Induction of a local pseudo-pregnancy via levonorgestrel-loaded microspheres for the treatment of endometriosis in a rabbit model

Research progress in rodent models of endometriosis

Endometriosis is a common and frequent disease in gynecology; its etiology and pathogenesis are partially understood and still not clear. The construction of suitable animal models is beneficial for basic research related to the disease. Currently, rodents have the advantages of low cost, fast reproduction, easy rearing, and a similar endometrial structure to humans. Depending on the purpose of the experiment, different molding methods have their advantages. In this paper, we describe the traditional methods of constructing endometriosis rodent models, compare their advantages and disadvantages, and introduce newly developed rodent models, such as cell line injection models, pain models, genetically engineered mouse models, fluorescent tracer models, iron overload models, chemical induction models, and methods of constructing rodent models of different subtypes of endometriosis. Fertility and treatment of endometriosis rodent models are also described. This study provides a reference for researchers in the selection of animal models for pathogenesis and drug treatment studies.

Nanotechnological approaches for the treatment of placental dysfunction: recent trends and future perspectives

The transitory placenta develops during pregnancy and mediates the blood flow between the mother and the developing baby. Placental dysfunction, including but not limited to placenta accreta spectrum, fetal growth restriction, preeclampsia and gestational trophoblastic disease, arises from abnormal placental development and can result in significant adverse maternal and fetal health outcomes. Unfortunately, there is a lack of treatment alternatives for these disorders. Nanocarriers offer versatility, including extended circulation, organ-specific targeting and intracellular transport, finely tuning therapeutic placental interactions. This thorough review explores nanotechnological strategies for addressing placental disorders, encompassing dysfunction insights, potential drug-delivery targets and recent strides in placenta-targeted nanoparticle (NP) therapies, instilling hope for effective placental malfunction treatment.

Diseases and conditions that impact maternal and fetal health and the potential for nanomedicine therapies

Maternal mortality rates in the United States have steadily increased since 1987 to the current rate of over 16 deaths per 100,000 live births. Whereas most of these deaths are related to an underlying condition, such as cardiovascular disease, many pregnant women die from diseases that emerge as a consequence of pregnancy. Both pre-existing and emergent diseases and conditions are difficult to treat in pregnant women because of the potential harmful effects of the treatment on the developing fetus. Often the health of the woman and the health of the baby are at odds and must be weighed against each other when medical treatment is needed, frequently leading to iatrogenic preterm birth. However, the use of engineered nanomedicines has the potential to fill the treatment gap for pregnant women. This review describes several conditions that may afflict pregnant women and fetuses and introduces how engineered nanomedicines may be used to treat these illnesses. Although the field of maternal-fetal nanomedicine is in its infancy, with additional research and development, engineered nanotherapeutics may greatly improve outcomes for pregnant women and their offspring in the future.

Evaluation of peritoneal endometriosis treatment using intralesional acetylsalicylic acid injection in rabbits

PURPOSE

To investigate the efficacy of intralesional 20% aspirin injection for treatment of experimental peritoneal endometriosis.

METHODS

Peritoneal endometriosis was experimentally induced in forty adult nulligravid female rabbits. On day 30 post-endometriosis induction, rabbits were randomly divided to assess early (10 days) and late (20 days) effects of intralesional injection of physiological saline solution (control groups) in comparison to intralesional injection of 20% bicarbonate aspirin solution (experimental groups) as follows: control group 1 (10 days, n=10); control group 2 (20 days, n=10); experimental group 3 (10 days, n=10); experimental group 4 (20 days, n=10). Resected tissues, including endometriosis foci, were qualitatively (general morphology and signs of inflammatory cells infiltrate, necrosis and apoptosis) and quantitatively (remaining endometriosis area) assessed by histopathological analysis.

RESULTS

Extensive necrosis, hemorrhage, apoptosis, and fibrosis were observed in the experimental groups 3 and 4. Groups 1 and 2 presented typical endometrial tissue cysts, respectively. Groups 3 and 4 showed sparse endometrial tissue foci and no endometrial tissue, respectively. Quantitative analysis revealed that aspirin-treated groups 3 and 4 had significantly (p<0.05) smaller remaining endometriosis area, compared to control groups 1 and 2.

CONCLUSION

Intralesional 20% aspirin injection caused total destruction of peritoneal endometriosis foci in rabbits.

Long-term regression of experimental endometriosis in a rat model treated with local application of levonorgestrel-loaded biodegradable microspheres

BACKGROUND

A previous study demonstrated that local application of levonorgestrel-loaded polylactic acid microspheres (LNG microspheres) resulted in significant regression of endometriotic cysts in a rabbit model for 6 months without disturbing the metabolic parameters or ovarian function. In order to investigate the feasibility of local application of LNG microspheres as a long-term maintenance treatment for endometriosis, the suppressive effect of a single intra-cystic injection of LNG microspheres was studied for 1 year in a rat model.

METHODS AND RESULTS

Twenty four rats with experimental endometriotic cysts were randomized to be treated with a single intra-cystic injection of LNG microspheres (n = 8); 6-month GnRH agonist (GnRHa, n = 8) or control (n = 8). Intra-cystic injection of LNG microspheres and GnRHa treatment caused comparable regression and atrophy in endometriotic cysts in the first 6 months. Compared with the control, the wet weight of the endometriotic cysts was significantly lower in both groups at Month 6 but by Month 12 only remained low in the LNG microspheres group (P < 0.01). The immunostaining of estrogen receptors (ERs) in both the epithelium and stroma and progesterone receptors (PRs) in the stroma was significantly weakened in the LNG microspheres group at Month 6 and was not fully restored at Month 12 (P < 0.01). Metabolic parameters and estrous cycle were not disturbed by local application of LNG microspheres.

CONCLUSIONS

In a rat endometriosis model, the suppressive effect of a single intra-cystic injection of LNG microspheres was comparable to that of GnRHa, and was maintained for 1 year. The down-regulation of ERs and PRs might serve as possible mechanism of long-term effectiveness.