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Development of techniques for the preservation and use of gonadal tissues are increasingly needed for the genetic management of the endangered African painted dog (Lycaon pictus). Here we evaluated two cryopreservation techniques for ovarian tissue (2 × 2 × 1 mm3 fragments, n = 11 individuals): needle immersed vitrification (NIV), with equilibration in a 7.5% dimethyl sulfoxide (DMSO) and 7.5% ethylene glycol (EG) solution, and vitrification in a 15% DMSO, 15% EG, and 0.5 M sucrose solution, and slow freezing in cryovials with either the equilibration (SF-E) or vitrification (SF-V) solutions. Following warming, tissues were either fixed and embedded for evaluation of density of morphologically normal follicles, semi-quantitative scoring of stromal cell preservation, and apoptotic index (TUNEL stain), and/or flash-frozen for expression of proliferation (PCNA), apoptosis (CASP3, BCL2), or oxidative stress (GPX3, SOD1, SOD2) pathway genes (n = 4). Needle immersed vitrification maintained higher density of morphologically normal follicles compared to the slow freezing protocols applied (p < 0.05), with no significant changes in expression of select genes among treatment groups. A slight increase in apoptotic index was observed in all cryopreservation groups, but only reached significance in SF-E compared with fresh tissue controls (p < 0.05). Future research should be dedicated to developing improved methods for ovarian tissue culture in the species, both as a means to evaluate the efficacy of tissue cryopreservation techniques and for the production of viable oocytes from banked ovarian tissue in the endangered African painted dog.
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@#Introduction: The cryopreservation of periodontal ligament stem cells (PDLSCs) required a good combination of CPA composition as a step in the preparation of PDLSCs. This study aimed to analyze the proliferative capacities and differentiation potentials of PDLSCs after slow-freezing cryopreservation with CPA in different combinations. Methods: The fourth passage of the primary PDL cells were examined their fibroblast-like morphology and colony forming unit-fibroblast (CFU-F), and characterized by surface markers for mesenchymal stem cells using flow cytometry. PDLSCs were divided into two groups of freshly-PDLSCs (fPDLSCs) and cryopreserved-PDLSCs (cPDLSCs). The PDLSCs were cryopreserved using slow freezing method with CPA in different combinations: 1) 90%FBS+10%DMEM (FD-group), 2) 90%DMEM+10%DMSO (DDs-group), 3) 90%FBS+10%DMSO (FDs-group), and 4) 100% Cell Banker (CB-group) as positive control. The proliferation of fPDLSCs and cPDLSCs were evaluated by trypan blue dye exclusion method. The multipotency of cells was assessed by Oil Red O, Alizarin Red, and Alcian Blue staining. Results: The primary PDL cells had fibroblast-like morphology and CFU-F ability. They expressed more than 95% positive MSC surface markers of CD90, CD73, CD150, and CD44, but showed less than 2% hematopoietic cell markers of CD11b/CD19/CD34/CD45 and HLA-DR. The cPDLSCs viability of FDs-group was 81.5% and 80% in -80oC and LN2, respectively. The fPDLSCs and cPDLSCs proliferation and doubling time were no statistically significant difference (p>0.05). They could differentiate into adipogenic, osteogenic, and chondrogenic differentiation. Conclusion: The cPDLSCs could maintain their proliferative capacities and differentiation potentials after slow-freezing cryopreservation with 90%FBS+10%DMSO in -80oC.
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STUDY QUESTION: Does storage time have any impact on the transcriptome of slowly frozen cryopreserved human metaphase II (MII) oocytes? SUMMARY ANSWER: The length of cryostorage has no effect on the gene expression profile of human MII oocytes. WHAT IS KNOWN ALREADY: Oocyte cryopreservation is a widely used technique in IVF for storage of surplus oocytes, as well as for fertility preservation (i.e. women undergoing gonadotoxic therapies) and oocyte donation programs. Although cryopreservation has negative impacts on oocyte physiology and it is associated with decrease of transcripts, no experimental data about the effect of storage time on the oocyte molecular profile are available to date. STUDY DESIGN, SIZE, DURATION: This study included 27 women, ≤38 years aged, without any ovarian pathology, undergoing IVF treatment. Surplus MII oocytes were donated after written informed consent. A total of 31 non-cryopreserved oocytes and 68 surviving slow-frozen/rapid-thawed oocytes (32 oocytes cryostored for 3 years and 36 cryostored for 6 years) were analyzed. PARTICIPANTS/MATERIALS, SETTING, METHODS: Pools of ≈10 oocytes for each group were prepared. Total RNA was extracted from each pool, amplified, labeled and hybridized on oligonucleotide microarrays. Analyses were performed by R software using the limma package. MAIN RESULTS AND THE ROLE OF CHANCE: Comparison of gene expression profiles between surviving thawed oocytes after 3 and 6 years of storage in liquid nitrogen found no differently expressed genes. The expression profiles of cryopreserved MII oocytes significantly differed from those of non-cryopreserved oocytes in 107 probe sets corresponding to 73 down-regulated and 29 up-regulated unique transcripts. Gene Ontology analysis by DAVID bioinformatics resource disclosed that cryopreservation deregulates genes involved in oocyte function and early embryo development, such as chromosome organization, RNA splicing and processing, cell cycle, cellular response to DNA damage and to stress, DNA repair, calcium ion binding, malate dehydrogenase activity and mitochondrial activity. Among the probes significantly up-regulated in cryopreserved oocytes, two corresponded to ovary-specific expressed large intergenic noncoding (linc)RNAs. LIMITATIONS, REASONS FOR CAUTION: Data validation in a larger cohort of samples would be beneficial, although we applied stringent criteria for gene selection (fold-change >3 or <1/3 and FDR < 0.1). Further research should be undertaken to verify experimentally that the length of cryostorage has no effect on gene expression profile of vitrified/warmed MII oocytes, as well as to include in analyses 'older' frozen oocytes. WIDER IMPLICATIONS OF THE FINDINGS: Confirmation that the length of storage does not alter the gene expression profile of frozen oocytes is noteworthy for the safety issue of long-term oocyte banking, i.e. fertility preservation, gamete donation. STUDY FUNDING/COMPETING INTEREST: This study was supported by a grant of the Italian Ministry of Health (CCM 2012) and by Ferring Pharmaceutical company. The authors have no conflicts of interest to declare.