Hypoxic State Research Articles

Assessing the Role of Blood Gas Analysis in COVID-19 Patients for Early Warning and Clinical Guidance.

To assess the role of blood gas analysis as an auxiliary tool for detecting and predicting the progression of COVID-19 in patients. A consecutive cohort study was conducted of 106 patients diagnosed with the novel coronavirus. Patients were divided into two groups based on age and the course of the disease (mild to moderate and severe). Blood gas analysis parameters were measured for all participants and results were compared between groups. This study was conducted in the Department of Laboratory Medicine, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China. Arterial/alveolar oxygen partial pressure ratio, reduced hemoglobin fraction, sodium ion, lactic acid, oxygen saturation, oxygen partial pressure, and oxyhemoglobin fraction. Findings indicated statistically significant differences between the two groups in the measured parameters. Blood gas analysis has the potential to more accurately assess the progression of COVID-19 in elderly patients, specifically related to respiratory and acid-base balance issues. This study underscores the importance for bedside nurses to pay close attention to acid-base balance, lung ventilation/ventilation function, and hypoxia status in elderly critically ill patients with COVID-19, in order to more effectively diagnose and predict the progression of the disease.

Early Detection of High-altitude Hypoxic Brain Injury by In Vivo Electrochemistry.

High-altitude hypoxic brain injury (HHBI) is a kind of acute mountain sickness and the survival rate of patients with HHBI can be improved only if it is detected and treated at the early stage. However, limited by speediness and accuracy, it is still very difficult for most of current approaches to realize the early detection of HHBI. We propose herein a novel strategy for this goal based on spatiotemporal changes in the brain oxygen level. As revealed by in vivo electrochemistry, the characteristic changes of brain oxygen level under the high-altitude exposure are directly associated with the brain hypoxia status. Given brain hypoxia is the main pathogenesis of HHBI, the degree of HHBI can be diagnosed by the variation of brain oxygen, making the early detection of HHBI feasible. In addition, the risk of HHBI for mouse exposed to high-altitude hypoxia environments can be also prognosed days in advance.

Early Detection of High‐altitude Hypoxic Brain Injury by In Vivo Electrochemistry

High‐altitude hypoxic brain injury (HHBI) is a kind of acute mountain sickness and the survival rate of patients with HHBI can be improved only if it is detected and treated at the early stage. However, limited by speediness and accuracy, it is still very difficult for most of current approaches to realize the early detection of HHBI. We propose herein a novel strategy for this goal based on spatiotemporal changes in the brain oxygen level. As revealed by in vivo electrochemistry, the characteristic changes of brain oxygen level under the high‐altitude exposure are directly associated with the brain hypoxia status. Given brain hypoxia is the main pathogenesis of HHBI, the degree of HHBI can be diagnosed by the variation of brain oxygen, making the early detection of HHBI feasible. In addition, the risk of HHBI for mouse exposed to high‐altitude hypoxia environments can be also prognosed days in advance.

Anti-VEGFR2 neutralising antibody slows the progression of multistep oral carcinogenesis.

Angiogenesis plays an important role in cancer growth and metastasis, and it is considered a therapeutic target to control tumour growth following anti-angiogenic therapy. However, it is still unclear when tissues initiate angiogenesis during malignant transformation from premalignant condition and whether this premalignant condition could be a therapeutic target of anti-angiogenic therapy. In this study, we aimed to analyse the onset of angiogenesis by evaluating morphological and functional alterations of microvessels during oral multistep carcinogenesis using a 4-nitroquinoline 1-oxide (4NQO)-induced oral carcinogenesis mouse model. In the study, we initially confirmed that with the use of 4NQO, oral lesions develop in a stepwise manner from normal mucosa through oral epithelial dysplasia (OED) to oral squamous cell carcinoma (OSCC). Evaluation of CD31-immunostained specimens revealed that microvessel density (MVD) increases in a stepwise manner from OEDs. Histological and functional analyses revealed the structural abnormalities and leakage of blood vessels had already taken place in OED. Then we evaluated the expression profiles of Hif1a and Vegfa along with hypoxic status and found that OED exhibited increased Vegfa expression under hypoxic conditions. Finally, we tested the possibility of OEDs as a target of anti-angiogenic therapy and found that anti-VEGFR2 neutralising antibody in OED slowed the disease progression from OED to OSCC. These data indicate that an angiogenic switch occurs at the premalignant stage and morphological, and functional alterations of microvessels already exist in OED. These findings also elucidate the tumour microenvironment, which gradually develops along with carcinogenic processes, and highlight usefulness of the 4NQO-induced carcinogenesis model in the study of epithelial and stromal components, which will support epithelial carcinogenesis. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

2-Aryl-Benzoimidazoles as Type II NADH Dehydrogenase Inhibitors of Mycobacterium tuberculosis.

The nonproton pumping type II NADH dehydrogenase in Mycobacterium tuberculosis is essential for meeting the energy needs in terms of ATP under normal aerobic and stressful hypoxic environmental states. Type II NADH dehydrogenase conduits electrons into the electron transport chain in Mycobacterium tuberculosis, which results in ATP synthesis. Therefore, the inhibition of NDH-2 ensures the abolishment of the entire ATP synthesis machinery. Also, type II NADH dehydrogenase is absent in the mammalian genome, thus making it a potential target for antituberculosis drug discovery. Herein, we have screened a commercially available library of drug-like molecules and have identified a hit having a benzimidazole core moiety (6, H37Rv mc26230; minimum inhibitory concentration (MIC) = 16 μg/mL and ATP IC50 = 0.23 μg/mL) interfering with the oxidative phosphorylation pathway. Extensive medicinal chemistry optimization resulted in analogue 8, with MIC = 4 μg/mL and ATP IC50 = 0.05 μg/mL against the H37Rv mc26230 strain of Mycobacterium tuberculosis. Compounds 6 and 8 were found to be active against mono- and multidrug-resistant mycobacterium strains and demonstrated a bactericidal response. The Peredox-mCherry experiment and identification of single-nucleotide polymorphisms in mutants of CBR-5992 (a known type II NADH dehydrogenase inhibitor) were used to confirm the molecules as inhibitors of the type II NADH dehydrogenase enzyme. The safety index >10 for the test active molecules revealed the safety of test molecules.

Systemic delivery of tannic acid-ferric-masked oncolytic adenovirus reprograms tumor microenvironment for improved therapeutic efficacy in glioblastoma.

Glioblastoma (GBM) represents the most aggressive primary brain tumor, and urgently requires effective treatments. Oncolytic adenovirus (OA) shows promise as a potential candidate for clinical antitumor therapy, including in the treatment of GBM. Nevertheless, the systemic delivery of OA continues to face challenges, leading to significantly compromised antitumor efficacy. In this study, we developed an innovative approach by encapsulating CXCL11-armed OA with tannic acid and Fe3+ (TA-Fe3+) to realize the systemic delivery of OA. The nanocarrier's ability to protect the OA from elimination by host immune response was evaluated in vitro and in vivo. We evaluated the antitumor effect and safety profile of OA@TA-Fe3+ in a GBM-bearing mice model. OA@TA-Fe3+ effectively safeguarded the virus from host immune clearance and extended its circulation in vivo. After targeting tumor sites, TA-Fe3+ could dissolve and release Fe3+ and OA. Fe3+-induced O2 production from H2O2 relieved the hypoxic state, and promoted OA replication, leading to a remarkable alteration of tumor immune microenvironment and enhancement in antitumor efficacy. Moreover, the systemic delivery of OA@TA-Fe3+ was safe without inflammation or organ damage. Our findings demonstrated the promising potential of systemically delivering the engineered OA for effective oncolytic virotherapy against GBM.

7068 Paraganglioma in Cyanotic Congenital Heart Disease

Abstract Disclosure: R. Lis: None. V. Hamidi: None. Paragangliomas arise from the non-chromaffin cells of the parasympathetic nervous system, which are composed of glomus cells. These function as chemoreceptors in response to hypoxia. Carotid body paragangliomas have been linked to conditions with chronic hypoxia. This was first seen in residents of high altitude locations in a case report presented by Saldana et. al and regression of a paraganglioma with resolution of hypoxia was reported by Gruber et. al. There have been few additional case reports of Paraganglioma in other hypoxic states. We present a rare case of a functional Paraganglioma in a patient with Cyanotic Congenital Heart Disease (CCHD).This is a 19 year old female with a history of CCHD due to double inlet left ventricle and transposition of the great arteries. Soon after birth, she had a fontan procedure. She subsequently developed fontan associated liver disease as well as chronic kidney disease, hypertension, sinus node dysfunction, and complete heart block. Her baseline oxygen saturation was 78-85%. Her heart rate was 40-49 beats per minute with upcoming plans for pacemaker placement. Her blood pressure ranged 90/50 to 150/80 mmHg on Amlodipine 5 mg and Lisinopril 2.5 mg. She routinely received abdominal imaging to monitor her liver disease. A liver MRI incidentally revealed a retroperitoneal mass concerning for a paraganglioma. Serum Normetanephrines were found to be 26.60 nmol/L (reference range less than 0.89). 24 hr Urine Norepinephrine was 1,187 ug/d (reference range 14-20). Further imaging was negative for additional sites of disease. Given her complete heart block, she was started on alpha blockade only prior to pacemaker placement. After the pacemaker was placed, she was started on beta blockade and underwent surgical resection of her paraganglioma. The pathology confirmed paraganglioma and mutation testing was negative for germline mutations including SDH, VHL, RET, NF1 mutations. Paragangliomas in patients with CCHD have been scarcely described in the literature given the rarity of both of these conditions. However, there is a relatively increased incidence of paragangliomas in the CCHD population due to chronic hypoxia triggering the hypoxia pathway. EPAS1 mutated HIF2alpha is often found to be the culprit in these patients. In addition, case reports have often described these patients to either be asymptomatic or have potential symptoms masked by their cardiac disease. Therefore, CCHD patients are at increased risk for paragangliomas and warrant additional awareness and regular screening. Screening has been proposed to start after 10 years of hypoxia in a case review by Agarwal et. al. as paraganglioma incidence in CCHD populations has not been seen before age 11. Incidence of recurrence is not yet widely studied, but significant concern for recurrence is warranted if the etiology of hypoxia is not reversed. Presentation: 6/3/2024

Combined PET Radiotracer Approach Reveals Insights into Stromal Cell-Induced Metabolic Changes in Pancreatic Cancer In Vitro and In Vivo.

Background/Objective Pancreatic stellate cells (PSCs) in pancreatic adenocarcinoma (PDAC) are producing extracellular matrix, which promotes the formation of a dense fibrotic microenvironment. This makes PDAC a highly heterogeneous tumor-stroma-driven entity, associated with reduced perfusion, limited oxygen supply, high interstitial fluid pressure, and limited bioavailability of therapeutic agents. Methods In this study, spheroid and tumor xenograft models of human PSCs and PanC-1 cells were characterized radiopharmacologically using a combined positron emission tomography (PET) radiotracer approach. [18F]FDG, [18F]FMISO, and [18F]FAPI-74 were employed to monitor metabolic activity, hypoxic metabolic state, and functional expression of fibroblast activation protein alpha (FAPα), a marker of activated PSCs. Results In vitro, PanC-1 and multi-cellular tumor spheroids demonstrated comparable glucose uptake and hypoxia, whereas FAPα expression was significantly higher in PSC spheroids. In vivo, glucose uptake as well as the transition to hypoxia were comparable in PanC-1 and multi-cellular xenograft models. In mice injected with PSCs, FAPα expression decreased over a period of four weeks post-injection, which was attributed to the successive death of PSCs. In contrast, FAPα expression increased in both PanC-1 and multi-cellular xenograft models over time due to invasion of mouse fibroblasts. Conclusion The presented models are suitable for subsequently characterizing stromal cell-induced metabolic changes in tumors using noninvasive molecular imaging techniques.

Design and Preparation of Lifetime-Based Dual Fluorescent/Phosphorescent Sensor of pH and Oxygen and its Exploration in Model Physiological Solutions and Cells.

In the present report, a novel dual pH-O2 sensor based on covalent conjugate of rhodamine 6G and cyclometalated iridium complex with poly(vinylpyrrolidone-block-vinyltetrazole) copolymer is reported. In model physiological solutions the sensor chromophores display independent phosphorescent and fluorescent lifetime responses onto variations in oxygen concentration and pH, respectively. Colocalization studies on Chinese hamster ovary cells demonstrate the preferential localization in endosomes and lysosomes. The fluorescent lifetime imaging microscopy-phosphorescent lifetime imaging microscopy (FLIM-PLIM) experiments show that the phosphorescent O2 sensor provides unambiguous information onto hypoxia versus normoxia cell status as well as semi-quantitative data on the oxygen concentration in cells in between these two states. However, the results of FLIM measurements indicate that dynamic lifetime interval of the sensor (≈0.5ns between pH values 5.0 and 8.0) is insufficient even for qualitative estimation of pH in living cells because half-width of lifetime distribution in the studied samples is higher than the sensor dynamic interval. Nevertheless, the variations in rhodamine emission intensity are much higher and allow rough discrimination of acidic and neutral cell conditions. Thus, the results of this study indicate that the suggested approach to the design of dual pH-O2 sensors makes possible to prepare the biocompatible and water-soluble conjugate with fast cellular uptake.

Injectable hydrogels for Fenton-like Mn2+/Fe2+ delivery with enhanced chemodynamic therapy prevent osteosarcoma recurrence and promote wound healing after excision surgery

Local recurrence of osteosarcoma and wound healing after excision surgery are major challenges in clinical research. The present anti-tumor treatments could inhibit normal tissues, resulting in difficulties in surgical wound healing. In this study, we constructed an injectable hydrogel as a platform to co-deliver MnO2 nanoparticles and ferrocene Fc, termed as (MnO2/Fc)@PLGA for osteosarcoma treatment and wound healing after excision. By simple local injection, the hydrogel could form a protective barrier on the surgical wound after osteosarcoma excision, which could promote wound healing and steady release of MnO2/Fc nanoparticles. The released MnO2/Fc might undergo the Fenton reaction through Mn2+/Fe2+ to inhibit osteosarcoma cells with chemodynamic therapy (CDT). Furthermore, MnO2 could catalyze endogenous H2O2 to produce O2, which eliminates the adverse effects of H2O2 and remodels the hypoxic state in the local lesions. The increased O2 facilitated surgical wound healing and anti-tumor effects by regulating the hypoxia inducible factor-1 functions. In conclusion, (MnO2/Fc)@PLGA hydrogel could effectively prevent local recurrence of osteosarcoma and promote wound healing after excision surgery, thereby providing a novel strategy for tumor treatment and tissue repair.

A Multi-Omics Prognostic Model Capturing Tumor Stemness and the Immune Microenvironment in Clear Cell Renal Cell Carcinoma.

Background: Cancer stem-like cells (CSCs), a distinct subset recognized for their stem cell-like abilities, are intimately linked to the resistance to radiotherapy, metastatic behaviors, and self-renewal capacities in tumors. Despite their relevance, the definitive traits and importance of CSCs in the realm of oncology are still not fully comprehended, particularly in the context of clear cell renal cell carcinoma (ccRCC). A comprehensive understanding of these CSCs' properties in relation to stemness, and their impact on the efficacy of treatment and resistance to medication, is of paramount importance. Methods: In a meticulous research effort, we have identified new molecular categories designated as CRCS1 and CRCS2 through the application of an unsupervised clustering algorithm. The analysis of these subtypes included a comprehensive examination of the tumor immune environment, patterns of metabolic activity, progression of the disease, and its response to immunotherapy. In addition, we have delved into understanding these subtypes' distinctive clinical presentations, the landscape of their genomic alterations, and the likelihood of their response to various pharmacological interventions. Proceeding from these insights, prognostic models were developed that could potentially forecast the outcomes for patients with ccRCC, as well as inform strategies for the surveillance of recurrence after treatment and the handling of drug-resistant scenarios. Results: Compared with CRCS1, CRCS2 patients had a lower clinical stage/grading and a better prognosis. The CRCS2 subtype was in a hypoxic state and was characterized by suppression and exclusion of immune function, which was sensitive to gefitinib, erlotinib, and saracatinib. The constructed prognostic risk model performed well in both training and validation cohorts, helping to identify patients who may benefit from specific treatments or who are at risk of recurrence and drug resistance. A novel therapeutic target, SAA2, regulating neutrophil and fibroblast infiltration, and, thus promoting ccRCC progression, was identified. Conclusions: Our findings highlight the key role of CSCs in shaping the ccRCC tumor microenvironment, crucial for therapy research and clinical guidance. Recognizing tumor stemness helps to predict treatment efficacy, recurrence, and drug resistance, informing treatment strategies and enhancing ccRCC patient outcomes.

A dual-responsive fluorescent probe for cellular hypoxia and tumor imaging based on nitroreductase and viscosity synergy

Nitroreductase (NTR), an enzyme that operates within the cytoplasm, relies on flavin mononucleotide or flavin adenine dinucleotide for its activity. In tumor cells, hypoxic conditions often lead to an increase in NTR levels. Consequently, the development of fluorescent probes capable of detecting NTR activity is crucial for the monitoring of hypoxia in biological systems. This study presents the one-step synthesis of a near-infrared fluorescent probe, DSM-NO2. The probe was highly sensitive to NTR and caused a fluorescence enhancement by 50-fold, with a detection limit as low as 1 ng/mL. Under hypoxic conditions in tumor cells, not only does NTR increase, but the cellular viscosity also rises. In high-viscosity environments, the fluorescence enhancement could reach up to 220-fold, and the detection limit could be further reduced to 55 pg/mL. The reaction mechanism was thoroughly investigated using mass spectrometry, molecular docking, and theoretical calculations. Moreover, the probe was successfully applied in the real-time monitoring and visualization analysis of NTR during the growth of Escherichia coli and in the hypoxic state of cancer cells. Additionally, through nebulized inhalation, the probe was successfully employed for in situ fluorescent imaging studies in a murine model of lung cancer.

CoCl2‐induced glioma hypoxia environment enhances CD47‐SIRPα to promote tumor immune evasion

AbstractElevated levels of tumor‐associated macrophages and microglia in the immune microenvironment of malignant gliomas promote tumor growth and progression. Although immune evasion has been implicated in these processes, the mechanisms underlying the regulation of CD47‐SIRPα‐mediated immune evasion under hypoxic conditions remain unclear. Therefore, this study aimed to explore the mechanisms through which CD47‐SIRPα modulates immune evasion in a cobalt chloride (CoCl2)‐induced hypoxic microenvironment of malignant gliomas. Human and mouse glioma cell lines were used to investigate immune evasion in vitro. After membrane protein extraction and nucleoplasmic isolation, we downregulated the expression levels of transport receptors to elucidate the regulation of CD47‐SIRPα transport. The CoCl2‐induced hypoxic microenvironment attenuated microglial phagocytosis in glioma cells. Enhanced CD47‐SIRPα interaction promoted immune evasion, which negatively affected tumor clearance. In addition, the intracellular transport of CD47 was promoted in the CoCl2‐induced hypoxic state. This process was regulated by regulator of chromosome condensation 1 (RCC1) and sortilin in the nuclear cytoplasm and cytoplasmic membrane, respectively. These results demonstrate the CD47‐SIRPα‐mediated immune escape mechanism of the CoCl2‐induced glioma hypoxic environment, which is associated with enhanced intracellular transport of CD47. Our findings provide a theoretical basis for the potential development of novel therapies targeting CD47‐SIRPα.

Identification and Validation of STC1 Act as a Biomarker for High-Altitude Diseases and Its Pan-Cancer Analysis.

High-altitude diseases, including acute mountain sickness (AMS), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE), are closely related to an individual's ability to adapt to hypoxic environments. However, specific research in this field is relatively limited, and further biomarker research and clinical trials are needed to clarify the exact role and potential therapeutic applications of key genes in high-altitude diseases. This study focuses on the role of the STC1 gene in high-altitude diseases and explores its expression patterns in different types of cancer. By using gene expression data analysis and functional experiments, we identified STC1 as a key gene affecting the development of altitude sickness. In addition, we also conducted expression and mutation analysis on STC1 in various cancer samples and found significant differences in the expression of this gene in 13 types of malignant tumors, which is associated with the hypoxic state in the tumor microenvironment. In addition, STC1 is significantly associated with patient prognosis and influences tumor immunity by mediating six types of immune cells (CD8+T cells, CD4+T cells, neutrophils, macrophages, monocytes, and B cells) in the tumor microenvironment. The expression and diagnostic value of STC1 were confirmed through GEO datasets and qPCR testing, indicating consistency with the results of bioinformatics analysis. These results indicate that STC1 is not only an important factor in the adaptive response to high-altitude diseases but may also play a role in the adaptation of cancer to low-oxygen environments. Our research provides a new perspective and potential targets for the discovery of biomarkers for high-altitude diseases and cancer treatment.

Inducing Immunogenic Cancer Cell Death through Oxygen‐Economized Photodynamic Therapy with Nitric Oxide‐Releasing Photosensitizers

AbstractPhotodynamic therapy (PDT) utilizes reactive oxygen species (ROS) for eradication of cancer cells. Its effectiveness is governed by the oxygen content, which is scarce in the hypoxic tumor microenvironment. We report herein two zinc(II) phthalocyanines substituted with two or four nitric oxide (NO)‐releasing moieties, namely ZnPc‐2NO and ZnPc‐4NO, which can suppress the mitochondrial respiration, thereby sparing more intracellular oxygen for PDT. Using HT29 human colorectal adenocarcinoma cells and A549 human lung carcinoma cells, we have demonstrated that both conjugates release NO upon interaction with the intracellular glutathione, which can reduce the cellular oxygen consumption rate and adenosine triphosphate generation and alter the mitochondrial membrane potential. They can also relieve the hypoxic status of cancer cells and decrease the expression of hypoxia‐inducible factor protein HIF‐1α. Upon light irradiation, both conjugates can generate ROS and induce cytotoxicity even under a hypoxic condition, overcoming the oxygen‐dependent nature of PDT. Interestingly, the photodynamic action of ZnPc‐2NO elicits the release of damage‐associated molecular patterns, inducing the maturation of dendritic cells and triggering an antitumor immune response. The immunogenic cell death caused by this oxygen‐economized PDT has been demonstrated through a series of in vitro and in vivo experiments.

Inducing Immunogenic Cancer Cell Death through Oxygen-Economized Photodynamic Therapy with Nitric Oxide-Releasing Photosensitizers.

Photodynamic therapy (PDT) utilizes reactive oxygen species (ROS) for eradication of cancer cells. Its effectiveness is governed by the oxygen content, which is scarce in the hypoxic tumor microenvironment. We report herein two zinc(II) phthalocyanines substituted with two or four nitric oxide (NO)-releasing moieties, namely ZnPc-2NO and ZnPc-4NO, which can suppress the mitochondrial respiration, thereby sparing more intracellular oxygen for PDT. Using HT29 human colorectal adenocarcinoma cells and A549 human lung carcinoma cells, we have demonstrated that both conjugates release NO upon interaction with the intracellular glutathione, which can reduce the cellular oxygen consumption rate and adenosine triphosphate generation and alter the mitochondrial membrane potential. They can also relieve the hypoxic status of cancer cells and decrease the expression of hypoxia-inducible factor protein HIF-1α. Upon light irradiation, both conjugates can generate ROS and induce cytotoxicity even under a hypoxic condition, overcoming the oxygen-dependent nature of PDT. Interestingly, the photodynamic action of ZnPc-2NO elicits the release of damage-associated molecular patterns, inducing the maturation of dendritic cells and triggering an antitumor immune response. The immunogenic cell death caused by this oxygen-economized PDT has been demonstrated through a series of in vitro and in vivo experiments.

The Bioactive Interface of Titanium Implant with Both Anti-Oxidative Stress and Immunomodulatory Properties for Enhancing Osseointegration under Diabetic Condition.

The poor implant-osseointegration under diabetic condition remains a challenge to be addressed urgently. Studies have confirmed that the diabetic pathological microenvironment is accompanied by excessive oxidative stress, imbalanced immune homeostasis, and persistent chronic inflammation, which seriously impairs the osteogenic process. Herein, a multifunctional bioactive interface with both anti-oxidative stress and immunomodulatory properties is constructed on titanium implants. Briefly, manganese dioxide nanosheets are coated onto mesoporous polydopamine nanoparticles loaded with carbon monoxide gas precursor, namely MnO2-CO@MPDA NPs, and then they are integrated on the titanium implant to obtain MCM-Ti. In the simulated diabetic microenvironment, under the action of MnO2 nanoenzymes, MCM-Ti can effectively eliminate intracellular reactive oxygen species while alleviating hypoxic state. Interestingly, the microenvironment mediates the responsive release of CO gas, which effectively drives macrophages toward M2 polarization, thereby ameliorating inflammatory response. The potential mechanism is that CO gas up-regulates the expression of heme oxygenase-1, further activating the Notch/Hes1/Stat3 signaling pathway. Furthermore, the conditioned medium derived from macrophages on MCM-Ti surface significantly enhances the osteogenic differentiation of BMSCs. In a type 2 diabetic rat model, MCM-Ti implant effectively alleviates the accompanying inflammation and enhances the osseointegration through the synergistic effects of resisting oxidative stress and remodeling immune homeostasis.

Dual roles of photosynthetic hydrogel with sustained oxygen generation in promoting cell survival and eradicating anaerobic infection

Tissue engineering offers a promising alternative for oral and maxillofacial tissue defect rehabilitation; however, cells within a sizeable engineered tissue construct after transplantation inevitably face prolonged and severe hypoxic conditions, which may compromise the survivability of the transplanted cells and arouse the concern of anaerobic infection. Microalgae, which can convert carbon dioxide and water into oxygen and glucose through photosynthesis, have been studied as a source of oxygen supply for several biomedical applications, but their promise in orofacial tissue regeneration remains unexplored. Here, we demonstrated that through photosynthetic oxygenation, Chlamydomonas reinhardtii (C. reinhardtii) supported dental pulp stem cell (DPSC) energy production and survival under hypoxia. We developed a multifunctional photosynthetic hydrogel by embedding DPSCs and C. reinhardtii encapsulated alginate microspheres (CAMs) within gelatin methacryloyl hydrogel (GelMA) (CAMs@GelMA). This CAMs@GelMA hydrogel can generate a sustainable and sufficient oxygen supply, reverse intracellular hypoxic status, and enhance the metabolic activity and viability of DPSCs. Furthermore, the CAMs@GelMA hydrogel exhibited selective antibacterial activity against oral anaerobes and remarkable antibiofilm effects on multispecies biofilms by disrupting the hypoxic microenvironment and increasing reactive oxygen species generation. Our work presents an innovative photosynthetic strategy for oral tissue engineering and opens new avenues for addressing other hypoxia-related challenges.

Hypoxia-inducible factors in postnatal mouse molar dental pulp development: insights into expression patterns, localisation and metabolic pathways.

Hypoxia is relevant to several physiological and pathological processesand this also applies for the tooth. The adaptive response to lowering oxygen concentration is mediated by hypoxia-inducible factors (HIFs). Since HIFs were shown to participate in the promotion of angiogenesis, stem cell survival, odontoblast differentiation and dentin formation, they may play a beneficial role in the tooth reparative processes. Although some data were generated in vitro, little is known about the in vivo context of HIFs in tooth development. In order to contribute to this field, the mouse mandibular first molar was used as a model.The expression and in situ localisation of HIFs were examined at postnatal (P) days P0, P7, P14, using RT-PCR and immunostaining. The expression pattern of a broad spectrum of hypoxia-related genes was monitored by customised PCR Arrays. Metabolic aspects were evaluated by determination of the lactate level and mRNA expression of the mitochondrial marker Nd1.The results show constant high mRNA expression of Hif1a, increasing expression of Hif2a, and very low expression of Hif3a during early postnatal molar development. In the examined period the localisation of HIFs in the nuclei of odontoblasts and the subodontoblastic layer identified their presence during odontoblastic differentiation. Additionally, the lower lactate level and higher expression of mitochondrial Nd1 in advanced development points to decreasing glycolysis during differentiation. Postnatal nuclear localisation of HIFs indicates a hypoxic state in specific areas of dental pulp as oxygen demands depend on physiological events such as crown and root dentin mineralization.

Features of reactions to stress in rats with passive-defense behavior after light desynchronosis and physical activity

An assessment was made of hematological parameters of peripheral blood and structural and functional changes in the adrenal glands in stress-unresistant rats (passive-defensive type of behavior in the open field test) after exposure to light deprivation and physical activity during the spring equinox. The experiment showed that light deprivation for 10 days reduces the total number of leukocytes, the absolute content of monocytes, granulocytes, lymphocytes and the level of corticosterone in the peripheral blood compared to the intact group, that was on a natural lighting regime. Histological analysis of the adrenal glands of this group showed, that in the zona fasciculata under such conditions there was nuclear hypertrophy, an increase in the nuclear-cytoplasmic ratio of adrenocorticocytes and a decrease in the size of the zona glomerulosa of the adrenal cortex of rats in relation to the intact group. Physical activity in the form of forced swimming until complete fatigue for 5 days in a row in natural light in stress-unresistant rats did not change the parameters of the peripheral blood of animals, however it led to an increase in the area of the cytoplasm, the nuclear-cytoplasmic ratio, as well as the formation of hypertrophy of the nuclei of adrenocorticocytes in the fascicle adrenal zones, which indicated the preparation of cells for increased synthetic activity. Keeping rats for 10 days in complete darkness before forced swimming every day for 5 days, on the one hand, formed a hypoxic state and exhaustion of the adrenal glands, on the other hand, stabilized the leukocyte pool of peripheral blood compared to similar indicators in intact rats.