In recent years, tissue regeneration has become a promising field for developing stem cell-based transplantation therapies for human patients. Adult stem cells are affected by the same aging mechanisms that involve somatic cells. One of the mechanisms involved in cellular aging is hyperactivation of mechanistic target of rapamycin complex 1 (mTORC1) and disruption of 5' adenosine monophosphate-activated protein kinase (AMPK). Aging of stem cells results in their impaired regenerative capacity and depletion of stem cell pools in adult tissue, which results in lower efficacy of stem cell therapy. By utilizing an effective therapeutic intervention for aged stem cells, stem cell therapy can become more promising for future application. mTORC1 inhibition is a practical approach to preserve the stem cell pool. In this article, we review the dynamic interaction between sirtuin (silent mating type information regulation 2 homolog) 1, AMPK, and mTORC1. We propose that using AMPK activators such as 5-aminoimidazole-4-carboxamide ribonucleotide, A769662, metformin, and oxidized nicotinamide adenine dinucleotide (NAD) are practical ways to be employed for achieving better optimized results in stem cell-based transplantation therapies.

Tissue engineering has yet to reach its ideal goal, i.e. creating profitable off-the-shelf tissues and organs, designing scaffolds and three-dimensional tissue architectures that can maintain the blood supply, proper biomaterial selection, and identifying the most efficient cell source for use in cell therapy and tissue engineering. These are still the major challenges in this field. Regarding the identification of the most appropriate cell source, aging as a factor that affects both somatic and stem cells and limits their function and applications is a preventable and, at least to some extents, a reversible phenomenon. Here, we reviewed different stem cell types, namely embryonic stem cells, adult stem cells, induced pluripotent stem cells, and genetically modified stem cells, as well as their sources, i.e. autologous, allogeneic, and xenogeneic sources. Afterward, we approached aging by discussing the functional decline of aged stem cells and different intrinsic and extrinsic factors that are involved in stem cell aging including replicative senescence and Hayflick limit, autophagy, epigenetic changes, miRNAs, mTOR and AMPK pathways, and the role of mitochondria in stem cell senescence. Finally, various interventions for rejuvenation and geroprotection of stem cells are discussed. These interventions can be applied in cell therapy and tissue engineering methods to conquer aging as a limiting factor, both in original cell source and in the in vitro proliferated cells.

Background: Physician burnout is a serious issue associated with physician attrition, mental and physical problems, and medical errors. Objectives: This study aimed to investigate the prevalence of overall burnout among interns-residents and general physicians (GPs)-specialists during the coronavirus disease 2019 (COVID-19) pandemic in Iran. Methods: This cross-sectional study was conducted among 220 interns-residents and 212 GPs-specialists in university-affiliated hospitals and clinics in Shiraz, Iran. A convenience sampling method was used to recruit the samples, and the data were gathered using Maslach Burnout Inventory that was previously validated for the Persian language. We used covariance analysis and multiple logistic regression to analyze the data. Results: The mean age of participants was 31.44 (ranged 21-62) years. Multiple logistic regression for GPs-specialists showed that working in COVID-19 wards during June-July (OR = 13.93, P = 0.01, CI: 3.61 - 53.51) was associated with increased odds of overall burnout. Moreover, older age among GPs-specialists was associated with decreased odds of overall burnout (OR = 0.94, P = 0.01, CI: 0.90 - 0.98). On the other hand, the odds of overall burnout among interns-residents was not significantly different between various periods (P = 0.94). Furthermore, age (OR = 0.24, P = 0.01, CI: 0.04 - 0.47) and being married (OR = 0.31, P = 0.02, CI: 0.12 - 0.81) were positively associated with decreased odds of overall burnout among interns-residents. Conclusions: This study revealed that the risk of professional burnout among specialists and GPs increased over time during the COVID-19 pandemic. Moreover, older physicians had a lower risk of burnout. Despite the disagreements regarding the association between burnout and the duration of exposure to patients during epidemics, the findings of this study have the potential to remind policymakers of the importance of the issue among physicians during pandemics to taking appropriate action to prevent this phenomenon.

Purpose To investigate the prevalence of cataract, refractive disorder, age-related macular disease (AMD), and glaucoma and their trends from 1990 to 2019 in Iran comparing to high-middle socio-demographic index (HMSDI) countries and globe using Global Burden of Disease (GBD) 2019 study. Methods Data of prevalence for blindness and visual impairment and four of its causes including cataract, refractive error, age-related macular disease (AMD), and glaucoma derived from the GBD Study. Using the Join-point analysis, the annual percent change (APC) was calculated to assess the trend of change in prevalence in each category of diseases from 1990 to 2019, stratified by sex and age, for Iran, HMSDI countries, and the globe. Results In 2019, refractive errors and cataract were the most common causes of blindness and VI for both genders in Iran, HMSDI countries and the Globe. Iran had higher age-standardized prevalence in all four categories of ophthalmologic disorders in comparison to HMSDI countries and the globe for both genders in 2019. In addition, age-specific prevalence of all four disorders in 2019 was higher in Iran compared to HMSDI countries. However, in terms of trends of prevalence from 1990 to 2019, the rate of reduction for four ophthalmologic disorders in Iran was higher than in HMSDI and the globe for males and females. Furthermore, Iran has greater percentage of reduction in prevalence for all age groups in all four disorders compared to HMSDI countries. Conclusion Prevalence of cataract, refractive errors, AMD, glaucoma in Iran was higher comparing to HMSDI countries in 2019 for both sex and all age groups, but trends of prevalence for all four disorders from 1990 to 2019 in Iran has higher slope of reduction in comparison to HMSDI countries for all ages and sex.

Background: Physician burnout is a serious issue associated with physician attrition, mental and physical problems, and medical errors. This study aimed to investigate prevalence of overall burnout among Interns-Residents and general physician (GPs)-Specialist during the COVID-19 pandemic in Iran.Methods: This cross-sectional study was conducted among 220 Interns-Residents and 212 GPs-Specialists in university affiliated hospitals and clinics in Shiraz, Iran. A random sampling method used to recruit the samples and the data gathered using a valid questionnaire. We used covariance analysis and multiple logistic regression to analyze the data.Results: Multiple logistic regression for GPs-Specialists showed that working in COVID-19 wards during June-July (OR = 13.93) was associated with increasing odds of overall burnout. However, older age was associated with decrease odds overall burnout (OR = 0.94). Multiple logistic regression for Interns-Residents revealed that age (OR = 1.24) and being single (OR = 1.66) were positively associated with overall burnout.Conclusions: The present finding could remind policy makers the importance of burnout issue among physicians during the pandemics and could persuade them for taking appropriate action in order to prevent this phenomenon. It is suggested that focusing on strategies such as improving organizational resilience, improvement of healthcare working environment, and development of coping skills among physicians could be helpful in this regard.