Dextran vitrification media prevents mucin coat and zona pellucida damage in rabbit embryo

The effect of sucrose supplementation on chondrocyte viability in porcine articular cartilage following vitrification

Vitrification can extend the banking life of articular cartilage (AC) and improve osteochondral transplantation success. Current vitrification protocols require optimization to enable them to be implemented in clinical practice. Sucrose as a non-permeating cryoprotective agent (CPA) and clinical grade chondroitin sulfate (CS) and ascorbic acid (AA) as antioxidants were investigated for their ability to improve a current vitrification protocol for AC. The aim of this study was to assess the impact of sucrose and CS/AA supplementation on post-warming chondrocyte viability in vitrified AC. Porcine osteochondral dowels were randomly vitrified and warmed with one established protocol (Protocol 1) and seven modified protocols (Protocols 2-8) followed by chondrocyte viability assessment. Sucrose supplementation in both vitrification and warming media (Protocol 4) resulted in significantly higher (p = 0.018) post-warming chondrocyte viability compared to the protocol without sucrose (Protocol 1). There was no significant difference (p = 0.298) in terms of post-warming chondrocyte viability between sucrose-supplemented DMEM + CS solution (Protocol 4) and Unisol-CV (UCV) + CS (Protocol 6) solution. Clinical grade CS and AA contributed to similar post-warming chondrocyte viability to previous studies using research grade CS and AA, indicating their suitability for clinical use. The addition of an initial step (step 0) to reduce the initial concentration of CPAs to minimize osmotic effects did not enhance chondrocyte viability in the superficial layer of AC. In conclusion, sucrose-supplemented DMEM + clinical grade CS (Protocol 4) could be an ideal protocol to be investigated for future use in clinical applications involving vitrified AC.

Evaluation of dextran for rabbit sperm cryopreservation: Effect on frozen-thawed rabbit sperm quality variables and reproductive performance

Effects were analysed of dextran supplementation to Me₂SO and acetamide rabbit semen freezing extenders on quality characteristics of rabbit spermatozoa and reproductive performance. The final concentration of cryoprotectants in pooled semen samples was 12.4 % Me₂SO for the A extenders, 10.7 % Me₂SO and 2.9 % acetamide for the D extenders and 8.9 % Me₂SO and 2.9 % acetamide in F extenders, with a supplementation of 1.7 % sucrose in all cases. There was not inclusion of dextran in the A0, D0, F0; while 5 % dextran was included in A5, D5, F5 and 10 % dextran in A10, D10 and F10 extenders. Sperm motility and viability rates were similar with use of the different extenders. Acrosome integrity after the freeze-thawing processes, however, was markedly greater when there was dextran supplementation of D and F extenders. Prolificacy was affected by extender composition. When there was artificial insemination (AI) using semen cryopreserved in the A extenders, number of kits born was similar to when there was AI with fresh semen when there was inclusion of 5% dextran for cryopreservation, while there was no effect on prolificacy when there was cryopreservation of semen using the D and F extenders. In conclusion, dextran supplementation of extenders containing Me₂SO and acetamide resulted in greater acrosome integrity. Furthermore, when there was AI using sperm preserved in cryo-diluents containing an intermediate concentration of Me₂SO, combined with inclusion of 5 % dextran, there was a marked beneficial effect on rabbit doe reproductive performance.

Review of non-permeating cryoprotectants as supplements for vitrification of mammalian tissues

Vitrification of mammalian tissues is important in the areas of human assisted reproduction, animal reproduction, and regenerative medicine. Non-permeating cryoprotectants (CPAs), particularly sucrose, are increasingly used in conjunction with permeating CPAs for vitrification of mammalian tissues. Combining non-permeating and permeating CPAs was found to further improve post-thaw viability and functionalities of vitrified mammalian tissues, showing the potential applications of such tissues in various clinical and veterinary settings. With the rising demand for the use of non-permeating CPAs in vitrification of mammalian tissues, there is a strong need for a timely and comprehensive review on the supplemental effects of non-permeating CPAs toward vitrification outcomes of mammalian tissues. In this review, we first discuss the roles of non-permeating CPAs including sugars and high molecular weight polymers in vitrification. We then summarize the supplemental effects of non-permeating CPAs on viability and functionalities of mammalian embryos, and ovarian, testicular, articular cartilage, tracheal, and kidney tissues following vitrification. Lastly, challenges associated with the use of non-permeating CPAs in vitrification of mammalian tissues are briefly discussed.

The harmful effect of removing the extracellular vitrification medium during embryo cryopreservation using a nylon mesh device in rabbit

During the last decades, many techniques have been developed to reduce sample volume and improve cooling and warming rates during embryo vitrification. The vast majority are based on the "minimum drop size" concept, in which the vitrification solution around embryos is reduced by aspiration, leaving a tiny part of volume surrounding embryos. However, novel cryodevices were aimed to remove the entire vitrification solution. This study was designed to compare the "minimum drop size" technique using Cryotop® with the nylon mesh as cryodevice on rabbit morula embryos. The outcomes assessed were the in vitro development rates (experiment 1) and the offspring rates at birth (experiment 2). Embryos were vitrified in a two-step procedure; equilibrium (10% EG + 10% Me2SO) for 2 min and vitrification (20% EG + 20% Me2SO) for 1 min. In experiment 1, embryos (n = 323) were warmed and subsequently in vitro cultured for 48 h to assess the embryo developmental capability to reach the hatching-hatched blastocyst stage. In experiment 2, embryos were transferred using the laparoscopic technique (n = 369) to assess the offspring rate at birth. In this context, rates of in vitro embryo development were similar between vitrified groups (0.73 ± 0.042% and 0.66 ± 0.047% for Cryotop® and nylon mesh device, respectively), but lower than in the fresh group (0.97 ± 0.016%, p < 0.05). In experiment 2, there were no significant differences in survival rates (offspring born/total embryos transferred) among the Cryotop® device group and fresh group (0.41 ± 0.049% and 0.49 ± 0.050%, respectively). But significantly lower value was obtained in the nylon mesh device group (0.18 ± 0.030%). These results indicate that nylon mesh is not suitable as cryodevice for rabbit morula vitrification, remaining those using the "minimum drop size" methodology as the best option.