الفهرس 
Review of LiteratureOnly 14 pages are availabe for public view
 |  | from | 303 |  |  |
| | | from | 303 | | |
Abstract
The results obtained from this study conclude that:
1. Aloin treatment has no deleterious impact on the heart health and function in the rats, as demonstrated by the normal serum CK-MB level, normal cardiac expression of miRNA-1, 320 and 195 genes in addition to the normal myocardial cells architecture (H&E and Toluidine blue staining). Ultrastructural examination of the left ventricle by TEM showed normal cardiomyocytes with normal cross striation. The absence of apoptotic cells was confirmed by negative caspase-3 immune staining.
2. Elevated serum c-Tn I level requires further investigation.
3. The slight oxidative stress induced by the strong ability of aloin to chelate iron, resulting in serum hyperferremia and defective erythropoiesis (Abdel-Moniem et al., 2022), might contribute to the enhanced production of the cardioprotective heat shock proteins (HSPs) 20, 60 and 70. Thus, the effect of combination of iron supplementation and aloin treatment on HSPs expression should be explored.
4. Subchronic DOX treatment of rats is cardiotoxic, manifested by cytomorphological changes in the myocardial cells and the presence of apoptotic bodies (H&E, Toluidine blue staining, and strong positive caspase-3 immunostaining).
5. In addition, TEM of the left ventricle in DOX-intoxicated rats showed massive histopathological changes in the cardiac architecture.
6. Furthermore, DOX cardiotoxicity is demonstrated by the drastic elevation in serum cardiac biomarkers (CK-MB & c-Tn I), as well as the dramatic production of HSP20, 60 and 70 in the myocardium, simultaneously with enhanced expression of cardiac miRNAs-1, 320 and 195.
7. The antithesis between aloin and DOX treatments concerning the miRNA genes and HSPs expression provides evidence that miRNAs often have numerous targets and that it is important to furtherly explore the target networks of miRNA-1, -320 and -195 which may be involved in maintaining cardiac output after damage.
Recommendations
Further studies on a large cohort of animals treated with aloin or DOX at a wide range of doses should be pursued to verify if HSPs act as repair proteins or correlate well with the severity of the heart injury. As well, a discriminative threshold for HSPs expression as cytoprotective markers or as prognostic and diagnostic markers for heart diseases should be established. This could be achieved by enhancing the overexpression of these proteins through a specific diet or by avoiding the use of practices or therapeutic procedures that could jeopardize the expression of heat shock proteins and their benefits. Also, the use of transgenic mice with HSPs knockouts for treatment with the cardiotoxin DOX is recommended.
Summary
Doxorubicin (DOX) is one of the powerful chemotherapeutic drugs available in the market for the treatment of a wide variety of cancers in the advanced stages. However, its adverse cardiotoxicity limits its clinical application in cancer treatment. Searching for a chemotherapeutic compound with minimal adverse effects has always been the focus of oncologists and cardiologists.
Aloin is the major bioactive compound obtained from the Aloe species. It is an anthraquinone glycoside with the chemical formula C21H22O9. Aloin was formerly used as a laxative in veterinary medicine. Other pharmacological activities of aloin have been reported, including antitumor, anti-oxidative and anti-inflammatory.
The cornerstone of the present study is to elucidate the previously reported cardioprotective effect of aloin treatment in the rat, compared to the cardiotoxin doxorubicin.
To achieve the targets of the present study, a total of 36 adult male Wistar rats were randomly allocated to three equally sized groups as follows: group I (Normal Controls), group II (Aloin-treated); rats received two im injections/week of aloin at its MTD (50 mg/kg bw) for 2 consecutive weeks, and group III (Doxorubicin-intoxicated); rats received three ip injections/week of DOX at a dose level of 2.5 mg/kg bw for two consecutive weeks. Two days after the termination of the treatment period, the animals were weighed, anaesthetized, and then dissected. from each rat, blood samples were withdrawn for the estimation of serum cardiac biomarkers; creatine kinase-MB (CK-MB) and troponin I (c-Tn I). The heart, liver, spleen and kidney were carefully excised and weighed to calculate the toxicity index. The left ventricle of the heart in each individual rat was separated for the analysis of protein expression of HSPs 20, 60 and 70 and the gene expression of selected miRNAs-1, -320 and -195 in the myocardium. In addition, histological (H&E staining and Toluidine blue staining), immunohistochemical, and transmission electron microscopy examinations of the left ventricle of the heart were performed.
Results obtained from this study are summarized as follows:
Both the aloin and DOX treatments significantly lowered the body weight of rats, although the effect of DOX was more pronounced.
The absolute and relative weights of some body organs, such as the heart, liver, spleen and kidney, were differentially affected in aloin- and DOX-treated rats. The absolute weight of the heart in aloin-treated rats was significantly decreased, whereas its relative weight was not significantly changed. The absolute and the relative weights of liver and kidney were increased. The absolute spleen weight was not affected, while its relative weight was increased. As for DOX-intoxicated rats, the absolute weights of the heart, liver and kidney were decreased, while their relative weights were not affected. For the spleen, both absolute and relative weights were decreased.
Aloin treatment showed no significant effect on the serum level of the cardiac biomarker; CK-MB, while the serum c-Tn I level was significantly elevated, compared to normal controls. In contrast, DOX intoxication produced a sharply significant elevation in the serum levels of both cardiac biomarkers.
Western blot analysis revealed a significant increase in the protein expression of HSPs (20, 60 and 70) in the myocardium of both aloin and DOX groups, compared to normal controls.
Gene expression of the miRNAs (1, 320 and 195) was not affected in aloin treatment, whereas a two fold increase in the gene expression of miRNA-1, 320 and 195 was recorded in the myocardium of DOX-intoxicated rats, compared to normal controls.
Microscopical examination (H&E and Toluidine
blue-stained sections) of the heart tissue of aloin-treated rats showed normal, regularly arranged cardiomyocytes with no evidence of cytoplasmic vacuolation. The immunohistochemically-stained sections of aloin-treated rats showed negative caspase-3 immune staining. Transmission electron microscopy (TEM) showed normal cardiomyocytes with normal cross striation.
Histopathological changes in the left ventricle sections of DOX-intoxicated rats were detected, including apoptotic figures with fragmented nuclei and vacuolar degeneration of cardiomyocytes, with the presence of small and large vacuoles in the cytoplasm in H&E and Toluidine
blue-stained sections. The immunohistochemically-stained sections of DOX-intoxicated rats showed a strong positive caspase-3 immune staining in the cytoplasm and/or nuclei of apoptotic cardiomyocytes. TEM photomicrographs showed rounded vacuoles in the cytoplasm of cardiomyocytes with the loss of cross striation.
In conclusion, aloin, a natural anthraquinone glycoside, is shown to be a safe chemotherapeutic compound for the heart health, compared to the cardiotoxin DOX.