The effect of cryopreservation media on the quality of ß-thalassemia mouse spermatozoa.

Background: The mouse model of human diseases is commonly used for biomedical study, including ß-thalassemia (ß-thal), an inherited hemoglobin disorder. Maintaining the mice strain by natural mating systems is costly and seems impractical, especially during the COVID-19 pandemic. Sperm-freezing is a cost-effective solution for ß-thal mouse colony management. Aim: To determine appropriate cryopreservation media for ß-thal mouse spermatozoa to establish a ß-thal mouse sperm bank. Methods: The epididymal spermatozoa of C57BL/6 wild-type (WT) and ß-globin gene knockout thalassemia (BKO) mice were frozen in four freezing media: I) raffinose-skim milk-monothioglycerol (MTG), II) raffinose-skim milk-glutamine, III) raffinose-egg yolk-glycerol, and IV) egg yolk-TES-Tris. The sperm quality was assessed prior to and following freeze-thawing. Results: Compared with WT counterparts, the viable spermatozoa before freezing exhibiting elevated levels of oxidative stress were significantly greater in BKO (p = 0.01). After thawing, the membrane integrity of BKO spermatozoa preserved in I was significantly lower (p = 0.001). The sperm viability and membrane integrity of BKO males were also inferior when media III and IV were used (p = 0.008-0.027). The amount of oxidative stress in the spermatozoon of BKO mice was significantly greater when preserved in I, III, and IV (p = 0.002-0.044). Comparing freezing media, the motility and acrosome integrity of WT and BKO spermatozoa preserved in IV were significantly higher than those in other media (p < 0.001 to p = 0.01). Spermatozoa with the highest mitochondrial membrane potential were observed in I in both genotypes (p = 0.012 to p > 0.05). The viability, membrane integrity, and oxidative stress of post-thaw BKO spermatozoa did not significantly differ among freezing solutions. Conclusion: Irrespective of freezing media, spermatozoa of BKO males are rather more sensitive to cryopreservation than those of WT. Raffinose-skim milk-MTG/glutamine, raffinose-egg yolk-glycerol, and egg yolk-TES-Tris can all be used to preserve BKO mouse spermatozoa. However, with slightly better sperm characteristics, egg yolk-TES-Tris may be a diluent of choice for BKO mouse sperm cryopreservation. The addition of a reducing agent to thawing media is also strongly recommended to efficiently prevent oxidative stress and therefore improve frozen-thawed sperm survival.

Missing and overexpressing proteins in domestic cat oocytes following vitrification and in vitro maturation as revealed by proteomic analysis.

BACKGROUND: The domestic cat serves as an animal model for assisted reproductive studies of endangered felid species. To date, there are no data on the protein alterations following cryopreservation of oocytes in felid family. METHODS: Immature (germinal vesicle) domestic cat oocytes were vitrified in the vitrification solution containing 35% ethylene glycol, 20% DMSO and 0.5 mM sucrose. The vitrified-warmed oocytes were matured (metaphase II) in vitro and subjected to proteomic analysis using 1DE SDS-PAGE prefractionation combined with LC-MS/MS. RESULTS: A total of 1712 proteins were identified in in vitro matured oocytes. Of the 1712 proteins, 1454 proteins were found in both groups, whereas, 258 proteins were differentially expressed between control and vitrified-warmed groups. In vitrified-warmed oocytes, the missing proteins were membrane and nuclear proteins; whereas, apoptosis and DNA repair proteins were overrepresented. CONCLUSIONS: The identified missing and overexpressed proteins in vitrified-warmed oocytes represent potential markers of cryoinjuries and the developmental pathways of oocytes. The findings of differential expressed proteins may contribute to effective ways of proteome analysis of oocyte/embryo quality in order to assess safety of cryopreservation in felid species.

Missing and overexpressing proteins in domestic cat oocytes following vitrification and in vitro maturation as revealed by proteomic analysis

BACKGROUND: The domestic cat serves as an animal model for assisted reproductive studies of endangered felid species. To date, there are no data on the protein alterations following cryopreservation of oocytes in felid family. METHODS: Immature (germinal vesicle) domestic cat oocytes were vitrified in the vitrification solution containing 35% ethylene glycol, 20% DMSO and 0.5 mM sucrose. The vitrified-warmed oocytes were matured (metaphase II) in vitro and subjected to proteomic analysis using 1DE SDS-PAGE prefractionation combined with LC-MS/MS. RESULTS: A total of 1712 proteins were identified in in vitro matured oocytes. Of the 1712 proteins, 1454 proteins were found in both groups, whereas, 258 proteins were differentially expressed between control and vitrified-warmed groups. In vitrified-warmed oocytes, the missing proteins were membrane and nuclear proteins; whereas, apoptosis and DNA repair proteins were overrepresented. CONCLUSIONS: The identified missing and overexpressed proteins in vitrified-warmed oocytes represent potential markers of cryoinjuries and the developmental pathways of oocytes. The findings of differential expressed proteins may contribute to effective ways of proteome analysis of oocyte/embryo quality in order to assess safety of cryopreservation in felid species.

The scorpion venom peptide BmKn2 induces apoptosis in cancerous but not in normal human oral cells.

AIM: This study aimed to investigate the mechanism of the induction of apoptosis of human oral cancer cells by the scorpion venom peptide BmKn2. METHODS: Human oral squamous carcinoma cells (HSC4), mouth epidermoid carcinoma cells (KB), human normal gingival cells (HGC) and dental pulp cells (DPC) were treated with BmKn-2 peptide for 24h. Cell viability was determined by the MTT assay. Apoptosis was assessed using phase contrast microscopy, by propidium iodide (PI) staining to assess nuclear morphology and by Annexin V staining. Apoptotic signaling pathways were investigated by quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and Western blotting. RESULTS: BmKn-2 showed potent cytotoxic effects towards both HSC4 and KB cells with the associated induction of apoptosis. The cells showed distinct morphological changes, nuclear disintegration and an increase in the number of Annexin V-positive cells. Interestingly, at concentrations which kill cancerous cells, BmKn-2 did not affect cell viability or mediate the induction of apoptosis in normal HGC or DPC. Induction of apoptosis by BmKn-2 in HSC4 and KB cells was associated with the activation of tumor suppress p53. Pro-apoptotic BAX expression was increased, whereas antiapoptotic BCL-2 expression was decreased in BmKn-2 exposed HSC4 and KB cells. BmKn-2 treated-oral cancer cells showed distinct upregulation of initiator caspase-9, with no effect on caspase-8 expression. Increased expression levels of executor caspases-3 and -7 were also found in treated cells for both oral cancers. CONCLUSION: This study has suggested for the first time that BmKn-2 exerts selective cytotoxic effects on human oral cancer cells by inducting apoptosis via a p53-dependent intrinsic apoptotic pathway. BmKn-2 peptide originally derived from a natural source shows great promise as a candidate treatment for oral cancer, with minimal effects on healthy tissue.