[Leonurine inhibits ferroptosis in renal tubular epithelial cells by activating p62/Nrf2/HO-1 signaling pathway].

To investigate the protective effect and the potential mechanism of leonurine(Leo) against erastin-induced ferroptosis in human renal tubular epithelial cells(HK-2 cells), an in vitro erastin-induced ferroptosis model was constructed to detect the cell viability as well as the expressions of ferroptosis-related indexes and signaling pathway-related proteins. HK-2 cells were cultured in vitro, and the effects of Leo on the viability of HK-2 cells at 10, 20, 40, 60, 80 and 100 µmol·L~(-1) were examined by CCK-8 assay to determine the safe dose range of Leo administration. A ferroptosis cell model was induced by erastin, a common ferroptosis inducer, and the appropriate concentrations were screened. CCK-8 assay was used to detect the effects of Leo(20, 40, 80 µmol·L~(-1)) and positive drug ferrostatin-1(Fer-1, 1, 2 µmol·L~(-1)) on the viability of ferroptosis model cells, and the changes of cell morphology were observed by phase contrast microscopy. Then, the optimal concentration of Leo was obtained by Western blot for nuclear factor erythroid 2-related factor 2(Nrf2) activation, and transmission electron microscope was further used to detect the characteristic microscopic morphological changes during ferroptosis. Flow cytometry was performed to detect reactive oxygen species(ROS), and the level of glutathione(GSH) was measured using a GSH assay kit. The expressions of glutathione peroxidase 4(GPX4), p62, and heme oxygenase 1(HO-1) in each group were quantified by Western blot. RESULTS:: showed that Leo had no side effects on the viability of normal HK-2 cells in the concentration range of 10-100 µmol·L~(-1). The viability of HK-2 cells decreased as the concentration of erastin increased, and 5 µmol·L~(-1) erastin significantly induced ferroptosis in the cells. Compared with the model group, Leo dose-dependently increased cell via-bility and improved cell morphology, and 80 µmol·L~(-1) Leo promoted the translocation of Nrf2 from the cytoplasm to the nucleus. Further studies revealed that Leo remarkably alleviated the characteristic microstructural damage of ferroptosis cells caused by erastin, inhibited the release of intracellular ROS, elevated GSH and GPX4, promoted the nuclear translocation of Nrf2, and significantly upregulated the expression of p62 and HO-1 proteins. In conclusion, Leo exerted a protective effect on erastin-induced ferroptosis in HK-2 cells, which might be associated with its anti-oxidative stress by activating p62/Nrf2/HO-1 signaling pathway.

Early development of reconstructed embryos after somatic cell nuclear transfer in a non-human primate.

To improve efficiency and assess variation in nuclear transfer techniques in non-human primates, we investigated the following factors: type of donor cell, interval between enucleation and cell injection, activation after electrical pulsing and cytokinesis inhibitors. An average of 16.4 oocytes were recovered from 91 retrievals; however, 15 (14%) additional retrieval attempts yielded no oocytes due to a failure of follicular stimulation. Oocyte maturation rates at 36, 38 and 40 h post-hCG were 46.2, 52.6 and 61.2%, respectively. The MII spindle could be seen clearly using polarized microscopy in 89.1% (614/689) of oocytes. Nuclei were seen in 42% of the NT couplets, 53% of those cleaved to the 2-cell stage and 63% of the 2-cell embryos developed to the 8-cell stage by Day 3. There was no difference in the occurrence of nuclear formation between couplets created using fibroblasts or cumulus cells, although embryos were more reliably produced with fibroblasts. The interval (2, 3 and 4 h) between enucleation and cell injection did not affect NT efficiency. Ethanol treatment after electrical pulses yielded more 2-cell NT embryos than did treatment with ionomycin, but the frequency of nuclear formation and development to the 8-cell stage was not different. Treatment of couplets with cycloheximide and cytochalasin B for 5 h after activation had no impact on NT efficiency.

Developmental competence of transported in-vitro matured macaque oocytes.

This study examines in-vitro maturation (IVM) in a non-human primate model, Macaca fascicularis. The animals had hormonal injections and laparoscopic oocyte retrieval (OR)) at 12- and 24- h after human chorionic gonadotrophin (HCG). The immature oocytes were placed in tightly capped tubes containing pre-equilibrated IVM medium and transported for 5 h in a dry portable 37 degrees C incubator without CO2 supplement. Meiotic spindle was observed at 36-38- h post-HCG by polarized microscopy in 72 and 84.5% of mature oocytes collected at 12- and 24- h post-HCG oocyte retrieval intervals respectively. However, abnormal spindle formations were detected in some IVM oocytes by confocal microscopy. The IVM oocytes were also randomly selected for (i) intracytoplasmic injection with frozen-thawed epididymal M. fascicularis spermatozoa and (ii) nuclear transfer (NT) with fresh M. fascicularis cumulus cells. Embryonic development of sperm-injected embryos was not affected by the 12- and 24- h post-HCG oocyte retrieval intervals (22.5 versus 27.9% respectively). However, embryonic development of NT embryos was significantly affected by the 12- h post-HCG oocyte retrieval interval (4.5 versus 31.7% respectively; P < 0.01). In conclusion, IVM of monkey oocytes in a dry portable incubator for 5 h did not affect the maturation rate. However, the ability of primate oocytes to develop after somatic cell nuclear transfer was affected by oocyte retrieval time post-HCG.

Dynamic changes in microtubules and early development of reconstructed embryos after somatic cell nuclear transfer in a non-human primate.

In order to improve somatic cell nuclear transfer (SCNT) efficiency and to understand cellular changes in SCNT, the dynamic changes in microtubules/DNA and early development of SCNT embryos with single or multiple pronuclei were investigated, along with activation timing on efficiency of SCNT, were studied in the Cynomolgus monkey. The confocal images showed that microtubules assembled around condensed DNA at 1h after cell injection; normal or abnormal reconstructed spindle formed at 2 h after cell injection; and reconstructed spindle separated at 2 h after activation. The results of nuclear formation showed that 61.3% of the reconstructed embryos did not form pronuclei; 19.3% formed a single nucleus, and 11.9% and 7.5% formed two and more than two reconstructed pronuclei, respectively. The cleavage and 8-cell development rates of SCNT embryos with pronuclei were significantly higher than those without pronuclei, but there was no difference in development rates among NT embryos with single, two and more then two pronuclei. Activation at 2 h after cell injection yielded more embryos with pronuclei and yielded 8-cell NT embryos more reliably than did activation at 3-4 h. In conclusion, microtubules assembled around condensed DNA at 1-2 h after cell injection, and formed a spindle at 2 h after SCNT, which separated at 2 h after activation; early development was affected by activation time, but no different between single and multiple pronuclei.

Influence of cysteamine supplementation and culture in portable dry-incubator on the in vitro maturation, fertilization and subsequent development of mouse oocytes.

The need to transport oocytes and embryos between two laboratories have prompted us to evaluate the effects of in vitro maturation of immature mouse oocytes in a CO2-deficient dry heat portable incubator and subsequent in vitro development of these fertilized mouse oocytes in a standard CO2 incubator. In addition, the effects of cysteamine supplementation on maturation rate and embryonic development during in vitro maturation (IVM) and culture of embryos in the portable incubator were also investigated. Germinal vesicle stage mouse oocytes, recovered at 40-h post-FSH from 6- to 8-week-old C57BL/6xCBA F1 healthy female mice, were matured in vitro in a modified TCM-199 supplemented with or without 100 microM cysteamine in a standard incubator (5% CO2; 37 degrees C) or cultured in a CO2-deficient dry heat portable incubator for 5 h at 37 degrees C and thereafter transferred to a standard incubator for further culture. The addition of cysteamine in the IVM medium significantly improved maturation rates of the GV mouse oocytes to metaphase II stage. However, cysteamine supplementation in the culture medium did not significantly improve fertilization and blastocyst formation rates of IVM and ovulated oocytes, and in vivo-derived zygotes. Culture conditions in a CO2-deficient dry heat portable incubator did not adversely affect the developmental competence of in vivo-derived zygotes and in vitro matured mouse oocytes after IVF or parthenogenetic activation. Cysteamine supplement in the IVM medium could enhance nuclear maturation of these immature oocytes during shipment.

The first cell cycle after transfer of somatic cell nuclei in a non-human primate.

Production of genetically identical non-human primates through somatic cell nuclear transfer (SCNT) can provide diseased genotypes for research and clarify embryonic stem cell potentials. Understanding the cellular and molecular changes in SCNT is crucial to its success. Thus the changes in the first cell cycle of reconstructed zygotes after nuclear transfer (NT) of somatic cells in the Long-tailed Macaque (Macaca fascicularis) were studied. Embryos were reconstructed by injecting cumulus and fibroblasts from M. fascicularis and M. silenus, into enucleated M. fascicularis oocytes. A spindle of unduplicated premature condensed chromosome (PCC spindle) from the donor somatic cell was formed at 2 hours after NT. Following activation, the chromosomes segregated and moved towards the two PCC spindle poles, then formed two nuclei. Twenty-four hours after activation, the first cell division occurred. A schematic of the first cell cycle changes following injection of a somatic cell into an enucleated oocyte is proposed. Ninety-three reconstructed embryos were transferred into 31 recipients, resulting in 7 pregnancies that were confirmed by ultrasound; unfortunately none progressed beyond 60 days.