Changes in morphology and cell number of inner cell mass of porcine blastocysts during freezing

Prevention of chemotherapy-induced premature ovarian insufficiency in mice by scaffold-based local delivery of human embryonic stem cell-derived mesenchymal progenitor cells

BACKGROUND

Premature ovarian insufficiency (POI) is one of the most serious side effects of chemotherapy in young cancer survivors. It may not only reduce fecundity but also affect lifelong health. There is no standard therapy for preserving ovarian health after chemotherapy. Recently, administration of embryonic stem cell-derived mesenchymal progenitor cells (ESC-MPCs) has been considered a new therapeutic option for preventing POI. However, the previous method of directly injecting cells into the veins of patients exhibits low efficacy and safety. This study aimed to develop safe and effective local delivery methods for the prevention of POI using two types of bioinspired scaffolds.

METHODS

Female mice received intraperitoneal cisplatin for 10 days. On day 11, human ESC-MPCs were delivered through systemic administration using intravenous injection or local administration using intradermal injection and intradermal transplantation with a PLGA/MH sponge or hyaluronic acid (HA) gel (GEL) type of scaffold. PBS was injected intravenously as a negative control. Ovarian function and fertility were evaluated 4 weeks after transplantation. Follicle development was observed using hematoxylin and eosin staining. The plasma levels of sex hormones were measured using ELISA. Expression levels of anti-Müllerian hormone (AMH) and ki-67 were detected using immunostaining, and the quality of oocytes and embryos was evaluated after in vitro fertilization. The estrous cycles were observed at 2 months after transplantation.

RESULTS

The local administration of human ESC-MPCs using the bioinspired scaffold to the backs of mice effectively prolonged the cell survival rate in vivo. The HA GEL group exhibited the best recovered ovarian functions, including a significantly increased number of ovarian reserves, estrogen levels, and AMH levels and decreased apoptotic levels. Furthermore, the HA GEL group showed improved quality of oocytes and embryos and estrous cycle regularity.

CONCLUSIONS

HA GEL scaffolds can be used as new delivery platforms for ESC-MPC therapy, and this method may provide a novel option for the clinical treatment of chemotherapy-induced POI.

Osmotic tolerance of in vitro produced porcine blastocysts assessed by their morphological integrity and cellular actin filament organization

This experiment investigated the osmotic tolerance limits of the morphology and the cellular actin filament organization of porcine blastocysts. In vitro produced Day 6 blastocysts were subjected to osmotic treatments with sucrose solutions of different osmolalities (75, 150, 210, 600, 1200, and 2400 mOsm) and one isotonic solution (NCSU-23, 285 mOsm). Blastocysts were then either fixed immediately, or cultured for 18 h and subsequently fixed with formalin. The morphology of the treated blastocysts was examined under a stereomicroscope and the integrity of the cellular actin filaments of the blastocysts was examined by confocal microscopy after staining with Alexa Fluor 488 phalloidin. The results indicated that there was a significant relationship between the osmotic levels and the probability of blastocysts exhibiting disrupted cellular actin filaments. In addition, blastocysts also collapsed in proportion to the levels of osmotic treatments. The osmotic tolerance limits which would maintain 70% of the blastocysts with their original morphology immediately after the treatment were 90 and 170%, respectively, of isotonicity. After 18 h of culture, the osmotic tolerance limits were 61 and 163%, respectively, of isotonicity. Similarly, the osmotic conditions relative to isotonicity which would maintain the integrity of cellular actin filaments in 70% of treated blastocysts had to be within the range of 87 and 147% immediately after the treatment and 87 and 169% after 18 h of culture. Collectively, these data indicate that in vitro produced porcine blastocysts are very sensitive to osmotic stress. This information can be used to optimize cryopreservation procedures for porcine embryos.

Use of a chemically defined system for the direct comparison of inner cell mass and trophectoderm distribution in murine, porcine and bovine embryos

The mammalian blastocyst comprises an inner cell mass (ICM) and a trophectoderm cell layer. In this study the allocation of blastomeres to either cell lineage was compared between murine, porcine and bovine blastocysts. Chemical permeation of trophectoderm cells by the Ca2+ ionophore A23187 in combination with DNA-specific fluorochromes resulted in the differential staining of trophectoderm and ICM. Confocal microscopy confirmed the exclusive permeation of trophectoderm and the internal localisation of intact ICM cells in bovine blastocysts. Overall, differential cell counts were obtained in approximately 85% of the embryos assessed. Mean (+/-SEM) total cell numbers were 72.2+/-3.1 and 93.1+/-5 for in vivo derived murine (n = 41) and porcine (n = 21) expanded blastocysts, respectively. Corresponding ICM cell number counts revealed ICM/total cell number ratios of 0.27 and 0.21, respectively. Comparison of in vivo (n = 20) and in vitro derived bovine embryos on day 8 (n = 29) or day 9 (n = 29) revealed a total cell number of 195.25+/-9.9, 166.14+/-9.9 and 105+/-6.7 at the expanded blastocyst stage with corresponding ICM/total cell ratios of 0.27, 0.23 and 0.23, respectively. While total cell numbers differed significantly among the three groups of bovine embryos (p < 0.05), the ICM/total cell ratio did not. These results indicate that a similar proportion of cells is allocated to the ICM among blastocysts of genetically divergent species.

Viability of bovine blastocysts obtained after 7, 8 or 9 days of culture in vitro following vitrification and one-step rehydration

This study examined morphological appearance, viability and hatching rates in relation to the total cell number following vitrification of in vitro produced bovine blastocysts and expanded blastocysts. In Experiment 1, embryos obtained after 7, 8 or 9 d of culture were pooled and equilibrated in either 10% ethylene glycol (EG) or 10% EG plus 0.3M trehalose in Dulbecco's phosphate buffered saline (DPBS) supplemented with 10% calf serum and 0.6% BSA for 5 min each, at room temperature, and then vitrified together in precooled vitrification solutions consisting of 40% EG (Treatment 1), 40% EG plus 0.3M trehalose (Treatment 2), 40% EG plus 0.3M trehalose and 20% polyvinylpyrrolidone (PVP, Treatment 3) in DPBS. The embryo viability and hatching rates of Treatment 1 (19 and 3%) differed significantly (P < 0.05) from those of Treatment 2 (56 and 31%) and Treatment 3 (70 and 43%). There was a significant difference (P < 0.05) in embryo viability between Treatment 2 (31%) and Treatment 3 (43%). In Experiment 2, Day 7, 8 and 9 embryos were vitrified separately, with higher viability and hatching rates in Experiment 1 than in Experiment 2. The viabilities of Day 7 (87%), 8 (71%) and 9 (46%) embryos differed significantly (P < 0.05). Again, there were significant differences (P < 0.01) among the hatching rates of Day 7 (75%), 8 (38%) and 9 (9%) embryos. The total cell number of hatched blastocysts was then determined by differential fluorochrome staining. The total cell number of Day 7, 8 and 9 embryos differed significantly (P < 0.05).