الفهرس 
Introduction and aim of the workOnly 14 pages are availabe for public view
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Abstract
Polycystic ovary syndrome (PCOS) is one of the most common endocrine diseases affecting females during reproductive life. Due to ill-defined pathogenesis, no definite treatment for PCOS is known till now. Therefore, there is a need for therapeutic alternatives to overcome this complex disease and its morbid complications. Aromatase is a rate-limiting enzyme that convert androgens to estrogens.
Letrozole is a non-steroidal aromatase inhibitor blocking the conversion of testosterone to estrogen, so that it has been widely used to induce polycystic ovary.
Recent researches about the stem cell biology provided new hopes in the treatment of complex diseases. Numerous studies suggest that the main therapeutic activity observed in mesenchymal stem cells (MSCs) are the paracrine factors secreted by these cells. These factors are present in the conditioned media (CM) of the MSCs. MSCs derived CM contain many biological factors such as transforming growth factors, insulin like growth factor, vascular endothelial growth factors , interleukin 10 and exosomes.
Exosomes alone were reported to have therapeutic role in many diseases, however, many obstacles hinder the use of exosomes as difficulties in complete isolation and strict quantifications.
This work aimed to compare the effect of mesenchymal stem cell derived-exosomes versus mesenchymal stem cell derived-conditioned media on the morphological and biochemical changes and functional improvement in experimentally induced rat model of polycystic ovary and the possible mechanisms of action.
This study was carried out on 70 albino rats (10 rats were used as a source of BM- MSCs for obtaining CM and exosomes, 12 adult males were used for breeding and th
remaining 48 females were divided into 4 equal groups). Control group: received caboxymethyl cellulose 1%; in a dose of 2 mg/kg/ day by oral gavage. PCO-group: rats received letrozole 2.5 mg tablets. Letrozole dissolved in carboxymethyl cellulose 1% at a dose of 1mg/kg/day for 5 weeks by oral gavage. Vaginal smear was done to make sure persistent di-estrous stage of rats. Six rats were sacrificed after 6 weeks. Exo-treated group: 12 rats received letrozole as mentioned in PCO group for 5 weeks then injected only once with about 150 μg proteins of exosomes derived from BM- MSCs suspended in 100 μl of PBS and injected in the tail vein. Animals were sacrificed after 6 weeks of exosomes injection. CM-treated group: 12 rats received letrozole as mentioned in PCO group for 5 weeks then injected only once with CM derived from BM-MSCs at a dose of about 0.5 ml in the tail vein. Animals were sacrificed after 6 weeks. Functional improvement was tested by breeding of females with males.
Results of this study showed that:
* Biochemical results:
There was a significant increase in the mean serum level of testosterone hormone, insulin hormone, insulin resistance, LH/FSH ratio, tissue level of TNF- α and FABP in the PCO group if compared to the control group. In the Exo-treated group, there was significant decreases if compared to the PCO group but significant increases if compared with the control group. On the other hand, these measurements in the CM- treated group showed significant decrease if compared with both the PCO group and the Exo-treated group and insignificant difference if compared with the control group. Serum level of estradiol hormone and tissue level of IL-10 was significantly decreased in the PCO group when compared to the control group. In the Exo-treated group, there was significant decreases when compared with the control group and significant increases when compared with the PCO group. The CM- treated group showed
insignificant differences with the control group and significant increase when compared with both the PCO group and the Exo-treated group.
* The hematoxylin and eosin stain results showed morphological changes in the PCO group when compared to the control group; the cortex was occupied by multiple large cystic follicles of vaiable size that contained acidophilic material without oocyte in their lumens. There was Absence of corpus luteum and growing follicles and many atretic follicles were observed. The wall of cystic follicle had marked thinning in the granulosa cell layer and thickening of theca cell layer. The ovarian medulla appeared congested with cellular infiltrate. The treated groups showed significant morphological improvement with reappearance of growing follicles and corpora lutea, but the Exo- treated group showed less improvement if compared to the CM-treated group in addition congested blood vessels in the medulla of the Exo-treated group was apparent.
* The Masson trichrome stain results showed significant increased collagen fibers deposition around the blood vessels and between the ovarian follicles in the PCO group, however, the amount of collagen deposition was significantly decreased in both treated groups with more significant decrease in the CM-treated group when compared to the Exo-treated group.
* The immunohistochemical results showed significant increases in the surface area fraction of P53, AMPK and VEGF immune-expression in the PCO group when compared to the control group. The treated groups showed significant decreases when compared with the PCO group, however, the CM-treated group had more significant decreases when compared to the Exo-treated group. Additionally, Oct 4 expression in the control group was mainly in the oocytes, and few stromal cells but it was very faint in the PCO group if compared with the control group. In the treated group, the expression was variant; in the Exo-treated group was mainly in the stromal cells, and
few oocytes, however, in the CM-treated group the expression was mainly in the oocytes, and few stromal cells.