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Background Informed consent is an obligatory requirement for research engaging human subjects. Informed consent form (ICF) should be provided for human subjects to confirm their willingness for voluntary participation in a study. Ethical and legal obligations necessitate the presence of informed consent essential items to be built into the ICF. Objective To evaluate the content of ICFs obtained from different genetic studies accomplished in Jordan and their adherence to ethical guidelines proposed by the International Conference on Harmonization-Good Clinical Practice (ICHGCP). Methods and Measures A total of 44 ICFs obtained from master theses and grant proposals at two major universities in Jordan were analyzed according to the good clinical practice criteria proposed by ICHGCP. ICFs were scored for the presence or absence of ICF main items/categories. Results Results show inadequate information present in the examined ICFs. The highest information score was 17 out of 20, while the lowest score was one out of 20. The average score for all studied ICFs was 6.18±3.65. Among essential items/categories that were absent from the majority of studied ICFs were a statement about voluntary participation, confidentiality of data, compensation to study participants, risk/benefits of the study, and researchers' contact information. Conclusion The ICFs were missing a number of required items. This could reflect inadequate knowledge about minimal informed consent requirements among Jordanian investigators highlighting the need for research ethical training in the country.

Background: Huge efforts are being made to control the spread and impacts of the coronavirus pandemic using vaccines. However, willingness to be vaccinated depends on factors beyond the availability of vaccines. The aim of this study was three-folded: to assess the prevalence of children’s vaccination against COVID-19, to explore parents’ attitudes towards children’s vaccination, and to discover the factors associated with parents’ hesitancy towards children’s vaccination in several countries in the Eastern Mediterranean Region (EMR). Methods: This study utilized a cross-sectional descriptive design. A sample of 3744 parents from eight countries, namely, Iraq, Jordan, Kuwait, Lebanon, Palestine, Qatar, Saudi Arabia (KSA), and the United Arab Emirates (UAE), was conveniently approached and surveyed using Google forms. The participants have responded to a 42-item questionnaire pertaining to socio-demographics, children vaccination status, knowledge about COVID-19 vaccines, and attitudes towards vaccinating children and the vaccine itself. Results: The prevalence of vaccinated children against COVID-19 was 32% as indicated by the parents. Concerning parents’ attitudes towards vaccines safety, about one third of participants (32.5%) believe that all vaccines are not safe. In the regression analysis, children’s vaccination was significantly correlated with parents’ age, education, occupation, parents’ previous COVID-19 infection, and their vaccination status. Participants aged ≥50 years and those aged 40-50 years had an odds ratio of 17.9 (OR=17.9, CI: 11.16-28.97) and 13.2 (OR=13.2, CI: 8.42-20.88); respectively, for vaccinating their children compared to those aged 18-29 years. Parents who had COVID-19 vaccine were about five folds more likely to vaccinate their children compared with parents who did not receive the vaccine (OR=4.9, CI: 3.12-7.70). The prevalence of children’s vaccination in the participating Arab countries is still not promising. Conclusion: To encourage parents, vaccinate their children against COVID-19, Arab governments should strategize accordingly. Reassurance of the efficacy and effectiveness of the vaccine should target the general population using educational campaigns, social media, and official TV and radio channels.

Frequencies of H1 and H2 haplotypes of the microtubule-associated protein tau (MAPT) gene were examined in two Jordanian samples. The criterion for haplotype assignment was the presence/absence of the intronic 238-bp deletion, located between exons 9 and 10 of the MAPT genomic region. We further compiled MAPT haplotype frequencies in Middle Eastern, South Asian, and European populations to widen the scope of analyses. Jordan MAPT*H2 haplotype frequencies peaked among worldwide samples analysed to date, with the Jordan general population featuring the top value (0.386). AMOVA tests results indicated spatial genetic structuring, as they unveiled significant differences in H2 frequencies between South Asia and Europe, with a hypothetical contact zone in the Middle East. The southeastern region of the Middle East shares low H2 frequencies with South Asia, while the northwestern area shows high H2 frequencies, similar to and even higher than observed in Europe. We suggest that high H2 frequencies could have originated at the beginning of the Neolithic in the western region of the Middle East, most likely through genetic drift episodes associated with founding events. Subsequently, the arrival of Neolithic farmers boosted the H2 haplotype spreading throughout Europe.

Background Medical genetic testing is an evolving side of clinical care that helps people to make informed medical and lifestyle decisions. The source of knowledge, personal beliefs, and attitude towards genetic testing are the main determinative factors of getting optimal utilization of such technology in reducing/prevention of diseases. Methods A structured survey was used to assess the knowledge, beliefs, and attitude regarding genetic testing among 463 young adults aged 18 years or older living in the North of Jordan. Results More than three-quarters (77.1%) of the respondents were familiar with the term genetic testing. The most common sources of knowledge were: education they received (44.8%), the internet (37.5%), and social media (17.2%). Most (93.9%) of the respondents believed that genetic testing is a useful tool to diagnose and prevent genetic diseases. Almost three-quarters (72.7%) of the respondents believed that the health care system provides advice or genetic counseling to those with a genetic disease. A total of 9.6% of the respondents thought that genetic testing might cause a physical risk to their lives. In addition, 11.3% of the respondents believed that genetic testing is forbidden and not permissible and about 6.3% did not agree in performing genetic testing in the future. Finally, about half (53.4%) of the respondents consider genetic testing affordable and the remainder consider it costly. Conclusion Our findings emphasize the importance of acquiring knowledge about genetic testing among young individuals, Issues related to knowledge were identified and should be further improved, such as cost prediction, safety, and the legitimacy of genetic testing to get better outcomes in the Jordanian community.

Introduction This study aimed to isolate bacterial pathogens from the dominant hand and mobile phones and to determine their antibiotic susceptibility profiles. The dominant hand and mobile surfaces were swabbed to detect the transmission of bacterial pathogens among university students. Methods Two hundred and twenty hand and mobile phone swabs were collected from the students of four different colleges in a Jordanian university between October and December 2017. The swabs were collected and transported to the Microbiology laboratory within one hour. At the lab, swabs were inoculated on nutrient agar, MacConkey agar, blood agar and mannitol salt agar. The subsequent bacterial isolates were identified by their cultural, morphological and biochemical characteristics. Results Eight bacterial species were isolated and identified in the current study, namely Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus, Micrococcus spp. and Escherichia coli. The percentage of isolated bacteria was 54.5%, 25.5%, 14.5% and 5.5% from veterinary, biology, biomedical engineering and chemistry students, respectively. Many isolates were highly resistant to most tested antibiotics. Conclusions Pathogenic bacteria were detected with multiple antibiotic resistance indexes. Hands and mobile phones can act as carriers for infectious agents, suggesting the need for proper hand hygiene and disinfecting mobile phones surfaces.

Background Sharing and reuse biosamples can facilitate biomedical research. Little is known about researchers’ perception and practice about sharing, reusing, and storing biosamples in Jordan. Therefore, the current study aimed to evaluate the practices of biomedical researchers in Jordan regarding biosamples management. Methods The study was cross-sectional and involved biomedical researchers from different parts of Jordan. A questionnaire was designed to achieve the aim of this study. The questionnaire was web-based and distributed via e-mails using Google forms. Results Opinions of Jordanian biomedical researchers from different academic ranks and institutional backgrounds were measured and recorded anonymously. The majority of the sample was males (57.9%), from public universities (64.3%), and (64.6%) were from health-related fields. About 82.9% of participants stored biosamples using codes, whereas the rest used the subject’s name. Sharing of biosamples was commonly practiced by 61.7% of Jordanian researchers locally, while 47.2% of the Jordanian researchers shared biosamples overseas. The reuse of biosamples in other projects was reported to be 55.4%. The majority explained the possibility of reusing and sharing biosamples in the consent form (range: 53–58%). Sharing and reusing biosamples were associated with gender, the number of publications in peer-reviewed international journals, and academic rank (P Conclusion Sharing and reusing biosamples are common among Jordanian biomedical researchers. Therefore, ethically grounded biosamples sharing and reuse standards are essential for protecting human subjects’ rights and privacy in Jordan.

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.

The aim of this study was to perform a systematic overview of the pharmacogenetic studies conducted in Jordan. A structured search of Medline was conducted for articles over the last decade (January 2010-July 2020). Studies were classified by design, sample size, drug-gene combination, and the significance of the results. Thirty-two studies met the criteria for review. Most pharmacogenomic studies had a case-only design (n = 23). Only five studies included500 participants. The total number of genetic variants in all studies was one hundred fifteen, which were found in forty genes, including dynamic (n = 27), and kinetic (n = 9) genes. The most commonly studied drugs were within the hematology and cardiology therapeutic areas and included statins, warfarin, aspirin, and clopidogrel. Most studies (n = 18) reported results with mixed p values [0.05 and0.05]. Pharmacogenomic research in Jordan is still in its infancy and is limited mainly to replication attempts. The need for standardization is imperative, especially in developing countries with scarce funding resources.

Background Informed consent is an obligatory requirement for research engaging human subjects. Informed consent form (ICF) should be provided for human subjects to confirm their willingness for voluntary participation in a study. Ethical and legal obligations necessitate the presence of informed consent essential items to be built into the ICF. Objective To evaluate the content of ICFs obtained from different genetic studies accomplished in Jordan and their adherence to ethical guidelines proposed by the International Conference on Harmonization—Good Clinical Practice (ICHGCP). Methods and Measures A total of 44 ICFs obtained from master theses and grant proposals at two major universities in Jordan were analyzed according to the good clinical practice criteria proposed by ICHGCP. ICFs were scored for the presence or absence of ICF main items/categories. Results Results show inadequate information present in the examined ICFs. The highest information score was 17 out of 20, while the lowest score was one out of 20. The average score for all studied ICFs was 6.18±3.65. Among essential items/categories that were absent from the majority of studied ICFs were a statement about voluntary participation, confidentiality of data, compensation to study participants, risk/benefits of the study, and researchers’ contact information. Conclusion The ICFs were missing a number of required items. This could reflect inadequate knowledge about minimal informed consent requirements among Jordanian investigators highlighting the need for research ethical training in the country.

Sulfurous springs have been traditionally used in medical treatment for different purposes. These beneficial effects of sulfurous water have been attributed to the presence of sulfurous compounds mainly in the form of hydrogen sulfide (H2S). The purpose of the present study is to explore the effects of long-term exposure to sulfurous springs on oxidative stress and antioxidant biomarkers responses in individuals who lived nearby the sulfurous springs. The studied area was Al- Hammah sulfurous springs, which is located in the northern part of the Jordan Rift Valley and host many sulfurous springs. Residents in sulfurous springs area are continuously exposed to water and gases emission more than the overall population. We have found that the sulphate levels were 7 times higher in sulfurous springs water samples than control water samples. The majority of the volunteers involved in the present study were more than ten years long residence and lived in range distance between one to five kilometers (less than 3 miles) away from main sulfurous spring, and visited the sulfurous spring at least once a month. We did not find any noticeable symptoms in sulfur spring residents such as headaches, nausea, breathing problems. The total oxidative stress (TOS) and oxidative stress index (OSI) in sulfurous spring residents were lower than control individuals. The total antioxidant capacity (TAC) and total nitric oxide (NOX) levels were higher in sulfurous spring residents compared to control group. Furthermore, we have highlighted that living nearby the sulfurous springs does not affect oxygen saturation levels (SPO2) or heart pulse rate . These findings suggest that long-term exposure to sulfurous springs boost the antioxidant capacity and reduce oxidative stress levels in the human body. Hence, visiting sulfurous springs can act as natural remedies to diminish oxidative stress as they show promising potential in several-oxidative stress-related diseases treatment., Environmental science; Public health; Oxidative stress; Antioxidant; Lipid peroxidation; Biomolecules; Aging; Al- Hammah springs; Antioxidant capacity; Hydrogen sulfide; Long term H2S exposure; Oxidative stress, Sulfurous springs treatment

Mammalian cells can utilize hydrogen sulfide (H2S) to support mitochondrial respiration. The aim of our study was to explore the potential role of S-sulfhydration (a H2S-induced posttranslational modification, also known as S-persulfidation) of the mitochondrial inner membrane protein ATP synthase (F1F0 ATP synthase/Complex V) in the regulation of mitochondrial bioenergetics. Using a biotin switch assay, we have detected S-sulfhydration of the α subunit (ATP5A1) of ATP synthase in response to exposure to H2S in vitro. The H2S generator compound NaHS induced S-sulfhydration of ATP5A1 in HepG2 and HEK293 cell lysates in a concentration-dependent manner (50–300 μM). The activity of immunocaptured mitochondrial ATP synthase enzyme isolated from HepG2 and HEK293 cells was stimulated by NaHS at low concentrations (10–100 nM). Site-directed mutagenesis of ATP5A1 in HEK293 cells demonstrated that cysteine residues at positions 244 and 294 are subject to S-sulfhydration. The double mutant ATP synthase protein (C244S/C294S) showed a significantly reduced enzyme activity compared to control and the single-cysteine-mutated recombinant proteins (C244S or C294S). To determine whether endogenous H2S plays a role in the basal S-sulfhydration of ATP synthase in vivo, we compared liver tissues harvested from wild-type mice and mice deficient in cystathionine-gamma-lyase (CSE, one of the three principal mammalian H2S-producing enzymes). Significantly reduced S-sulfhydration of ATP5A1 was observed in liver homogenates of CSE−/− mice, compared to wild-type mice, suggesting a physiological role for CSE-derived endogenous H2S production in the S-sulfhydration of ATP synthase. Various forms of critical illness (including burn injury) upregulate H2S-producing enzymes and stimulate H2S biosynthesis. In liver tissues collected from mice subjected to burn injury, we detected an increased S-sulfhydration of ATP5A1 at the early time points post-burn. At later time points (when systemic H2S levels decrease) S-sulfhydration of ATP5A1 decreased as well. In conclusion, H2S induces S-sulfhydration of ATP5A1 at C244 and C294. This post-translational modification may be a physiological mechanism to maintain ATP synthase in a physiologically activated state, thereby supporting mitochondrial bioenergetics. The sulfhydration of ATP synthase may be a dynamic process, which may be regulated by endogenous H2S levels under various pathophysiological conditions.

Aims: Thioredoxin reductase 1 (TrxR1) is a cancer target and essential selenoprotein that defends the cell against reactive oxygen species and regulates cellular signaling and redox pathways. Previous cell-based studies correlated TrxR1 acetylation with modulated cellular reduction activity, yet the function of specific acetylation sites on TrxR1 remains unknown. Innovation: We produced site-specifically acetylated TrxR1 variants that also contain selenocysteine (Sec). We demonstrated efficient high-fidelity protein synthesis with 22 different amino acids by simultaneous UAG codon reassignment to Nɛ-acetyl-lysine and UGA codon recoding to Sec. Results: We characterized TrxR1 variants acetylated at physiologically relevant sites and found that single acetylation sites increased TrxR1 activity, enhancing the apparent catalytic rate up to 2.7-fold. The activity increase in acetylated TrxR1 (acTrxR1) is reversible and is reduced following deacetylation with histone deacetylase. Conclusion: Here we present a novel mechanism through which acetylation increases TrxR1 activity by destabilizing low-activity TrxR1 multimers, increasing the population of active dimeric TrxR1. Antioxid. Redox Signal. 29, 377–388.

The genotoxic effects of cigarette smoke filtrate (SF) on the germ-line stages were examined in Drosophila melanogaster using the sex-linked recessive lethal test, which detects a broad spectrum of genetic alterations and proved to show correlations between mutagenicity and carcinogenicity of the tested chemicals. SF was extracted from fiberglass filter cartridges; each used in smoking 15 cigarettes. The proper SF concentrations (0.2 µL) in 0.45% NaCl saline were injected intraperitoneally in 2- to 3-day-old wild-type males, alongside with controls injected with 0.2 µL of saline. The genotoxicity effects of SF were examined in all spermatogenesis stages of treated males. Results showed that SF was toxic with an median lethal dose value of approximately 0.2% and induced significant sterility effects. The mutagenicity of SF (0.2%) was significantly stage specific and induced complete sex-linked recessive lethal mutations in the broods representing the spermatocytes and late and early spermatogonia, and induced mosaic mutations in the untreated progeny in the brood representing late spermatogonia. These results indicated, for the first time, that SF induces mosaic mutations, which could result from DNA instabilities and labile permutations that can be replicated and passed to future generations before being fixed into mutations in the untreated progeny of treated males, or originating from mutations that result in increasing hyperplasia of the gonad that subsequently produce the actual mutations in later cell cycles. Such delayed mutagenic effects of SF indicated that SF and, consequently, cigarette smoking have much greater genotoxicity than what was previously predicted.

Hydrogen sulfide (H2 S) and nitric oxide (NO) are major gasotransmitters produced in endothelial cells (ECs), contributing to the regulation of vascular contractility and structural integrity. Their interaction at different levels would have a profound impact on angiogenesis. Here, we showed that H2 S and NO stimulated the formation of new microvessels. Incubation of human umbilical vein endothelial cells (HUVECs-926) with NaHS (a H2 S donor) stimulated the phosphorylation of endothelial NO synthase (eNOS) and enhanced NO production. H2 S had little effect on eNOS protein expression in ECs. L-cysteine, a precursor of H2 S, stimulated NO production whereas blockage of the activity of H2 S-generating enzyme, cystathionine gamma-lyase (CSE), inhibited this action. CSE knockdown inhibited, but CSE overexpression increased, NO production as well as EC proliferation. LY294002 (Akt/PI3-K inhibitor) or SB203580 (p38 MAPK inhibitor) abolished the effects of H2 S on eNOS phosphorylation, NO production, cell proliferation and tube formation. Blockade of NO production by eNOS-specific siRNA or nitro-L-arginine methyl ester (L-NAME) reversed, but eNOS overexpression potentiated, the proliferative effect of H2 S on ECs. Our results suggest that H2 S stimulates the phosphorylation of eNOS through a p38 MAPK and Akt-dependent pathway, thus increasing NO production in ECs and vascular tissues and contributing to H2 S-induced angiogenesis.

The gasotransmitter hydrogen sulfide (H(2)S), which is generated by cystathionine γ-lyase (CSE), signals by modifying proteins through S-sulfhydration and potentially other mechanisms. A target protein for H(2)S is endothelial nitric oxide synthase (eNOS), an enzyme that generates nitric oxide (NO), which causes vasodilation. We investigated whether H(2)S-induced S-sulfhydration affected the S-nitrosylation and phosphorylation of eNOS and the functional effects of changes in these posttranslational modifications on eNOS activity. In vitro, different NO donors induced the S-nitrosylation of eNOS without affecting its S-sulfhydration, whereas the H(2)S donor sodium hydrosulfide (NaHS) decreased the S-nitrosylation of eNOS. Cys(443) was the primary S-sulfhydration site in eNOS and was one site that could be S-nitrosylated. Phosphorylation increases eNOS activity. Although exposure of eNOS-expressing HEK-293 cells to NaHS or vascular endothelial growth factor (VEGF) triggered the phosphorylation of wild-type and C443G-eNOS, VEGF did not affect the S-sulfhydration of eNOS and a mutant of eNOS that could not be phosphorylated was still S-sulfhydrated. eNOS can be present in cells in monomeric or dimeric form, but only eNOS dimers produce NO. In wild-type mice, eNOS proteins were predominantly dimerized, whereas eNOS from CSE-knockout (KO) mice, S-nitrosylated eNOS, and heterologously expressed C443G-eNOS was mostly monomeric. Accordingly, basal production of NO was lower in CSE-KO endothelial cells than in wild-type endothelial cells. Our data suggest that H(2)S increases eNOS activity by inducing the S-sulfhydration of eNOS, promoting its phosphorylation, inhibiting its S-nitrosylation, and increasing eNOS dimerization, whereas NO decreases eNOS activity by promoting the formation of eNOS monomers.

The repair of DNA damage is fundamental to normal cell development and replication. Hydrogen sulfide (H2S) is a novel gasotransmitter that has been reported to protect cellular aging. Here, we show that H2S attenuates DNA damage in human endothelial cells and fibroblasts by S-sulfhydrating MEK1 at cysteine 341, which leads to PARP-1 activation. H2S-induced MEK1 S-sulfhydration facilitates the translocation of phosphorylated ERK1/2 into nucleus, where it activates PARP-1 through direct interaction. Mutation of MEK1 cysteine 341 inhibits ERK phosphorylation and PARP-1 activation. In the presence of H2S, activated PARP-1 recruits XRCC1 and DNA ligase III to DNA breaks to mediate DNA damage repair, and cells are protected from senescence.

A growing body of evidence suggests that hydrogen sulfide (H2S) is a signaling molecule in mammalian cells. In the cardiovascular system, H2S enhances vasodilation and angiogenesis. H2S-induced vasodilation is hypothesized to occur through ATP-sensitive potassium channels (K-ATP); however, we recently demonstrated that it also increases cGMP levels in tissues. Herein, we studied the involvement of cGMP-dependent protein kinase-I in H2S-induced vasorelaxation. The effect of H2S on vessel tone was studied in phenylephrine-contracted aortic rings with or without endothelium. cGMP levels were determined in cultured cells or isolated vessel by enzyme immunoassay. Pretreatment of aortic rings with sildenafil attenuated NaHS-induced relaxation, confirming previous findings that H2S is a phosphodiesterase inhibitor. In addition, vascular tissue levels of cGMP in cystathionine gamma lyase knockouts were lower than those in wild-type control mice. Treatment of aortic rings with NaHS, a fast releasing H2S donor, enhanced phosphorylation of vasodilator-stimulated phosphoprotein in a time-dependent manner, suggesting that cGMP-dependent protein kinase (PKG) is activated after exposure to H2S. Incubation of aortic rings with a PKG-I inhibitor (DT-2) attenuated NaHS-stimulated relaxation. Interestingly, vasodilatory responses to a slowly releasing H2S donor (GYY 4137) were unaffected by DT-2, suggesting that this donor dilates mouse aorta through PKG-independent pathways. Dilatory responses to NaHS and L-cysteine (a substrate for H2S production) were reduced in vessels of PKG-I knockout mice (PKG-I-/-). Moreover, glibenclamide inhibited NaHS-induced vasorelaxation in vessels from wild-type animals, but not PKG-I-/-, suggesting that there is a cross-talk between K-ATP and PKG. Our results confirm the role of cGMP in the vascular responses to NaHS and demonstrate that genetic deletion of PKG-I attenuates NaHS and L-cysteine-stimulated vasodilation.

The goal of the current study was to investigate the role of exogenous and endogenous hydrogen sulfide (H 2 S) on neovascularization and wound healing in vitro and in vivo. Incubation of endothelial cells (ECs) with H 2 S enhanced their angiogenic potential, evidenced by accelerated cell growth, migration, and capillary morphogenesis on Matrigel. Treatment of chicken chorioallantoic membranes (CAMS) with H 2 S increased vascular length. Exposure of ECs to H 2 S resulted in increased phosphorylation of Akt, ERK, and p38. The K ATP channel blocker glibenclamide or the p38 inhibitor SB203580 abolished H 2 S-induced EC motility. Since glibenclamide inhibited H 2 S-triggered p38 phosphorylation, we propose that K ATP channels lay upstream of p38 in this process. When CAMs were treated with H 2 S biosynthesis inhibitors dl-propylargylglycine or beta-cyano-L-alanine, a reduction in vessel length and branching was observed, indicating that H 2 S serves as an endogenous stimulator of the angiogenic response. Stimulation of ECs with vascular endothelial growth factor (VEGF) increased H 2 S release, while pharmacological inhibition of H 2 S production or K ATP channels or silencing of cystathionine gamma-lyase (CSE) attenuated VEGF signaling and migration of ECs. These results implicate endothelial H 2 S synthesis in the pro-angiogenic action of VEGF. Aortic rings isolated from CSE knockout mice exhibited markedly reduced microvessel formation in response to VEGF when compared to wild-type littermates. Finally, in vivo, topical administration of H 2 S enhanced wound healing in a rat model, while wound healing was delayed in CSE −/− mice. We conclude that endogenous and exogenous H 2 S stimulates EC-related angiogenic properties through a K ATP channel/MAPK pathway.

The endothelium is a cellular monolayer that lines the inner surface of blood vessels and plays a central role in the maintenance of cardiovascular homeostasis by controlling platelet aggregation, vascular tone, blood fluidity and fibrinolysis, adhesion and transmigration of inflammatory cells, and angiogenesis. Endothelial dysfunctions are associated with various cardiovascular diseases, including atherosclerosis, hypertension, myocardial infarction, and cardiovascular complications of diabetes. Numerous studies have established the anti-inflammatory, anti-apoptotic, and anti-oxidant effects of hydrogen sulfide (H2S), the latest member to join the gasotransmitter family along with nitric oxide and carbon monoxide, on vascular endothelium. In addition, H2S may prime endothelial cells (ECs) toward angiogenesis and contribute to wound healing, besides to its well-known ability to relax vascular smooth muscle cells (VSMCs), and thereby reducing blood pressure. Finally, H2S may inhibit VSMC proliferation and platelet aggregation. Consistently, a deficit in H2S homeostasis is involved in the pathogenesis of atherosclerosis and of hyperglycaemic endothelial injury. Therefore, the application of H2S-releasing drugs or using gene therapy to increase endogenous H2S level may help restore endothelial function and antagonize the progression of cardiovascular diseases. The present article reviews recent studies on the role of H2S in endothelial homeostasis, under both physiological and pathological conditions, and its putative therapeutic applications.