Exploring the molecular mechanisms of MSC-derived exosomes in Alzheimer's disease: Autophagy, insulin and the PI3K/Akt/mTOR signaling pathway.

Alzheimer's disease (AD) is a devastating neurological condition characterized by cognitive decline, motor coordination impairment, and amyloid plaque accumulation. The underlying molecular mechanisms involve oxidative stress, inflammation, and neuronal degeneration. This study aimed to investigate the therapeutic effects of mesenchymal stem cell-derived exosomes (MSC-exos) on AD and explore the molecular pathways involved, including the PI3K/Akt/mTOR axis, autophagy, and neuroinflammation. To assess the potential of MSC-exos for the treatment of AD, rats were treated with AlCl3 (17 mg/kg/once/day) for 8 weeks, followed by the administration of an autophagy activator (rapamycin), or MSC-exos with or without an autophagy inhibitor (3-methyladenin; 3-MA+ chloroquine) for 4 weeks. Memory impairment was tested, and brain tissues were collected for gene expression analyses, western blotting, histological studies, immunohistochemistry, and transmission electron microscopy. Remarkably, the administration of MSC-exos improved memory performance in AD rats and reduced the accumulation of amyloid-beta (Aß) plaques and tau phosphorylation. Furthermore, MSC-exos promoted neurogenesis, enhanced synaptic function, and mitigated astrogliosis in AD brain tissues. These beneficial effects were associated with the modulation of autophagy and the PI3K/Akt/mTOR signalling pathway, as well as the inhibition of neuroinflammation. Additionally, MSC-exos were found to regulate specific microRNAs, including miRNA-21, miRNA-155, miRNA-17-5p, and miRNA-126-3p, further supporting their therapeutic potential. Histopathological and bioinformatic analyses confirmed these findings. This study provides compelling evidence that MSC-exos hold promise as a potential therapeutic approach for AD. By modulating the PI3K/Akt/mTOR axis, autophagy, and neuroinflammation, MSC-exos have the potential to improve memory, reduce Aß accumulation, enhance neurogenesis, and mitigate astrogliosis. These findings shed light on the therapeutic potential of MSC-exos and highlight their role in combating AD.

Chronic oestrogen deficiency induced by ovariectomy may cause lung fibrosis through activation of the renin-angiotensin system in rats.

CONTEXT: Oestrogen deficiency is linked with pulmonary fibrosis. Additionally, it may lead to over-activation of the renin-angiotensin system (RAS), which worsens lung fibrosis. OBJECTIVE: The present study aims to investigate the role of RAS on lung fibrosis associated with oestrogen deficiency in ovariectomised rats. MATERIALS AND METHODS: Serum 17ß-oestradiol (E2), arterial blood gases, plasma angiotensin II levels, lung tissue hydroxyproline content, and transforming growth factor beta 1 (TGF-ß1) concentration, the mRNA expression of angiotensin type 1 receptor (AT1R), and angiotensin-converting enzyme (ACE1) were evaluated. Moreover, lung tissues were examined by histopathology and immunohistochemistry. RESULTS: Hydroxyproline content, TGF-ß1 concentration, plasma angiotensin II, the relative mRNA expression of ACE1, and AT1R is found to increase in ovariectomised rats. The mentioned changes can be largely rescued by administration of RAS blockers. CONCLUSION: Oestrogen deficiency activates RAS, which consequently increases the expression of pro-fibrotic factors and stimulates the fibrotic cascade causing lung fibrosis.

Decreased level of plasma nesfatin-1 in rats exposed to cell phone radiation is correlated with thyroid dysfunction, oxidative stress, and apoptosis.

CONTEXT: Exposure to Electomagnetic radiation fields of cell phones causes thyroid dysfunction and a previous study revealed that nesfatin-1 may affect functions of the thyroid gland. OBJECTIVE: To study the role of nesfatin-1 on functions of rat's thyroid gland exposed to EMRF. MATERIALS AND METHODS: Thirty adult male rats were divided equally into 3 groups as group I, group II and group III. The experiment extended for 30 days then the plasma nesfatin-1 level, thyroid functions, and thyroid tissue oxidative stress were assessed. Also; histological and immunohistochemical study studies were done to evaluate structural and apoptotic changes of the thyroid gland. RESULTS: There was a significant decrease in plasma nesfatin-1 level and thyroid functions with an increase in oxidative stress and apoptosis. Interestingly, there was a correlation between nesfatin-1 level and markers of thyroid function, oxidative stress and apoptosis. CONCLUSION: Nesfatin-1 plays a role in thyroid dysfunctions of rats exposed to mobile phone radiation.

Bone marrow-derived mesenchymal stem cells combined with gonadotropin therapy restore postnatal oogenesis of chemo-ablated ovaries in rats via enhancing very small embryonic-like stem cells.

BACKGROUND: Very small embryonic-like stem cells (VSELs) are a rare population within the ovarian epithelial surface. They contribute to postnatal oogenesis as they have the ability to generate immature oocytes and resist the chemotherapy. These cells express markers of pluripotent embryonic and primordial germ cells. OBJECTIVE: We aimed to explore the capability of VSELs in restoring the postnatal oogenesis of chemo-ablated rat ovaries treated with bone marrow-derived mesenchymal stem cells (BM-MSCs) combined with pregnant mare serum gonadotropin (PMSG). METHODS: Female albino rats were randomly assigned across five groups: I (control), II (chemo-ablation), III (chemo-ablation + PMSG), IV (chemo-ablation + MSCs), and V (chemo-ablation + PMSG + MSCs). Postnatal oogenesis was assessed through measurement of OCT4, OCT4A, Scp3, Mvh, Nobox, Dazl4, Nanog, Sca-1, FSHr, STRA8, Bax, miR143, and miR376a transcript levels using qRT-PCR. Expression of selected key proteins were established as further confirmation of transcript expression changes. Histopathological examination and ovarian hormonal assessment were determined. RESULTS: Group V displayed significant upregulation of all measured genes when compared with group II, III or IV. Protein expression confirmed the changes in transcript levels as group V displayed the highest average density in all targeted proteins. These results were confirmed histologically by the presence of cuboidal germinal epithelium, numerous primordial, unilaminar, and mature Graafian follicles in group V. CONCLUSION: VSELs can restore the postnatal oogenesis in chemo-ablated ovaries treated by BM-MSCs combined with PMSG.

Alleviation of cardiac mitochondrial dysfunction and oxidative stress underlies the protective effect of vitamin D in chronic stress-induced cardiac dysfunction in rats.

Chronic stress is associated with oxidative stress and mitochondrial dysfunction. These mechanisms promote adverse cardiovascular events. Though many experimental studies have reported a protective effect of vitamin D (VitD) on cardiovascular system, its effect on cardiovascular system in case of chronic stress is not studied yet. The present study aimed to detect the effects of VitD treatment against chronic immobilization stress (CIS)-induced cardiac dysfunction, focusing mainly on mitochondrial function and oxidative stress in rats. CIS showed cardiac dysfunction as indicated by a significant decrease in the left ventricular end-diastolic and systolic diameters and decrease in ejection fraction and fractional shortening compared to the control group. This was accompanied by a significant decrease in tissue reserves of reduced glutathione (GSH), superoxide dismutase (SOD), ATP and cardiolipin as well as increase in malondialdehyde (MDA) and expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). All these effects were accompanied by a significant increase in plasma adrenaline and noradrenaline. Treatment with VitD ameliorated all the aforementioned CIS-induced effects except PGC-1α expression in a dose-dependent manner. To our knowledge, this is the first study describing the prophylactic cardioprotective effects of VitD against CIS by targeting mitochondrial function.

Mesenchymal Stem Cell-Derived Exosomes Ameliorated Diabetic Nephropathy by Autophagy Induction through the mTOR Signaling Pathway.

BACKGROUND: Diabetic nephropathy (DN) is a serious complication of diabetes mellitus and a common cause of end-stage renal disease. Autophagy has a defensive role against kidney damage caused by hyperglycemia. Mesenchymal stem cell (MSC)-derived exosomes are currently considered as a new promising therapy for chronic renal injury. However, the renal-protective mechanism of exosomes on DN is not completely understood. We examined the potential role of MSC-derived exosomes for enhancement of autophagy activity and their effect on DN. In our study, we used five groups of rats: control; DN; DN treated with exosomes; DN treated with 3-methyladenine (3-MA) and chloroquine (inhibitors of autophagy); and DN treated with 3-methyladenine (3-MA), chloroquine, and exosome groups. We assessed renal function, morphology, and fibrosis. Moreover, ratios of the autophagy markers mechanistic target of rapamycin (mTOR), Beclin-1, light chain-3 (LC3-II), and LC3-II/LC3-I were detected. Additionally, electron microscopy was used for detection of autophagosomes. RESULTS: Exosomes markedly improved renal function and showed histological restoration of renal tissues, with significant increase of LC3 and Beclin-1, and significant decrease of mTOR and fibrotic marker expression in renal tissue. All previous effects were partially abolished by the autophagy inhibitors chloroquine and 3-MA. CONCLUSION: We conclude that autophagy induction by exosomes could attenuate DN in a rat model of streptozotocin-induced diabetes mellitus.

The glucagon-like peptide-1 receptor agonist Exendin-4, ameliorates contrast-induced nephropathy through suppression of oxidative stress, vascular dysfunction and apoptosis independent of glycaemia.

Contrast-induced nephropathy (CIN) is a leading cause of hospital-acquired acute kidney injury, particularly in diabetic patients. Previous studies have shown renoprotective effects of glucagon-like peptide-1 (GLP-1) signalling; however, its role in CIN remains unexplored. This study investigates the prophylactic effect of exendin-4, a GLP-1R agonist, against CIN in a rat model mimicking both healthy and diabetic conditions. Animals were randomly divided into 7 groups: a control sham group (n = 8), and 2 identical sets of 3 disease groups, one received exendin-4 before exposure to contrast medium (CM), while the other served as untreated control. The 3 disease groups represented diabetes (n = 8), CIN (n = 8), or diabetes and CIN combined (n = 8). Untreated groups showed deteriorating renal function as indicated by significantly higher levels of serum creatinine and blood urea nitrogen, malondialdehyde, and endothelin-1 and caspase-3 expression compared to the sham control group. This was accompanied by a significant decrease in tissue reserves of reduced glutathione, superoxide dismutase, nitrate and endothelin nitric oxide synthase as well as deteriorating renal histology. The CM-induced changes in diabetic rats indicate impaired renal function, oxidative stress, vascular dysfunction, and apoptosis, and were significance higher in intensity compared to non-diabetic rats. Pretreatment with exendin-4 ameliorated all the aforementioned CM-induced nephropathic effects independent of the glycemic state. To our knowledge, this is the first study describing the prophylactic renoprotective effects of exendin-4 against CIN. With the current pharmaceutical use of exendin-4 as a hypoglycaemic agent, the GLP-1R agonist becomes an interesting candidate for human clinical trials on CIN prevention.

Combination of Obestatin and Bone Marrow Mesenchymal Stem Cells Prevents Aggravation of Endocrine Pancreatic Damage in Type II Diabetic Rats.

One of the new promising therapies in treatment of diabetes mellitus is mesenchymal stem cells (MSCs) which have an interesting therapeutic potentiality based on their paracrine effect and transdifferentiation potentiality. Also obestatin improves the generation of functional ß cells/islet-like cell clusters in vitro, suggesting implications for cell-based replacement therapy in diabetes. So the aim of this study was to evaluate the effect of combination of both MSCs and obestatin on an experimental model of type II diabetes mellitus (T2DM). Sixty male rats were divided into; group I (control group), group II (T2DM group) induced by administration of high fat diet (HFD) and injection of streptozotocin (STZ) in low dose, group III (T2DM treated with MSCs), group IV (T2DM treated with obestatin), group V (T2DM treated with MSCs and obestatin). Fasting blood glucose, C-peptide, insulin and lipid profile were measured. HOMA-IR and HOMA-ß were calculated. Pancreatic expression of insulin, glucagon like peptide -1 (GLP-1) and pancreatic duodenal homeobox 1 (Pdx1) mRNA levels were measured. In addition pancreatic histological changes, insulin and Bax were analyzed by immunohistochemical examination of islets of Langerhans. Diabetic rats showed significant increase in HOMA-IR, serum glucose and lipid profile levels with significant decrease in insulin, HOMA-ß, GLP-1 and Pdx1 levels. MSCs and obestatin caused significant improvement in all parameters with more significant improvement in combined therapy. The protective effects afforded by MSCs and obestatin may derive from improvement of the metabolic profile, antiapoptosis and by increase in pancreatic GLP-1and Pdx1 gene expression.

Protective effect of rimonabant, a canabinoid receptor 1 antagonist, on nonalcoholic fatty liver disease in a rat model through modulation of the hepatic expression of activin A and follistatin.

Non-alcoholic fatty liver disease (NAFLD) is a major cause of liver morbidity and mortality, and there is still no proven effective therapy. The endocannabinoid system plays an important role in various liver diseases. Activin A is a member of the transforming growth factor beta (TGF-ß) superfamily and inhibits hepatocyte growth. Follistatin antagonizes the biological actions of activin A. This study was designed to investigate the effect of rimonabant (a potent cannabinoid receptor1 (CB1) antagonist) on NAFLD induced with a choline-deficient (CD) diet in rats, as well as to detect whether it can alter the hepatic expression of activin A and follistatin. Forty rats were distributed among 4 groups: the control group, the rimonabant treatment group (normal rats that received rimonabant); the CD diet group (NAFLD induced with a CD diet); and the CD diet + rimonabant group (NAFLD treated with rimonabant). It was found that the CD diet caused significant increase in liver index, serum levels of liver enzymes, malondialdehyde (MDA), TGF-ß1, activin A, and CB1 expression in liver tissue, with a significant decrease in glutathione peroxidase (GSH-Px) and follistatin mRNA expression in liver tissues. The administration of rimonabant significantly improved all of the studied parameters compared with the group fed the CD diet alone. Histopathological examination supported these results. We concluded that rimonabant significantly counteracted NAFLD induced with the CD diet by decreasing oxidative stress and hepatic expression of TGF-ß1, and modulating the hepatic expression of activin A and follistatin.

A comparative study between the effect of 17-ß estradiol and angiotensin converting enzyme inhibitor on osteoporosis in ovariectomized rats.

Osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL) have been revealed in the pathogenesis of primary osteoporosis and other metabolic bone diseases. This study was designed to assess the effect of 17-ß estradiol (E2) treatment and angiotensin converting enzyme inhibitor (ACEI), captopril, on osteoporosis induced by ovariectomy in rats and discussing the role of OPG/RANKL ratio in their action. Thirty two adult female rats were divided into four equal groups. Group I: control group, Group II: ovariectomized (OVX) non treated group, Group III: OVX rats treated with E2, Group IV: OVX rats treated with captopril. OVX rats showed a significant decrease in serum Ca2+ and OPG levels with significant increase in serum RANKL, osteocalcin, alkaline phosphatase activity and urinary hydroxyproline levels. Treatment with captopril as well as E2 led to a significant improvement in bone markers levels with a significant increase in OPG/RANKL ratio. Image analysis technique revealed that there was a significant improvement in cortical bone thickness (CBT) and mean trabecular bone density (TBD) in OVX rats treated with either E2 or ACEI. So, we can conclude that the protective effect of E2 and ACEI on osteoporosis may be mediated by influencing OPG/RANKL signaling.

Could nitric oxide be a mediator of action of oxytocin on myocardial injury in rats? (Biochemical, histological and immunohistochemical study).

Oxytocin (OT) was revisited recently as a hormone of cardiovascular system with several new functions in cardiovascular regulation. But less is known about its role in acute myocardial injury (MI). The aim of our study was to investigate the possible protective effect of OT on the biochemical, histological and immunohistochemical changes of MI induced by isoprenaline (ISO) in adult male albino rats and studying the possible role of nitric oxide (NO) in its action. Forty male albino rats were divided into 5 groups: control rats (Group I), acute MI rats (Group II), rats pretreated with OT prior to induction of MI (Group III), rats injected with a combination of OT and atosiban (ATO, OT receptor antagonist) prior to induction of MI (Group IV). In Group V, a combination of OT and nitric oxide synthase inhibitor (L-NAME) were injected to the rats prior to induction of MI. The heart wall in all groups were taken and processed for histological, immunohistochemical, morphometrical and biochemical studies. We concluded that OT has antioxidant, anti-inflammatory and anti-apoptotic effects on MI and its effects is mediated through NO.