Local application of danazol-loaded hyaluronic acid hydrogel to endometriosis in a rat model

Exploring the Role of Hyaluronic Acid in Reproductive Biology and Beyond: Applications in Assisted Reproduction and Tissue Engineering

Hyaluronic acid (HA) plays a prominent role in various aspects of reproductive biology and assisted reproductive technologies (ART). This review describes the multifaceted influence of HA, ranging from primordial germ cell migration, ovarian follicle development, and ovulation in females to sperm structure, physiology, motility, and capacitation in males. In addition, HA also plays an important role in fertilization and promotes embryo implantation by mediating cellular adhesion and communication within the uterus. Against this physiological background, the review examines the current applications of HA in the context of ART. In addition, the article addresses the emerging field of reproductive tissue engineering, where HA-based hydrogels offer promising perspectives as they can support the development of mature oocytes and spermatogenesis in vitro. Overall, this review highlights the integral role of HA in the intricate mechanisms of reproductive biology and its growing importance for improving ART outcomes and the field of tissue engineering of the reproductive system.

OUP accepted manuscript

BACKGROUND

To provide the optimal milieu for implantation and fetal development, the female reproductive system must orchestrate uterine dynamics with the appropriate hormones produced by the ovaries. Mature oocytes may be fertilized in the fallopian tubes, and the resulting zygote is transported toward the uterus, where it can implant and continue developing. The cervix acts as a physical barrier to protect the fetus throughout pregnancy, and the vagina acts as a birth canal (involving uterine and cervix mechanisms) and facilitates copulation. Fertility can be compromised by pathologies that affect any of these organs or processes, and therefore, being able to accurately model them or restore their function is of paramount importance in applied and translational research. However, innate differences in human and animal model reproductive tracts, and the static nature of 2D cell/tissue culture techniques, necessitate continued research and development of dynamic and more complex in vitro platforms, ex vivo approaches and in vivo therapies to study and support reproductive biology. To meet this need, bioengineering is propelling the research on female reproduction into a new dimension through a wide range of potential applications and preclinical models, and the burgeoning number and variety of studies makes for a rapidly changing state of the field.

OBJECTIVE AND RATIONALE

This review aims to summarize the mounting evidence on bioengineering strategies, platforms and therapies currently available and under development in the context of female reproductive medicine, in order to further understand female reproductive biology and provide new options for fertility restoration. Specifically, techniques used in, or for, the uterus (endometrium and myometrium), ovary, fallopian tubes, cervix and vagina will be discussed.

SEARCH METHODS

A systematic search of full-text articles available in PubMed and Embase databases was conducted to identify relevant studies published between January 2000 and September 2021. The search terms included: bioengineering, reproduction, artificial, biomaterial, microfluidic, bioprinting, organoid, hydrogel, scaffold, uterus, endometrium, ovary, fallopian tubes, oviduct, cervix, vagina, endometriosis, adenomyosis, uterine fibroids, chlamydia, Asherman’s syndrome, intrauterine adhesions, uterine polyps, polycystic ovary syndrome and primary ovarian insufficiency. Additional studies were identified by manually searching the references of the selected articles and of complementary reviews. Eligibility criteria included original, rigorous and accessible peer-reviewed work, published in English, on female reproductive bioengineering techniques in preclinical (in vitro/in vivo/ex vivo) and/or clinical testing phases.

OUTCOMES

Out of the 10 390 records identified, 312 studies were included for systematic review. Owing to inconsistencies in the study measurements and designs, the findings were assessed qualitatively rather than by meta-analysis. Hydrogels and scaffolds were commonly applied in various bioengineering-related studies of the female reproductive tract. Emerging technologies, such as organoids and bioprinting, offered personalized diagnoses and alternative treatment options, respectively. Promising microfluidic systems combining various bioengineering approaches have also shown translational value.

WIDER IMPLICATIONS

The complexity of the molecular, endocrine and tissue-level interactions regulating female reproduction present challenges for bioengineering approaches to replace female reproductive organs. However, interdisciplinary work is providing valuable insight into the physicochemical properties necessary for reproductive biological processes to occur. Defining the landscape of reproductive bioengineering technologies currently available and under development for women can provide alternative models for toxicology/drug testing, ex vivo fertility options, clinical therapies and a basis for future organ regeneration studies.

Recent Advances in Polymer-Based Vaginal Drug Delivery Systems

The vagina has been considered a potential drug administration route for centuries. Most of the currently marketed and investigated vaginal formulations are composed with the use of natural or synthetic polymers having different functions in the product. The vaginal route is usually investigated as an administration site for topically acting active ingredients; however, the anatomical and physiological features of the vagina make it suitable also for drug systemic absorption. In this review, the most important natural and synthetic polymers used in vaginal products are summarized and described, with special attention paid to the properties important in terms of vaginal application. Moreover, the current knowledge on the commonly applied and innovative dosage forms designed for vaginal administration was presented. The aim of this work was to highlight the most recent research directions and indicate challenges related to vaginal drug administrations. As revealed in the literature overview, intravaginal products still gain enormous scientific attention, and novel polymers and formulations are still explored. However, there are research areas that require more extensive studies in order to provide the safety of novel vaginal products.

Synergistic regenerative effects of functionalized endometrial stromal cells with hyaluronic acid hydrogel in a murine model of uterine damage

Clinically intractable infertility and recurrent miscarriage due to irreversible endometrial damage need to be treated with biomaterial- and cell-based therapies. Some previous studies have reported on the efficacy of a collagen scaffold and/or bone marrow-derived mesenchymal stem cells. However, the functional differentiation of grafted cells was uncertain, and the time required for regeneration was long in these studies. Here, we show the synergistic regenerative effects of hyaluronic acid (HA) hydrogel with in vitro decidualized endometrial stromal cells (EMSCs) in a murine uterine infertility (synechiae) model. Decidualized EMSCs (dEMSCs) were encapsulated with HA hydrogel, combined with three different doses of fibrinogen/thrombin (5, 50, and 500 mIU/mL). The HA/fibrin gel showed biocompatibility when mixed with dEMSCs. The addition of thrombin enhanced gel formation (5 and 50 mIU/mL) and engraftment and enabled the effective release of adhesion molecules. Within two weeks, which is a short duration, treatment with hydrogel decreased the fibrous tissue and increased the thickness of the endometrium. The regenerated endometrium demonstrated functional recovery, as evidenced by the expression and secretion of molecules essential for embryonic implantation, such as Desmin, CD44, PECAM, and IGF-1. Transferred embryos successfully implanted and the normal development of implanted embryos (n = 37) were evaluated by co-localization of distinct markers of the three germ layers (Sox2, Nestin, Brachyury, AFP, and HNF4α). Live birth of offspring was achieved in the regenerated endometrium by HA hydrogel. Therefore, HA hydrogel-mixed dEMSCs can be an innovative treatment strategy with rapid recovery of endometrial damage and may also have therapeutic potential in intractable infertility or recurrent miscarriage. STATEMENT OF SIGNIFICANCE: Decidualized EMSCs (dEMSCs) encapsulated with HA hydrogel combined with fibrinogen/thrombin (50 mIU/mL) showed injectability and biocompatibility when mixed with dEMSCs. Hydrogel-encapsulated dEMSCs can be a useful treatment for damaged endometrium in short duration, with successful implantation and normal development in a murine model.

Superabsorbent Nanohydrogels of Poly (N-Isopropyl Acrylamide-Co-Itaconic Acid) Grafted on Starch — Synthesis and Swelling Study

Biopolymer-based superabsorbent nanohydrogel consisting of N-isopropylacrylamide and itaconic acid (IA) was grafted on to starch backbone in an aqueous solution in the absence of the cross-linker agents. The copolymerization reaction occurred in the presence of ammonium persulfate (APS) as an initiator. The effect of N-isopropylacrylamide-to-IA ratio and different concentrations of initiator were investigated. The nanohydrogel composition was characterized by Fourier transform infrared spectroscopy (FTIR). The thermal stability was analyzed by Thermogravimetric analysis (TGA). Differential scanning calorimetry (DSC) studies were employed for determination of lower critical solution temperature in hydrogels. Dynamic light scattering analysis showed a narrow size distribution around 70–200[Formula: see text]nm for the synthesized nanohydrogels. The effects of pH on swelling behavior of the hydrogel were investigated. The obtained nanohydrogels, due to their pH and thermo dual sensitive properties, have the potential to be used in the drug delivery systems.

The G-protein-coupled estrogen receptor (GPER) is expressed in normal human ovaries and is upregulated in ovarian endometriosis and pelvic inflammatory disease involving the ovary

Estrogens play a crucial role in maintaining ovarian function. Deregulation of estrogen signals is associated with fertility-impairing disorders. The aim of this study was to investigate whether the G-protein-coupled estrogen receptor (GPER) is present in the human ovary. Additionally, we  analyzed the folliculogenesis and ovarian endometriosis in GPER expression. Seventy-nine patients (ovarian endometriosis, n = 26; ovarian pelvic inflammatory disease [PID], n = 10; normal ovaries/endometrium, n = 30/13) were analyzed by immunohistochemistry. Normal ovaries were also assessed by real-time polymerase chain reaction and double immunofluorescence. The most intense expression of GPER was noted in the ovarian surface epithelium. Theca cells and oocytes were also significantly positive. Expression of GPER was more frequent in mature follicles/oocytes than in primordial ones, implying that GPER could be a selector during folliculogenesis. Moreover, GPER was upregulated in ovarian endometriosis and PID. Overexpression of GPER in both inflammation and endometriosis affecting the ovary may prove useful in explaining/predicting the main endometriosis-related symptoms.

Fertility inducing effect of aerial parts of Coccinia cordifolia L. in female rats

ETHNOPHARMACOLOGICAL RELEVANCE

The aerial parts of Coccinia cordifolia L. are used to treat female infertility in West Bengal state of India.

AIM OF THE STUDY

The present study was undertaken to evaluate the fertility inducing effect of aerial parts of Coccinia cordifolia L. in female rats.

MATERIALS AND METHODS

The effect of aqueous extract of Coccinia cordifolia L. on hyperprolactinemia induced infertility, endometriosis induced infertility and androgen-induced infertility was studied. The effect on serum estrogen level, serum progesterone level and reproductive tract was also evaluated in normal healthy female rats. The extract was administered orally at two different doses of 500 mg/kg and 1000 mg/kg.

RESULTS

In hyperprolactinemia induced infertility model, the numbers of uterine implants were almost 10 times more in the extract treated groups as compared to control. The high dose of extract also produced a significant increase in serum estrogen levels (p<0.01) and number of corpus luteum (p<0.05) in healthy female rats. The extract at both doses was effective in reducing the weight of endometrial implants by 70-80%, but failed to induce fertility in rats with endometriosis. The extract was ineffective in inducing fertility in androgen-induced infertility model.

CONCLUSIONS

The aqueous extract of Coccinia cordifolia L. induces fertility in hyperprolactinemia induced infertility model in female rats.

Hydrogel nanoparticles in drug delivery

Hydrogel nanoparticles have gained considerable attention in recent years as one of the most promising nanoparticulate drug delivery systems owing to their unique potentials via combining the characteristics of a hydrogel system (e.g., hydrophilicity and extremely high water content) with a nanoparticle (e.g., very small size). Several polymeric hydrogel nanoparticulate systems have been prepared and characterized in recent years, based on both natural and synthetic polymers, each with its own advantages and drawbacks. Among the natural polymers, chitosan and alginate have been studied extensively for preparation of hydrogel nanoparticles and from synthetic group, hydrogel nanoparticles based on poly (vinyl alcohol), poly (ethylene oxide), poly (ethyleneimine), poly (vinyl pyrrolidone), and poly-N-isopropylacrylamide have been reported with different characteristics and features with respect to drug delivery. Regardless of the type of polymer used, the release mechanism of the loaded agent from hydrogel nanoparticles is complex, while resulting from three main vectors, i.e., drug diffusion, hydrogel matrix swelling, and chemical reactivity of the drug/matrix. Several crosslinking methods have been used in the way to form the hydrogel matix structures, which can be classified in two major groups of chemically- and physically-induced crosslinking.

Evaluation of the efficacy of a danazol-loaded intrauterine contraceptive device on adenomyosis in an ICR mouse model

BACKGROUND

Danazol, a synthetic steroid with antigonadotrophic properties, has been widely used for the treatment of endometriosis and adenomyosis. However, the local application of danazol to the uterus to treat adenomyosis is controversial. The objective of this study is to develop an effective treatment for adenomyosis using danazol via intrauterine contraceptive device (IUCD) delivery.

METHODS

An adenomyosis animal model was established using Institute for Cancer Research, Swiss-derived (ICR) mice, grafted with a single pituitary gland (n = 30). Four months after grafting, IUCDs with three different quantities of danazol were prepared and used to treat the ICR mice with adenomyosis. After 2 months of treatment with a danazol-loaded IUCD, the number of adenomyosis nodules and the hematoxylin-eosin staining scores were measured and compared with mice given daily oral danazol and controls (no adenomyosis).

RESULTS

As the danazol dose increased, the nodule number decreased reaching significance at a dose of 2.0 mg per 20 g body weight (P = 0.002). When compared with oral administration, the plasma danazol concentrations with IUCD delivery were low and stable.

CONCLUSIONS

These results suggest that an IUCD loaded with an appropriate dose of danazol may be an effective treatment for adenomyosis and that human trials are warranted.

Metformin suppresses interleukin (IL)-1beta-induced IL-8 production, aromatase activation, and proliferation of endometriotic stromal cells

CONTEXT

Metformin, a widely used treatment for diabetes that improves insulin sensitivity, also has both antiinflammatory properties and a modulatory effect on ovarian steroid production, two actions that have been suggested to be efficacious in therapy for endometriosis.

OBJECTIVE

To determine whether metformin may be effective for the treatment of endometriosis, we evaluated the effects of this agent on inflammatory response, estradiol production, and proliferation of endometriotic stromal cells (ESCs).

DESIGN

ESCs derived from ovarian endometriomas were cultured with various concentrations of metformin.

MAIN OUTCOME MEASURES

IL-8 production, mRNA expression and aromatase activity, and 5-bromo-2'-deoxyuridine incorporation in ESCs were measured.

RESULTS

Metformin dose-dependently suppressed IL-1beta-induced IL-8 production, cAMP-induced mRNA expression and aromatase activity, and 5-bromo-2'-deoxyuridine incorporation in ESCs.

CONCLUSION

These results suggest that further investigation into the unique therapeutic potential of metformin as an antiendometriotic drug is warranted.

Influence of endometriosis on visceromotor and cardiovascular responses induced by vaginal distention in the rat

This study examined pseudoaffective responses elicited by vaginal distention in urethane-anesthetized rats, and tested hypotheses that responses would be increased by endometriosis (ENDO) and vary with the estrous cycle. Three groups were studied: ENDO, shamENDO, and Naive. ENDO was induced by autotransplanting small pieces of uterine horn (or, for shamENDO, fat) on mesenteric arteries. Ten weeks later, rats in proestrus or metestrus were anesthetized with urethane. Distendable latex balloons were inserted into the vaginal canal. While an increasing series of vaginal distentions was delivered, changes in electromyographic activity of the external oblique musculature (visceromotor response, VMR) and mean arterial pressure (pressor) responses were simultaneously measured. Vaginal distention produced VMR and pressor responses in all groups. These responses were significantly greater in ENDO than in the other groups, and greater in proestrus than metestrus. Although the overall amount of cystic tissue was greater in proestrous than metestrous rats, there was no correlation between these amounts and VMR or pressor responses. Acute spinalization (T8-T9) and bilateral pelvic, but not hypogastric, neurectomy attenuated both VMR and pressor responses, supporting the hypothesis that vaginal nociception involves suprathoracic spinal processing of information conveyed by the pelvic nerve. These effects on VMR and pressor responses to vaginal distention parallel behavioral escape responses to the same stimuli reported previously. The findings encourage continued use of VMR and pressor responses for further investigation of mechanisms underlying pain associated with ENDO and its potential treatment.

Danazol inhibits aromatase activity of endometriosis-derived stromal cells by a competitive mechanism

OBJECTIVE

To evaluate the inhibitory effect of danazol on estrogen (E) production in endometriosis.

DESIGN

Prospective randomized study.

SETTING

Academic research unit of the department of obstetrics and gynecology in a university hospital.

PATIENT(S)

Thirteen patients with endometriosis.

INTERVENTION(S)

Danazol was added to the culture of endometriosis-derived stromal cells or suspensions of microsomes prepared from chocolate cysts.

MAIN OUTCOME MEASURE(S)

The aromatase activities as well as mRNA and protein levels of aromatase in endometriosis-derived stromal cells or microsomes of endometriosis were examined.

RESULT(S)

Danazol treatment with a concentration greater than 10(-6) M significantly suppressed aromatase activity of endometriosis-derived stromal cells under basal and prostaglandin E(2) (PGE(2))-stimulated conditions. Danazol (10(-5) M) did not affect mRNA and protein levels of aromatase. Danazol competitively inhibited aromatase activity (by 1.7 x 10(-6) M of calculated Ki and 2.9 x 10(-5) M of Ki') of endometriosis microsomes.

CONCLUSION(S)

Danazol competitively inhibited aromatase activity in endometriosis-derived stromal cells without affecting either the mRNA or protein levels of aromatase. These results indicate the efficacy of local application of danazol to endometriotic lesions.