Technologies of cryoprotectant-free vitrification of human spermatozoa: asepticity as criterion of effectiveness.

This review describes 120 years history of technology for cryoprotectant-free cryopreservation of human spermatozoa by direct plunging into liquid nitrogen (vitrification). It is presented an explanation why cryoprotectant-free vitrification for some human ejaculates is better than conventional freezing and vitrification with the presence of cryoprotectants. Special attention is given to the extremely high viability of viruses, bacteria and micoplasmas after cryoprotectant-free cryopreservation in culture medium and even in distilled water. This fact increases the potential risk of disease transmission through liquid nitrogen. It is concretized the concept "asepticity" as obvious parameter for any medical assisted reproduction technology which includes the cooling of cells in liquid nitrogen. It is described the role of nonpermeable compounds of mediums for cryoprotectant-free vitrification: carbohydrates, proteins, lipoproteins, antioxidants. This review summarizes concerned data regarding two groups of different current technologies for cryoprotectant-free vitrification of human spermatozoa: with direct contact of spermatozoa with liquid nitrogen as well as with full isolation of these cells from liquid nitrogen (aseptic technologies).

Trehalose sustains a higher post-thaw sperm motility than sucrose in vitrified human sperm.

One of the cryopreservation methods that best preserves sperm function is vitrification. However, comparative studies have not been performed to evaluate the effect of nonpermeable cryoprotectors on sperm function for prolonged periods of time post-devitrification. These times are necessary, especially in in vitro fertilisation and intrauterine insemination, for gamete interaction and then fertilisation to occur, while maintaining motility to arrive at the fertilisation site. In this study, sucrose (.25 m) and trehalose (.1 and .05 m) were compared in essential parameters like motility and plasma membrane integrity for 12 hr. Post-devitrification sperm motility using .1 m trehalose was 68.9%, higher than that obtained with .05 m trehalose (59.9%, p < .0081) and .25 m sucrose (57.9%, p < .0002). Similar results were obtained at 6 and 12 hr with .1 m trehalose (58.0% and 42.3% respectively) compared to .05 m trehalose (p < .0184 and p < .033) and .25 m sucrose (p < .0001 and p < .0012).There was no difference between .25 m sucrose and .05 m trehalose. Membrane integrity was best preserved at time 0 by .1 m trehalose (p < .05), but there was no significance at 6 and 12 hr compared to sucrose. Our results suggest that for assisted reproduction techniques that require motile spermatozoa for a longer period of time, use of .1 m trehalose is recommended in the sperm vitrification technique.

Use of the fluorescent dye tetramethylrhodamine methyl ester perchlorate for mitochondrial membrane potential assessment in human spermatozoa.

Mitochondrial membrane potential (ΔΨm) is an indicator of sperm quality and its evaluation complements the standard semen analysis. The fluorescent dye JC-1 has been widely used to assess sperm ΔΨm; however, some problems have been detected under certain experimental conditions. Another fluorescent compound, tetramethylrhodamine methyl ester perchlorate (TMRM), has been used in somatic cells and bovine spermatozoa but not in human spermatozoa. TMRM accumulates in hyperpolarised mitochondria and the fluorescence intensity of this compound correlates with ΔΨm. Thus, the aim of this study was to evaluate and validate the usefulness of the fluorescent dye TMRM for measuring sperm ΔΨm. The results showed that TMRM accurately detects sperm populations displaying either high or low ΔΨm. Moreover, TMRM was able to measure sperm ΔΨm under the experimental conditions in which JC-1 had previously presented difficulties. Differences in ΔΨm according to sperm and semen quality were properly detected and a positive correlation between ΔΨm and conventional semen parameters was observed. Finally, a positive correlation was found between the ΔΨm measurement by TMRM and by the widely used JC-1. In conclusion, TMRM is a simple, time-effective method, easy to set in laboratories equipped with flow cytometry technology, and can accurately detect changes in ΔΨm with efficiency comparable to JC-1 without its limitations.

Short-term storage of salmonids semen in a sodium alginate-based extender.

Short-term storage of semen is a useful strategy for preservation of fish spermatozoa. However, there is a significantly decrease on sperm function mainly due to oxidative stress. In this way, sodium alginate plays an important role as free radical scavenger compound. Accordingly, the aim of our study was to analyse the effect of a sodium alginate-based extender on sperm function in the short-term storage of salmonids semen. Samples of Salmo salar, Oncorhynchus kisutch, and Oncorhynchus mykiss were stored in Storfish® (Ext-C) and Storfish® supplemented with sodium alginate (Ext-A) during 10 days at 4°C. After storage, motility, viability, mitochondrial membrane potential (ΔΨmit), superoxide anion (O2- ) level and DNA fragmentation (DNA Frag) were assessed. Ext-A had positive effect in preservation of sperm motility, viability, ΔΨmit, O2- level and DNA integrity in the three species analysed compared to control samples. In Ext-A, the spermatozoa of S. salar and O. mykiss showed significantly higher motility, viability and ΔΨmit than O. kisutch. However, O. kisutch and O. mykiss had significantly lower O2- level than S. salar, and DNA fragmentation in O. kisutch and S. salar was significantly lower than in samples of O. mykiss (p < 0.05). Dilution of salmonids semen in a sodium alginate-based extender is effective for protecting sperm quality during 10 days of short-term storage.

High temperature is essential for preserved human sperm function during the devitrification process.

Sperm vitrification is a cryopreservation method based on high-speed freezing by direct exposure of cells in liquid nitrogen (N2L), thereby avoiding the traditional cooling curves of freezing. The objective of this work was to determine the optimal warming temperature for vitrified human spermatozoa in order to maintain their fertilisation potential. Spermatozoa were cryopreserved by direct plunging into N2L and warmed at different temperatures for 5 and 10 s at 38, 40 and 42 °C. Sperm motility was evaluated by the CASA system and the sperm membrane function by HOST test. It was detected that progressive motility of sperm warmed at 38, 40 and 42 °C was 26.4 ± 8.4%; 56.6 ± 16.3% and 65.4 ± 15%, respectively, with statistically significant differences between the temperatures of 38 and 40 °C and 38 and 42 °C (P < 0.05). The plasma membrane function evaluated by HOST test was better preserved at 42 °C (76.3 ± 2.0%) compared to 40 °C (43 ± 2%) and 38 °C (65.6 ± 1.5%). The temperature in the thawing process can affect the motility and plasma membrane integrity and function. The warming at 42 °C for thawed vitrified sperm is the optimum temperature to preserve the sperm physiological parameters.

Cryopreservation of whole ovine ovaries with pedicles as a model for human: parameters of perfusion with simultaneous saturations by cryoprotectants.

BACKGROUND: The aim of this research was to study the effectiveness of perfusion of intact ovine ovaries with different rates of perfusion and time-period elapsed between extraction of these ovaries and the beginning of perfusion. METHODS: Ovaries were perfused through the arteria ovarica (ovarian arteries) with culture medium supplemented with 5% bovine calf serum, 6% dimethyl sulfoxide, 6% ethylene glycol, 0.15M sucrose, Indian ink, and 100 IU/mL heparin at room temperature (22 degrees C). In the first cycle of experiments, ovaries (n = 96) were perfused for 60 minutes just after extraction of ovaries at the following rates of perfusion (mL/hour): 150, 100, 75, 50, 25, 12.5, and 6.3. In the second cycle of experiments, ovaries (n = 26) were perfused at a rate of 25 mL/hour for 60 minutes after extraction of ovaries and their storage at room temperature for 2, 3, 4, and 5 hours, for groups 1, 2, 3, and, 4, respectively. Successful perfusion of blood vessels was detected visible by a blue coloration of the ovarian tissues. RESULTS: The first cycle of experiments showed that the optimal perfusion rates were 50 mL/hour and 25 mL/hour. In the second cycle of experiments, good perfusion of ovaries was established at a perfusion rate of 25 mL/hour for the ovaries of groups when 2 and 3 hours had elapsed after extraction. CONCLUSIONS: Effective perfusion of ovine intact ovaries with vascular pedicle was established using freezing medium at room temperature at the rate of perfusion of 25 mL/hour or 50 mL/hour. The ovaries must be perfused not later than 3 hours after the death of animals.

Effect of seminal plasma on Atlantic salmon (Salmo salar) sperm vitrification.

This study was designed to test a vitrification method in Atlantic salmon spermatozoa and determine the capacity of seminal plasma (SP) to protect these cells from cryoinjuries. The vitrification medium consisted of a standard buffer for fish spermatozoa (Cortland medium) + 10% DMSO + 2% BSA + 0.13-M sucrose + SP at concentrations of 30% (G30), 40% (G40), or 50% (G50). Fresh sperm was used as a control. To freeze the samples, 30-µL suspensions of spermatozoa from each group were dropped directly into liquid nitrogen. The resulting spheres were placed in cryotubes for storage in liquid nitrogen. The cryotubes with the vitrified spermatozoa were thawed by placing them in a water bath at 37 °C for 45 seconds. After thawing, the following sperm quality parameters were determined by flow cytometry: DNA fragmentation (terminal deoxynucleotidyl transferase dUTP nick end labeling), plasma membrane integrity (SYBR-14/PI, staining technique), and mitochondrial membrane potential (JC-1 staining). An optical microscope was used to assess subjectively sperm motility, whereas fertility was determined by the presence of neurulation using five replicates per treatment in a sample of 30 eggs. Spermatozoa quality variables were preserved best when the highest concentration of SP (50%) was used (DNA fragmentation, 9.2%; plasma membrane integrity, 98.6%; mitochondrial membrane integrity, 47.2%; motility, 44.1%; and fertility, 46.2%).

Protective effect of butylated hydroxytoluene on sperm function in human spermatozoa cryopreserved by vitrification technique.

Butylhydroxytoluene (BHT), a synthetic analogue of vitamin E, shows antioxidant and antiviral properties and has been successfully used for mammalian sperm cryopreservation. In this study, BHT was included in a vitrification solution to determine its cryoprotective effect on human spermatozoa. Spermatozoa were selected by swim-up and vitrified in close sealed straw using either a combination of human tubal fluid (HTF), sucrose and BHT 1 mm (VMBHT), or only HTF and sucrose (VM). The optimal concentration of BHT was determined by the observation of preserved progressive sperm motility (PSM) after warming and detection of plasma membrane (PMI), membrane mitochondrial potential (ΔΨm) and DNA integrity. The presence of reactive oxygen species (ROS) was also detected. The PSM was significantly higher in the VMBHT group (80.86 ± 5.41%) compared with the VM group (68.9 ± 3.67%) (P < 0.05). Butylhydroxytoluene significantly preserved DNA integrity (4.0 ± 0.1% versus 6.1 ± 1.6%; P < 0.05) and reduced ROS production (5.5 ± 2.2 versus 8.6 ± 1.8%; P < 0.05). Plasma membrane and ΔΨm showed no statistical differences. One millimolar BHT effectively maintained cell function and due to its antioxidant and antiviral properties could be used in semen cryopreservation of patients with viral infections transmitted by seminal plasma.

Quality of human spermatozoa: relationship between high-magnification sperm morphology and DNA integrity.

The aim of this work is to establish the relationship between the morphology of Intracytoplasmic Morphologically Selected Sperm Injection (IMSI)-selected spermatozoa and their DNA integrity. The 45 ejaculates were randomly distributed into three treatment groups: normozoospermic, oligoasthenozoospermic and oligoasthenotheratozoospermic samples. The evaluation of DNA integrity was performed using the sperm chromatin dispersion test. It was established that DNA integrity of spermatozoa is strongly dependent on ejaculate quality (P < 0.05). The count of spermatozoa with nonfragmented DNA in normozoospermic samples was high and independent from IMSI-morphological classes (Class 1 versus Class 3, respectively) (P > 0.1). With decreased ejaculate quality, the percentage of spermatozoa with nonfragmented DNA decreased significantly (P < 0.05) independent from morphological class. Nevertheless, the rate of IMSI-selected spermatozoa with fragmented DNA within of Class 1 in normozoospermic (Group 1), in oligoasthenozoospermic (Group 2) and in oligoasthenotheratozoospermic (Group 3) samples was 21.1%, 31.8% and 54.1%, respectively. In conclusion, there is a direct relationship between morphological parameters of spermatozoa and their DNA integrity. However, the IMSI technique alone is not enough for the selection of spermatozoa with intact nuclei.

In vitro perfusion of whole bovine ovaries by freezing medium: effect of perfusion rate and elapsed time after extraction.

BACKGROUND: Cryopreservation and transplantation of the whole ovary with vascular pedicle would be helpful to prevent posttransplantation ischemia. In fact, perfusion of the intact mammalian ovary through arteries and veins is the most technically difficult part of the whole cryopreservation process because of its complexity. It is important to develop the technology of long-time perfusion of intact ovaries by cryoprotectants at low temperatures because it was established earlier that 24-hour cooling to 5 degrees C before cryopreservation is beneficial for the freezing of human ovarian tissue. The aim of this research was to study the effectiveness of perfusion of intact bovine ovaries with different rates of perfusion and elapsed time between extraction of these ovaries and beginning of perfusion. METHODS: Arteria ovarica was cannulated and ovaries were perfused with Leibovitz L-15 medium + 100 IU/mL heparin + 5% bovine calf serum + 6% dimethyl sulfoxide + 6% ethylene glycol + 0.15 M sucrose + Indian ink at room temperature (22 degrees C). In the first cycle of experiments, ovaries (n = 145) were perfused for 60 minutes during 1 to 1.5 hours after extraction of ovaries in the slaughter house at perfusion rates of 150 mL/hour (2.5 mL/minute), 100 mL/hour (1.67 mL/minute), 75 mL/hour (1.25 mL/minute), 50 mL/hour (0.83 mL/minute), 25 mL/hour (0.42 mL/minute), and 12.5 mL/hour (0.21 mL/minute) for groups 1, 2, 3, 4, 5, and 6, respectively. In the second cycle of experiments, ovaries (n = 29) were perfused with a rate of 25 mL/hour (0.42 mL/minute) for 60 minutes during the following time-periods elapsed after extraction of ovaries in the slaughter house: 3 hours (n = 18), 4 hours (n = 5), 5 hours (n = 3), and 6 hours (n = 3) for groups 1, 2, 3, and 4, respectively. Ovaries in luteal and follicular phase of development were distributed randomly into groups. Successful perfusion of blood vessels was detected visibly by a blue coloration of the vascular pedicle and ovarian tissues. The percentage of Indian ink-perfused tissues was detected. The intensity of the vascular leakage and tissue damage was scored microscopically and noted as follows: lack of disruption (-), weak disruption (+), moderate disruption (++), and strong disruption RESULTS: The first cycle of experiments shows that an optimal perfusion rate was established for groups 4 and 5 (50 and 25 mL/hour, respectively). In the second cycle of experiments, good perfusion of ovaries with the perfusion rate of 25 mL/hour was established only for ovaries of group 1 (3 hours after extraction). The effectiveness of perfusion in group 2 (4 hours after extraction) was sharply decreased. CONCLUSIONS: Effective perfusion of bovine intact ovaries with vascular pedicle with freezing medium (6% ethylene glycol + 6% dimethyl sulfoxide + 0.15 M sucrose) at room temperature includes a rate of perfusion 25 or 50 mL/ hour. Ovaries must be perfused no later than 3 hours after the death of animals.

Vitrified sperm banks: the new aseptic technique for human spermatozoa allows cryopreservation at -86 °C.

The vitrification technique is simple, quick, cost-effective and has showed a significantly stronger cryoprotective effect in contrast to conventional freezing. The method is based on the rapid cooling of the cell by direct immersion in liquid nitrogen (LN (2) ), thereby avoiding the formation of ice crystals, due to the lower risk of water thawing, which impairs cell function. The aim of this study was to evaluate the effect of storage at -86 °C compared to the conventional -196 °C (under LN (2) ) on essential parameters of the functioning of aseptically vitrified human sperm. Sperm motility, integrity of mitochondrial membrane potential and the rate of DNA fragmentation were determined. The comparison of -86 °C and -196 °C demonstrated no statistical difference in sperm progressive motility (73% vs. 77%), integrity of mitochondrial membrane potential (71% vs. 74%) or DNA fragmentation (3.1% vs. 2.9%). In conclusion, aseptically vitrified sperm can be preserved at -86 °C; eliminating the use of LN (2) simplifies and significantly reduces the costs associated with storage in sperm banks by decreasing the time and space needed for storage, the effort in finding stored samples, and by improving safety for the operator. However, for prolonged storage further studies are needed.

Long-time cooling of human ovarian tissue before cryopreservation as obvious procedure: stimulation of follicular development and neo-vascularisation.

BACKGROUND: The positive effect of cooling on tissue cells is known. The aim of this research was to study the intensiveness of neo-vascularisation and follicular development in ovarian tissue after 24 hours cooling to 5 degrees C before cryopreservation. METHODS: Fifty six pieces from 7 patients were divided into the following four groups: Group 1: pieces cultured just after operation, Group 2: pieces cooled after operation to 5 degrees C for 24 hours and then cultured, Group 3: pieces frozen-thawed just after operation and then cultured, Group 4: pieces cooled after operation to 5 degrees C for 24 hours, frozen, thawed, and then cultured. Culture of ovarian pieces was performed in a chorioallantoic membrane (CAM)-system for 5 days. The efficacy of the tissue cooling was evaluated by the development of follicles and intensiveness of neo-vascularisation (by Desmin). RESULTS: For Group 1, 2, 3, and 4, mean density of follicles per 1 mm3 was 10.1, 11.1, 9.8, and 12.0, respectively (P1-2, 3-4 < 0.05). For these groups 91%, 92%, 90%, and 90% preantral follicles were morphologically normal (P1-2, 3-4 > 0.1). The immunohistochemical analysis showed that the intensiveness of neo-vascularisation observed in ovarian tissue of Group 2 (pre-cooled before culture) and Group 4 (pre-cooled before cryopreservation) was drastically increased. CONCLUSIONS: The 24 hour cooling to 5 degrees C before cryopreservation is beneficial for cryopreservation of human ovarian tissue.

Vitrification of human ICSI/IVF spermatozoa without cryoprotectants: new capillary technology.

The aim of this study was to develop and to test the standardized aseptic technology of permeable cryoprotectant-free vitrification of human spermatozoa in capillaries (for intracytoplasmic sperm injection [ICSI] or in vitro fertilization [IVF]). To test the effect of vitrification on basic sperm parameters, each of 68 swim-up-prepared ejaculates from oligo-astheno-terato-zoospermic patients were aliquoted and distributed into 3 groups: 1) nontreated control, 2) 10 µL of spermatozoa cryopreserved by slow conventional freezing with glycerol-contented medium, and 3) 10 µL of spermatozoa vitrified in 50-µL plastic capillaries in culture medium with 0.25 M sucrose. Spermatozoa motility (1, 24, and 48 hours after warming), plasma membrane integrity, acrosomal integrity, and spontaneous capacitation-like changes were determined after warming. Aseptic cryoprotectant-free vitrification showed a significantly stronger cryoprotective effect compared with conventional freezing. One hour after warming, motility, plasma membrane integrity, and acrosomal integrity were significantly higher than is observed for conventionally frozen spermatozoa (28% vs 18%, 56% vs 22%, and 55% vs 21%, respectively; P < .05), although lower than in fresh spermatozoa (35%, 96%, and 84%, respectively; P < .05). Capacitation-like changes did not differ significantly between vitrified and conventionally frozen samples (8% vs 9%, respectively; P > .1) (2% in fresh spermatozoa). The newly developed technology of aseptic vitrification of human spermatozoa in capillaries can effectively preserve these cells from cryo-injures. Spermatozoa, vitrified by this technology, are free from seminal plasma owing to swim-up preceding vitrification and are free from permeable cryoprotectants. They are ready for further use immediately after warming without any additional treatment. Therefore, the reported technology has a great potential for use in ICSI/IVF.

Cryoprotectant-free vitrification of fish (Oncorhynchus mykiss) spermatozoa: first report.

The aims of this investigation were to test a novel technology comprising cryoprotectant-free vitrification of the spermatozoa of rainbow trout and to study the ability of sucrose and components of seminal plasma to protect these cells from cryo-injuries. Spermatozoa were isolated and vitrified using three different media: Group 1: standard buffer for fish spermatozoa, Cortland(®) medium (CM, control); Group 2: CM + 1% BSA + 40% seminal plasma; and Group 3: CM + 1% BSA + 40% seminal plasma + 0.125 m sucrose. For cooling, 20-µl suspensions of cells from each group were dropped directly into liquid nitrogen. For warming, the spheres containing the cells were quickly submerged in CM + 1% BSA at 37 °C with gentle agitation. The quality of spermatozoa before and after vitrification was analysed by the evaluation of motility and cytoplasmic membrane integrity with SYBR-14/propidium iodide staining technique. Motility (86%, 81% and 82% for groups 1, 2 and 3, respectively) (P > 0.1) was not decreased significantly. At the same time, cytoplasmic membrane integrity of spermatozoa of Groups 1, 2 and 3 was changed significantly (30%, 87% and 76% respectively) (P < 0.05). All tested solutions can be used for vitrification of fish spermatozoa with good post-warming motility. However, cytoplasmic membrane integrity was maximal in Group 2 (CM + 1% BSA + 40% seminal plasma). In conclusion, this is the first report about successful cryoprotectant-free cryopreservation of fish spermatozoa by direct plunging into liquid nitrogen (vitrification). Vitrification of fish spermatozoa without permeable cryoprotectants is a prospective direction for investigations: these cells can be successfully vitrified with 1% BSA + 40% seminal plasma.

Cryopreservation of Ovarian Tissue: Detailed Description of Methods for Transport, Freezing and Thawing.

Purpose: In many cases cancer therapy leads to an irreversible reduction or even loss of ovarian reserve. Cryopreservation of ovarian tissue with subsequent thawing and re-transplantation of tissue after the cancer is in remission constitutes a promising method to preserve fertility in women. To date, more than 25 cases of live births after re-transplantation of cryopreserved ovarian tissue have been published worldwide. In Germany the first live birth after re-transplantation of cryopreserved tissue was in 2011. Material and Methods: After surgical removal of ovarian tissue in the Gynaecological Clinic of Dresden University, the tissue was sent to the Gynaecological Clinic of Bonn University in a special transport container at 5 °C and was frozen the next day using 1.5 M dimethyl sulfoxide cryosolution. In 2010 this ovarian tissue was thawed using a sucrose solution in the Gynaecological Clinic of Erlangen University Clinical Centre and was laparoscopically re-transplanted into the patient. Results: The patient became pregnant, the pregnancy was uneventful, and she gave birth to a healthy boy. Conclusion: Freezing of ovarian tissue with subsequent re-transplantation as described here is a viable method to preserve fertility in cancer patients.

Cryoprotectant-free vitrification of human spermatozoa in large (up to 0.5 mL) volume: a novel technology.

BACKGROUND: The aim of this study was to develop and to test the aseptic technology of cryoprotectant-free vitrification of human spermatozoa in large volume (for intrauterine insemination). Spermatozoa, vitrified by this technology, are free of permeant cryoprotectants and are ready for further use immediately after warming without any additional treatment (centrifugation or separation in the gradient for removal of cryoprotectant). METHODS: Each of 52 swim up-prepared ejaculates were divided into three aliquots and distributed into three treatment groups: Group 1: non-treated control; Group 2: spermatozoa cryopreserved by slow conventional freezing with glycerol-containing medium, and Group 3: spermatozoa vitrified in 0.5 mL insemination "French" straws in culture medium with 0.25 M sucrose. Sperm motility 1, 24 and 48 hours after warming, plasma membrane integrity and capacitation-like changes (spontaneous "cryo-capacitation" and acrosome reaction) were assessed after freezing-thawing. RESULTS: In contrast to conventional freezing, spermatozoa vitrified with aseptic cryoprotectant-free technology displayed superior functional characteristics. The motility rate, integrity rates of cytoplasmic, and acrosomal membranes were significantly higher after vitrification than after conventional freezing (76% vs 52%, 54% vs 28% and 44% vs 30%, respectively) (p < 0.05). However, there were no differences between vitrification and conventional freezing in the presence of glycerol in terms of percentage of spermatozoa expressing CTC-capacitation pattern (11% vs 10%, respectively) (p > 0.1). CONCLUSIONS: A basic protection from cryo-injury can be achieved for human spermatozoa using the novel technology of aseptic cryoprotectant-free vitrification in large volumes.

Canine sperm vitrification with sucrose: effect on sperm function.

The ability of sucrose to protect spermatozoa against mitochondrial damage, artificial acrosome reaction and DNA fragmentation during ultra-rapid cryopreservation in canine sperm was investigated. Swim-up selected spermatozoa of second-fraction semen were vitrified with different concentrations of sucrose (0.1, 0.25 and 0.4 m) in proportion 1 : 1 v/v with HTF-BSA 1%. From each group, 30-µl suspensions of cells were dropped directly into liquid nitrogen and stored for at least 24 h. Cells were thawed by submerging the spheres in HTF with 1% BSA at 37 °C. The number of progressively motile spermatozoa was significantly higher in the sucrose 0.25 m + HTF-BSA 1% (42.5 ± 2.3%, P < 0.01) than in HTF only (1.66 ± 0.3%). The same combination of sucrose 0.25 m + HTF-BSA 1% (42.7 ± 1.5%) had a stronger cryoprotective effect on the integrity of mitochondrial membrane potential (P < 0.05) and decreased the DNA fragmentation (2.8 ± 0.5%) as compared with HTF only (1.93 ± 0.6% and 5.6 ± 0.6% respectively). With respect to acrosome-reacted spermatozoa, no significant difference was found between the groups investigated (P > 0.05). It is concluded that sucrose, a nonpermeable cryoprotectant, can effectively preserve important physiological parameters such as mitochondrial membrane potential and DNA integrity during ultra-rapid cryopreservation.

Fish (Oncorhynchus mykiss) spermatozoa cryoprotectant-free vitrification: stability of mitochondrion as criterion of effectiveness.

The aim of the present investigations was to test a novel technology comprising cryoprotectant-free vitrification of the spermatozoa of rainbow trout and to study the ability of sucrose and components of seminal plasma to protect these cells from cryoinjuries. Spermatozoa were isolated and vitrified using five different mediums: Group 1: standard buffer for fish spermatozoa, Cortland(®)-medium (CM, control); Group 2: CM+1% bovine serum albumin (BSA); Group 3: CM+1% BSA+0.125 M sucrose; Group 4: CM+1% BSA+40% seminal plasma; and Group 5: CM+1% BSA+40% seminal plasma+0.125 M sucrose. For cooling, 20 µL suspensions of cells from each group were dropped directly into liquid nitrogen. For warming, the spheres containing the cells were quickly submerged in CM+1% BSA at 37 °C with gentle agitation. The quality of spermatozoa before and after vitrification was analysed by the evaluation of motility, cytoplasmic membrane integrity (SYBR-14/propidium iodide staining technique), and mitochondrial membrane integrity (JC-1 staining). Motility (86%, 71%, 80%, 81%, and 82%, for Groups 1, 2, 3, 4, and 5, respectively) and cytoplasmic membrane integrity (90%, 82%, 83%, 84%, and 87%, respectively) of spermatozoa in all the 5 groups were not decreased significantly. All tested solutions can be used for vitrification of fish spermatozoa with good post-warming motility and cytoplasmic membrane integrity. However, mitochondrial membrane potentials of the spermatozoa in Groups 1, 2, 3, 4, and 5 were changed significantly (6%, 50%, 37%, 55%, and 34%, respectively) (P(1,2,3,4,5)<0.001; P(2,3,4,5) <0.01)(P(3-5)>0.1). This rate was maximal in Group 4 (CM+1% BSA+40% seminal plasma). In conclusion, this is the first report about successful cryoprotectant-free cryopreservation of fish spermatozoa by direct plunging into liquid nitrogen (vitrification). Vitrification of fish spermatozoa without permeable cryoprotectants is a prospective direction for investigations: these cells can be successfully vitrified with 1% BSA+40% seminal plasma without significant loss of important physiological parameters.

Epidermal growth factor effects on marmoset monkey (Callithrix jacchus) oocyte in vitro maturation, IVF and embryo development are altered by gonadotrophin concentration during oocyte maturation.

BACKGROUND: This is the first study of the effect of epidermal growth factor (EGF) on marmoset monkey oocytes matured in vitro. METHODS: We have evaluated the effects of 10 ng/ml EGF in combination with 1 or 10 IU/ml of gonadotrophins (FSH/hCG 1:1 ratio) during in vitro maturation (IVM) of marmoset oocytes. Immature cumulus-oocyte complexes (COCs) were retrieved from ovarian antral follicles of unprimed monkeys. COCs from six animals (n= 268) used in this study were randomly distributed among four experimental groups: (A) 1 FSH +1 hCG; (B) 10 FSH +10 hCG; (C) 1 FSH +1 hCG + EGF; and (D) 10 FSH +10 hCG + EGF (where 1 and 10 are concentrations, IU/ml). After IVM, oocytes were fertilized in vitro and embryos were allowed to progress up to 87-88 h. RESULTS: the highest rate of total and radial cumulus expansion was observed in Group A, with the lowest in Group B (P < 0.05). Neither maturation nor fertilization rate were affected by gonadotrophin concentration or presence of EGF. Addition of EGF increased degeneration and decreased first cleavage rate, which was significantly lower in Group C than Group A (P < 0.005). Interestingly, in the EGF groups some embryos cleaved faster than without EGF. CONCLUSIONS: The effects of EGF are highly dependent on concentration of gonadotrophins present in IVM medium. EGF has a negative effect on oocytes in the presence of low gonadotrophins, but contrastingly partially protects oocytes from the negative effects of high gonadotrophins. We propose that these observed negative effects of EGF may suggest use of an inappropriate dose of growth factor.

Human ovarian tissue cryopreservation: quality of follicles as a criteria of effectiveness.

Experiments comparing vitrification and conventional freezing of mammalian ovarian tissue show that vitrification can also guarantee the storage of viable follicles after warming, but conventional freezing is more effective. The central goal of cryotechnology is the preservation of intact follicles. This article presents a critical opinion about the normality of follicles after vitrification of human ovarian tissue and microbial contamination as a result of direct contact of this tissue with liquid nitrogen at vitrification.