Intravascularly infused extracellular matrix as a biomaterial for targeting and treating inflamed tissues

Injectable myocardium-derived hydrogels with SDF-1α releasing for cardiac repair

Myocardial infarction (MI) is a predominant cause of morbidity and mortality globally. Therapeutic chemokines, such as stromal cell-derived factor 1α (SDF-1α), present a promising opportunity to treat the profibrotic remodeling post-MI if they can be delivered effectively to the injured tissue. However, direct injection of SDF-1α or physical entrapment in a hydrogel has shown limited efficacy. Here, we developed a sustained-release system consisting of SDF-1α loaded poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) and an injectable porcine cardiac decellularized extracellular matrix (cdECM) hydrogel. This system demonstrated a sustained release of SDF-1α over four weeks while there is one week release for SDF-1α directly encapsulated in the cdECM hydrogel during in vitro testing. The incorporation of PLGA NPs into the cdECM hydrogel significantly enhanced its mechanical properties, increasing the Young's modulus from 561 ± 228 kPa to 1007 ± 2 kPa and the maximum compressive strength from 639 ± 42 kPa to 1014 ± 101 kPa. This nanocomposite hydrogel showed good cell compatibility after 7 days of culture with H9C2 cells, while the released SDF-1α retained its bioactivity, as evidenced by its chemotactic effects in vitro. Furthermore, in vivo studies further highlighted its significant ability to promote angiogenesis in the infarcted area and improve cardiac function after intramyocardial injection. These results demonstrated the therapeutic potential of combining local release of SDF-1α with the cdECM hydrogel for MI treatment.

Sulfated chitosan directs the recovery of ischemic stroke by attenuating the inflammatory cascade

Background: Ischemic stroke is considered a fatal ischemic disease with high mortality and morbidity. Acute ischemic stroke is a cascade of inflammatory reactions, which not only causes vascular degeneration but also leads to neurological disorders. During this period, the rapid response of neutrophil-dominated granulocytes releases cytokines and chemokines to affect tissue repair. Thus, effective regulation of neutrophils appears to be the key in treating major organ injuries associated with inflammation. Methods: This study developed a semisynthetic sulfated chitosan (SCS) associated with the functional sulfated groups. The immunoregulatory effects of SCS on neutrophils were tested by Real-Time Quantitative Reverse Transcription (RT-PCR), ELISA and immunofluorescence staining at gene and protein levels in vitro. Flow cytometry, WB and PCR were used to study the effect of neutrophils on macrophages, indicating the regulation of the inflammatory cascade by SCS. Acute ischemic stroke model was established to verify the effectiveness and the regulation of inflammatory cascade of SCS. Finally, the lower limb ischemia model was used to verify the universality of SCS in the treatment of ischemic diseases, especially with regard to acute inflammatory-related major organ damage. Results: SCS can not only promote neutrophil apoptosis, but also enable neutrophils to produce vascular-related subsets to regulate immunity and promote angiogenesis. Neutrophil stimulated by SCS mediated macrophage polarization via IL-10-induced Stat3 signaling pathway to weaken the inflammatory cascade. In animal models of ischemic hind limb and ischemic stroke, SCS had demonstrated its ability to shorten the acute inflammatory period, as indicated by neutrophil, and accelerate the subsequent repair period characterized by the presence of M2 macrophages. Additionally, SCS effectively inhibits the expression of MMP-9 to provide a favorable environment for rapid extracellular matrix reconstruction. Encouragingly, treatment with SCS had been shown to reduce the expansion of the infarct volume by approximately 20% in our experiments. Conclusion: This study underscores the effect of SCS in regulating the heterogeneity of neutrophils in order to suppress the initiation of inflammation to treat ischemic stroke. Crucially, our approach relies on non-exogenous growth factors and cells, highlighting its remarkable potential for clinical translatability in the treatment of major organ injuries.

Protein-Like Polymers Targeting Keap1/Nrf2 as Therapeutics for Myocardial Infarction

Myocardial infarction (MI) results in oxidative stress to the myocardium and frequently leads to heart failure (HF). There is an unmet clinical need to develop therapeutics that address the inflammatory stress response and prevent negative left ventricular remodeling. Here, the Keap1/Nrf2 protein-protein interaction is specifically targeted, as Nrf2 activation is known to mitigate the inflammatory response following MI. This is achieved using a Nrf2-mimetic protein-like polymer (PLP) to inhibit the Keap1-Nrf2 interaction. The PLP platform technology provides stability in vivo, potent intracellular bioactivity, and multivalency leading to high avidity Keap1 binding. In vitro and in vivo assays to probe cellular activity and MI therapeutic utility are employed. These Keap1-inhibiting PLPs (Keap1i-PLPs) impart cytoprotection from oxidative stress via Nrf2 activation at sub-nanomolar concentrations in primary cardiomyocytes. Single-digit mg kg-1, single-dose, intravenous PLP administration significantly improves cardiac function in rats post-MI through immunomodulatory, anti-apoptotic, and angiogenic mechanisms. Thus Keap1i-PLPs disrupt key intracellular protein-protein interactions following intravenous, systemic administration in vivo. These results have broad implications not only for MI but also for other oxidative stress-driven diseases and conditions.

Injectable hydrogel with miR-222-engineered extracellular vesicles ameliorates myocardial ischemic reperfusion injury via mechanotransduction

Cardiac ischemic reperfusion injury (IRI) significantly exacerbates cardiac dysfunction and heart failure, causing high mortality. Despite the severity of IRI, effective therapeutic strategies remain elusive. Acellular cardiac patches have shown considerable efficacy in delivering therapeutics directly to cardiac tissues. Herein, we develop injectable GelMA (GEL) hydrogels with controlled mechanical properties. Targeting miR-222-engineered extracellular vesicles (TeEVs), tailored with cardiac-ischemia-targeting peptides (CTPs), are developed as ischemic TeEV therapeutics. These TeEVs are encapsulated within mechanical hydrogels to create injectable TeEV-loaded cardiac patches, enabling minimal invasiveness to attenuate IRI. The injectable patches facilitate the precise targeting of TeEVs for the efficient rescue of damaged cells. Persistent delivery of TeEVs into the infarcted region alleviates acute IRI and mitigated remodeling post IRI. This is linked to focal adhesion activation, cytoskeleton force enhancement, and nuclear force-sensing preservation. These findings may pave the way for force-sensing approaches to cardiac therapy using bioengineered therapeutic patches.

Incorporating Bone-Derived ECM into Macroporous Microribbon Scaffolds Accelerates Bone Regeneration

Tissue-derived extracellular matrix (tdECM) hydrogels serve as effective scaffolds for tissue regeneration by promoting a regenerative immune response. While most tdECM hydrogels are nanoporous and tailored for soft tissue, macroporosity is crucial for bone regeneration. Yet, there's a shortage of macroporous ECM-based hydrogels for this purpose. The study aims to address this gap by developing a co-spinning technique to integrate bone-derived ECM (bECM) into gelatin-based, macroporous microribbon (µRB) scaffolds. The effect of varying doses of bECM on scaffold properties was characterized. In vitro studies revealed 15% bECM as optimal for promoting MSC osteogenesis and macrophage (Mφ) polarization. When implanted in a mouse critical-sized cranial bone defect model, 15% bECM with tricalcium phosphate (TCP) microparticles significantly accelerated bone regeneration and vascularization, filling over 55% of the void by week 2. Increasing bECM to 25% enhanced mesenchymal stem cell (MSC) recruitment and decreased M1 Mφ polarization but reduced overall bone formation and vascularization. The findings demonstrate co-spun gelatin/bECM hydrogels as promising macroporous scaffolds for robust endogenous bone regeneration, without the need for exogenous cells or growth factors. While this study focused on bone regeneration, this platform holds the potential for incorporating various tdECM into macroporous scaffolds for diverse tissue regeneration applications.

ROS scavenging and corneal epithelial wound healing by a self-crosslinked tissue-adhesive hydrogel based-on dual-functionalized hyaluronic acid

Reactive oxygen species (ROS) scavenging is a viable approach to promote corneal epithelium wound healing. This study created a single-component hydrogel (HA Gel) with a novel dual-functionalized hyaluronic acid derivative (HA-GA-PBA) containing gallol and phenylboronic acid (PBA) moieties. Both of these moieties were dual-functional. Specifically, they not only functioned as structural building blocks for hydrogel formation, but also served as bioactive ingredients for therapeutic purpose. Dynamic covalent complexation between gallol and PBA moieties led to the self-crosslinked HA Gel, which was antioxidative and tissue-adhesive. It was demonstrated that the hydrogel enhanced the proliferation rate of human corneal epithelial cells by over 2.5 folds. When treating the mouse corneal alkali burn model with HA Gel, the corneal epithelial healing percentages reached 69.19 ± 9.41 % and 84.12 ± 6.09 % on day 3 and 5, respectively, which were significantly higher than the placebo group (51.14 ± 9.63 % and 67.32 ± 10.54 % on day 3 and 5, respectively). Meanwhile, reduced scar formation and inflammation was observed. These findings indicated HA Gel could find applications in various of ocular diseases for improved corneal epithelial wound healing.

Pathophysiological mechanisms of ARDS: a narrative review from molecular to organ-level perspectives

BACKGROUND

Acute respiratory distress syndrome (ARDS) remains a life-threatening pulmonary condition with persistently high mortality rates despite significant advancements in supportive care. Its complex pathophysiology involves an intricate interplay of molecular and cellular processes, including cytokine storms, oxidative stress, programmed cell death, and disruption of the alveolar-capillary barrier. These mechanisms drive localized lung injury and contribute to systemic inflammatory response syndrome and multiple organ dysfunction syndrome. Unlike prior reviews that primarily focus on isolated mechanisms, this narrative review synthesizes the key pathophysiological processes of ARDS across molecular, cellular, tissue, and organ levels.

MAIN BODY

By integrating classical theories with recent research advancements, we provide a comprehensive analysis of how inflammatory mediators, metabolic reprogramming, oxidative stress, and immune dysregulation synergistically drive ARDS onset and progression. Furthermore, we critically evaluate current evidence-based therapeutic strategies, such as lung-protective ventilation and prone positioning, while exploring innovative therapies, including stem cell therapy, gene therapy, and immunotherapy. We emphasize the significance of ARDS subtypes and their inherent heterogeneity in guiding the development of personalized treatment strategies.

CONCLUSIONS

This narrative review provides fresh perspectives for future research, ultimately enhancing patient outcomes and optimizing management approaches in ARDS.

Repeated birth injuries lead to long-term pelvic floor muscle dysfunction in the preclinical rat model

BACKGROUND

Vaginal childbirth is a key risk factor for pelvic floor muscle injury and dysfunction, and subsequent pelvic floor disorders. Multiparity further exacerbates these risks. Using the rat model, validated for the studies of the human pelvic floor muscles, we have previously identified that a single simulated birth injury results in pelvic floor muscle atrophy and fibrosis.

OBJECTIVE

To test the hypothesis that multiple birth injuries would further overwhelm the muscle regenerative capacity, leading to functionally relevant pathological alterations long-term.

STUDY DESIGN

Sprague-Dawley rats underwent simulated birth injury and were allowed to recover for 8 weeks before undergoing additional birth injury. Animals were sacrificed at acute (3 and 7 days postinjury), subacute (21, 28, and 35 days postinjury), and long-term (8 and 12 weeks postinjury) time points post second injury (N=3-8/time point), and the pubocaudalis portion of the rat levator ani complex was harvested to assess the impact of repeated birth injuries on muscle mechanical and histomorphological properties. The accompanying transcriptional changes were assessed by a customized NanoString panel. Uninjured animals were used as controls. Data with a parametric distribution were analyzed by a 2-way analysis of variance followed by post hoc pairwise comparisons using Tukey's or Sidak's tests; nonparametrically distributed data were compared with Kruskal-Wallis test followed by pairwise comparisons with Dunn's test. Data, analyzed using GraphPad Prism v8.0, San Diego, CA, are presented as mean ± standard error of the mean or median (range).

RESULTS

Following the first simulated birth injury, active muscle force decreased acutely relative to uninjured controls (12.9±0.9 vs 25.98±2.1 g/mm2, P<.01). At 4 weeks, muscle active force production recovered to baseline and remained unchanged at 8 weeks after birth injury (P>.99). Similarly, precipitous decrease in active force was observed immediately after repeated birth injury (18.07±1.2 vs 25.98±2.1 g/mm2, P<.05). In contrast to the functional recovery after a single birth injury, a long-term decrease in muscle contractile function was observed up to 12 weeks after repeated birth injuries (18.3±1.6 vs 25.98±2.1 g/mm2, P<.05). Fiber size was smaller at the long-term time points after second injury compared to the uninjured group (12 weeks vs uninjured control: 1485 (60.7-5000) vs 1989 (65.6-4702) μm2, P<.0001). The proportion of fibers with centralized nuclei, indicating active myofiber regeneration, returned to baseline at 8 weeks post-first birth injury, (P=.95), but remained elevated as far as 12 weeks post-second injury (12 weeks vs uninjured control: 7.1±1.5 vs 0.84±0.13%, P<0.0001). In contrast to the plateauing intramuscular collagen content after 4 weeks post-first injury, fibrotic degeneration increased progressively over 12 weeks after repeated injury (12 weeks vs uninjured control: 6. 7±1.1 vs 2.03±0.2%, P<.001). Prolonged expression of proinflammatory genes accompanied by a greater immune infiltrate was observed after repeated compared to a single birth injury.

CONCLUSION

Overall, repeated birth injuries lead to a greater magnitude of pathological alterations compared to a single injury, resulting in more pronounced pelvic floor muscle degeneration and muscle dysfunction in the rat model. The above provides a putative mechanistic link between multiparity and the increased risk of pelvic floor dysfunction in women.

Biomedical applications of functional hydrogels: Innovative developments, relevant clinical trials and advanced products

Functional hydrogels are used for numerous biomedical applications such as tissue engineering, wound dressings, lubricants, contact lenses and advanced drug delivery systems. Most of them are based on synthetic or natural polymers forming a three-dimensional network that contains aqueous media. Among synthetic polymers, poly(meth)acrylates, polyethyleneglycols, poly(vinylalcohols), poly(vinylpyrrolidones), PLGA and poly(urethanes) are of high relevance, whereas natural polymers are mainly polysaccharides such as hyaluronic acid, alginate or chitosan and proteins such as albumin, collagen or elastin. In contrast to most synthetic polymers, natural polymers are biodegradable. Both synthetic and natural polymers are often chemically modified in order to improve or induce favorable properties and functions like high mechanical strength, stiffness, elasticity, high porosity, adhesive properties, in situ gelling properties, high water binding capacity or drug release controlling properties. Within this review we provide an overview about the broad spectrum of biomedical applications of functional hydrogels, summarize innovative approaches, discuss the concept of relevant functional hydrogels that are in clinical trials and highlight advanced products as examples for successful developments.

An injectable subcutaneous colon-specific immune niche for the treatment of ulcerative colitis

As a chronic autoinflammatory condition, ulcerative colitis is often managed via systemic immunosuppressants. Here we show, in three mouse models of established ulcerative colitis, that a subcutaneously injected colon-specific immunosuppressive niche consisting of colon epithelial cells, decellularized colon extracellular matrix and nanofibres functionalized with programmed death-ligand 1, CD86, a peptide mimic of transforming growth factor-beta 1, and the immunosuppressive small-molecule leflunomide, induced intestinal immunotolerance and reduced inflammation in the animals' lower gastrointestinal tract. The bioengineered colon-specific niche triggered autoreactive T cell anergy and polarized pro-inflammatory macrophages via multiple immunosuppressive pathways, and prevented the infiltration of immune cells into the colon's lamina propria, promoting the recovery of epithelial damage. The bioengineered niche also prevented colitis-associated colorectal cancer and eliminated immune-related colitis triggered by kinase inhibitors and immune checkpoint blockade.

Hydrogel in the Treatment of Traumatic Brain Injury

The high prevalence of traumatic brain injury (TBI) poses an important global public health challenge. Current treatment modalities for TBI primarily involve pharmaceutical interventions and surgical procedures; however, the efficacy of these approaches remains limited. In the field of regenerative medicine, hydrogels have garnered significant attention and research efforts. This review provides an overview of the existing landscape and pathological manifestations of TBI, with a specific emphasis on delineating the therapeutic potential of hydrogels incorporated with various bioactive agents for TBI management. Particularly, the review delves into the utilization and efficacy of hydrogels based on extracellular matrix (ECM), stem cell-loaded, drug-loaded, self-assembled peptide structures or conductive in the context of TBI treatment. These applications are shown to yield favorable outcomes such as tissue damage mitigation, anti-inflammatory effects, attenuation of oxidative stress, anti-apoptotic properties, promotion of neurogenesis, and facilitation of angiogenesis. Lastly, a comprehensive analysis of the merits and constraints associated with hydrogel utilization in TBI treatment is presented, aiming to steer and advance future research endeavors in this domain.

Circadian Rhythm-Regulated ADSC-Derived sEVs and a Triphasic Microneedle Delivery System to Enhance Tendon-to-Bone Healing

Modulating the inflammatory microenvironment to reconstruct the fibrocartilaginous layer while promoting tendon repair is crucial for enhancing tendon-to-bone healing in rotator cuff repair (RCR), a persistent challenge in orthopedics. Small extracellular vesicles (sEVs) hold significant potential to modulate inflammation, yet the efficient production of highly bioactive sEVs remains a substantial barrier to their clinical application. Moreover, achieving minimally invasive local delivery of sEVs to the tendon-to-bone interface presents significant technical difficulties. Herein, the circadian rhythm of adipose-derived stem cells is modulated to increase the yield and enhance the inflammatory regulatory capacity of sEVs. Circadian rhythm-regulated sEVs (CR-sEVs) enhance the cyclic adenosine monophosphate signaling pathway in macrophage (Mφ) via platelet factor 4 delivery, thereby inhibiting Mφ M1 polarization. Subsequently, a triphasic microneedle (MN) scaffold with a tip, stem, and base is designed for the local delivery of CR-sEVs (CR-sEVs/MN) at the tendon-to-bone junction, incorporating tendon-derived decellularized extracellular matrix in the base to facilitate tendon repair. CR-sEVs/MN mitigates inflammation, promotes fibrocartilage regeneration, and enhances tendon healing, thereby improving biomechanical strength and shoulder joint function in a rat RCR model. Combining CR-sEVs with this triphasic microneedle delivery system presents a promising strategy for enhancing tendon-to-bone healing in clinical settings.

Pericardial Delivery of Sodium Alginate-Infusible Extracellular Matrix Composite Hydrogel Promotes Angiogenesis and Intercellular Electrical Conduction after Myocardial Infarction

Injectable extracellular matrix (iECM) is a versatile biological material with beneficial properties such as good degradability, promotion of cell survival, immunomodulation, and facilitation of vascular formation. However, intravenous injection of iECM faces challenges like a short retention time in vivo and low concentration at the lesion site. To address these issues, we prepared a composite hydrogel composed of sodium alginate and iECM and administered it via intrapericardial injection, forming a structure akin to cardiac patches within the pericardium. Compared with intramyocardial injection, intrapericardial injection avoids direct myocardial injury and ectopic tumor formation, offering less invasiveness and better biocompatibility. This study demonstrates that the sodium alginate/infusible extracellular matrix (SA/iECM) composite hydrogel can effectively prolong the local retention time of iECM in the heart, enhance electrical conduction between cardiomyocytes, promote angiogenesis at ischemic myocardial sites, inhibit apoptosis in the infarcted region, mitigate left ventricular remodeling postmyocardial infarction (MI), and improve cardiac function after infarction. Precise coordination of cardiomyocyte contraction and relaxation depends on the rhythmic occurrence of calcium-dependent action potentials. Cardiac dysfunction is partially attributed to the disruption of the excitation-contraction coupling (ECC) mechanism, which is associated with prolonged intracellular Ca2+ transients and alterations in contraction and relaxation Ca2+ levels. Our results show that the SA/iECM composite hydrogel improves electrical conduction, as evidenced by increased Cx43 expression and enhanced intercellular electrical connectivity. This research establishes that intrapericardial injection of a SA/iECM composite hydrogel is a safe and effective treatment modality, providing a theoretical basis for the use of biomaterials in MI therapy.

Advances in preclinical surgical therapy of cardiovascular diseases

Cardiovascular disease is the most common cause of death worldwide, resulting in millions of deaths annually. Currently, there are still some deficiencies in the treatment of cardiovascular diseases. Innovative surgical treatments are currently being developed and tested in response to this situation. Large animal models, which are similar to humans in terms of anatomy, physiology, and genetics, play a crucial role in connecting basic research and clinical applications. This article reviews recent preclinical studies and the latest clinical advancements in cardiovascular disease based on large animal models, with a focus on targeted delivery, neural regulation, cardiac remodeling, and hemodynamic regulation. It provides new perspectives and ideas for clinical translation and offers new methods for clinical treatment.

Understanding the multi-functionality and tissue-specificity of decellularized dental pulp matrix hydrogels for endodontic regeneration

Dental pulp is the only soft tissue in the tooth which plays a crucial role in maintaining intrinsic multi-functional behaviors of the dentin-pulp complex. Nevertheless, the restoration of fully functional pulps after pulpitis or pulp necrosis, termed endodontic regeneration, remained a major challenge for decades. Therefore, a bioactive and in-situ injectable biomaterial is highly desired for tissue-engineered pulp regeneration. Herein, a decellularized matrix hydrogel derived from porcine dental pulps (pDDPM-G) was prepared and characterized through systematic comparison against the porcine decellularized nerve matrix hydrogel (pDNM-G). The pDDPM-G not only exhibited superior capabilities in facilitating multi-directional differentiation of dental pulp stem cells (DPSCs) during 3D culture, but also promoted regeneration of pulp-like tissues after DPSCs encapsulation and transplantation. Further comparative proteomic and transcriptome analyses revealed the differential compositions and potential mechanisms that endow the pDDPM-G with highly tissue-specific properties. Finally, it was realized that the abundant tenascin C (TNC) in pDDPM served as key factor responsible for the activation of Notch signaling cascades and promoted DPSCs odontoblastic differentiation. Overall, it is believed that pDDPM-G is a sort of multi-functional and tissue-specific hydrogel-based material that holds great promise in endodontic regeneration and clinical translation. STATEMENT OF SIGNIFICANCE: Functional hydrogel-based biomaterials are highly desirable for endodontic regeneration treatments. Decellularized extracellular matrix (dECM) preserves most extracellular matrix components of its native tissue, exhibiting unique advantages in promoting tissue regeneration and functional restoration. In this study, we prepared a porcine dental pulp-derived dECM hydrogel (pDDPM-G), which exhibited superior performance in promoting odontogenesis, angiogenesis, and neurogenesis of the regenerating pulp-like tissue, further showed its tissue-specificity compared to the peripheral nerve-derived dECM hydrogel. In-depth proteomic and transcriptomic analyses revealed that the activation of tenascin C-Notch axis played an important role in facilitating odontogenic regeneration. This biomaterial-based study validated the great potential of the dental pulp-specific pDDPM-G for clinical applications, and provides a springboard for research strategies in ECM-related regenerative medicine.

Paintable Decellularized-ECM Hydrogel for Preventing Cardiac Tissue Damage

The tissue-specific heart decellularized extracellular matrix (hdECM) demonstrates a variety of therapeutic advantages, including fibrosis reduction and angiogenesis. Consequently, recent research for myocardial infarction (MI) therapy has utilized hdECM with various delivery techniques, such as injection or patch implantation. In this study, a novel approach for hdECM delivery using a wet adhesive paintable hydrogel is proposed. The hdECM-containing paintable hydrogel (pdHA_t) is simply applied, with no theoretical limit to the size or shape, making it highly beneficial for scale-up. Additionally, pdHA_t exhibits robust adhesion to the epicardium, with a minimal swelling ratio and sufficient adhesion strength for MI treatment when applied to the rat MI model. Moreover, the adhesiveness of pdHA_t can be easily washed off to prevent undesired adhesion with nearby organs, such as the rib cages and lungs, which can result in stenosis. During the 28 days of in vivo analysis, the pdHA_t not only facilitates functional regeneration by reducing ventricular wall thinning but also promotes neo-vascularization in the MI region. In conclusion, the pdHA_t presents a promising strategy for MI treatment and cardiac tissue regeneration, offering the potential for improved patient outcomes and enhanced cardiac function post-MI.

Chronological-Programmed Black Phosphorus Hydrogel for Responsive Modulation of the Pathological Microenvironment in Myocardial Infarction

Electroactive hydrogels have garnered extensive interest as a promising approach to myocardial tissue engineering. However, the challenges of spatiotemporal-specific modulation of individual pathological processes and achieving nontoxic bioresorption still remain. Herein, inspired by the entire postinfarct pathological processes, an injectable conductive bioresorbable black phosphorus nanosheets (BPNSs)-loaded hydrogel (BHGD) was developed via reactive oxide species (ROS)-sensitive disulfide-bridge and photomediated cross-linking reaction. Significantly, the chronologically programmed BHGD hydrogel can achieve graded modulation during the inflammatory, proliferative, and maturation phases of myocardial infarction (MI). More details, during early infarction, the BHGD hydrogel can effectively reduce ROS levels in the MI area, inhibit cellular oxidative stress damage, and promote macrophage M2 polarization, creating a favorable environment for damaged myocardium repair. Meanwhile, the ROS-responsive structure can protect BPNSs from degradation and maintain good conductivity under MI microenvironments. Therefore, the BHGD hydrogel possesses tissue-matched modulus and conductivity in the MI area, facilitating cardiomyocyte maturation and electrical signal exchange, compensating for impaired electrical signaling, and promoting vascularization in infarcted areas in the maturation phase. More importantly, all components of the hydrogel degrade into nontoxic substances without adverse effects on vital organs. Overall, the presented BPNS-loaded hydrogel offers an expandable and safe option for clinical treatment of MI.

Strongly Adhesive, Self-Healing, Hemostatic Hydrogel for the Repair of Traumatic Brain Injury

With wide clinical demands, therapies for traumatic brain injury (TBI) are a major problem in surgical procedures and after major trauma. Due to the difficulty in regeneration of neurons or axons after injury, as well as the inhibition of blood vessel growth by the formation of neural scars, existing treatment measures have limited effectiveness in repairing brain tissue. Herein, the biomultifunctional hydrogels are developed for TBI treatment based on the Schiff base reaction of calcium ion (Ca2+)-cross-linked oxidized sodium alginate (OSA) and carboxymethyl chitosan (CMCS). The obtained COCS hydrogel exhibits excellent adhesion to wet tissues, self-repair capability, and antimicrobial properties. What's particularly interesting is that the addition of Ca2+ increases the hydrogel's extensibility, enhancing its hemostatic capabilities. Biological assessments indicate that the COCS hydrogel demonstrates excellent biocompatibility, hemostatic properties, and the ability to promote arterial vessel repair. Importantly, the COCS hydrogel promotes the growth of cerebral microvessels by upregulating CD31, accelerates the proliferation of astrocytes, enhances the expression of GFAP, and stimulates the expression of neuron-specific markers such as NEUN and β-tubulin. All of these findings highlight that the strongly adhesive, self-healing, hemostatic hydrogel shows great potential for the repair of traumatic brain injury and other tissue repair therapy.

Special Issue "Role of Apoptosis and Cellular Senescence in Cancer and Aging"

The intention of this Special Issue is to elucidate the role of apoptosis and cellular senescence in different pathological processes, such as cancer and aging [...].

Infusible Extracellular Matrix Biomaterial Promotes Vascular Integrity and Modulates the Inflammatory Response in Acute Traumatic Brain Injury

Traumatic brain injury (TBI) affects millions of people each year and, in many cases, results in long-term disabilities. Once a TBI has occurred, there is a significant breakdown of the blood-brain barrier resulting in increased vascular permeability and progression of the injury. In this study, the use of an infusible extracellular matrix-derived biomaterial (iECM) for its ability to reduce vascular permeability and modulate gene expression in the injured brain is investigated. First, the pharmacokinetics of iECM administration in a mouse model of TBI is characterized, and the robust accumulation of iECM at the site of injury is demonstrated. Next, it is shown that iECM administration after injury can reduce the extravasation of molecules into the brain, and in vitro, iECM increases trans-endothelial electrical resistance across a monolayer of TNFα-stimulated endothelial cells. In gene expression analysis of brain tissue, iECM induces changes that are indicative of downregulation of the proinflammatory response 1-day post-injury/treatment and neuroprotection at 5 days post-injury/treatment. Therefore, iECM shows potential as a treatment for TBI.

Advances in the design, generation, and application of tissue-engineered myocardial equivalents

Due to the limited regenerative ability of cardiomyocytes, the disabling irreversible condition of myocardial failure can only be treated with conservative and temporary therapeutic approaches, not able to repair the damage directly, or with organ transplantation. Among the regenerative strategies, intramyocardial cell injection or intravascular cell infusion should attenuate damage to the myocardium and reduce the risk of heart failure. However, these cell delivery-based therapies suffer from significant drawbacks and have a low success rate. Indeed, cardiac tissue engineering efforts are directed to repair, replace, and regenerate native myocardial tissue function. In a regenerative strategy, biomaterials and biomimetic stimuli play a key role in promoting cell adhesion, proliferation, differentiation, and neo-tissue formation. Thus, appropriate biochemical and biophysical cues should be combined with scaffolds emulating extracellular matrix in order to support cell growth and prompt favorable cardiac microenvironment and tissue regeneration. In this review, we provide an overview of recent developments that occurred in the biomimetic design and fabrication of cardiac scaffolds and patches. Furthermore, we sift in vitro and in situ strategies in several preclinical and clinical applications. Finally, we evaluate the possible use of bioengineered cardiac tissue equivalents as in vitro models for disease studies and drug tests.

Proregenerative extracellular matrix hydrogel mitigates pathological alterations of pelvic skeletal muscles after birth injury

Pelvic floor disorders, including pelvic organ prolapse and urinary and fecal incontinence, affect millions of women globally and represent a major public health concern. Pelvic floor muscle (PFM) dysfunction has been identified as one of the leading risk factors for the development of these morbid conditions. Childbirth, specifically vaginal delivery, has been recognized as the most important potentially modifiable risk factor for PFM injury; however, the precise mechanisms of PFM dysfunction after parturition remain elusive. In this study, we demonstrated that PFMs exhibit atrophy and fibrosis in parous women with symptomatic pelvic organ prolapse. These pathological alterations were recapitulated in a preclinical rat model of simulated birth injury (SBI). The transcriptional signature of PFMs after injury demonstrated an impairment in muscle anabolism, persistent expression of genes that promote extracellular matrix (ECM) deposition, and a sustained inflammatory response. We also evaluated the administration of acellular injectable skeletal muscle ECM hydrogel for the prevention of these pathological alterations. Treatment of PFMs with the ECM hydrogel either at the time of birth injury or 4 weeks after injury mitigated PFM atrophy and fibrosis. By evaluating gene expression, we demonstrated that these changes are mainly driven by the hydrogel-induced enhancement of endogenous myogenesis, ECM remodeling, and modulation of the immune response. This work furthers our understanding of PFM birth injury and demonstrates proof of concept for future investigations of proregenerative biomaterial approaches for the treatment of injured pelvic soft tissues.

Endothelial Senescence and Its Impact on Angiogenesis in Alzheimer's Disease

Endothelial cells are constantly exposed to environmental stress factors that, above a certain threshold, trigger cellular senescence and apoptosis. The altered vascular function affects new vessel formation and endothelial fitness, contributing to the progression of age-related diseases. This narrative review highlights the complex interplay between senescence, oxidative stress, extracellular vesicles, and the extracellular matrix and emphasizes the crucial role of angiogenesis in aging and Alzheimer's disease. The interaction between the vascular and nervous systems is essential for the development of a healthy brain, especially since neurons are exceptionally dependent on nutrients carried by the blood. Therefore, anomalies in the delicate balance between pro- and antiangiogenic factors and the consequences of disrupted angiogenesis, such as misalignment, vascular leakage and disturbed blood flow, are responsible for neurodegeneration. The implications of altered non-productive angiogenesis in Alzheimer's disease due to dysregulated Delta-Notch and VEGF signaling are further explored. Additionally, potential therapeutic strategies such as exercise and caloric restriction to modulate angiogenesis and vascular aging and to mitigate the associated debilitating symptoms are discussed. Moreover, both the roles of extracellular vesicles in stress-induced senescence and as an early detection marker for Alzheimer's disease are considered. The intricate relationship between endothelial senescence and angiogenesis provides valuable insights into the mechanisms underlying angiogenesis-related disorders and opens avenues for future research and therapeutic interventions.

Natural biomarocmolecule-based antimicrobial hydrogel for rapid wound healing: A review

Antibacterial hydrogels are a type of hydrogel that is designed to inhibit the growth of bacteria and prevent infections. These hydrogels typically contain antibacterial agents that are either integrated into the polymer network or coated onto the surface of the hydrogel. The antibacterial agents in these hydrogels can work through a variety of mechanisms, such as disrupting bacterial cell walls or inhibiting bacterial enzyme activity. Some examples of antibacterial agents that are commonly used in hydrogels include silver nanoparticles, chitosan, and quaternary ammonium compounds. Antibacterial hydrogels have a wide range of applications, including wound dressings, catheters, and medical implants. They can help to prevent infections, reduce inflammation, and promote tissue healing. In addition, they can be designed with specific properties to suit different applications, such as high mechanical strength or controlled release of antibacterial agents over time. Hydrogel wound dressings have come a long way in recent years, and the future looks very promising for these innovative wound care products. Overall, the future of hydrogel wound dressings is very promising, and we can expect to see continued innovation and advancement in this field in the years to come.