Effect of Human Endothelial Progenitor Cell (EPC)- or Mouse Vascular Endothelial Growth Factor-Derived Vessel Formation on the Survival of Vitrified/Warmed Mouse Ovarian Grafts

Medical Grade Honey as a Promising Treatment to Improve Ovarian Tissue Transplantation

Ovarian tissue cryopreservation is a female fertility preservation technique that presents major challenges for the maintenance of follicular viability after transplantation. The aim of this study was to evaluate and compare the application of L-Mesitran Soft^®, a product containing 40% medical grade honey (MGH), with other strategies to improve ovarian grafts’ viability. For this purpose, bovine ovarian tissue was vitrified, warmed and randomly assigned to culture groups: (1) control, (2) MGH 0.2% in vitro, (3) MGH in vivo (direct application in the xenotransplantation), (4) vascular endothelial growth factor (VEGF 50 ng/mL) and (5) vitamin D (100 Nm), during a 48 h period. A sixth group (6) of fragments was thawed on transplantation day and was not cultured. The tissue was xenotransplanted into immunodeficient (Rowett nude homozygous) ovariectomized rats. Grafts were analyzed 48 h after culture, and 7 and 28 days after transplantation. The tissue was subjected to histological and immunohistochemical analysis. Treatments using MGH showed the highest angiogenic and cell proliferation stimulation, with cellular apoptosis, within a healthy cellular turnover pathway. In conclusion, MGH should be considered as a potentially effective and less expensive strategy to improve ovarian tissue transplantation.

Role of Stem Cells in the Ovarian Tissue Cryopreservation and Transplantation for Fertility Preservation

Although the cancer survival rate has increased, cancer treatments, including chemotherapy and radiotherapy, can cause ovarian failure and infertility in women of reproductive age. Preserving fertility throughout cancer treatment is critical for maintaining quality of life. Fertility experts should propose individualized fertility preservation methods based on the patient’s marital status, pubertal status, partner status, and the urgency of treatment. Widely practiced fertility preservation methods, including ovarian transposition and embryo and oocyte cryopreservation, are inappropriate for prepubertal girls or those needing urgent initiation of cancer treatment. Ovarian tissue cryopreservation and transplantation, an emerging new technology, may be a solution for these cancer patients. The use of stem cells in ovarian tissue cryopreservation and transplantation increases oxygenation, angiogenesis, and follicle survival rates. This review discusses the recent advances in ovarian tissue cryopreservation and transplantation with special focus on the use of stem cells to improve fertilization techniques.

Current and Future Perspectives for Improving Ovarian Tissue Cryopreservation and Transplantation Outcomes for Cancer Patients

Although advances in cancer treatment and early diagnosis have significantly improved cancer survival rates, cancer therapies can cause serious side effects, including ovarian failure and infertility, in women of reproductive age. Infertility following cancer treatment can have significant adverse effects on the quality of life. However, established methods for fertility preservation, including embryo or oocyte cryopreservation, are not always suitable for female cancer patients because of complicated individual conditions and treatment methods. Ovarian tissue cryopreservation and transplantation is a promising option for fertility preservation in pre-pubertal girls and adult patients with cancer who require immediate treatment, or who are not eligible to undergo ovarian stimulation. This review introduces various methods and strategies to improve ovarian tissue cryopreservation and transplantation outcomes, to help patients and clinicians choose the best option when considering the potential complexity of a patient's situation. Effective multidisciplinary oncofertility strategies, involving the inclusion of a highly skilled and experienced oncofertility team that considers cryopreservation methods, thawing processes and devices, surgical procedures for transplantation, and advances in technologies, are necessary to provide high-quality care to a cancer patient.

Effects of Human Endothelial Progenitor Cell and Its Conditioned Medium on Oocyte Development and Subsequent Embryo Development

Human endothelial progenitor cells (EPCs) secrete numerous growth factors, and they have been applied to regenerative medicine for their roles in angiogenesis as well as neovascularization. Angiogenesis is one of the essential factors for the maturation of ovarian follicles; however, the physiological function of EPCs or their derivatives on in vitro culture systems has not been fully understood. The aim of this study was to evaluate the effectiveness of EPCs and their conditioned medium (EPC-CM) on oocyte development and subsequent embryo development. In the results, the oocyte development and subsequent embryo development were significantly improved in EPCs and the EPC-CM group. In addition, markedly increased levels of growth factors/cytokines, such as basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), insulin growth factor-1 (IGF-1), interleukin-10 (IL-10), and epidermal growth factor (EGF), were observed in medium from the EPC-CM group. Additionally, EPC-CM after in vitro maturation (IVM) had significantly decreased reactive oxygen species (ROS) levels compared to those of other groups. Transcriptional levels of growth factor receptor-related genes (FGFR2, IGF1R) and anti-apoptotic-related gene (BCL2) were significantly upregulated in cumulus cells/oocytes from the EPC-CM group compared with those from the control. Furthermore, the expression levels of cumulus expansion-related genes (PTGS2, TNFAIP6, HAS2) and oocyte-maturation-related factors (GDF9, BMP15) were significantly enhanced in the EPC-CM group. Consequently, the present study provides the first evidence that EPC-CM contains several essential growth factors for oocyte development by regulating genes involved in oocyte maturation.

METTL1 limits differentiation and functioning of EPCs derived from human-induced pluripotent stem cells through a MAPK/ERK pathway

Transplantation of endothelial progenitor cells (EPCs) has high therapeutic potential for ischemia-related ailments like heart attacks and claudication. Due to limited EPC sources, direct reprogramming is a fast-developing way to convert human-induced pluripotent stem cells (hiPSCs) into EPCs fit for transplantation. However, the procedural efficacy was affected by multiple factors, including epigenetic modifications. Recent studies have shown that m⁷G methylation mediated by Methyltransferase like 1 (METTL1) is required for mouse embryonic stem cells (mESCs) to differentiate normally. Yet, its contributions to EPC differentiation still require elucidation. Here, using immunofluorescence microscopy and Fluorescence-activated Cell Sorting (FACS), we found that the typical EPC markers were significantly increased in METTL1 knockdown (METTL1-KD) hiPSCs-derived EPCs compared to those of control types. In addition, we found that METTL1 knockdown activates the MAPK/ERK signaling pathway during EPCs differentiation from hiPSCs. Furthermore, functional properties of METTL1-KD EPCs were significantly raised above those of control hiPSCs-derived EPCs. Moreover, we proved that METTL1-KD hiPSCs-derived EPCs significantly accelerate vascular smooth muscle cell proliferation and 'phenotype switching' through a co-culture system. To sum up, our results demonstrate that METTL1-KD significantly promotes the differentiation of EPCs along with their in vitro functions, and this effect may be achieved through activation of the MAPK/ERK signaling pathway. This enhances current knowledge of EPC generation from hiPSCs and presents a new therapeutic target of vascular diseases.

Therapeutic effects of human umbilical cord mesenchymal stem cell-derived microvesicles on premature ovarian insufficiency in mice

BACKGROUND

Premature ovarian insufficiency (POI) is one of the leading causes of female infertility, which is caused by an abnormal ovarian reserve. Currently, there is no effective treatment to restore the fertility of POI patients. Recent studies suggested that microvesicles (MVs) released from mesenchymal stem cells (MSCs) exert therapeutic effects in various degenerative diseases. In this study, the effect of human umbilical cord MSC-derived MVs (HUCMSC-MVs) on the restoration of ovarian function in a chemotherapy-induced POI mouse model is investigated.

METHODS

MVs were obtained from the supernatant of cultured HUCMSCs. The localization of PKH26-labeled HUCMSC-MVs in ovarian tissues was observed by confocal laser scanning microscopy. Histomorphometric analysis was performed to count the number of ovarian follicles and vessels. The ovarian sections were stained with anti-CD34 to evaluate angiogenesis. The levels of estradiol (E2) and follicle-stimulating hormone (FSH) were measured by enzyme-linked immunosorbent serologic assay. The mRNA expression of angiogenesis-related cytokines and the protein expression of AKT in mouse ovaries were measured by quantitative RT-PCR and western blot analysis. The parametric variables were compared by Student's t test and analysis of variance. The non-parametric variables were compared by the Mann-Whitney U test. Categorical variables were compared by χ² test. P < 0.05 was considered statistically significant.

RESULTS

PKH26-labeled HUCMSC-MVs were detectable within the ovaries and migrated to the ovarian follicles 24 h after transplantation. The transplantation of HUCMSC-MVs could increase the body weight and number of ovarian follicles (primordial, developing, and preovulatory follicles), induce ovarian angiogenesis, and recover the disturbed estrous cycle of POI mice. The expression levels of total AKT, p-AKT, and angiogenic cytokines (including VEGF, IGF, and angiogenin) in the ovaries of POI mice were markedly upregulated after HUCMSC-MVs transplantation, suggesting that HUCMSC-MVs transplantation might recover ovarian function by inducing angiogenesis via the PI3K/AKT signaling pathway.

CONCLUSIONS

This study provides valuable insight into the effects of HUCMSC-MVs on ovarian tissue angiogenesis and on the restoration of ovarian function in POI mice, which may be helpful to develop a treatment strategy for POI patients.

LncRNA H19 Knockdown in Human Amniotic Mesenchymal Stem Cells Suppresses Angiogenesis by Associating with EZH2 and Activating Vasohibin-1

Human amniotic mesenchymal stem cells (HAMSCs) are promising seed cells with great advantages in promoting angiogenesis. However, the mechanisms underlying angiogenesis facilitated by HAMSCs are still unclear. Long noncoding RNA H19 is involved in many biological processes, such as enhancing angiogenesis and proliferation, invasion, and migration of cancer cells. In this study, we constructed HAMSCs of stable low-expression H19 (HAMSC-shH19) and the scramble control (HAMSC-shNC) using lentiviral vectors, and in a three-dimensional coculture with human umbilical vein endothelial cells (HUVECs) to investigate the effect of H19 knockdown in HAMSCs on angiogenesis. Our results demonstrated that H19 knockdown significantly inhibited the angiogenic function of HAMSCs at an early stage in vitro and in vivo. The results of CCK8 and transwell assays demonstrated that the conditioned medium secreted by HAMSCs reduced proliferation and migration of HUVECs after downregulating H19. The angiogenesis factors expressed and secreted by HAMSC-shH19 were decreased compared with those secreted by the control, while angiogenesis inhibitors were elevated. Furthermore, we conducted chromatin immunoprecipitation and RNA-binding protein immunoprecipitation assays and found that H19 could interact with the histone methyltransferase Enhancer of Zeste homolog 2 (EZH2) and that H19 knockdown inhibited the ability of EZH2 to recruit methyl groups to the promoter region of the angiogenesis inhibitor gene vasohibin-1 (VASH1), thus increasing VASH1 expression and secretion of HAMSCs, suppressing angiogenesis. In summary, our study identified H19 as an important regulator in HAMSCs for promoting angiogenesis, which would help to construct ideal gene-modified seed cells to enhance angiogenesis in regenerative medicine.

Effect of co-culture human endothelial progenitor cells with porcine oocytes during maturation and subsequent embryo development of parthenotes in vitro

Human endothelial progenitor cells (EPCs) have been applied to regenerative medicine for their roles in angiogenesis as well as neovascularization, and these angiogenetic functions have beneficial effects on maturation of ovarian follicles. However, little information is available on whether EPCs on culture systems affect oocyte maturation and subsequent embryo development. Therefore, the objective of this study was to investigate the effect of EPC co-culture on porcine oocytes during in vitro maturation (IVM) and subsequent embryo development, and to examine gene expression in cumulus cells, oocytes and blastocysts. The effect of co-culture using EPC on porcine oocyte IVM was investigated. Oocytes were activated using electrical stimulation and embryo developmental competence was estimated. The expression of the genes related to cumulus expansion, oocyte maturation, embryo development, and apoptosis were analyzed. In result, there was a significantly increased maturation rate in EPC group compared with control (p < 0.05). Also, oocytes co-cultured with EPCs exhibited significantly improved blastocyst formation rates (p < 0.05). The expression of mRNAs associated with cumulus expansion and apoptosis in cumulus cells was significantly up-regulated in EPC group. Also, markedly increased levels of GDF9, BMP15, and BCL2 were observed in oocytes from the EPC group. Blastocysts in the co-culture group showed significantly higher SOX2, OCT4, and NANOG levels. In conclusion, co-culturing porcine oocytes with EPCs improves their maturation by regulating genes involved in cumulus cell expansion, oocyte maturation, and apoptosis. Moreover, EPC co-culture during IVM enhanced embryo development as shown by increased blastocyst formation rate and pluripotency-related gene expression.

Hyaluronic acid-based hydrogel scaffold without angiogenic growth factors enhances ovarian tissue function after autotransplantation in rats

One of the problems encountered during ovarian transplantation is that the number of primordial follicles in the grafts is considerably reduced 2 d after transplantation due to post-transplantation ischemia. This study investigates if the use of hyaluronic acid-based hydrogel (HABH) with and without vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) could prevent or minimize ischemia-induced follicle loss during ovarian autotransplantation and thereby restore ovarian tissue function in the rat model. In this study, twenty four female rats were subjected to bilateral ovariectomy and were randomly divided into 3 groups for ovarian tissue autotransplantation. Group A included rats with ovarian tissue without HABH, VEGF and bFGF, group B comprised rats with ovarian tissue encapsulated with HABH and group C had rats with ovarian tissue encapsulated with HABH containing VEGF and bFGF. Three days after transplantation, the grafts were assessed through histological and hormonal analyses. Apoptotic, angiogenic and maturation genes expressions were also analyzed. The mean number of follicles in all developmental stages increased in group B (P  <  0.05). The level of FSH decreased in group B (P  <  0.05) whereas, the expression level of VEGF gene increased in group B (P  <  0.05). No significant changes were observed in the expression levels of maturation and apoptotic genes in all groups. In conclusion, ovarian encapsulation with HABH alone can prevent or minimize ischemia-induced follicle loss, preserve the follicular pool, promote follicular survival, facilitate angiogenesis, and restore hormone levels. However, its efficiency in a clinical setting and in comparison with other hydrogels needs further investigation.

Significant improvement of direct reprogramming efficacy of fibroblasts into progenitor endothelial cells by ETV2 and hypoxia

Background

Endothelial progenitor cell (EPC) transplantation is a promising therapy for ischemic diseases such as ischemic myocardial infarction and hindlimb ischemia. However, limitation of EPC sources remains a major obstacle. Direct reprogramming has become a powerful tool to produce EPCs from fibroblasts. Some recent efforts successfully directly reprogrammed human fibroblasts into functional EPCs; however, the procedure efficacy was low. This study therefore aimed to improve the efficacy of direct reprogramming of human fibroblasts to functional EPCs.

Methods

Human fibroblasts isolated from foreskin were directly reprogrammed into EPCs by viral ETV2 transduction. Reprogramming efficacy was improved by culturing transduced fibroblasts in hypoxia conditions (5 % oxygen). Phenotype analyses confirmed that single-factor ETV2 transduction successfully reprogrammed dermal fibroblasts into functional EPCs.

Results

Hypoxia treatment during the reprogramming procedure increased the efficacy of reprogramming from 1.21 ± 0.61 % in normoxia conditions to 7.52 ± 2.31 % in hypoxia conditions. Induced EPCs in hypoxia conditions exhibited functional EPC phenotypes similar to those in normoxia conditions, such as expression of CD31 and VEGFR2, and expressed endothelial gene profiles similar to human umbilical vascular endothelial cells. These cells also formed capillary-like networks in vitro.

Conclusion

Our study demonstrates a new simple method to increase the reprogramming efficacy of human fibroblasts to EPCs using ETV2 and hypoxia.

Restoration of ovarian tissue function and estrous cycle in rat after autotransplantation using hyaluronic acid hydrogel scaffold containing VEGF and bFGF

This study investigates the effect of hyaluronic acid (HA) containing VEGF and bFGF on restoration of ovarian function after ovarian autotransplantation. Twenty-four rats were randomly divided into three groups for ovarian autotransplantation: group A (ovaries without HA, VEGF and bFGF), group B (ovaries encapsulated with HA) and group C (ovaries encapsulated with HA containing VEGF and bFGF). The grafts were assessed using vaginal smears, histological, hormonal, and the genes expression analysis. The duration of first estrous cycle was shorter in group C than in group A (p < 0.01). The mean number of primordial follicles was protected in group C. The level of estradiol was higher in group A than in group C (p < 0.01). The expression level of Cellular-Myelocytomatosis (C-Myc) in group C was lower than in group B (p < 0.05). HA containing VEGF and bFGF can ensure follicular survival, decrease apoptosis and recover ovarian function after auto-transplantation.

VEGF and FGF2 Improve Revascularization, Survival, and Oocyte Quality of Cryopreserved, Subcutaneously-Transplanted Mouse Ovarian Tissues

This study was conducted to investigate the effect of the vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) on revascularization, survival, and oocyte quality of cryopreserved, subcutaneously-transplanted mouse ovarian tissue. Autologous subcutaneous transplantation of vitrified-thawed mouse ovarian tissues treated with (experimental group) or without (control group) VEGF and FGF2 was performed. After transplantation to the inguinal region for two or three weeks, graft survival, angiogenesis, follicle development, and oocyte quality were examined after gonadotropin administration. VEGF coupled with FGF2 (VEGF/FGF2) promoted revascularization and significantly increased the survival rate of subcutaneously-transplanted cryopreserved ovarian tissues compared with untreated controls. The two growth factors did not show long-term effects on the ovarian grafts. In contrast to the untreated ovarian grafts, active folliculogenesis was revealed as the number of follicles at various stages and of mature oocytes in antral follicles after gonadotropin administration were remarkably higher in the VEGF/FGF2-treated groups. Although the fertilization rate was similar between the VEGF/FGF2 and control groups, the oocyte quality was much better in the VEGF/FGF2-treated grafts as demonstrated by the higher ratio of blastocyst development. Introducing angiogenic factors, such as VEGF and FGF2, may be a promising strategy to improve revascularization, survival, and oocyte quality of cryopreserved, subcutaneously-transplanted mouse ovarian tissue.

The beneficial effects of polyethylene glycol-superoxide dismutase on ovarian tissue culture and transplantation

PURPOSE

Reducing the ischemic damage from free radicals that is inflicted on ovarian tissue is critical for successful ovarian tissue transplantation. Polyethylene glycol-superoxide dismutase (PEG-SOD) is mimetic of superoxide dismutase (SOD) and powerful free radical scavenger acts by reducing superoxide anions. The objective of study was to evaluate effects of PEG-SOD on mouse ovarian tissues in in vitro culture and in autotransplantation.

METHODS

Ovaries were collected and randomly divided into four groups that received different doses of PEG-SOD. To assess effects of PEG-SOD on in vitro cultures, four different doses of PEG-SOD were applied to in vitro culture media during in vitro culturing following ovarian tissue vitrification and warming. To evaluate effects of PEG-SOD on ovarian tissue transplantation, four different doses of PEG-SOD were applied for 2, 7, and 21 days to mice following vitrified-warmed mouse ovarian tissue autotransplantation.

RESULTS

The percentage of primordial follicles was maintained at the highest dose of PEG-SOD for 2 h in vitro, and there was a significant decrease in the percentage of apoptotic follicles at 2 h, but not at later time points. The highest dose of PEG-SOD also maintained primordial, primary, and secondary follicles 2 days post-transplantation, but only primordial follicles were maintained up to 21 days after transplantation.

CONCLUSIONS

PEG-SOD is protective mainly toward primordial follicles only for a short interval in vitro, presumably via antioxidant effects. PEG-SOD may be a promising additive for preserving ovarian tissue integrity, at least for primordial follicles, up to 21 days post-transplantation.

Scaffold-based delivery of adipose tissue-derived stem cells in rat frozen-thawed ovarian autografts: preliminary studies in a rat model

PURPOSE

This study aimed to evaluate whether a gelatin-based Gelfoam sponge is feasible as a scaffold for adipose tissue-derived stem cell (ASC) therapy in rat frozen-thawed ovarian autografts.

METHODS

Two sets of studies were performed. The in vitro set evaluated ASCs' viability in the Gelfoam scaffold at different times of co-culturing (after 24, 48, 72, 96, and 120 h). The in vivo set used 20 12-week-old adult female Wistar rats. Frozen-thawed ovarian grafts were treated with ASCs delivered in Gelfoam scaffolds immediately after an autologous retroperitoneal transplant (ASCs-GS, n = 10). The controls received Gelfoam with a culture medium (GS, n = 10). Assessment of graft quality was conducted by vaginal smears (until euthanasia on the 30th postoperative day), histological analyses, follicular density, and viability and fibrosis. Immunohistochemical staining for VEGF-A expression, vascular network (vWF), apoptosis (caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)), cell proliferation (Ki-67), and hormone receptors (estrogen and progesterone) were performed.

RESULTS

The cells remained viable in Gelfoam for up to 120 h of co-culturing. The graft morphology was similar among the groups. ASC therapy promoted the earlier resumption of the estrous phase (GS 16.6 ± 3 vs. ASCs-GS 12.8 ± 1.3 days) and enhanced estrogen receptors compared with the controls (p < 0.05) without interfering with the quantity and viability of the ovarian follicles, fibrosis, endothelial cells, VEGF immunoexpression, apoptosis, or cell proliferation (p > 0.05).

CONCLUSION

The Gelfoam scaffold could be a feasible and safe non-invasive technique for ASC delivery in the treatment of frozen-thawed ovarian autografts. Future studies should evaluate the real benefit of this treatment on the survival and endocrine activity of the graft.