For decades, mesenchymal stem (MSCs) cells have been used for cardiovascular diseases as regenerative therapy. This review is an attempt to summarize the types of MSCs involved in myocardial infarction (MI) therapy, as well as its possible mechanisms effects, especially the paracrine one in MI focusing on the studies (human and animal) conducted within the last 10 years. Recently, reports showed that MSC therapy could have infarct-limiting effects after MI in both experimental and clinical trials. In this context, various types of MSCs can help cardiac regeneration by either revitalizing the cardiac stem cells or revascularizing the arteries and veins of the heart. Furthermore, MSCs could produce paracrine growth factors that increase the survival of nearby cardiomyocytes, as well as increase angiogenesis through recruitment of stem cell from bone marrow or inducing vessel growth from existing capillaries. Recent research suggests that the paracrine effects of MSCs could be mediated by extracellular vesicles including exosomes. Exosomal microRNAs (miRNAs) released by MSCs are promising therapeutic hotspot target for MI. This could be attributed to the role of miRNA in cardiac biology, including cardiac regeneration, stem cell differentiation, apoptosis, neovascularization, cardiac contractility and cardiac remodeling. Furthermore, gene-modified MSCs could be a recent promising therapy for MI to enhance the paracrine effects of MSCs, including better homing and effective cell targeted tissue regeneration. Although MSC therapy has achieved considerable attention and progress, there are critical challenges that remains to be overcome to achieve the most effective successful cell-based therapy in MI.

Myocardial infarction (MI) results in dysfunction and irreversible loss of cardiomyocytes and is of the most serious health threats today. Mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) have been explored as promising cell therapy in MI and regenerative therapy. Recently, reports investigated the potential therapeutic effects of MSCs or HSCs transplantation after MI in numerous experimental and clinical studies; however, their results are controversy and needs more explorations. The current review is an attempt to clarify the therapeutic potentials of MSCs and HSCs in MI therapy, as well as their possible effects; especially the paracrine one and the exosome-derived stem cell among animal models as well as clinical trials conducted within the last 10 years. In this context, various sources of MSCs and HSCs have been addressed in helping cardiac regeneration by either revitalizing the cardiac stem cells niche or revascularizing the arteries and veins of the heart. In addition, both MSCs and HSCs could produce paracrine mediators and growth factors which led to cardiomyocytes protection, angiogenesis, immunemodulation, antioxidants, anti-apoptotic, anti-inflammatory, antifibrotic, as well as increasing cardiac contractility. Recently, microRNAs (miRNAs), post-transcriptional regulators of gene expression, and long non-coding RNA (lncRNA), a miRNA sponge, are recent stem cell-derived mediators can be promising targets of MSCs and HSCs through their paracrine effects. Although MSCs and HSCs have achieved considerable achievements, however, some challenges still remain that need to be overcome in order to establish it as a successful technique. The present review clarified the mechanistic potentials of MSCs and HSCs especially paracrine effects involved in MI including human and animal studies and the challenges challenges regarding type, differentiation, route, and number of injections.

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The consistent increase of Coronavirus disease 2019 (COVID-19) cases parallel with the rate of deaths and the controversial response regarding the vaccines caused an increase in the burden of psychological diseases. This study aimed to evaluate the psychological condition of healthcare workers (HCWs) in a pediatric cancer hospital and to identify the knowledge, attitude, and perception (KAP) of HCWs toward COVID-19 vaccination. A cross-sectional observational study was conducted between April to May 2021. A validated, confidential survey was employed to measure the mental health of HCWs and the KAP toward COVID-19 vaccines. The total responses were 395, of which 11.4% physicians, 18.5% pharmacists, and 70.1% were nurses. Sixty-six percent of HCWs had different degrees of anxiety and depression. Nurses significantly accounted for the highest anxiety levels (P = 0.003), while the cumulative anxiety score was significantly higher in HCWs who had a positive history of COVID-19 infection (P = 0.026). Although 67.6% of HCWs believe that “vaccines are essential for us,”, the vaccination rate was 21.3%. The Factors associated with not receiving the vaccine were younger ages (P = 0.014), nurses (P = 3.6987 × 10–7), negative history of COVID-19 infection (P = 0.043) and believing that infections can happen after taking the vaccine (P = 1.5833 × 10–7). Healthcare organizations must take serious intervention to decrease the mental load on HCWs and facilitate the vaccination process.