Q2 and EY/Q2 treatment groups had greater (P ≤ 0.05) sperm viability rates and less apoptotic-like changes and lipid peroxidation. The CoQ10 compound could be explored as a novel potential antioxidant for cryopreservation of ram semen because with used of this compound in the present study there was an improved post-thawed sperm quality.

Dietary supplementation with flaxseed oil as source of Omega-3 fatty acids improves seminal quality and reproductive performance in aged broiler breeder roosters

Reproductive performance in aged broiler breeder roosters is not desirable. The purpose of this study was to assess the effects of dietary flaxseed oil and vitamin E on the semen parameters, hormonal profiles, fatty acid analysis of sperm, and fertility performance of aged roosters. Twenty four roosters were assigned into four treatments and received their diets as following: 1) basal diet as control group (CTRL), 2) basal diet supplemented with 200 mg/kg vitamin E (CTRL + VITE), 3) basal diet supplemented with 2% flaxseed oil (FLAX) and 4) basal diet supplemented with 2% flaxseed oil plus 200 mg/kg vitamin E (FLAX + VITE). Roosters were fed their diets for 60 days and then, different characteristics of reproduction in the roosters were examined during experiment. Different diets affected semen parameters (P ≤ 0.05) except semen volume and morphology. Various characteristics of semen were significant (P ≤ 0.05) during different times of experiment excluding the total motility, membrane integrity and morphology. The higher percentage of sperm concentration, total motility, progressive motility, viability and membrane integrity accorded with a lower lipid peroxidation were observed in the roosters fed diet of FLAX + VITE (P ≤ 0.05). A higher concentration of testosterone was detected in roosters fed FALX + VITE at day 60 (P ≤ 0.05). Moreover, the percentage docosapantaenoic acid (DPA), docosahexaenoic acid (DHA) of sperm were increased in the diet of FLAX (P ≤ 0.05). Finally, rate of fertility after artificial insemination was significantly higher in the diet of FLAX + VITE. It seems that supplementation of aged roosters' diet with flaxseed oil and VITE improves the semen performance and fertility potential that can be a suitable strategy to preserve the reproductive performance of aged rooters.

Improvement in Semen Conservation of the Indigenous Czech Endangered Old Kladruber Horse: Special Focus on the Type of Extender and Packaging System

The aim of our study was to investigate the effect of two freezing extenders and two packaging systems on motility, plasma membrane (PM) integrity, and the apoptotic status of frozen-thawed (F-T) spermatozoa of the endangered Old Kladruber stallions. The collected semen (n = 6 stallions, three collections each) was diluted either with Gent or Lactose-EDTA (Lact) extender. Two aliquots of semen from each collection diluted in this way were prepared and then loaded into 5-mL aluminum tubes or 0.5-mL plastic straws. After thawing and then at 15 minutes intervals within 1 hour, the samples were analyzed for motility (CASA), PM integrity (CFDA/PI), and apoptotic changes of the spermatozoa (Yo-Pro-1/PI). Using Gent, the samples exhibited higher motility, kinematic parameters, higher representation of spermatozoa in medium, and fast subpopulation, as well as more spermatozoa with intact PMs and fewer spermatozoa with apoptotic changes compared with Lact extender (P < .05). Progressive motility and PM integrity was superior when using Gent and 5-mL aluminum tubes as compared with the rest of the combinations (P < .05). Kinematic parameters, percentage of spermatozoa in fast subpopulation and apoptotic status was superior in Gent and 0.5-mL straws as compared with the rest of the combinations (P < .05). Moreover, we revealed that F-T semen reacts diametrically differently when two different extenders and packaging systems are used. The study concludes that the combination of Gent and 0.5-mL straws represent adequate freezing system to maintain the appropriate quality of spermatozoa of this endangered breed.

Sperm cryopreservation: A review on current molecular cryobiology and advanced approaches

The cryopreservation of spermatozoa was introduced in the 1960s as a route to fertility preservation. Despite the extensive progress that has been made in this field, the biological and biochemical mechanisms involved in cryopreservation have not been thoroughly elucidated to date. Various factors during the freezing process, including sudden temperature changes, ice formation and osmotic stress, have been proposed as reasons for poor sperm quality post-thaw. Little is known regarding the new aspects of sperm cryobiology, such as epigenetic and proteomic modulation of sperm and trans-generational effects of sperm freezing. This article reviews recent reports on molecular and cellular modifications of spermatozoa during cryopreservation in order to collate the existing understanding in this field. The aim is to discuss current freezing techniques and novel strategies that have been developed for sperm protection against cryo-damage, as well as evaluating the probable effects of sperm freezing on offspring health.

Effect of egg yolk plasma and soybean lecithin on rooster frozen-thawed sperm quality and fertility

This experiment was conducted to study the effects of egg yolk plasma (10%, 15% and 20%), soybean lecithin (0.5%, 1% and 1.5%) and whole egg yolk (WEY) (control) on post-thawed sperm quality, hatchability and fertility outcomes. In experiment 1, sperm motility, abnormalities, membrane integrity, viability, apoptosis status, mitochondrial activity were studied following freeze-thawing. The best quality of frozen-thawed rooster sperm was chosen to be used for the assessment of the hatchability and fertility rate in experiment 2. The significantly higher percentages of post-thawing sperm total and progressive sperm motilities, membrane integrity, viability were observed in 1% soybean lecithin and 20% egg yolk plasma in comparison with 0.5 and 1% soybean lecithin, 10% egg yolk plasma and control, except for 15% egg yolk plasma (P < 0.05). Using 20% egg yolk plasma in the extender improved mitochondrial activity. Supplementation of 1% soybean lecithin and 20% egg yolk plasma into the extender resulted in the least percentages of dead sperm (P < 0.05). Sperm abnormalities and early apoptosis did not differ in various extender supplementations. In experiment 2, higher percentages of hatchability and fertility rate were observed in semen containing 1% soybean lecithin and 20% egg yolk plasma compared with the WEY group. The results showed that supplementation of the rooster sperm extender with 1% soybean lecithin and 20% egg yolk plasma resulted in higher quality of frozen-thawed sperm.

Helium-neon laser irradiation of cryopreserved ram sperm enhances cytochrome c oxidase activity and ATP levels improving semen quality

This study examines whether and how helium-neon laser irradiation (at fluences of 3.96-9 J/cm(2)) of cryopreserved ram sperm helps improve semen quality. Pools (n = 7) of cryopreserved ram sperm were divided into four aliquots and subjected to the treatments: no irradiation (control) or irradiation with three different energy doses. After treatment, the thawed sperm samples were compared in terms of viability, mass and progressive sperm motility, osmotic resistance, as well as DNA and acrosome integrity. In response to irradiation at 6.12 J/cm(2), mass sperm motility, progressive motility and viability increased (P < 0.05), with no significant changes observed in the other investigated properties. In parallel, an increase (P < 0.05) in ATP content was detected in the 6.12 J/cm(2)-irradiated semen samples. Because mitochondria are the main cell photoreceptors with a major role played by cytochrome c oxidase (COX), the COX reaction was monitored using cytochrome c as a substrate in both control and irradiated samples. Laser treatment resulted in a general increase in COX affinity for its substrate as well as an increase in COX activity (Vmax values), the highest activity obtained for sperm samples irradiated at 6.12 J/cm(2) (P < 0.05). Interestingly, in these irradiated sperm samples, COX activity and ATP contents were positively correlated, and, more importantly, they also showed positive correlation with motility, suggesting that the improved sperm quality observed was related to mitochondria-laser light interactions.