الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 85 |  |  |
| | | from | 85 | | |
Abstract
Annually, 17.9 million people die from CVDs on a global scale, estimating about 31% of all deaths worldwide.
Currently, heart transplantation is the only therapeutic option for a failing heart. However, due to shortage of donor organs, it is important to find other alternatives such as stem cell-based myocardial regeneration therapy.
Stem cell-based myocardial regeneration therapy has recently gained extensive attention, being one of the most promising treatments for the damaged myocardial tissue.
Stem cells are a class of undifferentiated cells capable of self-renewal and multilineage differentiation. This occurs through a process of asymmetric mitosis that leads to two daughter cells, one identical to the stem cell and one capable of differentiation into a more mature cell when given the appropriate environmental cues.
5-azacytidine (5-aza), a chemical analogue of cytidine, is known as a demethylation pharmaceutical that can induce mesenchymal stem cells (MSCs) differentiation into cardiomyocyte-like cells by activating some dormant genes through demethylation.
The present work aimed to standardize a protocol ensuring the best differentiation of bone marrow mesenchymal stem cells (BM-MSCs) into cardiomyocytes by exposure of stem cells to 5-aza with minimal toxicity.
The material& methods of this work included ten male albino rats as a source of stem cells weighing 20 -25 grams and aged about 2 weeks. The practical work was done at the Center of Excellence for Research in Regenerative medicine and its Applications (CERRMA).
Characterization of undifferentiated BM- MSCs was done by:
1. Daily examination of the cultured cells using phase contrast inverted microscope.
2. Flow cytometric analysis of the cultured cells’ surface markers using anti CD90 and CD34.
At the third passage, MSCs were divided into five groups: group I: (control group) received 5-aza free-complete cultured medium, group II: exposed to differentiation medium containing 5-aza only for 24h, group III: exposed to differentiating medium containing 5-aza for 72 h, group IV: the medium was renewed twice weekly by differentiation medium (containing 5-aza), group V: daily renewal of 5-aza containing medium was done. group II, III, IV, V were exposed to the same concentration of 5-aza which was 10μmol/L. The experiment was terminated after 3 weeks from the induction time.
Morphological changes of the cultured cells were observed under the phase contrast inverted microscope. The effect of different durations of 5- aza exposure on BM-MSCs viability was evaluated by cell counting kit 8 assay. Detection of cardiac-specific proteins; cardiac troponin I and connexin 43 was done using quantitative reverse transcription-PCR.