Single-cell transcriptome analysis reveals the effectiveness of cytokine priming irrespective of heterogeneity in mesenchymal stromal cells.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) are recognized as a potential cell-based therapy for regenerative medicine. Short-term inflammatory cytokine pre-stimulation (cytokine priming) is a promising approach to enhance regenerative efficacy of MSCs. However, it is unclear whether their intrinsic heterogenic nature causes an unequal response to cytokine priming, which might blunt the accessibility of clinical applications. METHODS: In this study, by analyzing the single-cell transcriptomic landscape of human bone marrow MSCs from a naïve to cytokine-primed state, we elucidated the potential mechanism of superior therapeutic potential in cytokine-primed MSCs. RESULTS: We found that cytokine-primed MSCs had a distinct transcriptome landscape. Although substantial heterogeneity was identified within the population in both naïve and primed states, cytokine priming enhanced the several characteristics of MSCs associated with therapeutic efficacy irrespective of heterogeneity. After cytokine-priming, all sub-clusters of MSCs possessed high levels of immunoregulatory molecules, trophic factors, stemness-related genes, anti-apoptosis markers and low levels of multi-lineage and senescence signatures, which are critical for their therapeutic potency. CONCLUSIONS: In conclusion, our results provide new insights into MSC heterogeneity under cytokine stimulation and suggest that cytokine priming reprogrammed MSCs independent of heterogeneity.

Mechanotransduction of mesenchymal stem cells and hemodynamic implications.

Mesenchymal stem cells (MSCs) possess the capacity for self-renewal and multipotency. The traditional approach to manipulating MSC's fate choice predominantly relies on biochemical stimulation. Accumulating evidence also suggests the role of physical input in MSCs differentiation. Therefore, investigating mechanotransduction at the molecular level and related to tissue-specific cell functions sheds light on the responses secondary to mechanical forces. In this review, a new frontier aiming to optimize the cultural parameters was illustrated, i.e. spatial boundary condition, which recapitulates in vivo physiology and facilitates the investigations of cellular behavior. The concept of mechanical memory was additionally addressed to appreciate how MSCs store imprints from previous culture niches. Besides, different types of forces as physical stimuli were of interest based on the association with the respective signaling pathways and the differentiation outcome. The downstream mechanoreceptors and their corresponding effects were further pinpointed. The cardiovascular system or immune system may share similar mechanisms of mechanosensing and mechanotransduction; for example, resident stem cells in a vascular wall and recruited MSCs in the bloodstream experience mechanical forces such as stretch and fluid shear stress. In addition, baroreceptors or mechanosensors of endothelial cells detect changes in blood flow, pass over signals induced by mechanical stimuli and eventually maintain arterial pressure at the physiological level. These mechanosensitive receptors transduce pressure variation and regulate endothelial barrier functions. The exact signal transduction is considered context dependent but still elusive. In this review, we summarized the current evidence of how mechanical stimuli impact MSCs commitment and the underlying mechanisms. Future perspectives are anticipated to focus on the application of cardiovascular bioengineering and regenerative medicine.

Mechanical and chemical cues synergistically promote human venous smooth muscle cell osteogenesis through integrin ß1-ERK1/2 signaling: A cell model of hemodialysis fistula calcification.

Arteriovenous fistula (AVF) is the vascular access of choice for renal replacement therapy. However, AVF is susceptible to calcification with a high prevalence of 40%-65% in chronic hemodialysis patients. Repeated needle puncture for hemodialysis cannulation results in intimal denudation of AVF. We hypothesized that exposure to blood shear stress in the medial layer promotes venous smooth muscle cell (SMC) osteogenesis. While previous studies of shear stress focused on arterial-type SMCs, SMCs isolated from the vein had not been investigated. This study established a venous cell model of AVF using the fluid shear device, combined with a high phosphate medium to mimic the uremic milieu. Osteogenic gene expression of venous SMCs upon mechanical and chemical cues was analyzed in addition to the activated cell signaling pathways. Our findings indicated that upon shear stress and high phosphate environment, mechanical stimulation (shear stress) had an additive effect in up-regulation of an early osteogenic marker, Runx2. We further identified that the integrin ß1-ERK1/2 signaling pathway was responsible for the molecular basis of venous SMC osteogenesis upon shear stress exposure. Mitochondrial biogenesis also took part in the early stage of this venopathy pathogenesis, evident by the up-regulated mitochondrial transcription factor A and mitochondrial DNA polymerase γ in venous SMCs. In conclusion, synergistic effects of fluid shear stress and high phosphate induce venous SMC osteogenesis via the ERK1/2 pathway through activating the mechanosensing integrin ß1 signaling. The present study identified a promising druggable target for reducing AVF calcification, which deserves further in vivo investigations.

Application of a deep learning system in glaucoma screening and further classification with colour fundus photographs: a case control study.

BACKGROUND: To verify efficacy of automatic screening and classification of glaucoma with deep learning system. METHODS: A cross-sectional, retrospective study in a tertiary referral hospital. Patients with healthy optic disc, high-tension, or normal-tension glaucoma were enrolled. Complicated non-glaucomatous optic neuropathy was excluded. Colour and red-free fundus images were collected for development of DLS and comparison of their efficacy. The convolutional neural network with the pre-trained EfficientNet-b0 model was selected for machine learning. Glaucoma screening (Binary) and ternary classification with or without additional demographics (age, gender, high myopia) were evaluated, followed by creating confusion matrix and heatmaps. Area under receiver operating characteristic curve (AUC), accuracy, sensitivity, specificity, and F1 score were viewed as main outcome measures. RESULTS: Two hundred and twenty-two cases (421 eyes) were enrolled, with 1851 images in total (1207 normal and 644 glaucomatous disc). Train set and test set were comprised of 1539 and 312 images, respectively. If demographics were not provided, AUC, accuracy, precision, sensitivity, F1 score, and specificity of our deep learning system in eye-based glaucoma screening were 0.98, 0.91, 0.86, 0.86, 0.86, and 0.94 in test set. Same outcome measures in eye-based ternary classification without demographic data were 0.94, 0.87, 0.87, 0.87, 0.87, and 0.94 in our test set, respectively. Adding demographics has no significant impact on efficacy, but establishing a linkage between eyes and images is helpful for a better performance. Confusion matrix and heatmaps suggested that retinal lesions and quality of photographs could affect classification. Colour fundus images play a major role in glaucoma classification, compared to red-free fundus images. CONCLUSIONS: Promising results with high AUC and specificity were shown in distinguishing normal optic nerve from glaucomatous fundus images and doing further classification.

Extracorporeal Shockwave Therapy in the Treatment of Trigger Finger: A Randomized Controlled Study.

OBJECTIVES: To determine the efficacy of extracorporeal shockwave therapy (ESWT) and to determine the ideal energy flux density of wide-focused ESWT in the treatment of trigger finger (TF). DESIGN: Double-blind randomized controlled trial. SETTING: A university hospital. PARTICIPANTS: A total of 60 patients (N=60) with grade II TF according to the Quinnell classification were randomly and evenly allocated to 3 treatment groups. INTERVENTIONS: Three treatment groups included a high-energy ESWT (HS) group (energy flux density of 0.01 mJ/mm2, 5.8 bar, 1500 impulses, once per week for 4wk), a low-energy ESWT (LS) group (energy flux density of 0.006 mJ/mm2, 3 bar, 1500 impulses, once per week for 4wk), and a sham intervention group (sham group). All participants received 6 months of follow-up after intervention when only painkillers were allowed as concomitant treatment. MAIN OUTCOME MEASURES: Clinical outcomes were followed at baseline and 1, 3, and 6 months after intervention, including pain score, frequency of triggering, severity of triggering, functional impact of triggering, and quick Disabilities of the Arm, Shoulder, and Hand questionnaire (qDASH). RESULTS: All groups showed significant improvements from baseline in all clinical parameters, except for functional impact of triggering, 6 months after the interventions. However, the HS group demonstrated a higher magnitude of improvement than the LS and sham groups. In addition, the HS group reported significantly lower pain (P=.01) and lower qDASH (P=.008) than the sham group 6 months after the interventions. No adverse effects were reported in the HS and LS groups within 6 months of follow-up. CONCLUSIONS: Wide-focused ESWT is a safe and effective but dose-dependent alternative facilitating pain relief and functional improvement in the treatment of grade II TF according to the Quinnell classification.

Deep Learning Application for Vocal Fold Disease Prediction Through Voice Recognition: Preliminary Development Study.

BACKGROUND: Dysphonia influences the quality of life by interfering with communication. However, a laryngoscopic examination is expensive and not readily accessible in primary care units. Experienced laryngologists are required to achieve an accurate diagnosis. OBJECTIVE: This study sought to detect various vocal fold diseases through pathological voice recognition using artificial intelligence. METHODS: We collected 189 normal voice samples and 552 samples of individuals with voice disorders, including vocal atrophy (n=224), unilateral vocal paralysis (n=50), organic vocal fold lesions (n=248), and adductor spasmodic dysphonia (n=30). The 741 samples were divided into 2 sets: 593 samples as the training set and 148 samples as the testing set. A convolutional neural network approach was applied to train the model, and findings were compared with those of human specialists. RESULTS: The convolutional neural network model achieved a sensitivity of 0.66, a specificity of 0.91, and an overall accuracy of 66.9% for distinguishing normal voice, vocal atrophy, unilateral vocal paralysis, organic vocal fold lesions, and adductor spasmodic dysphonia. Compared with the accuracy of human specialists, the overall accuracy rates were 60.1% and 56.1% for the 2 laryngologists and 51.4% and 43.2% for the 2 general ear, nose, and throat doctors. CONCLUSIONS: Voice alone could be used for common vocal fold disease recognition through a deep learning approach after training with our Mandarin pathological voice database. This approach involving artificial intelligence could be clinically useful for screening general vocal fold disease using the voice. The approach includes a quick survey and a general health examination. It can be applied during telemedicine in areas with primary care units lacking laryngoscopic abilities. It could support physicians when prescreening cases by allowing for invasive examinations to be performed only for cases involving problems with automatic recognition or listening and for professional analyses of other clinical examination results that reveal doubts about the presence of pathologies.

Machine Learning Analysis of Time-Dependent Features for Predicting Adverse Events During Hemodialysis Therapy: Model Development and Validation Study.

BACKGROUND: Hemodialysis (HD) therapy is an indispensable tool used in critical care management. Patients undergoing HD are at risk for intradialytic adverse events, ranging from muscle cramps to cardiac arrest. So far, there is no effective HD device-integrated algorithm to assist medical staff in response to these adverse events a step earlier during HD. OBJECTIVE: We aimed to develop machine learning algorithms to predict intradialytic adverse events in an unbiased manner. METHODS: Three-month dialysis and physiological time-series data were collected from all patients who underwent maintenance HD therapy at a tertiary care referral center. Dialysis data were collected automatically by HD devices, and physiological data were recorded by medical staff. Intradialytic adverse events were documented by medical staff according to patient complaints. Features extracted from the time series data sets by linear and differential analyses were used for machine learning to predict adverse events during HD. RESULTS: Time series dialysis data were collected during the 4-hour HD session in 108 patients who underwent maintenance HD therapy. There were a total of 4221 HD sessions, 406 of which involved at least one intradialytic adverse event. Models were built by classification algorithms and evaluated by four-fold cross-validation. The developed algorithm predicted overall intradialytic adverse events, with an area under the curve (AUC) of 0.83, sensitivity of 0.53, and specificity of 0.96. The algorithm also predicted muscle cramps, with an AUC of 0.85, and blood pressure elevation, with an AUC of 0.93. In addition, the model built based on ultrafiltration-unrelated features predicted all types of adverse events, with an AUC of 0.81, indicating that ultrafiltration-unrelated factors also contribute to the onset of adverse events. CONCLUSIONS: Our results demonstrated that algorithms combining linear and differential analyses with two-class classification machine learning can predict intradialytic adverse events in quasi-real time with high AUCs. Such a methodology implemented with local cloud computation and real-time optimization by personalized HD data could warn clinicians to take timely actions in advance.

Associations between aging and second molar diseases in patients having adjacent impacted third molar extraction.

PURPOSE: There is limited evidence available regarding when the best time to extract impacted lower third molars (iLM3). Thus, the current study is aimed to examine the association between the age of patients during the time of extraction of their iLM3 and the sequelae of their adjacent second molar (LM2) in order to find a better time to remove iLM3. METHODS: Retrospective cohort study was conducted with a total of 15,432 patients from ages 16-45 years old who had their first surgical extraction of iLM3. Statistical analysis was performed to evaluate variables in association with the sequalae of LM2. Adjusted odds ratios (AOR) were calculated to show the influence of the age of patients by multivariate regression model. RESULTS: Patients who had iLM3 extraction over 22 years of age had a significantly higher risk of having LM2 pulpal disease (AOR: from 2.84 in 23-25 age to 11.58 in >35 age). Significantly higher risk of having LM2 periodontal conditions was found in individuals over 31 years of age (AOR: 1.47 in 31-35 age, 1.90 in >35 age), with prior periodontitis (AOR: 1.97) or complicated odontectomy (AOR: 1.43). The risk of LM2 being extracted due to an untreatable condition was highest in patients more than 35 years old (AOR: 14.38). CONCLUSION: The age of patients having iLM3 extracted was independently associated with various LM2 sequelae. We suggest that patients can have their iLM3 extracted in their college/university age (19-22-year-old) to minimize complications on the adjacent LM2.

Molecular Mechanisms of Mesenchymal Stem Cell-Based Therapy in Acute Kidney Injury.

Acute kidney injury (AKI) causes a lot of harm to human health but is treated by only supportive therapy in most cases. Recent evidence shows that mesenchymal stem cells (MSCs) benefit kidney regeneration through releasing paracrine factors and extracellular vesicles (EVs) to the recipient kidney cells and are considered to be promising cellular therapy for AKI. To develop more efficient, precise therapies for AKI, we review the therapeutic mechanism of MSCs and MSC-derived EVs in AKI and look for a better understanding of molecular signaling and cellular communication between donor MSCs and recipient kidney cells. We also review recent clinical trials of MSC-EVs in AKI. This review summarizes the molecular mechanisms of MSCs' therapeutic effects on kidney regeneration, expecting to comprehensively facilitate future clinical application for treating AKI.

Alteration of 3D Matrix Stiffness Regulates Viscoelasticity of Human Mesenchymal Stem Cells.

Human mesenchymal stem cells (hMSCs) possess potential of bone formation and were proposed as ideal material against osteoporosis. Although interrogation of directing effect on lineage specification by physical cues has been proposed, how mechanical stimulation impacts intracellular viscoelasticity during osteogenesis remained enigmatic. Cyto-friendly 3D matrix was prepared with polyacrylamide and conjugated fibronectin. The hMSCs were injected with fluorescent beads and chemically-induced toward osteogenesis. The mechanical properties were assessed using video particle tracking microrheology. Inverted epifluorescence microscope was exploited to capture the Brownian trajectory of hMSCs. Mean square displacement was calculated and transformed into intracellular viscoelasticity. Two different stiffness of microspheres (12 kPa, 1 kPa) were established. A total of 45 cells were assessed. hMSCs possessed equivalent mechanical traits initially in the first week, while cells cultured in rigid matrix displayed significant elevation over elastic (G') and viscous moduli (G") on day 7 (p < 0.01) and 14 (p < 0.01). However, after two weeks, soft niches no longer stiffened hMSCs, whereas the effect by rigid substrates was consistently during the entire differentiation course. Stiffness of matrix impacted the viscoelasticity of hMSCs. Detailed recognition of how microenvironment impacts mechanical properties and differentiation of hMSCs will facilitate the advancement of tissue engineering and regenerative medicine.

Alteration of Young's modulus in mesenchymal stromal cells during osteogenesis measured by atomic force microscopy.

Mechanical properties of biological tissues are increasingly recognized as an important parameter for the indication of disease states as well as tissue homeostasis and regeneration. Multipotent mesenchymal stromal/stem cells (MSCs), which play important roles in bone formation and remodeling, are potential cell sources for regenerative medicine. However, the cellular mechanical properties of differentiating MSCs corresponding to the substrate stiffness has not been sufficiently studied. In this study, we used Atomic Force Microscopy (AFM) to measure changes of stiffness of human MSCs cultured in rigid Petri dish and on polyacrylamide (PA) substrates during osteogenic differentiation. The results showed that the Young's modulus of MSC cytoplasmic outer region increased over time during osteogenesis. There is a strong linear correlation between the osteogenic induction time and the Young's modulus of the cells cultured in rigid Petri dishes in the first 15 days after the induction; the Young's modulus approaches to a plateau after day 15. On the other hand, the Young's moduli of MSCs cultured on PA gels with stiffness of 7 kPa and 42 kPa also increase over time during osteogenic differentiation, but the inclination of such increase is much smaller than that of MSCs differentiating in rigid dishes. Herein, we established a protocol of AFM measurement to evaluate the maturation of stem cell osteogenic differentiation at the single cell level and could encourage further AFM applications in tissue engineering related to mechanobiology.

Prediction of the development of acute kidney injury following cardiac surgery by machine learning.

BACKGROUND: Cardiac surgery-associated acute kidney injury (CSA-AKI) is a major complication that results in increased morbidity and mortality after cardiac surgery. Most established prediction models are limited to the analysis of nonlinear relationships and fail to fully consider intraoperative variables, which represent the acute response to surgery. Therefore, this study utilized an artificial intelligence-based machine learning approach thorough perioperative data-driven learning to predict CSA-AKI. METHODS: A total of 671 patients undergoing cardiac surgery from August 2016 to August 2018 were enrolled. AKI following cardiac surgery was defined according to criteria from Kidney Disease: Improving Global Outcomes (KDIGO). The variables used for analysis included demographic characteristics, clinical condition, preoperative biochemistry data, preoperative medication, and intraoperative variables such as time-series hemodynamic changes. The machine learning methods used included logistic regression, support vector machine (SVM), random forest (RF), extreme gradient boosting (XGboost), and ensemble (RF + XGboost). The performance of these models was evaluated using the area under the receiver operating characteristic curve (AUC). We also utilized SHapley Additive exPlanation (SHAP) values to explain the prediction model. RESULTS: Development of CSA-AKI was noted in 163 patients (24.3%) during the first postoperative week. Regarding the efficacy of the single model that most accurately predicted the outcome, RF exhibited the greatest AUC (0.839, 95% confidence interval [CI] 0.772-0.898), whereas the AUC (0.843, 95% CI 0.778-0.899) of ensemble model (RF + XGboost) was even greater than that of the RF model alone. The top 3 most influential features in the RF importance matrix plot were intraoperative urine output, units of packed red blood cells (pRBCs) transfused during surgery, and preoperative hemoglobin level. The SHAP summary plot was used to illustrate the positive or negative effects of the top 20 features attributed to the RF. We also used the SHAP dependence plot to explain how a single feature affects the output of the RF prediction model. CONCLUSIONS: In this study, machine learning methods were successfully established to predict CSA-AKI, which determines risks following cardiac surgery, enabling the optimization of postoperative treatment strategies to minimize the postoperative complications following cardiac surgeries.

Wearable Motion Sensor Device to Facilitate Rehabilitation in Patients With Shoulder Adhesive Capsulitis: Pilot Study to Assess Feasibility.

BACKGROUND: Adhesive capsulitis (AC) of the shoulder is a common disorder that painfully reduces the shoulder range of motion (ROM) among middle-aged individuals. Although physical therapy with home-based exercises is widely advised to restore ROM in the treatment of AC, clinical results vary owing to inconsistent patient compliance. OBJECTIVE: In this study, we aimed to verify the feasibility of a treatment model that involves applying a wearable motion sensor device to assist patients conduct home-based exercises to improve training compliance and the accuracy of exercises, with the ultimate goal of improving the functional recovery of patients with AC. METHODS: The motion sensor device was comprised of inertial measurement unit-based sensors and mobile apps for patients and physicians, offering shoulder mobility tracing, home-based exercise support, and progress monitoring. The interrater reliability of shoulder mobility measurement using the motion sensor device on 10 healthy participants and 15 patients with AC was obtained using an intraclass correlation coefficient analysis and compared with the assessments performed by two highly experienced physicians. A pilot prospective control trial was then carried out to allocate the 15 patients with AC to two groups: home-based exercise group and motion sensor-assisted rehabilitation group. Changes in active and passive shoulder ROM, pain and functional scores, and exercise completion rates were compared between the groups during a treatment period of 3 months. RESULTS: Shoulder ROM, as measured using the motion sensor device, exhibited good to excellent reliability based on the comparison with the measurements of two physicians (intraclass correlation coefficient range, 0.771 to 0.979). Compared with patients with AC in the home-based exercise group, those in the motion sensor-assisted rehabilitation group exhibited better shoulder mobility and functional recovery and a higher exercise completion rate during and after 3 months of rehabilitation. CONCLUSIONS: Motion sensor device-assisted home-based rehabilitation for the treatment of AC is a useful treatment model for telerehabilitation that enhances the compliance of patients through training, thus improving functional recovery. This helps overcome important obstacles in physiotherapy at home by providing comprehensible and easily accessible exercise instructions, enhancing compliance, ensuring the correctness of exercise, and monitoring the progress of patients.

Mesenchymal stem cells prolong survival and prevent lethal complications in a porcine model of fulminant liver failure.

BACKGROUND: Fulminant liver failure (FLF) is a life-threatening disease. METHODS: Lethal FLF was induced by ischemia-reperfusion (I-R) injury in mini-pigs, and MSCs were infused via splenic vein after reperfusion. RESULTS: Accumulated survival within 28 days was significantly improved by MSCs (P = 0.0348). Notably, MSCs maintained blood-gas homeostasis in the first 24 hours and prevented FLF-induced elevation of prothrombin time, international normalized ratio, and creatinine and ammonia levels in the first 3 days. With MSCs, serum levels of liver enzymes gradually decreased after 3 days, and platelet count was back to normal at 1 week of FLF. MSCs promoted liver regeneration within 2 weeks and differentiated into functional hepatocytes at 2-4 weeks after transplantation, evidenced by increase in Ki67-positive cells, detectable human hepatocyte growth factor, human vascular endothelial growth factor, human hepatocyte-specific antigen, and human albumin-expressing cells in the liver at different time points. Reactive oxidative species (ROS) were accumulated after FLF and eliminated at 4 weeks after MSC transplantation. CONCLUSIONS: Together, MSCs prolong the survival and prevent lethal sequelae of I-R injury-induced FLF by maintenance of liver-function homeostasis and rescue of ROS in the acute stage and by homing and differentiation into hepatocytes in the subacute stage.

The role of EpCAM in tumor progression and the clinical prognosis of endometrial carcinoma.

OBJECTIVE: EpCAM is a transmembrane glycoprotein that functions as an epithelial marker in endometrial tissues. However, the correlation between EpCAM and endometrial carcinoma (EC) is not clear. METHODS: This study investigated the association between EpCAM and EC. Immunohistochemistry staining and bioinformatics analysis disclosed the clinical importance of low EpCAM expression. The migratory ability of cells expressing low EpCAM levels was studied in transwell invasion assays in vitro and an orthotopic intra-uterine tumor injection model in vivo. The Connectivity MAP was used to identify drugs that effectively inhibit cells with low EpCAM expression. RESULTS: According to immunohistochemistry analysis results, low EpCAM expression was associated with an advanced stage and lymph node metastasis in patients with endometrioid EC, and high EpCAM expression favored survival. EpCAM silencing promoted cell invasion, and EpCAM re-expression in EpCAM-silenced EC cells attenuated their invasiveness. EpCAM suppression in an orthotopic uterine implantation model promoted the lymph node metastasis of EC cells. According to quantitative PCR and promoter reporter analyses, estrogen receptor alpha signaling regulated EpCAM expression by enhancing its promoter activity. As shown in the Connectivity MAP analysis, transamin inhibited the invasiveness of EpCAM-silenced EC cells. CONCLUSIONS: The loss of EpCAM may increase the malignancy of EC, and these findings provide new insights into the prognostic role of EpCAM in patients with EC.

Dexamethasone-induced cellular tension requires a SGK1-stimulated Sec5-GEF-H1 interaction.

Dexamethasone, a synthetic glucocorticoid, is often used to induce osteoblast commitment of mesenchymal stem cells (MSCs), and this process requires RhoA-dependent cellular tension. The underlying mechanism is unclear. In this study, we show that dexamethasone stimulates expression of fibronectin and integrin α5 (ITGA5), accompanied by an increase in the interaction of GEF-H1 (also known as ARHGEF2) with Sec5 (also known as EXOC2), a microtubule (MT)-regulated RhoA activator and a component of the exocyst, respectively. Disruption of this interaction abolishes dexamethasone-induced cellular tension and GEF-H1 targeting to focal adhesion sites at the cell periphery without affecting dexamethasone-induced levels of ITGA5 and fibronectin, and the extracellular deposition of fibronectin at adhesion sites is specifically inhibited. We demonstrate that dexamethasone stimulates the expression of serum-glucocorticoid-induced protein kinase 1 (SGK1), which is necessary and sufficient for the induction of the Sec5-GEF-H1 interaction. Given the function of SGK1 in suppressing MT growth, our data suggest that the induction of SGK1 through treatment with dexamethasone alters MT dynamics to increase Sec5-GEF-H1 interactions, which promote GEF-H1 targeting to adhesion sites. This mechanism is essential for the formation of fibronectin fibrils and their attachment to integrins at adhesion sites in order to generate cellular tension.

Determinants of Receiving Palliative Care and Ventilator Withdrawal Among Patients With Prolonged Mechanical Ventilation.

OBJECTIVES: Increasing numbers of patients with prolonged mechanical ventilation generates a tremendous strain on healthcare systems. Patients with prolonged mechanical ventilation suffer from long-term poor quality of life. However, no study has ever explored the willingness to receive palliative care or terminal withdrawal and the factors influencing willingness. DESIGN: Cross-sectional study. SETTING: Five different hospitals of Taipei City Hospital system. PATIENTS: Adult patients with ventilatory support for more than 60 days. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We identified the family members of 145 consecutive patients with prolonged mechanical ventilation in five hospitals of Taipei City Hospital system and enrolled family members for 106 patients (73.1%). We collected information from patient families' regarding concepts (knowledge, attitude, and experiences) of palliative care, caregiver burden, family function, patient quality of life, and physician-family communications. From the medical record, we obtained duration of hospitalization, consciousness level, disease severity, medical cost, and the presence of do-not-resuscitate orders. The vast majority of family members agreed with the concept of palliative care (90.4%) with 17.3% of the family members agreeing to ventilator withdrawal currently and 67.5% terminally in anticipation of death. Approximately half of the family members regretted having chosen prolonged mechanical ventilation (56.7%). Reduced patient quality of life and increased family understanding of palliative care significantly associated with increased caregiver willingness to endorse palliative care and withdraw life-sustaining agents in anticipation of death. Longer duration of ventilator usage and hospitalization was associated with increased feelings of regret about choosing prolonged mechanical ventilation. CONCLUSIONS: During prolonged mechanical ventilation, physicians should thoroughly discuss its benefits and burdens. Families should be given the opportunity to discuss the circumstances under which they might request the implementation of palliative care or withdrawal of mechanical ventilation in order to avoid prolonging the dying process.

Stromal Tissue Rigidity Promotes Mesenchymal Stem Cell-Mediated Corneal Wound Healing Through the Transforming Growth Factor ß Signaling Pathway.

The healing of a corneal epithelial defect is essential for preventing infectious corneal ulcers and subsequent blindness. We previously demonstrated that mesenchymal stem cells (MSCs) in the corneal stroma, through a paracrine mechanism, yield a more favorable therapeutic benefit for corneal wound re-epithelialization than do MSCs in the corneal epithelium. In this study, MSCs were grown on a matrix with the rigidity of the physiological human vitreous (1 kPa), corneal epithelium (8 kPa), or corneal stroma (25 kPa) for investigating the role of corneal tissue rigidity in MSC functions regarding re-epithelialization promotion. MSC growth on a 25-kPa dish significantly promoted the wound healing of human corneal epithelial (HCE-T) cells. Among growth factors contributing to corneal epithelial wound healing, corneal stromal rigidity selectively enhanced transforming growth factor-beta (TGF-ß) secretion from MSCs. Inhibitors of TGF-ß pan receptor, TGF-ß receptor 1, and Smad2 dose dependently abrogated MSC-mediated HCE-T wound healing. Furthermore, MSCs growth on a matrix with corneal stromal rigidity enhanced the ability of themselves to promote corneal re-epithelialization by activating matrix metalloproteinase (MMP) expression and integrin ß1 production in HCE-T cells through TGF-ß signaling pathway activation. Smad2 activation resulted in the upregulation of MMP-2 and -13 expression in HCE-T cells, whereas integrin ß1 production favored a Smad2-independent TGF-ß pathway. Altogether, we conclude that corneal stromal rigidity is a critical factor for MSC-induced promotion of corneal re-epithelialization. The activation of the TGF-ß signaling pathway, which maintains the balance between integrin and MMP expression, in HCE-T cells is the major pathway responsible for MSC-mediated wound healing. Stem Cells 2016;34:2525-2535.

Oscillatory shear stress mediates directional reorganization of actin cytoskeleton and alters differentiation propensity of mesenchymal stem cells.

Shear stress stimuli differentially regulate cellular functions based on the pattern, magnitude as well as duration of the flow. Shear stress can modify intracellular kinase activities and cytoskeleton reorganization to result in changes of cell behavior. Mesenchymal stem cells (MSCs) are mechano-sensitive cells, but little is known about the effects of oscillatory shear stress (OS). In this study, we demonstrate that OS of 0.5 ± 4 dyn/cm(2) induces directional reorganization of F-actin to mediate the fate choice of MSCs through the regulation of ß-catenin. We also found that intercellular junction molecules are the predominant mechanosensors of OS in MSCs to deliver the signals that result in directional rearrangement of F-actin, as well as the increase of phosphorylated ß-catenin (pß-catenin) after 30 minutes of OS stimulation. Depolymerization of F-actin and increase in pß-catenin also lead to the upregulation of Wnt inhibitory factors sclerostin and dickkopf-1. Inhibition of ß-catenin/Wnt signaling pathway is accompanied by the upregulation of sex determining region Y-box2 and NANOG to control self-renewal. In conclusion, the reorganization of actin cytoskeleton and increase in ß-catenin phosphorylation triggered by OS regulate the expression of pluripotency genes via the ß-catenin/Wnt signaling pathway to differentially direct fate choices of MSCs at different time points. Results from this study have provided new information regarding how MSCs respond to mechanical cues from their microenvironment in a time-dependent fashion, and such biophysical stimuli could be administered to guide the fate and differentiation of stem cells in addition to conventional biochemical approaches.