Effects of high glucose and severe hypoxia on the biological behavior of mesenchymal stem cells at various passages.

BACKGROUND: Mesenchymal stem cells (MSCs) have been extensively studied for therapeutic potential, due to their regenerative and immunomodulatory properties. Serial passage and stress factors may affect the biological characteristics of MSCs, but the details of these effects have not been recognized yet. AIM: To investigate the effects of stress factors (high glucose and severe hypoxia) on the biological characteristics of MSCs at different passages, in order to optimize the therapeutic applications of MSCs. METHODS: In this study, we investigated the impact of two stress conditions; severe hypoxia and high glucose on human adipose-tissue derived MSCs (hAD-MSCs) at passages 6 (P6), P8, and P10. Proliferation, senescence and apoptosis were evaluated measuring WST-1, senescence-associated beta-galactosidase, and annexin V, respectively. RESULTS: Cells at P6 showed decreased proliferation and increased apoptosis under conditions of high glucose and hypoxia compared to control, while the extent of senescence did not change significantly under stress conditions. At P8 hAD-MSCs cultured in stress conditions had a significant decrease in proliferation and apoptosis and a significant increase in senescence compared to counterpart cells at P6. Cells cultured in high glucose at P10 had lower proliferation and higher senescence than their counterparts in the previous passage, while no change in apoptosis was observed. On the other hand, MSCs cultured under hypoxia showed decreased senescence, increased apoptosis and no significant change in proliferation when compared to the same conditions at P8. CONCLUSION: These results indicate that stress factors had distinct effects on the biological processes of MSCs at different passages, and suggest that senescence may be a protective mechanism for MSCs to survive under stress conditions at higher passage numbers.

The potential protective role of vitamin D and calcium supplements in reducing cardiovascular disease risk among elderly patients with osteopenia.

BACKGROUND: Cardiovascular disease and low bone mineral density are major health problems in the elderly. These two conditions are considered independent of each other and age-related diseases. The aim of this study is to investigate the association between low bone mineral density (BMD) and cardiovascular disease (CVD) incidents, and the effect of vitamin D and calcium supplement on the incidence of CVD in patients with low BMD. METHODS: A total of 1047 patients (597 females/450 males) with the age of 65 years and more were diagnosed with osteopenia for 13 years or more. The study also included 220 patients (107 females/113 males) with osteopenia who already took calcium and vitamin D continually since their diagnosis. BMD was measured by dual-energy X-ray absorptiometry. The incidence of any cardiovascular diseases in the study patients and the presence of corresponding risk factors were collected and analyzed. RESULTS: In both elderly Arab females and males, there was an association between total hip and femoral neck BMD and the possibility to have CVD. On the other hand, the results showed that patients who use calcium and vitamin D supplements showed a significant reduction in the incidence of CVD comparing to the non-treated patients. CONCLUSION: Low total hip and femoral neck BMD were associated with a higher chance to have CVD incidents in both elderly Arab males and females; moreover, calcium and vitamin D supplements have a possible protective role in reducing cardiovascular disease in elderly patients with osteopenia.

Comparing the effect of using 2-Mercaptoethanol in the cell culture medium of different cell passages of human mesenchymal stem cells.

Preparing a suitable cell culture medium that supports the biological needs of the growing cells is crucial to enhancing the success rate of any in vitro and in vivo experiments and minimizing undesirable interferences.  Mesenchymal stem cells ( MSCs) which are powerful regenerative stem cells require being grown in proper culture media to preserve their stemness and therapeutic properties. MSCs are usually grown in Dulbecco's Modified Eagle low glucose Medium (DMEM low glucose) which contains 5.6 mmol/L of glucose and is supplemented with Fetal Bovine Serum (FBS), antibiotics, and 2-Mercaptoethanol. The addition of 2-Mercaptoethanol to the cell culture medium was proposed long ago and has continued to be used until now. Despite the positive effects of adding 2-Mercaptoethanol in the cell culture medium, its use is still controversial and needs continuous updates to limit its interference with experimental treatments. Herein, we found that 2-Mercaptoethanol is beneficial to enhancing the proliferation and survival of MSCs at higher passage numbers while its effect is negligible for earlier passages. This concise study provides updates regarding the suitable time to add 2-Mercaptoethanol which can minimize its intermeddling with the experimental design and treatments.

Addressing the impact of high glucose microenvironment on the immunosuppressive characteristics of human mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are a therapeutically efficient type of stem cells validated by their ability to treat many inflammatory and chronic conditions. The biological and therapeutic characteristics of MSCs can be modified depending on the type of microenvironment at the site of transplantation. Diabetes mellitus (DM) is a commonly diagnosed metabolic disease characterized by hyperglycemia, which alters over time the cellular and molecular functions of many cells and causes their damage. Hyperglycemia can also impact the success rate of MSCs transplantation; therefore, it is extremely significant to investigate the effect of high glucose on the biological and therapeutic attributes of MSCs, particularly their immunomodulatory abilities. Thus, in this study, we explored the effect of high glucose on the immunosuppressive characteristics of human adipose tissue-derived mesenchymal stem cells (hAD-MSCs). We found that hAD-MSCs cultured in high glucose lost their immunomodulatory abilities and became detectable by immune cells. The decline in the immunosuppressive capabilities of hAD-MSCs was mediated by significant decrease in the levels of IDO, IL-10, and complement factor H and substantial increase in the activity of immunoproteasome. The protein levels of AMP-activated protein kinase (AMPK) and phosphofructokinase-1 (PFK-1), which are integral regulators of glycolysis, revealed a marked decline in high glucose exposed MSCs. The findings of our study indicated the possibility of immunomodulatory shift in MSCs after being cultured in high glucose, which can be translationally employed to explain their poor survival and short-lived therapeutic outcomes in diabetic patients.

The toxic profile of tramadol combined with nicotine on the liver and testicles: evidence from endoplasmic reticulum stress.

BACKGROUND: Tramadol is one of the most commonly abused substances in the Middle East. Furthermore, smoking is extremely common among the population. METHODS: An experimental study was performed on Sprague-Dawley rats to explore the effects of both nicotine and tramadol on the liver and testes. The tramadol was administered at 10 and 20 mg/kg, respectively, while the nicotine was administered at 125 mg/kg. Histological examination and androgen receptor ELISA assay showed mild effects on the liver and proofed safety on the testis. Western blot analysis of BIP (immunoglobulin heavy-chain binding protein) and CHOP (CCAAT-enhancer-binding protein homologous protein) revealed that fewer problems were induced by adding nicotine to tramadol. Autophagy marker LCIII and apoptosis marker caspase-8 showed similar effects to CHOP and BIP on liver samples. The real-time PCR of BIP expression showed similar but not identical results. CONCLUSIONS: The results showed mild endoplasmic reticulum stress, autophagy, and apoptosis in the liver samples. Histological examination revealed stable spermatogenesis with average androgen receptor blood levels in the different groups.

Neurological Effects of Combining Low Toxic Dose of Tramadol and Nicotine: An Animal Model Evidence of Endoplasmic Reticulum Stress.

Tramadol abuse is a common problem in the Middle East in conjunction with smoking. The current study applied immunohistochemistry, western blot, real-time PCR, and ELISA to test the combination toxicity. Low toxic doses of tramadol induced animal brain cortex inflammation and hippocampus injury. Adding nicotine reverted hippocampus pathological changes without triggering marked brain injury. The expression of CHOP protein with real-time PCR showed mild endoplasmic reticulum stress (ER) in rat's brain. Histological, immunohistochemical, and western blotting analysis of CHOP (CCAAT-enhancer-binding protein homologous protein) and BIP (immunoglobulin heavy chain-binding protein) chaperones demonstrated endoplasmic reticulum stress in the brains of animals. Furthermore, the levels of apoptosis and autophagy markers demonstrated a mild reaction. The blood level of serotonin was high in all study groups, with a marked increase in the combined one. The high serotonin levels in the blood can be critical and associated with a high risk of serious withdrawal and pathological consequences. Serotonin receptor blockers such as olanzapine may increase systemic serotonin levels and need further investigation to utterly pinpoint their roles in managing mood disorders. In conclusion, the combination of tramadol and nicotine is less harmful than expected. However, serious withdrawal effects can occur as a result of high systemic serotonin effects.

Mechanisms of analgesic effect of mesenchymal stem cells in osteoarthritis pain.

Osteoarthritis (OA) is the most common musculoskeletal disease, and it is a major cause of pain, disability and health burden. Pain is the most common and bothersome presentation of OA, but its treatment is still suboptimal, due to the short-term action of employed analgesics and their poor adverse effect profile. Due to their regenerative and anti-inflammatory properties, mesenchymal stem cells (MSCs) have been extensively investigated as a potential therapy for OA, and numerous preclinical and clinical studies found a significant improvement in joint pathology and function, pain scores and/or quality of life after administration of MSCs. Only a limited number of studies, however, addressed pain control as the primary end-point or investigated the potential mechanisms of analgesia induced by MSCs. In this paper, we review the evidence reported in literature that support the analgesic action of MSCs in OA, and we summarize the potential mechanisms of these antinociceptive effects.

The impact of multiple sclerosis on the size and morphology of corpus callosum: an MRI-based retrospective study / Impacto de la esclerosis múltiple en el tamaño y la morfología del cuerpo calloso: un estudio retrospectivo basado en resonancia magnética

SUMMARY: The corpus callosum (CC) includes the majority of fibers linking the two brain hemispheres. Several cross sectional studies showed an association between callosal atrophy and malfunction and neurodegenerative diseases, which may play a role in their pathological manifestations. As a result, the accurate quantification of the corpus callosum is important to have normative values according to sex, age and ethnicity. The purpose of this study is to determine the size of CC in patients suffering from multiple sclerosis, and compare it to CC size in healthyindividuals. Midsagittal size of CC were recorded prospectively from 404 routine MR brain examinations in normal individuals. The internal skull surface was measured to calculate CC/ internal skull surface ratio. Two groups of patients were studied: 200 (100 male /100 female) healthy individuals and 204 (101 males/103 females) with multiple sclerosis (MS). Mean surface area of CC in controls was 6.58±1.04 cm2 and there was no significant difference between males and females (P< 0.627). CC/ internal skull surface ratio was 4.44±0.77 %. MS patients showed a significant decrease in CC size compared to normal controls. Using MR imaging, we measured the mean sizes of the various portions of the CC in normal individuals, in addition to MS patients; these values may provide a useful basis to determine changes occurring in CC structures.

El cuerpo calloso (CC) incluye la mayoría de las fibras que unen los dos hemisferios cerebrales. Varios estudios transversales mostraron una asociación entre la atrofia y el mal funcionamiento calloso y las enfermedades neurodegenerativas, lo que puede desempeñar un papel en sus manifestaciones patológicas. En consecuencia, la cuantificación precisa del cuerpo calloso es importante para tener valores normativos según sexo, edad y etnia. El propósito de este estudio fue determinar el tamaño de CC en pacientes que padecen esclerosis múltiple y compararlo con el tamaño de CC en individuos sanos. El tamaño sagital medio del CC se registró prospectivamente a partir de 404 exámenes cerebrales de RM de rutina en individuos normales. Se midió la superficie interna del cráneo para calcular la relación CC/superficie interna del cráneo. Se estudiaron dos grupos de pacientes: 200 (100 hombres/100 mujeres) sanos y 204 (101 hombres/103 mujeres) con esclerosis múltiple (EM). El área superficial media de CC en los controles fue de 6,58±1,04 cm2 y no hubo diferencia significativa entre hombres y mujeres (P< 0,627). La relación CC/superficie interna del cráneo fue de 4,44±0,77 %. Los pacientes con EM mostraron una disminución significativa en el tamaño de CC en comparación con los controles normales. Usando imágenes de RM, medimos los tamaños medios de las diversas porciones del CC en individuos normales, además de pacientes con EM; estos valores pueden proporcionar una base útil para determinar los cambios que ocurren en las estructuras CC.

The Molecular and Functional Changes of Neural Stem Cells in Alzheimer's Disease: Can They be Reinvigorated to Conduct Neurogenesis.

Alzheimer's disease (AD) is considered one of the most complicated neurodegenerative disorders, and it is associated with progressive memory loss and remarkable neurocognitive dysfunction that negatively impacts the ability to perform daily living activities. AD accounts for an estimated 60-80% of dementia cases. AD's previously known pathological basis is the deposition of amyloid ß (Aß) aggregates and the formation of neurofibrillary tangles by tau hyperphosphorylation in the cell bodies of neurons that are located in the hippocampus, neocortex, and certain other regions of the cerebral hemispheres and limbic system. The lack of neurotransmitter acetylcholine and the activation of oxidative stress cascade may also contribute to the pathogenesis of AD. These pathological events can lead to irreversible loss of neuronal networks and the emergence of memory impairment and cognitive dysfunction that can engender an abnormal change in the personality. AD cannot be cured, and to some extent, the prescribed medications can only manage the symptoms associated with this disease. Several studies have reported that the regenerative abilities of neural stem/progenitor cells (NSCs) remarkably decline in AD, which disturbs the balancing power to control its progression. Exogenous infusion or endogenous activation of NSCs may be the ultimate solution to restore the neuronal networks in the brain of AD patients and regenerate the damaged areas responsible for memory and cognition. In this mini-review, we will touch upon the fate of NSCs in AD and the utilization of neurogenesis using modified NSCs to restore cognitive functions in AD.

Human mesenchymal stem cells exhibit altered mitochondrial dynamics and poor survival in high glucose microenvironment.

BACKGROUND: Mesenchymal stem cells (MSCs) are a type of stem cells that possess relevant regenerative abilities and can be used to treat many chronic diseases. Diabetes mellitus (DM) is a frequently diagnosed chronic disease characterized by hyperglycemia which initiates many multisystem complications in the long-run. DM patients can benefit from MSCs transplantation to curb down the pathological consequences associated with hyperglycemia persistence and restore the function of damaged tissues. MSCs therapeutic outcomes are found to last for short period of time and ultimately these regenerative cells are eradicated and died in DM disease model. AIM: To investigate the impact of high glucose or hyperglycemia on the cellular and molecular characteristics of MSCs. METHODS: Human adipose tissue-derived MSCs (hAD-MSCs) were seeded in low (5.6 mmol/L of glucose) and high glucose (25 mmol/L of glucose) for 7 d. Cytotoxicity, viability, mitochondrial dynamics, and apoptosis were deplored using specific kits. Western blotting was performed to measure the protein expression of phosphatidylinositol 3-kinase (PI3K), TSC1, and mammalian target of rapamycin (mTOR) in these cells. RESULTS: hAD-MSCs cultured in high glucose for 7 d demonstrated marked decrease in their viability, as shown by a significant increase in lactate dehydrogenase (P < 0.01) and a significant decrease in Trypan blue (P < 0.05) in these cells compared to low glucose control. Mitochondrial membrane potential, indicated by tetramethylrhodamine ethyl ester (TMRE) fluorescence intensity, and nicotinamide adenine dinucleotide (NAD+)/NADH ratio were significantly dropped (P < 0.05 for TMRE and P < 0.01 for NAD+/NADH) in high glucose exposed hAD-MSCs, indicating disturbed mitochondrial function. PI3K protein expression significantly decreased in high glucose culture MSCs (P < 0.05 compared to low glucose) and it was coupled with significant upregulation in TSC1 (P < 0.05) and downregulation in mTOR protein expression (P < 0.05). Mitochondrial complexes I, IV, and V were downregulated profoundly in high glucose (P < 0.05 compared to low glucose). Apoptosis was induced as a result of mitochondrial impairment and explained the poor survival of MSCs in high glucose. CONCLUSION: High glucose impaired the mitochondrial dynamics and regulatory proteins in hAD-MSCs ensuing their poor survival and high apoptosis rate in hyperglycemic microenvironment.

Prodigious therapeutic effects of combining mesenchymal stem cells with magnetic nanoparticles.

Mesenchymal stem cells (MSCs) have gained wide-ranging reputation in the medical research community due to their promising regenerative abilities. MSCs can be isolated from various resources mostly bone marrow, Adipose tissues and Umbilical cord. Huge advances have been achieved in comprehending the possible mechanisms underlying the therapeutic functions of MSCs. Despite the proven role of MSCs in repairing and healing of many disease modalities, many hurdles hinder the transferring of these cells in the clinical settings. Among the most reported problems encountering MSCs therapy in vivo are loss of tracking signal post-transplantation, insufficient migration, homing and engraftment post-infusion, and undesirable differentiation at the site of injury. Magnetic nano particles (MNPs) have been used widely for various biomedical applications. MNPs have a metallic core stabilized by an outer coating material and their ma gnetic properties can be modulated by an external magnetic field. These magnetic properties of MNPs were found to enhance the quality of diagnostic imaging procedures and can be used to create a carrying system for targeted delivery of therapeutic substances mainly drug, genes and stem cells. Several studies highlighted the advantageous outcomes of combining MSCs with MNPs in potentiating their tracking, monitoring, homing, engraftment and differentiation. In this review, we will discuss the role of MNPs in promoting the therapeutic profile of MSCs which may improve the success rate of MSCs transplantation and solve many challenges that delay their clinical applicability.

Undergraduate medical students' perceptions regarding stem cells: Is there a need for incorporating a stem cells elective course in the academic curriculum?

Stem cell therapy has recently progressed from the preclinical to the early clinical trial arena for a variety of diseases. Moreover, the medical students lack the deep and full understanding of its significance and potential as the promising future cure for diverse diseases worldwide. This study aims at evaluating the knowledge, awareness, and perception of medical students as far as stem cells applications are related in the medical field. A cross-sectional survey was carried out using online questionnaires, which were distributed via e-mail to cover all medical faculties in Jordan. The data show that medical students are supportive of using stem cells and their therapeutic applications, and most of them are willing and enthusiastically want to improve their knowledge about stem cells; however, due to the tight schedule and the lack of an elective course about stem cells in the curriculum, many of them are not ready to undergo further training in regenerative medicine unless it becomes part of the assigned training and part of the learning objectives for medical students. These findings indicated the need to update the medical school curriculum with new hits in medicine and expand the range of courses offered for medical students so they can be up-to-date with the quick advances in different medical disciplines.

Corpus callosum anatomical changes in Alzheimer patients and the effect of acetylcholinesterase inhibitors on corpus callosum morphometry.

The Corpus Callosum (CC) is an important structure that includes the majority of fibers connecting the two brain hemispheres. Several neurodegenerative diseases may alter CC size and morphology leading to its atrophy and malfunction which may play a role in the pathological manifestations found in these diseases. The purpose of the current study is to determine any possible changes in CC size in patients suffering from Alzheimer's disease. The Study also investigated the effect of acetylcholinesterase inhibitors (AChEIs) on the size of CC and its association with improvement in the Alzheimer disease severity scores. Midsagittal size of CC were recorded prospectively from 439 routine T1-weighted MRI brain images in normal individuals. The internal skull surface was measured to calculate CC/ internal skull surface ratio. Two groups of patients were studied: 300 (150 male / 150 female) were healthy subjects and 130 (55 males / 75 females) had Alzheimer disease. Out of the 130 Alzheimer disease pateints, 70 patients were treated with Donepezil or Rivastigmine or both. The size of the CC was measured based on T1-weighted MRI images after the treatment to investigate any possible improvement in CC size. The mean surface area of CC in controls was 6.53±1.105 cm2. There was no significant difference between males and females (P < 0.627), and CC/ internal skull surface ratio was 4.41±0.77%. Patients with mild or severe Alzheimer disease showed a significant reduction in CC size compared to healthy controls. Treating mild Alzheimer patients with either Donepezil or Rivastigmine exerts a comparable therapeutic effect in improving the CC size. There was more improvement in the size of CC in patients with severe Alzheimer disease by using combined therapy of Donepezil and Rivastigmine than using single a medication. we measured the mean size of the various portions of the corpus callosum in normal individuals and Alzheimer patients before and after taking Donepezil and Rivastigmine. Alzheimer patients have pronounced reduction in CC which is corrected after taking Donepezil and Rivastigmine leading to remarkable improvement in Alzheimer disease severity scores.

Hypoxia disturbs the Migration and Adhesion characteristics of Mesenchymal Stem Cells.

Mesenchymal stem cells (MSCs) have been successfully used in treating many diseases which being verified by many preclinical and clinical trials.  Despite the exciting therapeutic potential of MSCs, multiple challenges encountered which hinder researchers from achieving successful clinical translations. Many studies have showed that moderate hypoxia (1-7% O2) considered as an important regulator of MSCs homing, migration, and differentiation. Additionally, low oxygen tension levels have been implicated in the maintenance of MSCs quiescence and plasticity in general. On the other hand, severe hypoxia (<1% O2) negatively affects the in vitro therapeutic potential of MSCs and causing their poor survival. Using Elisa assay we assessed some major adhesion markers that are known to be secreted by MSCs and play a role in cell-cell and cell-matrix adhesion under normoxia (21% O2) and severe hypoxia (0.5% O2). These markers including: SDF1-α, CXCR4, FAK, VEGF and ICAM-1. The results showed a significant drop in the adhesion markers in MSCs under severe hypoxia in comparing to normoxia, which causes a disruption in the cell-cell adhesion abilities of MSCs and ultimately can affect the incorporation of MSCs at the host site. These Findings can open new avenue to improve the attachment of MSCs at the transplantation site by targeting the adhesion and chemokines markers.

Assessing the racial differences in Q angle measurements in relevance to articular cartilage of the femoral condyle: a retrospective ultrasound study / Evaluación de las diferencias raciales en las mediciones del ángulo Q en relación con el cartílago articular del cóndilo femoral: un estudio ecográfico retrospectivo

SUMMARY: The Q-angle is defined as the acute angle formed by the vectors for combined pull of the quadriceps femoris muscle and the patellar tendon. This study aimed to investigate the variations in Q angle with respect to race. Moreover, this study performed ultrasound to evaluate of the thickness of articular cartilage covering the medial and lateral femoral condyle in volunteers with an increased Q angle. The study included 487 Jordanian and 402 Malaysians with age range 18-23 years. Moreover, the study included 30 participants aged between 18 and 22 years, with a total of 15 volunteers with Q >14° and 15 patients with Q ≤14°. Both Q angle and condylar distance were measured by well-trained medical practitioners according to a well-established protocol. The thickness of articular cartilage covering the medial and lateral femoral condyle of the femoral bone was measured using ultrasound. Regardless of race, Q angle was greater in females. Furthermore, Q angle was significantly greater in Arab volunteers compared to Malay volunteers. Q angle significantly increase with increasing condylar distance in both races. Finally, the statistical analysis showed a significantly reduced thickness of articular cartilage on both medial and lateral femoral condyle (P = 0.05) in the Q >14° group. Multiple factors including race and condylar distance and even the articular cartilage of femoral condyle should be considered during the examination and management of knee fractures and condylar diseases.

RESUMEN: El ángulo Q se define como el ángulo agudo formado por los vectores de tracción combinada del músculo cuádriceps femoral y el tendón patelar. Este estudio tuvo como objetivo investigar las variaciones en el ángulo Q con respecto a la raza. Además, se realizó una ecografía para evaluar el grosor del cartílago articular que cubre los cóndilos femorales medial y lateral en voluntarios con un ángulo Q aumentado. El estudio incluyó a 487 jordanos y 402 malayos con un rango de edad de 18 a 23 años. Además, el estudio incluyó a 30 participantes con edades comprendidas entre 18 y 22 años, 15 voluntarios con Q> 14 ° y 15 pacientes con Q ≤ 14 °. Tanto el ángulo Q como la distancia condilar fueron medidos por médicos bien entrenados de acuerdo con un protocolo establecido. El grosor del cartílago articular que cubre los cóndilos femorales medial y lateral del fémur se midió mediante ecografía. Independientemente del grupo racial, el ángulo Q fue mayor en las mujeres. Además, el ángulo Q fue significativamente mayor en los voluntarios árabes en comparación con los voluntarios malayos. El ángulo Q se aumenta significativamente al incrementarse la distancia condilar en ambas grupos raciales. Finalmente, el análisis estadístico mostró una reducción significativa del grosor del cartílago articular en los cóndilos femorales medial y lateral (P = 0,05) en el grupo Q> 14. Durante la exploración y el tratamiento de las fracturas de rodilla y de las enfermedades condilares, se deben considerar múltiples factores, incluida la raza y la distancia condilar e incluso el cartílago articular del cóndilo femoral.

Mesenchymal stem cells and COVID-19: What they do and what they can do.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or coronavirus disease 2019 (COVID-19) pandemic has exhausted the health systems in many countries with thousands cases diagnosed daily. The currently used treatment guideline is to manage the common symptoms like fever and cough, but doesn't target the virus itself or halts serious complications arising from this viral infection. Currently, SARS-CoV-2 exhibits many genetic modulations which have been associated with the appearance of highly contagious strains. The number of critical cases of COVID-19 increases markedly, and many of the infected people die as a result of respiratory failure and multiple organ dysfunction. The regenerative potential of mesenchymal stem cells (MSCs) has been extensively studied and confirmed. The impressive immunomodulation and anti-inflammatory activity of MSCs have been recognized as a golden opportunity for the treatment of COVID-19 and its associated complications. Moreover, MSCs regenerative and repairing abilities have been corroborated by many studies with positive outcomes and high recovery rates. Based on that, MSCs infusion could be an effective mechanism in managing and stemming the serious complications and multiple organ failure associated with COVID-19. In the present review, we discuss the commonly reported complications of COVID-19 viral infection and the established and anticipated role of MSCs in managing these complications.

Msx1 haploinsufficiency modifies the Pax9-deficient cardiovascular phenotype.

BACKGROUND: Successful embryogenesis relies on the coordinated interaction between genes and tissues. The transcription factors Pax9 and Msx1 genetically interact during mouse craniofacial morphogenesis, and mice deficient for either gene display abnormal tooth and palate development. Pax9 is expressed specifically in the pharyngeal endoderm at mid-embryogenesis, and mice deficient for Pax9 on a C57Bl/6 genetic background also have cardiovascular defects affecting the outflow tract and aortic arch arteries giving double-outlet right ventricle, absent common carotid arteries and interruption of the aortic arch. RESULTS: In this study we have investigated both the effect of a different genetic background and Msx1 haploinsufficiency on the presentation of the Pax9-deficient cardiovascular phenotype. Compared to mice on a C57Bl/6 background, congenic CD1-Pax9-/- mice displayed a significantly reduced incidence of outflow tract defects but aortic arch defects were unchanged. Pax9-/- mice with Msx1 haploinsufficiency, however, have a reduced incidence of interrupted aortic arch, but more cases with cervical origins of the right subclavian artery and aortic arch, than seen in Pax9-/- mice. This alteration in arch artery defects was accompanied by a rescue in third pharyngeal arch neural crest cell migration and smooth muscle cell coverage of the third pharyngeal arch arteries. Although this change in phenotype could theoretically be compatible with post-natal survival, using tissue-specific inactivation of Pax9 to maintain correct palate development whilst inducing the cardiovascular defects was unable to prevent postnatal death in the mutant mice. Hyoid bone and thyroid cartilage formation were abnormal in Pax9-/- mice. CONCLUSIONS: Msx1 haploinsufficiency mitigates the arch artery defects in Pax9-/- mice, potentially by maintaining the survival of the 3rd arch artery through unimpaired migration of neural crest cells to the third pharyngeal arches. With the neural crest cell derived hyoid bone and thyroid cartilage also being defective in Pax9-/- mice, we speculate that the pharyngeal endoderm is a key signalling centre that impacts on neural crest cell behaviour highlighting the ability of cells in different tissues to act synergistically or antagonistically during embryo development.

Anatomy education of medical students during the COVID 19 pandemic / Educación en anatomía de estudiantes de medicina durante la pandemia de COVID-19

SUMMARY: COVID-19 created extraordinary challenges to anatomy education and teaching practices, as the anatomists try to achieve best knowledge delivery level for their discipline, without the use of traditional teaching aids such as the cadavers and microscopic slides. The present study was conducted to collect medical students' response and opinions regarding the pros and cons of online teaching vs traditional teaching. 2263 medical studentswere recruited from the first three academic years. A multiple choice close-ended questionnaire regarding their opinion about virtual teaching mode for the anatomy discipline during COVID-19 pandemic was designed and circulated via emails.The majority (78.12 %) of the students agreed that they missed their traditional anatomy learning mode. Moreover, (92.92 %) of the students missed their campus and the college social life. The students strongly felt there is a gap and difficulty in understanding the topics that required practicing and visual orientation such as dissections, models, microscopic slides which help them in better memorizing and recalling the anatomical terms. The lack of proper devices and the absence of high quality internet were among the top reported issues that negatively affect online learning. These results indicated that, compared with traditional methods of teachings, the online learning in the medical schools had relatively poor planning and required continuous and combined efforts in order to improve the quality of online teaching specially for anatomy discipline, which may be an essential response for any unforeseen situation such as the COVID-19 pandemic. We should look at the current situation as an opportunity to apply modern anatomy education approaches which may be a necessity at the present time, with huge accomplishments achieved in the information and online technology field.

RESUMEN: La pandemia de COVID-19 creó desafíos extraordinarios para la educación y las prácticas de enseñanza de la anatomía, debido al objetivo del anatomista de lograr el mejor nivel de educación para su disciplina sin el uso materiales didácticos tradicionales, tal como los cadáveres y las láminas microscópicas. En este studio se analizó la respuesta y las opiniones de los estudiantes sobre los pros y los contras de la enseñanza en línea frente a la enseñanza tradicional. Se reclutaron 2263 estudiantes de medicina de los tres primeros años académicos. Se diseñó un cuestionario cerrado de opción múltiple con respecto a su opinión sobre el método de enseñanza virtual para la disciplina de anatomía durante la pandemia de COVID-19 y se distribuyó por correo electrónico. Además, (92,92 %) de los estudiantes dejaron de participar en la vida social universitaria y se ausentaron del campus. Los estudiantes sintieron fuertemente que hay una brecha y dificultad para comprender los temas que requieren práctica y orientación visual, como disecciones, modelos, diapositivas microscópicas que les ayudan a memorizar y recordar mejor los términos anatómicos. La falta de internet de calidad, y de dispositivos adecuados se encuentran entre los principales problemas reportados que afectan negativamente el aprendizaje en línea. Estos resultados indicaron que, en comparación con los métodos tradicionales de enseñanza, el aprendizaje en línea en las escuelas de medicina tenía una planificación relativamente deficiente y requería una planificación continua, además de esfuerzos para mejorar la calidad de la enseñanza en línea de anatomía, lo que que podría ser de apoyo fundamental ante cualquier situación imprevista como la pandemia de COVID-19. Actualmente, se debe considerar esta situación como una oportunidad para aplicar enfoques modernos de educación en anatomía con importantes logros en el campo de la tecnología informática y en línea.

Cross talk between 26S proteasome and mitochondria in human mesenchymal stem cells' ability to survive under hypoxia stress.

Mesenchymal stem cells (MSCs) are regarded as unique cells which play an imperative role in the field of regenerative medicine. They are characterized by the self-renewal capacity, multi-lineage differentiation abilities and immunomodulation properties which render them perfectly ideal cell type for treating a wide range of chronic diseases. Despite these enchanted features, there are many hurdles that need to be circumvented to ensure their long-term survival and viability after transplantation. Recently, hypoxia has been indicated as one of the most baffling stress conditions that can affect the survival rate of MSCs either positively or negatively depending on the level of hypoxia. MSCs can survive well under moderate hypoxia, but die shortly if they were exposed to severe hypoxia without clearly convincing explanation for this enigma. The current study reveals a novel mechanism of 26S proteasome in controlling the ability of BM-MSCs to withstand hypoxic stress by maintaining proper mitochondrial function. The results indicated that 26S proteasome remains functioning once BM- MSCs are exposed to moderate hypoxia (2.5%O2) and preserves their survival and proliferation mediated by intact mitochondrial performance, whereas 26S proteasome becomes inactive when BM-MSCs faces severe hypoxia that lead to poor mitochondrial function and less chance to survive longer. The outcomes of this study demonstrated the importance of 26S proteasome machinery in enhancing the resistance of BM-MSCs to hypoxic stress condition which may help in better planning future studies that target this system. Schematic representation summarizing the findings of the current study. 26S proteasome function preservation in normoxia and moderate hypoxia leads to maintain appropriate proliferation and mitochondrial activity in human BM-MSCs and promote their survival. On the opposite side, severe hypoxia disrupts the 26S proteasome function leading to significant reduction in the proliferation, survival and mitochondrial dynamics in human BM-MSCs causing their death.

Pax9 is required for cardiovascular development and interacts with Tbx1 in the pharyngeal endoderm to control 4th pharyngeal arch artery morphogenesis.

Developmental defects affecting the heart and aortic arch arteries are a significant phenotype observed in individuals with 22q11 deletion syndrome and are caused by a microdeletion on chromosome 22q11. TBX1, one of the deleted genes, is expressed throughout the pharyngeal arches and is considered a key gene, when mutated, for the arch artery defects. Pax9 is expressed in the pharyngeal endoderm and is downregulated in Tbx1 mutant mice. We show here that Pax9-deficient mice are born with complex cardiovascular malformations that affect the outflow tract and aortic arch arteries with failure of the 3rd and 4th pharyngeal arch arteries to form correctly. Transcriptome analysis indicated that Pax9 and Tbx1 may function together, and mice double heterozygous for Tbx1/Pax9 presented with a significantly increased incidence of interrupted aortic arch when compared with Tbx1 heterozygous mice. Using a novel Pax9Cre allele, we demonstrated that the site of this Tbx1-Pax9 genetic interaction is the pharyngeal endoderm, therefore revealing that a Tbx1-Pax9-controlled signalling mechanism emanating from the pharyngeal endoderm is required for crucial tissue interactions during normal morphogenesis of the pharyngeal arch artery system.