Adipose tissue and ovarian aging: Potential mechanism and protective strategies

Efficacy and safety of mesenchymal stem cell therapy for ovarian ageing in a mouse model

BACKGROUND

Ovarian ageing is one of the major issues that impacts female fertility. Mesenchymal stem cell (MSC)-based therapy has made impressive progress in recent years. However, the efficacy and safety of MSCs, as nonautologous components, remain to be further verified.

METHODS

Two common sources of MSCs, umbilical cord-derived MSCs (UC-MSCs) and adipose tissue-derived MSCs (AD-MSCs), were orthotopically transplanted into a mouse model of ovarian ageing to evaluate their therapeutic effects. The safety of the treatment was further evaluated, and RNA sequencing was performed to explore the underlying mechanisms involved.

RESULTS

After orthotopic transplantation of MSCs into the ovary, the oestrous cycle, ovarian weight, number and proportion of primary follicles, granulosa cell proliferation, and angiogenesis were improved. The effects of AD-MSCs were superior to those of UC-MSCs in several indices, such as post-transplant granulosa cell proliferation, ovarian weight and angiogenesis. Moreover, the tumorigenesis, acute toxicity, immunogenicity and biodistribution of MSCs were evaluated, and both AD-MSCs and UC-MSCs were found to possess high safety profiles. Through RNA sequencing analysis, enhancement of the MAPK cascade was observed, and long-term effects were mainly linked to the activation of immune function.

CONCLUSIONS

Orthotopic transplantation of MSCs displays significant efficacy and high safety for the treatment of ovarian ageing in mice.

An update on the secretory functions of brown, white, and beige adipose tissue: Towards therapeutic applications

Adipose tissue, including white adipose tissue (WAT), brown adipose tissue (BAT), and beige adipose tissue, is vital in modulating whole-body energy metabolism. While WAT primarily stores energy, BAT dissipates energy as heat for thermoregulation. Beige adipose tissue is a hybrid form of adipose tissue that shares characteristics with WAT and BAT. Dysregulation of adipose tissue metabolism is linked to various disorders, including obesity, type 2 diabetes, cardiovascular diseases, cancer, and infertility. Both brown and beige adipocytes secrete multiple molecules, such as batokines, packaged in extracellular vesicles or as soluble signaling molecules that play autocrine, paracrine, and endocrine roles. A greater understanding of the adipocyte secretome is essential for identifying novel molecular targets in treating metabolic disorders. Additionally, microRNAs show crucial roles in regulating adipose tissue differentiation and function, highlighting their potential as biomarkers for metabolic disorders. The browning of WAT has emerged as a promising therapeutic approach in treating obesity and associated metabolic disorders. Many browning agents have been identified, and nanotechnology-based drug delivery systems have been developed to enhance their efficacy. This review scrutinizes the characteristics of and differences between white, brown, and beige adipose tissues, the molecular mechanisms involved in the development of the adipocytes, the significant roles of batokines, and regulatory microRNAs active in different adipose tissues. Finally, the potential of WAT browning in treating obesity and atherosclerosis, the relationship of BAT with cancer and fertility disorders, and the crosstalk between adipose tissue with circadian system and circadian disorders are also investigated.

Periovarian Adipose Tissue - an Impact on Ovarian Functions

Periovarian adipose tissue (POAT) is a type of gonadal white adipose tissue that surrounds the ovary. POAT is a source of various bioactive molecules, such as adipokines, cytokines, chemokines, growth factors and hormones. Thereby it could influence crucial ovarian functions. Recent findings showed that removal of POAT affects folliculogenesis and steroidogenesis in the ovary. Furthermore, changes in the morphology and function of POAT were observed in women during menopause or polycystic ovary syndrome. Although the relationship between the body's energy status and fertility in females is generally well known, the contribution of POAT remains still elusive. Therefore, the objective of this review is summarizing the actual state of knowledge about POAT function in physiological and pathological processes within the ovary.

The influence of the gut microbiome on ovarian aging

Ovarian aging occurs prior to the aging of other organ systems and acts as the pacemaker of the aging process of multiple organs. As life expectancy has increased, preventing ovarian aging has become an essential goal for promoting extended reproductive function and improving bone and genitourinary conditions related to ovarian aging in women. An improved understanding of ovarian aging may ultimately provide tools for the prediction and mitigation of this process. Recent studies have suggested a connection between ovarian aging and the gut microbiota, and alterations in the composition and functional profile of the gut microbiota have profound consequences on ovarian function. The interaction between the gut microbiota and the ovaries is bidirectional. In this review, we examine current knowledge on ovary-gut microbiota crosstalk and further discuss the potential role of gut microbiota in anti-aging interventions. Microbiota-based manipulation is an appealing approach that may offer new therapeutic strategies to delay or reverse ovarian aging.

New insight into the role of macrophages in ovarian function and ovarian aging

Macrophages (MΦs) are the most abundant leukocytes in mammalian ovaries that have heterogeneity and plasticity. A body of evidence has indicated that these cells are important in maintaining ovarian homeostasis and they play critical roles in ovarian physiological events, such as folliculogenesis, ovulation, corpus luteum formation and regression. As females age, ovarian tissue microenvironment is typified by chronic inflammation with exacerbated ovarian fibrosis. In response to specific danger signals within aged ovaries, macrophages polarize into different M1 or M2 phenotypes, and specialize in unique functions to participate in the ovarian aging process. In this review, we will focus on the physiologic roles of MΦs in normal ovarian functions. Furthermore, we will discuss the roles of MΦs in the process of ovarian senescence, as well as the novel techniques applied in this field.

Microenvironmentally Responsive Chemotherapeutic Prodrugs and CHEK2 Inhibitors Self-Assembled Micelles: Protecting Fertility and Enhancing Chemotherapy

Chemotherapy is a widely used and effective adjuvant treatment for cancer, and it has unavoidable damage to female fertility, with statistics showing 38% of women who have received chemotherapy are infertile. How to reduce fertility toxicity while enhancing the oncologic chemotherapy is a clinical challenge. Herein, co-delivery micelles (BML@PMP) are developed, which are composed of a reduction-sensitive paclitaxel prodrug (PMP) for chemotherapy and a CHEK2 inhibitor (BML277) for both fertility protection and chemotherapy enhancement. BML@PMP achieves fertility protection through three actions: (1) Due to the enhanced permeability and retention (EPR) effect, BML@PMP is more enriched in the tumor, while very little in the ovary (about 1/10th of the tumor). (2) Glutathione (GSH) triggers the release of PTX, and with low levels of GSH in the ovary, the amount of PTX released in the ovary is correspondingly reduced. (3) BML277 inhibits oocyte apoptosis by inhibiting the CHEK2-TAp63α pathway. Because of the different downstream targets of CHEK2 in tumor cells and oocytes, BML277 also enhances chemotherapeutic efficacy by reducing DNA damage repair which is activated through the CHEK2 pathway. This bidirectional effect of CHEK2 inhibitor-based co-delivery system represents a promising strategy for improving oncology treatment indices and preventing chemotherapy-associated fertility damage.

The effects and mechanism of taxanes on chemotherapy-associated ovarian damage: A review of current evidence

Chemotherapy is often a cause of premature ovarian insufficiency and infertility since the ovarian follicles are extremely sensitive to the effects of chemotherapeutic agents. Different chemotherapeutic agents with varying mechanisms of action may damage ovarian function differently. Taxanes are widely used in clinical cancer treatment, but the specific reproductive toxicological information is still controversial. This review described the impact and duration of taxanes on ovarian function in women and analyzed the possible reasons for different conclusions. Furthermore, the toxicity of taxanes on ovarian function and its possible mechanisms were discussed. The potential protective strategies and agents against ovarian damage induced by taxanes are also reviewed.