Motion-Accommodating Dual-Layer Hydrogel Dressing to Deliver Adipose-Derived Stem Cells to Wounds.

BACKGROUND: Current dressing materials cannot secure a cell survival-promoting wound environment for stem cell delivery due to insufficient assimilation to skin motion. The authors developed a novel motion-accommodating dual-layer hydrogel dressing for stem cell delivery into such wounds. METHODS: Dorsal hand skin movement was evaluated to determine the potential range of deformation for a dressing. The outer hydrogel (OH) was fabricated with an alginate-acrylamide double-network hydrogel with a covalently cross-linked elastomer coat. The tough adhesive consisted of a chitosan-based bridging polymer and coupling reagents. OH material properties and adhesiveness on porcine skin were measured. An oxidized alginate-based inner hydrogel (IH) containing human adipose-derived stem cells (ASCs) was evaluated for cell-supporting and cell-releasing properties. The OH's function as a secondary dressing, and dual-layer hydrogel cell delivery potential in wounds were assessed in a rodent model. RESULTS: The dual-layer hydrogel consisted of OH and IH. The OH target range of deformation was up to 25% strain. The OH adhered to porcine skin, and showed significantly higher adhesion energy than common secondary dressings and endured 900 flexion-extension cycles without detachment. OH showed a similar moisture vapor transmission rate as moisture-retentive dressings. IH maintained embedded cell survival for three days with significant cell release on the contacting surface. OH showed less fibrotic wound healing than other secondary dressings in vivo. The dual-layer hydrogel successfully delivered ASCs into open wounds of nude mice (13 ± 3 cells/HPF). CONCLUSIONS: The novel dual-layer hydrogel can accommodate patient movement and deliver ASCs into the wound bed by securing the wound microenvironment.

Modulation of FGF pathway signaling and vascular differentiation using designed oligomeric assemblies.

Many growth factors and cytokines signal by binding to the extracellular domains of their receptors and driving association and transphosphorylation of the receptor intracellular tyrosine kinase domains, initiating downstream signaling cascades. To enable systematic exploration of how receptor valency and geometry affect signaling outcomes, we designed cyclic homo-oligomers with up to 8 subunits using repeat protein building blocks that can be modularly extended. By incorporating a de novo-designed fibroblast growth factor receptor (FGFR)-binding module into these scaffolds, we generated a series of synthetic signaling ligands that exhibit potent valency- and geometry-dependent Ca2+ release and mitogen-activated protein kinase (MAPK) pathway activation. The high specificity of the designed agonists reveals distinct roles for two FGFR splice variants in driving arterial endothelium and perivascular cell fates during early vascular development. Our designed modular assemblies should be broadly useful for unraveling the complexities of signaling in key developmental transitions and for developing future therapeutic applications.

Interferon-γ induces combined pyroptotic angiopathy and APOL1 expression in human kidney disease.

Elevated interferon (IFN) signaling is associated with kidney diseases including COVID-19, HIV, and apolipoprotein-L1 (APOL1) nephropathy, but whether IFNs directly contribute to nephrotoxicity remains unclear. Using human kidney organoids, primary endothelial cells, and patient samples, we demonstrate that IFN-γ induces pyroptotic angiopathy in combination with APOL1 expression. Single-cell RNA sequencing, immunoblotting, and quantitative fluorescence-based assays reveal that IFN-γ-mediated expression of APOL1 is accompanied by pyroptotic endothelial network degradation in organoids. Pharmacological blockade of IFN-γ signaling inhibits APOL1 expression, prevents upregulation of pyroptosis-associated genes, and rescues vascular networks. Multiomic analyses in patients with COVID-19, proteinuric kidney disease, and collapsing glomerulopathy similarly demonstrate increased IFN signaling and pyroptosis-associated gene expression correlating with accelerated renal disease progression. Our results reveal that IFN-γ signaling simultaneously induces endothelial injury and primes renal cells for pyroptosis, suggesting a combinatorial mechanism for APOL1-mediated collapsing glomerulopathy, which can be targeted therapeutically.

Durable lymph-node expansion is associated with the efficacy of therapeutic vaccination.

Following immunization, lymph nodes dynamically expand and contract. The mechanical and cellular changes enabling the early-stage expansion of lymph nodes have been characterized, yet the durability of such responses and their implications for adaptive immunity and vaccine efficacy are unknown. Here, by leveraging high-frequency ultrasound imaging of the lymph nodes of mice, we report more potent and persistent lymph-node expansion for animals immunized with a mesoporous silica vaccine incorporating a model antigen than for animals given bolus immunization or standard vaccine formulations such as alum, and that durable and robust lymph-node expansion was associated with vaccine efficacy and adaptive immunity for 100 days post-vaccination in a mouse model of melanoma. Immunization altered the mechanical and extracellular-matrix properties of the lymph nodes, drove antigen-dependent proliferation of immune and stromal cells, and altered the transcriptional features of dendritic cells and inflammatory monocytes. Strategies that robustly maintain lymph-node expansion may result in enhanced vaccination outcomes.

Targeting Wavefront Discontinuity Lines for Scar-Related Ventricular Tachycardia Ablation: A Novel Functional Substrate Ablation Approach.

BACKGROUND: The boundaries of critical isthmuses for re-entrant ventricular tachycardia (VT) are formed by wave-front discontinuities (fixed lines of block, slow propagation, and rotational propagation) seen during baseline rhythm. It is unknown whether wavefront discontinuities can be automatically identified and targeted for ablation using electroanatomic mapping systems. OBJECTIVES: The purpose of this study was to assess the electrophysiologic characteristics of automatically projected wavefront discontinuity lines (WADLs) and outcomes of an ablation strategy targeting WADLs in a mixed cohort of VT patients. METHODS: Late activation substrate maps were analyzed from 1 or more baseline rhythm wavefronts. WADLs were identified using the Carto Extended Early Meets Late module. Number, total length, and distance to critical VT sites were measured. VT recurrence and VT-free survival were followed. RESULTS: In total, 49 patients underwent 52 ablations with 71 unique substrate maps analyzed (18.8% epicardial; 62.0% right ventricular paced, 28.2% sinus rhythm, 9.9% left ventricular paced). A total of 28 VT critical sites were identified in 24 patients. WADLs were present in 49 of 71 (69.0%) maps. WADLs were present regardless of cardiomyopathy etiology, mapping wavefront, or surface. At a WADL threshold of 30%, 73.9% of critical VT sites were in close proximity (≤15 mm) to a WADL. VT-free survival was 62% at 1 year, with a competing risk model estimating a 1-year risk of VT recurrence of 23%. CONCLUSIONS: WADLs can be automatically projected in a majority of patients in a mixed cohort of cardiomyopathy etiology, mapped wavefronts, and myocardial surfaces mapped. Targeting WADLs results in low rate of VT recurrence at 1 year.

Treating Erythromelalgia with Interosseous Membrane Stimulation: An Autonomic Basis for the Condition and Its Treatment.

Background: Erythromelalgia, which has primary and secondary presentations, causes heat, pain, and redness in the skin. The condition seems to have an autonomic basis, with vasomotor dysfunction causing dilatation of some blood vessels and constriction of others. No consistently effective treatments have been reported. Anticonvulsant, antidepressant, antihistamine, anti-inflammatory, antihypertensive, analgesic, nutritional, and topical approaches have been tried as were lidocaine infusions, nerve blocks, and thoracic and lumbar sympathectomies. Interosseous membrane stimulation appears to affect the local autonomic milieu in the extremity being treated. This approach was used on a patient with erythromelalgia. Case: A 36-year-old woman with erythromelalgia was treated with interosseous membrane stimulation. Eight treatments were given over a 1-year timeframe at 1-3-month intervals. Results: This patient repeatedly experienced much relief from her burning paresthesias, swelling, diaphoresis, and ruddy discoloration of her extremities for 6-8 hours following each treatment. The intensity of her discomfort subsided gradually over time. Conclusions: Interosseous membrane stimulation is a safe, simple, and effective treatment for erythromelalgia, which is notoriously refractory to treatment. This patient's response to treatment might have been a result of localized derangement of her autonomic nervous system. It is possible that manipulation of the autonomic milieu of an extremity is a significant factor in the mechanism of action of interosseous membrane stimulation.

Genetics of cystogenesis in base-edited human organoids reveal therapeutic strategies for polycystic kidney disease.

In polycystic kidney disease (PKD), microscopic tubules expand into macroscopic cysts. Among the world's most common genetic disorders, PKD is inherited via heterozygous loss-of-function mutations but is theorized to require additional loss of function. To test this, we establish human pluripotent stem cells in allelic series representing four common nonsense mutations, using CRISPR base editing. When differentiated into kidney organoids, homozygous mutants spontaneously form cysts, whereas heterozygous mutants (original or base corrected) express no phenotype. Using these, we identify eukaryotic ribosomal selective glycosides (ERSGs) as PKD therapeutics enabling ribosomal readthrough of these same nonsense mutations. Two different ERSGs not only prevent cyst initiation but also limit growth of pre-formed cysts by partially restoring polycystin expression. Furthermore, glycosides accumulate in cyst epithelia in organoids and mice. Our findings define the human polycystin threshold as a surmountable drug target for pharmacological or gene therapy interventions, with relevance for understanding disease mechanisms and future clinical trials.

Recommendations on fit-for-purpose criteria to establish quality management for microphysiological systems and for monitoring their reproducibility.

Cell culture technology has evolved, moving from single-cell and monolayer methods to 3D models like reaggregates, spheroids, and organoids, improved with bioengineering like microfabrication and bioprinting. These advancements, termed microphysiological systems (MPSs), closely replicate tissue environments and human physiology, enhancing research and biomedical uses. However, MPS complexity introduces standardization challenges, impacting reproducibility and trust. We offer guidelines for quality management and control criteria specific to MPSs, facilitating reliable outcomes without stifling innovation. Our fit-for-purpose recommendations provide actionable advice for achieving consistent MPS performance.

The prevalence of incivility in hospitals and the effects of incivility on patient safety culture and outcomes: A systematic review and meta-analysis.

AIM: Workplace incivility is a barrier to safe and high-quality patient care in nursing workplaces and more broadly in tertiary hospitals. The present study aims to systematically review the existing evidence to provide a comprehensive understanding of the prevalence of co-worker incivility experienced and witnessed by nurses and other healthcare professionals, the effects of incivility on patient safety culture (PSC) and patient outcomes, and the factors which mediate the relationship between incivility and patient safety. METHODS: A systematic review with narrative synthesis and meta-analysis was undertaken to synthesize the data from 41 studies. DATA SOURCES: Databases searched included MEDLINE, PubMed, SCOPUS, CINAHL, PsycInfo, ProQuest, Emcare and Embase. Searches were conducted on 17 August 2021 and repeated on 15 March 2023. RESULTS: The pooled prevalence of experienced incivility was 25.0%. The pooled prevalence of witnessed incivility was 30.1%. Workplace incivility was negatively associated with the PSC domains of teamwork, reporting patient safety events, organization learning/improvement, management support for safety, leadership, communication openness and communication about error. The composite pooled effect size of incivility on these domains of PSC was OR = 0.590, 95% CI [0.515, 0.676]. Workplace incivility was associated with a range of patient safety outcomes (PSOs) including near misses, adverse events, reduced procedural and diagnostic performance, medical error and mortality. State depletion, profession, psychological responses to incivility, information sharing, help seeking, workload and satisfaction with organizational communication were found to mediate the relationship between incivility and patient safety. CONCLUSION: Experienced and witnessed incivility is prevalent in tertiary hospitals and has a deleterious effect on PSC and PSOs. A better understanding of the mechanisms of this relationship will support the development of interventions aimed at reducing both incivility and patient harm. IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE IMPACT: This study quantifies the effect of incivility on PSC and outcomes. It provides support that interventions focusing on incivility are a valuable mechanism for improving patient care. It guides intervention design by highlighting which domains of PSC are most associated with incivility. It explores the profession-specific experiences of workplace incivility. REPORTING METHOD: This report adheres to PRISMA reporting guidelines. PATIENT OR PUBLIC CONTRIBUTION: No patient or public contribution. The focus of this study is the nursing and healthcare workforce, therefore, patient or public involvement not required.

A tough bioadhesive hydrogel supports sutureless sealing of the dural membrane in porcine and ex vivo human tissue.

Complete sequestration of central nervous system tissue and cerebrospinal fluid by the dural membrane is fundamental to maintaining homeostasis and proper organ function, making reconstruction of this layer an essential step during neurosurgery. Primary closure of the dura by suture repair is the current standard, despite facing technical, microenvironmental, and anatomic challenges. Here, we apply a mechanically tough hydrogel paired with a bioadhesive for intraoperative sealing of the dural membrane in rodent, porcine, and human central nervous system tissue. Tensile testing demonstrated that this dural tough adhesive (DTA) exhibited greater toughness with higher maximum stress and stretch compared with commercial sealants in aqueous environments. To evaluate the performance of DTA in the range of intracranial pressure typical of healthy and disease states, ex vivo burst pressure testing was conducted until failure after DTA or commercial sealant application on ex vivo porcine dura with a punch biopsy injury. In contrast to commercial sealants, DTA remained adhered to the porcine dura through increasing pressure up to 300 millimeters of mercury and achieved a greater maximum burst pressure. Feasibility of DTA to repair cerebrospinal fluid leak in a simulated surgical context was evaluated in postmortem human dural tissue. DTA supported effective sutureless repair of the porcine thecal sac in vivo. Biocompatibility and adhesion of DTA was maintained for up to 4 weeks in rodents after implantation. The findings suggest the potential of DTA to augment or perhaps even supplant suture repair and warrant further exploration.

Instant tough adhesion of polymer networks.

Generating strong rapid adhesion between hydrogels has the potential to advance the capabilities of modern medicine and surgery. Current hydrogel adhesion technologies rely primarily on liquid-based diffusion mechanisms and the formation of covalent bonds, requiring prolonged time to generate adhesion. Here, we present a simple and versatile strategy using dry chitosan polymer films to generate instant adhesion between hydrogel-hydrogel and hydrogel-elastomer surfaces. Using this approach we can achieve extremely high adhesive energies (>3,000 J/m2), which are governed by pH change and non-covalent interactions including H-bonding, Van der Waals forces, and bridging polymer entanglement. Potential examples of biomedical applications are presented, including local tissue cooling, vascular sealing, prevention of surgical adhesions, and prevention of hydrogel dehydration. We expect these findings and the simplicity of this approach to have broad implications for adhesion strategies and hydrogel design.

Natural Polymer-Polyphenol Bioadhesive Coacervate with Stable Wet Adhesion, Antibacterial Activity, and On-Demand Detachment.

Medical adhesives are emerging as an important clinical tool as adjuvants for sutures and staples in wound closure and healing and in the achievement of hemostasis. However, clinical adhesives combining cytocompatibility, as well as strong and stable adhesion in physiological conditions, are still in demand. Herein, a mussel-inspired strategy is explored to produce adhesive coacervates using tannic acid (TA) and methacrylate pullulan (PUL-MA). TA|PUL-MA coacervates mainly comprise van der Waals forces and hydrophobic interactions. The methacrylic groups in the PUL backbone increase the number of interactions in the adhesives matrix, resulting in enhanced cohesion and adhesion strength (72.7 Jm-2), compared to the non-methacrylated coacervate. The adhesive properties are kept in physiologic-mimetic solutions (72.8 Jm-2) for 72 h. The photopolymerization of TA|PUL-MA enables the on-demand detachment of the adhesive. The poor cytocompatibility associated with the use of phenolic groups is here circumvented by mixing reactive oxygen species-degrading enzyme in the adhesive coacervate. This addition does not hamper the adhesive character of the materials, nor their anti-microbial or hemostatic properties. This affordable and straightforward methodology, together with the tailorable adhesivity even in wet environments, high cytocompatibility, and anti-bacterial activity, enables foresee TA|PUL-MA as a promising ready-to-use bioadhesive for biomedical applications.

Wound pH-Modulating Strategies for Diabetic Wound Healing.

Significance: Chronic diabetic wounds on the lower extremities (diabetic foot ulcers, DFU) are one of the most prevalent and life-threatening complications of diabetes, responsible for significant loss of quality of life and cost to the health care system. Available pharmacologic treatments fail to achieve complete healing in many patients. Recent studies and investigational treatments have highlighted the potential of modulating wound pH in DFU. Recent Advances: Data from in vitro, preclinical, and clinical studies highlight the role of pH in the pathophysiology of DFU, and topical administration of pH-lowering agents have shown promise as a therapeutic strategy for diabetic wounds. In this critical review, we describe the role of pH in DFU pathophysiology and present selected low-molecular-weight and hydrogel-based pH-modulating systems for wound healing and infection control in diabetic wounds. Critical Issues: The molecular mechanisms leading to pH alterations in diabetic wounds are complex and may differ between in vitro models, animal models of diabetes, and the human pathophysiology. Wound pH-lowering bandages for DFU therapy must be tested in established animal models of diabetic wound healing and patients with diabetes to establish a comprehensive benefit-risk profile. Future Directions: As our understanding of the role of pH in the pathophysiology of diabetic wounds is deepening, new treatments for this therapeutic target are being developed and will be tested in preclinical and clinical studies. These therapeutic systems will establish a target product profile for pH-lowering treatments such as an optimal pH profile for each wound healing stage. Thus, controlling wound bed pH could become a powerful tool to accelerate chronic diabetic wound healing.

Single-cell census of human tooth development enables generation of human enamel.

Tooth enamel secreted by ameloblasts (AMs) is the hardest material in the human body, acting as a shield to protect the teeth. However, the enamel is gradually damaged or partially lost in over 90% of adults and cannot be regenerated due to a lack of ameloblasts in erupted teeth. Here, we use single-cell combinatorial indexing RNA sequencing (sci-RNA-seq) to establish a spatiotemporal single-cell census for the developing human tooth and identify regulatory mechanisms controlling the differentiation process of human ameloblasts. We identify key signaling pathways involved between the support cells and ameloblasts during fetal development and recapitulate those findings in human ameloblast in vitro differentiation from induced pluripotent stem cells (iPSCs). We furthermore develop a disease model of amelogenesis imperfecta in a three-dimensional (3D) organoid system and show AM maturation to mineralized structure in vivo. These studies pave the way for future regenerative dentistry.

Correlation Between Functional Substrate Mapping and Cardiac Computed Tomography-Derived Wall Thinning for Ventricular Tachycardia Ablation.

BACKGROUND: Functional substrate mapping during baseline rhythm can identify arrhythmogenic tissue during ventricular tachycardia (VT) ablation. Wall thinning and wall thickness channels (WTCs) derived from computed tomography angiography have been shown to correlate with low voltage and VT isthmuses. The correlation between functional substrate mapping, wall thinning, and WTCs in patients with infarct- or non-infarct-related cardiomyopathies (ICM and NICM, respectively) has not been previously described. OBJECTIVES: The purpose of this study was to correlate cardiac CTA-derived myocardial wall thinning with functional VT substrate mapping using isochronal late activation mapping. METHODS: In 34 patients with ICM or NICM undergoing VT ablation who had a preprocedure computed tomography angiography, myocardial wall thinning was segmented in layers of 1 to 5 mm. Areas of wall thinning and WTCs were then spatially correlated with deceleration zones (DZs) from registered left ventricular endocardial isochronal late activation maps. RESULTS: In 21 ICM patients and 13 NICM patients, ICM patients had greater surfaces areas of wall thinning (P < 0.001). In ICM patients, 94.1% of primary DZs were located on areas of wall thinning, compared to 20% of DZs in NICM patients overall but 50% if there was any wall thinning present. Fifty-nine percent of DZs in ICM patients and 56% of DZs in NICM patients were located near WTCs. The positive predictive value for WTC in localizing DZs was 22.5% and 37.8% in ICM and NICM patients, respectively. CONCLUSIONS: Wall thinning is highly sensitive for functional substrate in ICM patients. WTCs had modest sensitivity for functional substrate but low positive predictive value for identifying DZs in ICM and NICM patients. These findings suggest that wall thinning may facilitate more efficient mapping in ICM patients, but WTCs are insufficient to localize wavefront discontinuities.

Procedural Adaptations to Avoid Haemodynamic Instability During Catheter Ablation of Scar-related Ventricular Tachycardia.

Classically, catheter ablation for scar-related ventricular tachycardia (VT) relied upon activation and entrainment mapping of induced VT. Advances in post-MI therapies have led to VTs that are faster and haemodynamically less stable, because of more heterogeneous myocardial fibrosis patterns. The PAINESD score is one means of identifying patients at highest risk for haemodynamic decompensation during attempted VT induction, who may, therefore, benefit from alternative ablation strategies. One strategy is to use temporary mechanical circulatory support, although this warrants formal assessment of cost-effectiveness. A second strategy is to minimise or avoid VT induction altogether by employing a family of 'substrate'-based approaches aimed at identifying VT isthmuses during sinus or paced rhythm. Substrate mapping techniques are diverse, and focus on the timing, morphology and amplitude of local ventricular electrograms - sometimes aided by advanced non-invasive cardiac imaging modalities. In this review, the evolution of VT ablation over time is discussed, with an emphasis on procedural adaptations to the challenge of haemodynamic instability.

Mechanoresponsive Drug Release from a Flexible, Tissue-Adherent, Hybrid Hydrogel Actuator.

Soft robotic technologies for therapeutic biomedical applications require conformal and atraumatic tissue coupling that is amenable to dynamic loading for effective drug delivery or tissue stimulation. This intimate and sustained contact offers vast therapeutic opportunities for localized drug release. Herein, a new class of hybrid hydrogel actuator (HHA) that facilitates enhanced drug delivery is introduced. The multi-material soft actuator can elicit a tunable mechanoresponsive release of charged drug from its alginate/acrylamide hydrogel layer with temporal control. Dosing control parameters include actuation magnitude, frequency, and duration. The actuator can safely adhere to tissue via a flexible, drug-permeable adhesive bond that can withstand dynamic device actuation. Conformal adhesion of the hybrid hydrogel actuator to tissue leads to improved mechanoresponsive spatial delivery of the drug. Future integration of this hybrid hydrogel actuator with other soft robotic assistive technologies can enable a synergistic, multi-pronged treatment approach for the treatment of disease.

Aging and injury affect nuclear shape heterogeneity in tendon.

Tissue level properties are commonly studied using histological stains assessed with qualitative scoring methods. As qualitative evaluation is typically insensitive, quantitative analysis provides additional information about pathological mechanisms, but cannot capture structural heterogeneity across cell subpopulations. However, molecular analyses of cell and nuclear behavior have identified that cell and more recently also nuclear shape are highly associated with cell function and malfunction. This study combined a Visually Aided Morpho-Phenotyping Image Recognition analysis that automatically segments cells based on their shape with an added capacity to further discriminate between cells in certain protein-rich extracellular matrix regions. We used tendon as a model system given the enormous changes in organization and cell and nuclear shape they undergo during aging and injury. Our results uncover that multiple shape modes of nuclei exist during maturity and aging in rat tendon and that distinct subgroups of cell nuclei shapes exist in proteoglycan-rich regions during aging. With injury, several immunomarkers (αSMA, CD31, CD146) were associated with more rounded shape modes. In human tendons, the cell nuclei at sites of injury were found to be more rounded relative to uninjured tissues. To conclude, the tendon tissue changes occurring during aging and injury could be associated with a variation in cell nuclear morphology and the appearance of various region-specific subpopulations. Thus, the methodologies developed allow for a deeper understanding of cell heterogeneity during tendon aging and injury and may be extended to study further clinical applications.

Generation of functionally distinct T-cell populations by altering the viscoelasticity of their extracellular matrix.

The efficacy of adoptive T-cell therapies largely depends on the generation of T-cell populations that provide rapid effector function and long-term protective immunity. Yet it is becoming clearer that the phenotypes and functions of T cells are inherently linked to their localization in tissues. Here we show that functionally distinct T-cell populations can be generated from T cells that received the same stimulation by altering the viscoelasticity of their surrounding extracellular matrix (ECM). By using a model ECM based on a norbornene-modified collagen type I whose viscoelasticity can be adjusted independently from its bulk stiffness by varying the degree of covalent crosslinking via a bioorthogonal click reaction with tetrazine moieties, we show that ECM viscoelasticity regulates T-cell phenotype and function via the activator-protein-1 signalling pathway, a critical regulator of T-cell activation and fate. Our observations are consistent with the tissue-dependent gene-expression profiles of T cells isolated from mechanically distinct tissues from patients with cancer or fibrosis, and suggest that matrix viscoelasticity could be leveraged when generating T-cell products for therapeutic applications.