Role of astaxanthin as an efficient antioxidant on the in vitro maturation and vitrification of porcine oocytes.

As one of the most powerful natural antioxidants, astaxanthin (Ax) has begun to be applied to the field of reproductive biology. Here we used porcine oocyte as a model to explore how Ax improves the oocyte potential during in vitro maturation (IVM), and we also investigated the cytoprotective effects of Ax on the vitrified oocytes. Ax supplementation (final concentration of 2.5 µM) was subjected for immature oocytes during vitrification and subsequent IVM; fresh oocytes were also matured in vitro in the presence or absence of 2.5 µM Ax. Our results showed that Ax significantly increased the survival rate of vitrified oocytes, and promoted the blastocyst yield of both fresh and vitrified oocytes after parthenogenetic activation and somatic cell nuclear transfer. The oocytes treated with Ax displayed significantly lower reactive oxygen species generation and higher glutathione level. Vitrification of oocytes had no impact on caspase-3, cathepsin B and autophagic activities; Ax significantly decreased the cathepsin B activity in both fresh and vitrified oocytes. Moreover, the relative fluorescence intensity of lysosomes was significantly increased in vitrified oocytes, which was recovered by Ax treatment. The mitochondrial activity did not differ between fresh and vitrified oocytes, and was significantly enhanced in Ax-treated oocytes. Furthermore, Ax significantly restored the decreased expression of BMP15, ZAR1, POU5F1, GPX4 and LAMP2 genes in vitrified oocytes. Both fresh and vitrified oocytes treated with Ax showed significantly higher mRNA levels of GDF9, POU5F1, SOD2, NRF2 and ATG5. Taken together, this study provides new perspectives in understanding the mechanisms by which Ax improves the developmental competence of both fresh and vitrified porcine oocytes.

Inhibitory effects of astaxanthin on postovulatory porcine oocyte aging in vitro.

Mammalian oocytes represent impaired quality after undergoing a process of postovulatory aging, which can be alleviated through various effective ways such as reagent treatment. Accumulating evidences have revealed the beneficial effects of astaxanthin (Ax) as a potential antioxidant on reproductive biology. Here, porcine matured oocytes were used as a model to explore whether Ax supplement can protect against oocyte aging in vitro and the underlying mechanism, and therefore they were cultured with or without 2.5 µM Ax for an additional 24 h. Aged oocytes treated with Ax showed improved yield and quality of blastocysts as well as recovered expression of maternal genes. Importantly, oxidative stress in aged oocytes was relieved through Ax treatment, based on reduced reactive oxygen species and enhanced glutathione and antioxidant gene expression. Moreover, inhibition in apoptosis and autophagy of aged oocyte by Ax was confirmed through decreased caspase-3, cathepsin B and autophagic activities. Ax could also maintain spindle organization and actin expression, and rescue functional status of organelles including mitochondria, endoplasmic reticulum, Golgi apparatus and lysosomes according to restored fluorescence intensity. In conclusion, Ax might provide an alternative for ameliorating the oocyte quality following aging in vitro, through the mechanisms mediated by its antioxidant properties.

TMT-based quantitative proteomic analysis of cumulus cells derived from vitrified porcine immature oocytes following in vitro maturation.

As the immature oocytes are submitted to cryopreservation, their surrounding cumulus cells (CCs) will inevitably suffer, which may have some adverse effects on subsequent oocyte maturation and development. So far, little is known about the molecular differences in CCs of immature oocytes after vitrification. The aim of this study therefore was to analyze the protein profile of CCs derived from vitrified porcine immature oocytes following in vitro maturation, using TMT-based quantitative proteomic approach. A total of 5910 proteins were identified, and 88 of them presented significant difference, with 46 up-regulated and 42 down-regulated proteins. Gene Ontology enrichment analysis revealed that cell cycle phase transition, mitotic cell cycle phase transition, positive regulation of cell differentiation and regulation of oogenesis were significantly down-regulated within the biological process. After Kyoto Encyclopedia of Genes and Genomes pathway analysis, some up-regulated proteins were significantly enriched in TGF-beta signaling pathway and 4 pathways related to steroid hormones. Furthermore, 10 selected proteins were quantified and verified by a parallel reaction monitoring technique, indicating a high reliability of the TMT results. In conclusion, vitrification affects protein profile of CCs as well as their biological functions, which will offer a new perspective to understand the reasons for decline in maturation quality of vitrified immature oocytes.

Quality of vitrified porcine immature oocytes is improved by coculture with fresh oocytes during in vitro maturation.

It is essential to enhance the in vitro maturation (IVM) condition for immature oocytes after cryopreservation, particularly if limited numbers of oocytes collected from specific donors. The objective of this study was to determine if quality of vitrified porcine immature oocytes was enhanced by coculturing with fresh oocytes during IVM. To distinguish fresh versus vitrified oocytes, we used two types of coculture systems: (a) transwell two-chamber coculture; (b) labeling and tracing fresh oocytes with CellTracker™ Green CMFDA during conventional culture. Coculture systems significantly accelerated meiotic progression of vitrified oocytes and significantly increased blastocyst formation rates following parthenogenetic activation and somatic cell nuclear transfer. Reactive oxygen species generation in vitrified oocytes was ameliorated by the coculture conditions, with no significant difference between fresh and vitrified oocytes for intracellular glutathione level. Both coculture systems significantly increased rate of normal mitochondrial distribution in vitrified oocytes, but did not affect fluorescence intensity of mitochondria. The percentage of oocytes with normal endoplasmic reticulum (ER) distribution and ER fluorescence intensity were significantly higher in vitrified oocytes cocultured with fresh oocytes. After 20 hr of IVM, mRNA expression of COX2, HAS2, PTX3, and TNFAIP6 remained significantly higher in cumulus cells derived from vitrified oocytes and coculture systems significantly decreased the expression of these genes. Additionally, coculture methods prevented the reduction of mRNA expression for BMP15, ZAR1, POU5F1, and DNMT3A in vitrified oocytes. In conclusion, oocyte quality and subsequent embryo development of vitrified porcine immature oocytes were significantly improved by fresh oocyte coculture during IVM.

Transcriptome analysis of porcine immature oocytes and surrounding cumulus cells after vitrification and in vitro maturation.

Cryopreservation impairs oocyte quality, which may be associated with abnormal gene expression. Currently, alteration of mRNA levels in vitrified porcine oocytes has not been well characterized. The aim of this study was to analyze transcriptome profiles with RNA sequencing (RNA-seq) in porcine immature oocytes and their surrounding cumulus cells (CCs) after vitrification and in vitro maturation (IVM). There were 19 upregulated and 18 downregulated genes differentially expressed in vitrified oocytes, with no significant GO enrichment or KEGG pathway identified for these genes. In addition, CCs derived from vitrified oocytes had 40 significantly upregulated and 100 significantly downregulated genes. In total, 7 GO terms were significantly enriched in molecular function and biological process, and only MAPK signaling pathway reached significant enrichment based on KEGG analysis. Moreover, selected differentially expressed genes had similar expression patterns through comparison between results from qRT-PCR and RNA-Seq. In conclusion, our data provided detailed information on mRNA transcriptomes in porcine immature oocytes and CCs after vitrification and IVM, which offered now insights regarding reduced developmental potential of the vitrified oocytes.

Effect of Knockout Serum Replacement During Postwarming Recovery Culture on the Development and Quality of Vitrified Parthenogenetic Porcine Blastocysts.

The postwarming recovery culture, as one of the steps in cryopreservation process, is directly correlated with the survival and quality of embryos. Generally, recovery medium includes undefined serum or serum components that may cause the instability of results and other problems. The objective of this study was to evaluate the effect of knockout serum replacement (KSR) as a substitute for serum during recovery culture on the development and quality of vitrified parthenogenetic porcine blastocysts. Fetal bovine serum (FBS) was used as a positive control. The expanded blastocysts on day 5 were vitrified by the Cryotop method, and recovered with 10% (v/v) KSR or 10% (v/v) FBS for 48 hours after warming. Survival and hatching rates of vitrified blastocysts were significantly increased by KSR or FBS supplementation. The vitrified blastocysts recovered in KSR or FBS exhibited significantly decreased percentages of membrane damage and apoptosis, and increased total cells. Addition of KSR or FBS during recovery culture significantly reduced reactive oxygen species levels, and improved mitochondrial activity and adenosine triphosphates content in the vitrified blastocysts. Vitrification did not affect the gene expression of PCNA, CDX2, and CPT1, but significantly increased mRNA levels of POU5F1 and uPA. KSR added to the recovery medium significantly upregulated mRNA levels of PCNA and CPT1, and downregulated POU5F1 mRNA levels. The expression levels of PCNA, CDX2, CPT1, and uPA in vitrified blastocysts were significantly upregulated by addition of FBS to recovery medium. Moreover, the BAX: BCL2L1 ratio was similar between fresh and vitrified blastocysts, and KSR or FBS supplementation had no effect on the value. In conclusion, our data showed that KSR supplementation during recovery culture can improve the development and quality of vitrified parthenogenetic porcine blastocysts. These findings provide a useful reference that KSR could be used to replace FBS as a defined serum supplement for recovery culture of vitrified blastocysts.

The Replacement of Monosaccharide by Mannitol or Sorbitol in the Freezing Extender Enhances Cryosurvival of Ram Spermatozoa.

In this study, the protective effects of monosaccharides (glucose and fructose) and sugar alcohols (mannitol, sorbitol, and xylitol) on frozen ram spermatozoa were evaluated and compared. The motility, moving velocity, and hypoosmotic swelling capability of spermatozoa frozen with monosaccharide or sugar alcohol were measured using a computer-assisted spermatozoa analyzer system. The acrosome status, membrane integrity, distribution of phosphatidylserine (PS), and mitochondrial membrane potential (MMP) were analyzed using fluorescence staining and flow cytometry. The results indicated that similar to glucose or fructose, the presence of sugar alcohol in the freezing extender cannot significantly improve the motility and moving velocity of ram spermatozoa equilibrated at 5°C. In terms of motility, pathway velocity, curve velocity, hypoosmotic swelling capability, acrosome and membrane integrity, and MMP, the inclusion of mannitol or sorbitol in the extender can significantly improve the quality of frozen-thawed ram spermatozoa compared to glucose or fructose. However, the effects of mannitol or sorbitol on linear velocity and PS distribution of frozen-thawed spermatozoa were similar to those of the monosaccharides (p > 0.05). In addition, the ability of xylitol to protect acrosome and maintain MMP in frozen-thawed spermatozoa was significantly higher compared with glucose or fructose (p < 0.05), although it could not improve the other evaluated parameters. Finally, there is no significant difference existing between mannitol and sorbitol with respect to the above evaluated parameters. In conclusion, the replacement of glucose or fructose by mannitol or sorbitol in a freezing extender can improve the postthaw quality of ram spermatozoa under specific freezing conditions. Moreover, the protective effects of mannitol and sorbitol on frozen-thawed ram spermatozoa are superior to that of xylitol. However, in the presence of sugar alcohols, the cryoinjury on spermatozoa membrane is still serious. In the future, the question of protecting the membrane of frozen-thawed spermatozoa needs further research.

Cryotop vitrification of porcine parthenogenetic embryos at the early developmental stages.

The objective of this study was to evaluate the effects of early developmental stages at which Cryotop vitrification is performed on subsequent survival and in vitro development of porcine parthenogenetic activation embryos. The zygotes that were cultured for 4, 8, and 18 hours post electric activation (h.p.a.) and two- and four-cell embryos were vitrified, warmed, and continuously cultured for the remaining period. The zygotes vitrified at 4, 8, and 18 h.p.a. showed similar percentages of survival, cleavage, and blastocyst formation. No difference in viability was observed after vitrification of two- and four-cell embryos, but the embryos vitrified at the two-cell stage exhibited significantly higher blastocyst formation rate than those vitrified at the four-cell stage. However, vitrifying embryos resulted in significantly decreased survival and development rates, regardless of the developmental stage of the embryos. In addition, the final developmental stage, diameter, apoptotic index, and the number of inner cell mass, trophectoderm, and total cells of blastocysts derived from embryos vitrified at any stage of the early culture were similar to those of fresh blastocysts. In conclusion, our data indicate that the early-stage porcine parthenogenetically activated embryos including the zygote, two cells, and four cells have a high ability to survive cryopreservation; these viable embryos after vitrification can produce respectable development rates and good-quality blastocysts.

Meiotic maturation and developmental capability of ovine oocytes at germinal vesicle stage following vitrification using different cryodevices.

In order to assess effects of vitrification on ovine oocytes at the germinal vesicle (GV) stage, the conventional plastic straw (CS), the open-pulled straw (OPS), and Cryoloop were used to vitrify ovine oocytes. Oocytes were randomly divided into five groups: (1) Control; (2) Oocytes exposed to vitrification and dilution solutions without any cryopreservation (toxicity); (3) Oocytes vitrified using CS (CS); (4) Oocytes vitrified using OPS (OPS), and (5) Oocytes vitrified using Cryoloop (Cryoloop). The viability, cumulus cell expansion, nuclear maturation after in vitro maturation (IVM), and developmental capability of vitrified oocytes following parthenogenetic activation (PA) or in vitro fertilization (IVF) were assessed. The pretreatment in the vitrification and dilution solutions without any freezing or thawing did not adversely influence oocytes. The viability of vitrified oocytes were significantly declined compared to unfrozen oocytes (P < 0.05). The viability of oocytes vitrified using open-pulled straws or Cryoloop was significantly higher than that in the CS group (P < 0.05). After IVM, the percentage of oocytes reaching to the metaphase II (MII) stage was significantly higher with Cryoloop and OPS following by CS. However, the in vitro maturing percentage of vitrified oocytes was significantly less than that of unfrozen oocytes (P < 0.05). After PA, the developmental capability of vitrified oocytes was significantly decreased compared to unfrozen oocytes. The cleavage rate of oocytes vitrified using conventional plastic straws was significantly less than those of the other freezing groups (P < 0.05). The cleaving capability of oocytes vitrified using Cryoloop was significantly increased compared to the OPS group. However, there was no significant difference existing amongst the freezing groups as concerning the blastocyst rate. Following IVF, the developmental capability of vitrified oocytes was severely damaged compared to that of unfrozen oocytes. The cleavage rate of oocytes vitrified with Cryoloop was similar to that of oocytes vitrified with open-pulled straws. However, the cleavage rate of vitrified oocytes in the CS group was significantly less than that in the OPS or Cryoloop group (P < 0.05). None of oocytes vitrified using conventional plastic straw developed to the blastocyst stage following IVF. There was no significant difference existing between OPS and Cryoloop with respect to the blastocyst rate. After staining with cFDA and PI, cumulus cells surrounding oocytes were partly damaged by vitrification and thawing while the membrane of vitrified oocyte still remained intact. In conclusion, vitrification can seriously damage ovine immature oocytes and cumulus cells surrounding oocytes, which may subsequently affect their developmental capability. Finally, this study further proves that increasing the freezing and thawing velocity benefits survival of vitrified immature oocytes.

Effects of Hoechst33342 staining on the viability and flow cytometric sex-sorting of frozen-thawed ram sperm.

Cytometric sorting of frozen-thawed sperm can overcome difficulties caused by the unavailability of sorting facilities on farms where semen is collected from male livestock. In order to optimize the cytometric sex-sorting procedure, effects of Hoechst33342 staining on the viability and cytometric sorting efficiency of frozen-thawed ram sperm were evaluated. The frozen-thawed sperm were stained with Hoechst33342 at various dye concentrations (80 µM, 120 µM, 160 µM, 200 µM, 240 µM, or 320 µM) for 45 min to evaluate effects of dye dose. The frozen-thawed sperm were stained with 160 µM Hoechst33342 for various durations (0 min, 15 min, 30 min, 45 min, 60 min, 75 min, or 90 min) to evaluate effects of staining duration. Sperm motility and moving velocity were analyzed using a computer-assisted sperm analysis system (CASAS). Acrosome status, membrane integrity, and distribution of phosphatidylserine (PS) in Hoechst33342-stained sperm were analyzed using flow cytometry after staining with fluorescein isothiocyanate-labeled lectin from pisum sativum (FITC-PSA), Annexin V, or propidium iodide (PI). The fertility of Hoechst33342-stained sperm was analyzed by in vitro fertilization (IVF). A high-speed cell sorter was used to evaluate effects of Hoechst33342 staining on cytometric sex-sorting of frozen-thawed sperm. The motility, moving velocity, membrane integrity, and PS distribution of Hoechst33342-stained sperm were significantly different from that of immediately thawed sperm (P<0.05). However, there is no significant difference existing among the Hoechst33342-stained groups with respect to the above evaluated parameters. Additionally, along with the staining durations, the adverse effects of the staining procedure on sperm showed a steady increase. However, Hoechst33342 staining did not damage acrosome and in vitro fertilizing capability of frozen-thawed ram sperm. Results of cytometric sorting indicated that frozen-thawed sperm can be efficiently sorted into two sperm populations with X and Y chromosome when the Hoechst33342 concentration was 160 µM. Moreover, when the staining duration was equal to or longer than 45 min, the frozen-thawed sperm can be successfully sorted in the presence of 160µM Hoechst33342. In conclusion, Hoechst33342 staining can detrimentally influence viability of frozen-thawed ram sperm except acrosome and in vitro fertilizing capability. Accordingly, the minimum values of Hoechst33342 concentration and staining duration can be set at 160 µM and 45 min respectively. However, the maximum values of Hoechst33342 concentration and staining duration were not determined based on the current study. Further research on how to reduce injuries caused by freezing, thawing, and Hoechst33342 staining on frozen-thawed ram sperm is needed.

Primordial follicle assembly was regulated by Notch signaling pathway in the mice.

Notch signaling pathway, a highly conserved cell signaling system, exists in most multicellular organisms. The objective of this study was to examine Notch signaling pathway in germ cell cyst breakdown and primordial follicle formation. The receptor and ligand genes of Notch pathway (Notch1, Notch2, Jagged1, Jagged2 and Hes1) were extremely down-regulated after newborn mouse ovaries were cultured then exposed to DAPT or L-685,458 in vitro (P < 0.01). Since DAPT or L-685,548 inhibits Notch signaling pathway, the expression of protein LHX8 and NOBOX was significantly reduced during the formation of the primordial follicles. Down-regulated mRNA expression of specific genes including Lhx8, Figla, Sohlh2 and Nobox, were also observed. The percentages of female germ cells in germ cell cysts and primordial follicles were counted after culture of newborn ovaries for 3 days in vitro. The result showed female germ cells in cysts was remarkably up-regulated while as the oocytes in primordial follicles was significantly down-regulated (P < 0.05). In conclusion, Notch signaling pathway may regulate the formation of primordial follicle in mice.

Establishment and cryopreservation of a skin fibroblast cell line derived from Yunnan semi-fine wool sheep in the presence of synthetic ice blocker.

In this study, the fibroblasts cell line derived from ear marginal tissue of Yunnan semi-fine wool sheep was successfully established using the primary explants technique and cryopreservation technology. Additionally, the protective effect of synthetic ice blocker (SIB) including 1, 3-cyclohexanediol (1, 3-CHD) and 1, 4-cyclohexanediol (1, 4-CHD) on frozen fibroblast cells was also assessed and compared. Propidium iodide (PI) was used to stain the dead cells following cryopreservation and thawing. The results showed that compared with Medium 199 (M199) and Dulbecco's modified Eagle's medium : Nutrient Mixture F-12 (1 : 1) Mixture (DMEM/F12), Dulbecco's modified Eagle's medium (DMEM) may be more suitable for the primary culture of fibroblast cells of Yunnan semi-fine wool sheep. The growth curve of cells is a typical "S" type. After subculture for four days, the cells entered the plateau phase and began to degenerate. Biological analysis showed that the population doubling time (PDT) for subculturing fibroblast cells was approximately 26h. The Karyotyping data indicated that the percentage of fibroblast cells with normal chromosome number 2n = 54 was over 90% following subculture for 10 passages. Moreover, the tests for bacteria, fungi, viruses and mycoplasma were negative. After serial subculture for 5 generations, the fibroblast cells were cryopreserved in the presence or absence of 1, 3-CHD or 1, 4-CHD. The data indicated that with increase of the synthetic ice blocker concentrations, the viability of frozen-thawed fibroblast cells was firstly increased and then decreased. When the concentration of 1, 3-CHD or 1, 4-CHD was 50 mM, the viable percentage of frozen-thawed fibroblast cells was 91.93% +/- 2.24% and 94.13% +/- 0.55% respectively and significantly higher than that of the cells frozen in the absence of synthetic ice blockers (88.10% +/- 1.49%, P < 0.05). In conclusion, the skin fibroblast cell line of Yunnan semi-fine wool sheep was firstly established in this study. Additionally, the presence of synthetic ice blocker can increase the viability of frozen-thawed sheep fibroblast cell line.

The effects of trehalose and sucrose on frozen spermatozoa of Yunnan semi-fine wool sheep during a non-mating season.

To improve the quality of frozen spermatozoa of Yunnan semi-fine wool sheep, the protective effect of trehalose and sucrose on frozen ram spermatozoa during a non-mating season was evaluated and compared in this study. Briefly, following collection by electric stimulation, equilibration at degree C following dilution with the freezing extender, and pre-freezing in liquid nitrogen vapor, the ram spermatozoa were frozen in liquid nitrogen. After thawing, viability, motility, acrosome status, membrane integrity, and phosphatidylserine (PS) distribution was determined using a computer-assisted spermatozoa analysis system and flow cytometry. The data indicated disaccharide can improve the quality of frozen ram spermatozoa. With a trehalose concentration of 100mM, the post-thaw viability and motility (80.56 +/- 6.89% and 46.07 +/- 5.84 %) of ram spermatozoa were significantly more than those of ram spermatozoa frozen with no disaccharide (65.46 +/- 18.96 % and 34.62 +/- 9.32%, P<0.05). However, the effect of sucrose on the viability, motility, and moving velocity of ram spermatozoa was similar to that of the control group (p > 0.05). Compared with sucrose, trehalose can significantly increase the motility of frozen ram spermatozoa (p<0.05). In addition, addition of trehalose or sucrose can efficiently protect the acrosome of frozen spermatozoa. Moreover, when the concentration of trehalose or sucrose was 100mM, the protective effect of trehalose or sucrose on the membrane integrity and PS distribution was significantly higher than that of the control group (p>0.05). However, the protective effect of trehalose on viability, moving velocity, acrosome status, membrane integrity, and PS distribution of frozen ram spermatozoa was similar to that of sucrose (p>0.05). In conclusion, the protective effect of trehalose on frozen sheep spermatozoa is superior to that of sucrose. Addition of 100mM of trehalose in the freezing extenders can improve the post-thaw quality of ram spermatozoa with respect to viability, motility, and linear velocity. Moreover, presence of disaccharide can protect acrosome and membrane of frozen sheep spermatozoa.

[Effects of loaded buffer with epigallocatechin gallate on physiological functions of platelets].

This study was aimed to explore the change of aggregation and activation of platelets loaded with epigallocatechin gallate (EGCG). The platelets were treated by loading buffer with different concentrations of EGCG (0, 2.5, 5, 7.5, 10, 12.5, 15, 20 and 30 mmol/L) and were divided into 2.5, 5, 10 mmol/L groups and control group. The physiological and biochemical functions of platelets were observed, including recovery rate, aggregation and activation of platelets. The platelet counts were determined by Counter Cell-DYN 1200. The aggregation activities were tested through turbidimetry, the platelet apoptosis was detected by flow cytometry. The results showed that the concentrations of EGCG loading in platelets of 2.5, 5 and 10 mmol/L groups were 0.4006 ± 0.12, 1.0527 ± 0.1503, 1.6902 ± 0.1112 mmol/L respectively. Along with the increasing of EGCG concentrations in loading-buffer, the EGCG absorbed by platelets increased too. When the concentration of EGCG in loading-buffer exceeded 15 mmol/L, the EGCG absorbed by platelets did not increase. The recovery rate in 2.5 mmol/L loading buffer group was 82.45 ± 0.360% which was lower than that in control group (90.33 ± 1.115%) (p < 0.05). As compared with control group, the recovery rate in 5 mmol/L loading buffer group (57.51 ± 2.468)% and 10 mmol/L loading buffer group (47.45 ± 2.030)% were even significantly lower (p < 0.01). When ADP was used as the inducer, the maximal aggregation rate (MAR) in control group was (63.6 ± 4.037)%, which was higher than that in other EGCG-loading groups (p < 0.01). And the aggregation activity of platelets negatively correlated with the concentration of EGCG in loading-buffer. When THR was used as the inducer, the MAR in control group was (89.3 ± 6.533)% and higher than that those in other groups (p < 0.05), especially in groups with loading-buffer higher than 10 mmol/L EGCG (70.1 ± 5.400%) (p < 0.01). In the experiment of cellular apoptosis, the early apoptosis easy appeared in platelets loaded with EGCG. It is concluded that the EGCG loading in platelets markedly influences the physiological and biochemical functions of platelets, the apoptosis easy occurs in platelets loaded with EGCG. The EGCG accelerates the course of platelet apoptosis.

[Healing effect of lyophilized platelets on rat chronic wound model].

Platelets carry over 20 growth factors, which all have been shown to improve wound healing, particularly recalcitrant wound healing. The aim of this study was to investigate the healing effect of lyophilized platelets on the chronic wounds through establishing diabetic rat chronic wound model. Healthy male SD rats were intraperitoneally injected with streptozotocin (STZ) solution at the dose of 65 mg/kg. The blood glucose and weights were observed every week. The re-epithelialization rates of normal control group (NDR), diabetic group (DR) and diabetic treatment group (TLP) was analysed. Two full thickness skin wounds were incised in the back of the rats. The re-epithelialization rates were observed at 1, 3, 5, 7 and 12 days. The results showed that after induced by streptozotocin for 72 hours, the blood glucose of the DR group was higher than 16.7 mmol/L. 1 week after induced by STZ, the weight of the DR group was significant lighter than that of the NDR group (p < 0.05). The re-epithelialization rate of DR group were lower than that of NDR. After 12 day treatment, the re-epithelialization rates of NDR and TLP groups were 88.1% and 81.8%, which were significantly higher than that of DR group (62.8%). It is concluded that diabetic rat model established by the intraperitoneal injection of streptozotocin can be used as a better diabetic chronic wound model. And the lyophilized platelets have healing effect on diabetic chronic wounds.

Addition of oligosaccharide decreases the freezing lesions on human red blood cell membrane in the presence of dextran and glucose.

Although incubation with glucose before freezing can increase the recovery of human red blood cells frozen with polymer, this method can also result in membrane lesions. This study will evaluate whether addition of oligosaccharide (trehalose, sucrose, maltose, or raffinose) can improve the quality of red blood cell membrane after freezing in the presence of glucose and dextran. Following incubation with glucose or the combinations of glucose and oligosaccharides for 3h in a 37°C water bath, red blood cells were frozen in liquid nitrogen for 24h using 40% dextran (W/V) as the extracellular protective solution. The postthaw quality was assessed by percent hemolysis, osmotic fragility, mean corpuscle volume (MCV), distribution of phosphatidylserine, the postthaw 4°C stability, and the integrity of membrane. The results indicated the loading efficiency of glucose or oligosaccharide was dependent on their concentrations. Moreover, addition of trehalose or sucrose could efficiently decrease osmotic fragility of red blood cells caused by incubation with glucose before freezing. The percentage of damaged cell following incubation with glucose was 38.04±21.68% and significantly more than that of the unfrozen cells (0.95±0.28%, P<0.01). However, with the increase of the concentrations of trehalose, the percentages of damaged cells were decreased steadily. When the concentration of trehalose was 400mM, the percentage of damaged cells was 1.97±0.73% and similar to that of the unfrozen cells (P>0.05). Moreover, similar to trehalose, raffinose can also efficiently prevent the osmotic injury caused by incubation with glucose. The microscopy results also indicated addition of trehalose could efficiently decrease the formation of ghosts caused by incubation with glucose. In addition, the gradient hemolysis study showed addition of oligosaccharide could significantly decrease the osmotic fragility of red blood cells caused by incubation with glucose. After freezing and thawing, when both glucose and trehalose, sucrose, or maltose were on the both sides of membrane, with increase of the concentrations of sugar, the percent hemolysis of frozen red blood cells was firstly decreased and then increased. When the total concentration of sugars was 400mM, the percent hemolysis was significantly less than that of cells frozen in the presence of dextran and in the absence of glucose and various oligosaccharides (P<0.01). However, when both glucose and trehalose were only on the outer side of membrane, with increase of the concentrations of sugars, the percent hemolysis was increased steadily. Furthermore, addition of oligosaccharides can efficiently decrease the osmotic fragility and exposure of phosphatidylserine of red blood cells frozen with glucose and dextran. In addition, trehalose or raffinose can also efficiently mitigate the malignant effect of glucose on the postthaw 4°C stability of red blood cells frozen in the presence of dextran. Finally, addition of trehalose can efficiently protect the integrity of red blood cell membrane following freezing with dextran and glucose. In conclusion, addition of oligosaccharide can efficiently reduce lesions of freezing on red blood cell membrane in the presence of glucose and dextran.

In vivo circulation of mouse red blood cells frozen in the presence of dextran and glucose.

Loading with monosaccharide can improve the quality of human red blood cells (hRBCs) frozen with polymer. But in vivo life span of hRBCs frozen with polymer and sugar is not determined. In this study, following incubation with glucose, mouse red blood cells (mRBCs) were frozen in liquid nitrogen for 24h using dextran as the extracellular protectant. After thawing, hemolysis, exposure of PS, and osmotic fragility of frozen mRBCs were determined in vitro. After transfusion of fluorescein isothiocyanate (FITC)-labeled mRBCs, the 24h recovery and half life span of frozen mRBCs were determined. The data indicated the postthaw hemolysis of mRBCs frozen with dextran and glucose were significantly less than that of cells frozen with dextran (17.23%+/-5.21% vs 25.96%+/-10.07%, P=0.034). But freezing can also result in exposure of phosphatidylserine and increase of osmotic fragility of mRBCs. After transfusion, the 24h recovery of mRBCs frozen in the absence or presence of glucose was similar to that of the control cells (P=0.748 and 0.971). However, the half life span of mRBCs frozen in the absence or presence of glucose was significantly less than that of the control cells (P=0.000). In addition, incubation with glucose can not increase the life span of frozen red blood cells (7.16+/-0.93 d vs 7.15+/-0.34 d, P=0.982). In conclusion, incubation with monosaccharide could significantly increase the recovery of mRBCs frozen with polymer. Although freezing can significantly shorten the half life span of frozen cells, it can not influence the 24h recovery of frozen mRBCs. In addition, incubation with monosaccharide before freezing can not increase the life span of frozen mRBCs. So according to the above data, to increase the life span of hRBCs frozen with polymer and monosaccharide, the osmotic fragility of the frozen RBCs must be decreased in the future.

Effects of pre-freeze incubation of human red blood cells with various sugars on postthaw recovery when using a dextran-rapid cooling protocol.

Polymer has been used as substitute to replace glycerol for cryopreservation of red blood cells (RBCs). But polymer can not penetrate cell membrane, it can not efficiently protect the inner membrane. In this study, RBCs were incubated with glucose, fructose, galactose or trehalose and frozen in liquid nitrogen for 24 h using dextran as the extracellular protectant. The postthaw quality was assessed by RBC hemolysis, RBC morphology, PS distribution, osmotic fragility, and the 4 degrees C stability. The results indicated the loading efficiency of monosaccharide was significantly higher than that of trehalose. Adding trehalose and 40% dextran caused more serious hemolysis before freezing. The percent hemolysis of RBCs loaded with high concentration of trehalose was approximately 16% and significantly more than that of RBCs loaded with glucose (approximately 5%, P<0.05). Intracellular trehalose can not increase the postthaw recovery of RBCs compared with cells frozen without sugar. However, low concentration of intracellular glucose or galactose can reduce the percent hemolysis to less than 5% and significantly less than that of RBCs frozen without sugar (P<0.05). Finally, the ability of galactose or fructose to maintain the 4 degrees C stability was significantly more than that of glucose. In conclusion, the injuries caused by trehalose loading may directly lead to postthaw hemolysis and poor quality of RBCs. However, monosaccharide can enhance the recovery of frozen RBCs. The cryoprotective effect of galactose may be better than that of glucose or fructose. In the future, we will continue to look for a safe and efficient trehalose loading process and try to decrease the osmotic fragility of RBCs frozen with polymers and sugars.

[Inhibitory effect of trehalose on phosphatidylserine exposure, osmotic fragility and membrane lipid peroxidation damage of erythrocytes induced by high concentration of glucose].

Though high concentration of glucose can benefit the survival of lyophilized human red blood cells, the high concentration of glucose can result in serious damage of red blood cells. This study was aimed to investigate the inhibitory effect of trehalose on damage of red blood cells induced by high concentration of glucose. After incubation with the high concentration of glucose buffer containing different concentrations of trehalose for three hours at 37 degrees C, the phosphatidylserine exposure and the osmotic fragility of cells were analyzed by flow cytometry and the lipid peroxidation of membrane was evaluated by TBA method. The results showed that the high concentration of glucose could lead to phosphatidylserine exposure, osmotic fragility increase, and lipid peroxidation damage which were dependent on the glucose concentrations and incubation temperature. However, trehalose could effectively prevent the phosphatidylserine exposure, osmotic fragility increase, and lipid peroxidation damage induced by high concentration glucose. With increase of the trehalose concentrations. As the trehalose concentration increases, the phosphatidylserine exposure, maloni-aldehyde concentration and cell debris rate decreased gradually. In conclusion, the high concentration of glucose can lead to phosphatidylserine exposure, osmotic fragility increase, and lipid peroxidation damage of red blood cells. However, trehalose can inhibit the damaging effects of high concentration of glucose on red blood cells, which may be useful for the application of sugars to lyophilization of red blood cells.

[Mechanism of erythrocyte phosphatidylserine exposure induced by high concentrated glucose].

This study was aimed to investigate the mechanism of phosphatidylserine exposure of human erythrocytes induced by high concentrated glucose. After exposure to high concentrated glucose, the phosphatidylserine (PS) exposure and forward scatter value were analyzed by flow cytometry; the activities of caspase-3 and caspase-8 were detected; The inhibitory effect of leupeptin on cell PS exposure induced by high concentrated glucose was observed by flow cytometry and fluorescent microscopy. The results showed that the high concentrated glucose could induce PS exposure of erythrocytes and this inducing efficiency was dependent on the glucose concentrations. With increase of the glucose concentrations, the percentages of cells with exposed PS also increased. When the glucose concentration was 0.8 mol/L, the PS exposure was over 80%. However, caspase-3 and caspase-8 were not activated during PS exposure of cells induced by high concentrated glucose, but leupeptin could significantly inhibit PS exposure and volume shrinkage induced by high concentrated glucose. With increase of the leupeptin concentrations, the percentage of cells with exposed PS decreased and the cell volume increased. It is concluded that the high concentrated glucose can result in serious PS exposure, which does not depend on caspase. It can be hypothesized that the PS exposure of erythrocytes induced by high concentrated glucose may be controlled by an unknown pathway sensitive to leupeptin.