Janus liposozyme for the modulation of redox and immune homeostasis in infected diabetic wounds.

Diabetic foot ulcers often become infected, leading to treatment complications and increased risk of loss of limb. Therapeutics to manage infection and simultaneously promote healing are needed. Here we report on the development of a Janus liposozyme that treats infections and promotes wound closure and re-epithelialization. The Janus liposozyme consists of liposome-like selenoenzymes for reactive oxygen species (ROS) scavenging to restore tissue redox and immune homeostasis. The liposozymes are used to encapsulate photosensitizers for photodynamic therapy of infections. We demonstrate application in methicillin-resistant Staphylococcus aureus-infected diabetic wounds showing high ROS levels for antibacterial function from the photosensitizer and nanozyme ROS scavenging from the liposozyme to restore redox and immune homeostasis. We demonstrate that the liposozyme can directly regulate macrophage polarization and induce a pro-regenerative response. By employing single-cell RNA sequencing, T cell-deficient Rag1-/- mice and skin-infiltrated immune cell analysis, we further reveal that IL-17-producing γδ T cells are critical for mediating M1/M2 macrophage transition. Manipulating the local immune homeostasis using the liposozyme is shown to be effective for skin wound repair and tissue regeneration in mice and mini pigs.

Fish swim bladders as valve leaflets enhance the durability of transcatheter aortic valve replacement devices.

Transcatheter aortic valve replacement (TAVR) has emerged as an effective therapy for inoperable patients with severe aortic stenosis (AS). However, calcification-induced limited durability restricts its application. Fish swim bladders (FSB), which are resistant to calcific degeneration, offer a viable solution to this challenge. In this study, we developed a new TAVR device using FSB as the valve leaflet. Furthermore, the in vitro durability, in vivo performance, and size selection of this TAVR device were assessed by an experimental study and finite element analysis. A self-expandable TAVR device was fabricated by suturing the FSB films into a 23 mm nitinol alloy frame. Further, hemodynamic performance, such as effective orifice area, transvalvular pressure difference and regurgitant fraction, the durability was tested by the pulsatile flow test and accelerated fatigue test, according to the ISO 5840-3. The effect of release size on hydrodynamic performance was also investigated. Finally, the in vivo performance of the TAVR device were examined using a porcine implantation model. The results showed that the strength of the FSB films satisfied the requirements for valve leaflets. The hemodynamic performance of the FSB TAVR device met the requirements of ISO 5840-3 standards. After 400 million cycles, the FSB showed no fiber loss, torn, perforation, or other valve failure phenomena. In porcine models, the devices were well-positioned, functioned well with no stenosis immediately after the operation. Collectively, we successfully developed a TAVR device with FSB as valve leaflets that exhibited good fatigue resistance. STATEMENT OF SIGNIFICANCE: The source of material for the leaflets of commercialized biological heart valves (BHVs) is mainly bovine pericardium, but this material suffers the following problems: large and uneven thickness of the material, the presence of α-Gal and Neu5Gc antigens, and the susceptibility to structural valve degradation (SVD). New material for BHVs leaflets is rarely reported. In this study, we prepared a transcatheter aortic valve (TAV) and performed long-term in vitro and short-term in vivo studies using fish swim bladder (FSB) as the leaflets. The study confirmed that FSB TAV device can complete 400 million fatigue tests and maintain the good morphology of the leaflets, and that it still maintains good functionality after a certain amount of compression, indicating that FSB is a promising material for leaflets.

Layer-by-Layer Assembly of Renal-Targeted Polymeric Nanoparticles for Robust Arginase-2 Knockdown and Contrast-Induced Acute Kidney Injury Prevention.

The mitochondrial enzyme arginase-2 (Arg-2) is implicated in the pathophysiology of contrast-induced acute kidney injury (CI-AKI). Therefore, Arg-2 represents a candid target for CI-AKI prevention. Here, layer-by-layer (LbL) assembled renal-targeting polymeric nanoparticles are developed to efficiently deliver small interfering RNA (siRNA), knockdown Arg-2 expression in renal tubules, and prevention of CI-AKI is evaluated. First, near-infrared dye-loaded poly(lactic-co-glycolic acid) (PLGA) anionic cores are electrostatically coated with cationic chitosan (CS) to facilitate the adsorption and stabilization of Arg-2 siRNA. Next, nanoparticles are coated with anionic hyaluronan (HA) to provide protection against siRNA leakage and shielding against early clearance. Sequential electrostatic layering of CS and HA improves loading capacity of Arg-2 siRNA and yields LbL-assembled nanoparticles. Renal targeting and accumulation is enhanced by modifying the outermost layer of HA with a kidney targeting peptide (HA-KTP). The resultant kidney-targeting and siRNA loaded nanoparticles (PLGA/CS/HA-KTP siRNA) exhibit proprietary accumulation in kidneys and proximal tubular cells at 24 h post-tail vein injection. In iohexol-induced in vitro and in vivo CI-AKI models, PLGA/CS/HA-KTP siRNA delivery alleviates oxidative and nitrification stress, and rescues mitochondrial dysfunction while reducing apoptosis, thereby demonstrating a robust and satisfactory therapeutic effect. Thus, PLGA/CS/HA-KTP siRNA nanoparticles offer a promising candidate therapy to protect against CI-AKI.

Self-Assembly of Heterogeneous Ferritin Nanocages for Tumor Uptake and Penetration.

Well-defined nanostructures are crucial for precisely understanding nano-bio interactions. However, nanoparticles (NPs) fabricated through conventional synthesis approaches often lack poor controllability and reproducibility. Herein, a synthetic biology-based strategy is introduced to fabricate uniformly reproducible protein-based NPs, achieving precise control over heterogeneous components of the NPs. Specifically, a ferritin assembly toolbox system is developed that enables intracellular assembly of ferritin subunits/variants in Escherichia coli. Using this strategy, a proof-of-concept study is provided to explore the interplay between ligand density of NPs and their tumor targets/penetration. Various ferritin hybrid nanocages (FHn) containing human ferritin heavy chains (FH) and light chains are accurately assembled, leveraging their intrinsic binding with tumor cells and prolonged circulation time in blood, respectively. Further studies reveal that tumor cell uptake is FH density-dependent through active binding with transferrin receptor 1, whereas in vivo tumor accumulation and tissue penetration are found to be correlated to heterogeneous assembly of FHn and vascular permeability of tumors. Densities of 3.7 FH/100 nm2 on the nanoparticle surface exhibit the highest degree of tumor accumulation and penetration, particularly in tumors with high permeability compared to those with low permeability. This study underscores the significance of nanoparticle heterogeneity in determining particle fate in biological systems.

Elastic porous microspheres/extracellular matrix hydrogel injectable composites releasing dual bio-factors enable tissue regeneration.

Injectable biomaterials have garnered increasing attention for their potential and beneficial applications in minimally invasive surgical procedures and tissue regeneration. Extracellular matrix (ECM) hydrogels and porous synthetic polymer microspheres can be prepared for injectable administration to achieve in situ tissue regeneration. However, the rapid degradation of ECM hydrogels and the poor injectability and biological inertness of most polymeric microspheres limit their pro-regenerative capabilities. Here, we develop a biomaterial system consisting of elastic porous poly(l-lactide-co-ε-caprolactone) (PLCL) microspheres mixed with ECM hydrogels as injectable composites with interleukin-4 (IL-4) and insulin-like growth factor-1 (IGF-1) dual-release functionality. The developed multifunctional composites have favorable injectability and biocompatibility, and regulate the behavior of macrophages and myogenic cells following injection into muscle tissue. The elicited promotive effects on tissue regeneration are evidenced by enhanced neomusle formation, vascularization, and neuralization at 2-months post-implantation in a male rat model of volumetric muscle loss. Our developed system provides a promising strategy for engineering bioactive injectable composites that demonstrates desirable properties for clinical use and holds translational potential for application as a minimally invasive and pro-regenerative implant material in multiple types of surgical procedures.

dECM restores macrophage immune homeostasis and alleviates iron overload to promote DTPI healing.

Due to its highly insidious and rapid progression, deep tissue pressure injury (DTPI) is a clinical challenge. Our previous study found that DTPI may be a skeletal muscle injury dominated by macrophage immune dysfunction due to excessive iron accumulation. Decellularized extracellular matrix (dECM) hydrogel promotes skeletal muscle injury repair. However, its role in polarizing macrophages and regulating iron metabolism in DTPI remains unclear. Here, porcine dECM hydrogel was prepared, and its therapeutic function and mechanism in repairing DTPI were investigated. The stimulus of dECM hydrogel toward RAW264.7 cells resulted in a significantly higher percentage of CD206+ macrophages and notably decreased intracellular divalent iron levels. In mice DTPI model, dECM hydrogel treatment promoted M1 to M2 macrophage conversion, improved iron metabolism and reduced oxidative stress in the early stage of DTPI. In the remodeling phase, the dECM hydrogel remarkably enhanced revascularization and accelerated skeletal muscle repair. Furthermore, the immunomodulation of dECM hydrogels in vivo was mainly involved in the P13k/Akt signaling pathway, as revealed by GO and KEGG pathway analysis, which may ameliorate the iron deposition and promote the healing of DTPI. Our findings indicate that dECM hydrogel is promising in skeletal muscle repair, inflammation resolution and tissue injury healing by effectively restoring macrophage immune homeostasis and normalizing iron metabolism.

Machine-Learning-Assisted Nanozyme Design: Lessons from Materials and Engineered Enzymes.

Nanozymes are nanomaterials that exhibit enzyme-like biomimicry. In combination with intrinsic characteristics of nanomaterials, nanozymes have broad applicability in materials science, chemical engineering, bioengineering, biochemistry, and disease theranostics. Recently, the heterogeneity of published results has highlighted the complexity and diversity of nanozymes in terms of consistency of catalytic capacity. Machine learning (ML) shows promising potential for discovering new materials, yet it remains challenging for the design of new nanozymes based on ML approaches. Alternatively, ML is employed to promote optimization of intelligent design and application of catalytic materials and engineered enzymes. Incorporation of the successful ML algorithms used in the intelligent design of catalytic materials and engineered enzymes can concomitantly facilitate the guided development of next-generation nanozymes with desirable properties. Here, recent progress in ML, its utilization in the design of catalytic materials and enzymes, and how emergent ML applications serve as promising strategies to circumvent challenges associated with time-expensive and laborious testing in nanozyme research and development are summarized. The potential applications of successful examples of ML-aided catalytic materials and engineered enzymes in nanozyme design are also highlighted, with special focus on the unified aims in enhancing design and recapitulation of substrate selectivity and catalytic activity.

Near-infrared-II photoacoustic imaging and photo-triggered synergistic treatment of thrombosis via fibrin-specific homopolymer nanoparticles.

The formation of an occlusive thrombus in the blood vessel is the main culprit for numerous life-threatening cardiovascular diseases that represent the leading cause of morbidity and mortality worldwide. Herein, we develop a polymer nanoplatform that integrates long-wavelength second near-infrared (NIR-II) photoacoustic imaging-based thrombosis detection and antithrombotic activity. We design and synthesize a semiconducting homopolymer with strong absorption in the NIR-II region and molecular motion that boosts photothermal conversion and photoacoustic signal. We dope the homopolymer with a thermosensitive nitric oxide donor to formulate a nanoplatform, on which a fibrin-specific ligand is functionalized to ensure selective thrombus targeting. We show that with strong NIR-II light harvesting capability, bright photoacoustic signal and active thrombus accumulation ability, the NIR-II photoacoustic nanoprobes are able to sensitively and selectively delineate thrombi. We find that the nanoplatform also displays rapid and efficient blood clot removal activity with nearly complete blood flow restoration in both carotid thrombosis models and low extremity arterial thrombosis models under NIR-II light trigger by integrating a thrombus-localized photothermal effect and on-demand nitric oxide release. This nanoplatform offers a versatile approach for the diagnosis and treatment of life-threatening diseases caused by various thrombotic disorders.

Micro-nanofiber composite biomimetic conduits promote long-gap peripheral nerve regeneration in canine models.

Peripheral nerve injuries may result in severe long-gap interruptions that are challenging to repair. Autografting is the gold standard surgical approach for repairing long-gap nerve injuries but can result in prominent donor-site complications. Instead, imitating the native neural microarchitecture using synthetic conduits is expected to offer an alternative strategy for improving nerve regeneration. Here, we designed nerve conduits composed of high-resolution anisotropic microfiber grid-cordes with randomly organized nanofiber sheaths to interrogate the positive effects of these biomimetic structures on peripheral nerve regeneration. Anisotropic microfiber-grids demonstrated the capacity to directionally guide Schwann cells and neurites. Nanofiber sheaths conveyed adequate elasticity and permeability, whilst exhibiting a barrier function against the infiltration of fibroblasts. We then used the composite nerve conduits bridge 30-mm long sciatic nerve defects in canine models. At 12 months post-implant, the morphometric and histological recovery, gait recovery, electrophysiological function, and degree of muscle atrophy were assessed. The newly regenerated nerve tissue that formed within the composite nerve conduits showed restored neurological functions that were superior compared to sheaths-only scaffolds and Neurolac nerve conduit controls. Our findings demonstrate the feasibility of using synthetic biophysical cues to effectively bridge long-gap peripheral nerve injuries and indicates the promising clinical application prospects of biomimetic composite nerve conduits.

Bionic peptide scaffold in situ polarization and recruitment of M2 macrophages to promote peripheral nerve regeneration.

Tissue regeneration requires exogenous and endogenous signals, and there is increasing evidence that the exogenous microenvironment may play an even more dominant role in the complex process of coordinated multiple cells. The short-distance peripheral nerve showed a spontaneous regenerative phenomenon, which was initiated by the guiding role of macrophages. However, it cannot sufficiently restore long-distance nerve injury by itself. Based on this principle, we firstly constructed a proinflammatory model to prove that abnormal M2 expression reduce the guidance and repair effect of long-distance nerves. Furthermore, a bionic peptide hydrogel scaffold based on self-assembly was developed to envelop M2-derived regenerative cytokines and extracellular vesicles (EVs). The cytokines and EVs were quantified to mimic the guidance and regenerative microenvironment in a direct and mild manner. The bionic scaffold promoted M2 transformation in situ and led to proliferation and migration of Schwann cells, neuron growth and motor function recovery. Meanwhile, the peptide scaffold combined with CX3CL1 recruited more blood-derived M2 macrophages to promote long-distance nerve reconstruction. Overall, we systematically confirmed the important role of M2 in regulating and restoring the injury peripheral nerve. This bionic peptide hydrogel scaffold mimicked and remodeled the local environment for M2 transformation and recruitment, favoring long-distance peripheral nerve regeneration. It can help to explicate regulative effect of M2 may be a cause not just a consequence in nerve repair and tissue integration, which facilitating the development of pro-regenerative biomaterials.

Macrophage metabolism reprogramming EGCG-Cu coordination capsules delivered in polyzwitterionic hydrogel for burn wound healing and regeneration.

Excessive reactive oxygen species (ROS) at severe burn injury sites may promote metabolic reprogramming of macrophages to induce a deteriorative and uncontrolled inflammation cycle, leading to delayed wound healing and regeneration. Here, a novel bioactive, anti-fouling, flexible polyzwitterionic hydrogel encapsulated with epigallocatechin gallate (EGCG)-copper (Cu) capsules (termed as EGCG-Cu@CBgel) is engineered for burn wound management, which is dedicated to synergistically exerting ROS-scavenging, immune metabolic regulation and pro-angiogenic effects. EGCG-Cu@CBgel can scavenge ROS to normalize intracellular redox homeostasis, effectively relieving oxidative damages and blocking proinflammatory signal transduction. Importantly, EGCG-Cu can inhibit the activity of hexokinase and phosphofructokinase, alleviate accumulation of pyruvate and convert it to acetyl coenzyme A (CoA), whereby inhibits glycolysis and normalizes tricarboxylic acid (TCA) cycle. Additionally, metabolic reprogramming of macrophages by EGCG-Cu downregulates M1-type polarization and the expression of proinflammatory cytokines both in vitro and in vivo. Meanwhile, copper ions (Cu2+) released from the hydrogel facilitate angiogenesis. EGCG-Cu@CBgel significantly accelerates the healing of severe burn wound via promoting wound closure, weakening tissue-damaging inflammatory responses and enhancing the remodeling of pathological structure. Overall, this study demonstrates the great potential of bioactive hydrogel dressing in treating burn wounds without unnecessary secondary damage to newly formed skin, and highlights the importance of immunometabolism modulation in tissue repair and regeneration.

Decellularized Scaffolds with Double-Layer Aligned Microchannels Induce the Oriented Growth of Bladder Smooth Muscle Cells: Toward Urethral and Ureteral Reconstruction.

There is a great clinical need for regenerating urinary tissue. Native urethras and ureters have bidirectional aligned smooth muscle cells (SMCs) layers, which plays a pivotal role in micturition and transporting urine and inhibiting reflux. Thus far, urinary scaffolds have not been designed to induce the native-mimicking aligned arrangement of SMCs. In this study, a tubular decellularized extracellular matrix (dECM) with an intact internal layer and bidirectional aligned microchannels in the tubular wall, which is realized by the subcutaneous implantation of a template, followed by the removal of the template, and decellularization, is engineered. The dense and intact internal layer effectively increases the leakage pressure of the tubular dECM scaffolds. Rat-derived dECM scaffolds with three different sizes of microchannels are fabricated by tailoring the fiber diameter of the templates. The rat-derived dECM scaffolds exhibiting microchannels of ≈65 µm show suitable mechanical properties, good ability to induce the bidirectional alignment and growth of human bladder SMCs, and elevated higher functional protein expression in vitro. These data indicate that rat-derived tubular dECM scaffolds manifesting double-layer aligned microchannels may be promising candidates to induce the native-mimicking regeneration of SMCs in urethra and ureter reconstruction.

Platinum Black/Gold Nanoparticles/Polyaniline Modified Electrochemical Microneedle Sensors for Continuous In Vivo Monitoring of pH Value.

Continuous in vivo monitoring (CIVM) of pH value is essential for personalized medicine, as many diseases are closely related to acid-base imbalances. However, conventional pH meters are limited in their ability to perform CIVM due to excessive blood consumption, large device volume, frequent calibration, and inadequate real-time monitoring. There is thus an urgent need for a portable method for CIVM of pH value. To address this need, we propose a minimally invasive, continuous monitoring solution in the form of an implantable pH microneedle sensor (MNS) in this study. The MNS is based on the integration of an acupuncture needle (AN) and a Ag/AgCl reference electrode. We fabricate the sensor by electrochemically depositing platinum black and gold nanoparticles onto the AN and further modifying it with polyaniline to increase its sensitivity to hydrogen ions. The pH value is obtained by calculating the open circuit voltage between the modified AN and the reference electrode. The resulting MNS demonstrates excellent selectivity and a high nernstian response to pH (-57.4 mV per pH) over a broad range (pH = 4.0 to pH = 9.0). Both in vitro and in vivo experiments have verified the performance of the sensor, showcasing its potential for biomedical research and clinical practice. The MNS provides an alternative to conventional pH meters, offering a less invasive and more convenient way to perform CIVM of pH value. Moreover, this electrochemical implantable sensor based on AN and silver wires provides a simple and sensitive method for continuous in vivo detection of other biomarkers.

Biomimetic polymeric transcatheter heart valve leaflets with low calcification and good regenerative ability.

Transcatheter aortic valve replacement (TAVR) technology is quickly advancing in clinic, however, as it expands to low-risk populations and younger patients (age <65 years), device durability is becoming a major challenge. Tissue-engineered heart valves (TEHVs) are a potential alternative. In this study, a bionic tri-layer tissue-engineered heart valve was constructed using poly (L-lactate-co-ε-caprolactone) (PLCL), gelatin (GEL), hyaluronic acid (HA) and silk fibroin (SF), to simulate the fibrosa, spongiosa and ventricular layer of natural heart valves. To obtain a scaffold with sufficient strength and regenerative capacity, we optimized the ratio of components of each layer. The physical and mechanical properties were tested, and the cytocompatibility, calcification deposition and regeneration potential were tested in a rat model of subcutaneous implantation. Finally, the hydrodynamic function of the new TAVR device was verified. The results demonstrated that the strength of the tri-layer valve could reach up to 10 MPa, significantly higher than that of the PLCL and mono-layer groups. Most importantly, calcification related gene expression was down-regulated in the TEHV groups compared to valvular interstitial cells (VICs) treated with calcification induced medium, and calcification levels of TEHVs in in vivo assay were below 0.5 µg mg-1. Besides, we found HA in the middle layer was very conducive to rapid cell infiltration and good angiogenesis, which ultimately promoted host tissue regeneration at 8 weeks after implantation. Collectively, we provide a bionic tri-layer electrospun leaflet with appropriate mechanical strength, low calcification and good regenerative capacity, which has great potential as a TEHV leaflet.

Bioinspired, Anticoagulative, 19 F MRI-Visualizable Bilayer Hydrogel Tubes as High Patency Small-Diameter Vascular Grafts.

The clinical patency of small-diameter vascular grafts (SDVGs) (ID < 6 mm) is limited, with the formation of mural thrombi being a major threat of this limitation. Herein, a bilayered hydrogel tube based on the essential structure of native blood vessels is developed by optimizing the relation between vascular functions and the molecular structure of hydrogels. The inner layer of the SDVGs comprises a zwitterionic fluorinated hydrogel, avoiding the formation of thromboinflammation-induced mural thrombi. Furthermore, the position and morphology of the SDVGs can be visualized via 19 F/1 H magnetic resonance imaging. The outer poly(N-acryloyl glycinamide) hydrogel layer of SDVGs provides matched mechanical properties with native blood vessels through the multiple and controllable intermolecular hydrogen-bond interactions, which can withstand the accelerated fatigue test under pulsatile radial pressure for 380 million cycles (equal to a service life of 10 years in vivo). Consequently, the SDVGs exhibit higher patency (100%) and more stable morphology following porcine carotid artery transplantation for 9 months and rabbit carotid artery transplantation for 3 months. Therefore, such a bioinspired, antithrombotic, and visualizable SDVG presents a promising design approach for long-term patency products and great potential of helping patients with cardiovascular diseases.

A facile bioorthogonal chemistry-based reversible to irreversible strategy to surmount the dilemma between injectability and stability of hyaluronic acid hydrogels.

Injectable and stable hydrogels have great promise for clinical applications. Fine-tuning the injectability and the stability of the hydrogels at different stages has been challenging due to the limited number of coupling reactions. A distinct "reversible to irreversible" concept using a thiazolidine-based bioorthogonal reaction between 1,2-aminothiols and aldehydes in physiological conditions to surmount the dilemma between injectability and stability is presented for the first time. Upon mixing aqueous solutions of aldehyde-functionalized hyaluronic acid (SA-HA) and cysteine-capped ethylenediamine (DI-Cys), SA-HA/DI-Cys hydrogels formed through reversible hemithioacetal crosslinking within 2 min. The reversible kinetic intermediate facilitated thiol-triggered gel-to-sol transition, shear-thinning and injectability of the SA-HA/DI-Cys hydrogel but then converted to the irreversible thermodynamic network after injection, thereby permitting the resulting gel with improved stability. As compared to the Schiff base hydrogels, the hydrogels generated from this simple, yet effective concept awarded improved protection to the embedded mesenchymal stem cells and fibroblast during injection, retained the cells homogeneously within the gel, and allowed them further proliferation in vitro and in vivo. There is potential for the proposed approach of "reversible to irreversible" based on thiazolidine chemistry to be applied as a general coupling technique for developing injectable and stable hydrogels for biomedical applications.

Insight on Oxygen-Supplying Biomaterials Used to Enhance Cell Survival, Retention, and Engraftment for Tissue Repair.

Oxygen is one of the essential requirements for cell survival, retention, and proliferation. The field of regenerative medicine and tissue engineering (TE) has realized considerable achievements for the regeneration of tissues. However, tissue regeneration still lacks the full functionality of solid organ implantations; limited cell survival and retention due to oxidative stress and hypoxia in the deeper parts of tissues remains a perpetual challenge. Especially prior to neovascularization, hypoxia is a major limiting factor, since oxygen delivery becomes crucial for cell survival throughout the tissue-engineered construct. Oxygen diffusion is generally limited in the range 100-200 µm of the thickness of a scaffold, and the cells located beyond this distance face oxygen deprivation, which ultimately leads to hypoxia. Furthermore, before achieving functional anastomosis, implanted tissues will be depleted of oxygen, resulting in hypoxia (<5% dissolved oxygen) followed by anoxic (<0.5% dissolved oxygen) microenvironments. Different types of approaches have been adopted to establish a sustained oxygen supply both in vitro and in vivo. In this review, we have summarized the recent developments in oxygen-generating and/or releasing biomaterials for enhancing cell survival in vitro, as well as for promoting soft and hard tissue repair, including skin, heart, nerve, pancreas, muscle, and bone tissues in vivo. In addition, redox-scavenging biomaterials and oxygenated scaffolds have also been highlighted. The surveyed results have shown significant promise in oxygen-producing biomaterials and oxygen carriers for enhancing cell functionality for regenerative medicine and TE applications. Taken together, this review provides a detailed overview of newer approaches and technologies for oxygen production, as well as their applications for bio-related disciplines.

Engineered Cytokine-Primed Extracellular Vesicles with High PD-L1 Expression Ameliorate Type 1 Diabetes.

Type 1 diabetes (T1D), which is a chronic autoimmune disease, results from the destruction of insulin-producing ß cells targeted by autoreactive T cells. The recent discovery that mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) function as therapeutic tools for autoimmune conditions has attracted substantial attention. However, the in vivo distribution and therapeutic effects of MSC-EVs potentiated by pro-inflammatory cytokines in the context of T1D have yet to be established. Here, it is reported that hexyl 5-aminolevulinate hydrochloride (HAL)-loaded engineered cytokine-primed MSC-EVs (H@TI-EVs) with high expression of immune checkpoint molecule programmed death-legend 1 (PD-L1) exert excellent inflammatory targeting and immunosuppressive effects for T1D imaging and therapy. The accumulated H@TI-EVs in injured pancreas not only enabled the fluorescence imaging and tracking of TI-EVs through the intermediate product protoporphyrin (PpIX) generated by HAL, but also promoted the proliferative and anti-apoptotic effects of islet ß cells. Further analysis revealed that H@TI-EVs exhibited an impressive ability to reduce CD4+ T cell density and activation through the PD-L1/PD-1 axis, and induced M1-to-M2 macrophage transition to reshape the immune microenvironment, exhibiting high therapeutic efficiency in mice with T1D. This work identifies a novel strategy for the imaging and treatment of T1D with great potential for clinical application.

Functionalization of in vivo tissue-engineered living biotubes enhance patency and endothelization without the requirement of systemic anticoagulant administration.

Vascular regeneration and patency maintenance, without anticoagulant administration, represent key developmental trends to enhance small-diameter vascular grafts (SDVG) performance. In vivo engineered autologous biotubes have emerged as SDVG candidates with pro-regenerative properties. However, mechanical failure coupled with thrombus formation hinder translational prospects of biotubes as SDVGs. Previously fabricated poly(ε-caprolactone) skeleton-reinforced biotubes (PBs) circumvented mechanical issues and achieved vascular regeneration, but orally administered anticoagulants were required. Here, highly efficient and biocompatible functional modifications were introduced to living cells on PB lumens. The 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-N-methoxy (DMPE)-PEG-conjugated anti-coagulant bivalirudin (DPB) and DMPE-PEG-conjugated endothelial progenitor cell (EPC)-binding TPS-peptide (DPT) modifications possessed functionality conducive to promoting vascular graft patency. Co-modification of DPB and DPT swiftly attained luminal saturation without influencing cell viability. DPB repellent of non-specific proteins, DPB inhibition of thrombus formation, and DPB protection against functional masking of DPT's EPC-capture by blood components, which promoted patency and rapid endothelialization in rat and canine artery implantation models without anticoagulant administration. This strategy offers a safe, facile, and fast technical approach to convey additional functionalization to living cells within tissue-engineered constructs.

Machine-learning-assisted single-vessel analysis of nanoparticle permeability in tumour vasculatures.

The central dogma that nanoparticle delivery to tumours requires enhanced leakiness of vasculatures is a topic of debate. To address this, we propose a single-vessel quantitative analysis method by taking advantage of protein-based nanoprobes and image-segmentation-based machine learning (nano-ISML). Using nano-ISML, >67,000 individual blood vessels from 32 tumour models were quantified, revealing highly heterogenous vascular permeability of protein-based nanoparticles. There was a >13-fold difference in the percentage of high-permeability vessels in different tumours and >100-fold penetration ability in vessels with the highest permeability compared with vessels with the lowest permeability. Our data suggest passive extravasation and transendothelial transport were the dominant mechanisms for high- and low-permeability tumour vessels, respectively. To exemplify the nano-ISML-assisted rational design of nanomedicines, genetically tailored protein nanoparticles with improved transendothelial transport in low-permeability tumours were developed. Our study delineates the heterogeneity of tumour vascular permeability and defines a direction for the rational design of next-generation anticancer nanomedicines.