Anti-Sca-1 antibody-functionalized vascular grafts improve vascular regeneration via selective capture of endogenous vascular stem/progenitor cells

NIR-programmable 3D-printed shape-memory scaffold with dual-thermal responsiveness for precision bone regeneration and bone tumor management

Clinically, intraoperative treatment of bone tumors presents several challenges, including the effective inactivation of tumors and filling of irregular bone defects after tumor removal. In this study, intelligent thermosensitive composite materials with shape-memory properties were constructed using polylactic acid (PLA) and polycaprolactone (PCL), which have excellent biocompatibility and degradability. Additionally, beta-tricalcium phosphate (β-TCP), with its osteogenic properties, and magnesium (Mg) powder, with its photothermal and bone-promoting abilities, were incorporated to improve the osteogenic potential of the composite and enable the material to respond intelligently to near-infrared (NIR) light. Utilizing 3D printing technology, the composite material was prepared into an NIR-responsive shape-memory bone-filling implant that deforms when the scaffold temperature increases to 48 ℃ under NIR laser irradiation. Moreover, at a lower temperature of 42 ℃, mild photothermal therapy promotes macrophage polarization toward the M2 phenotype. This process regulates the secretion of interleukin (IL)-4, IL-10, tumor necrosis factor-α, IL-6, and bone morphogenetic protein (BMP)-2, reducing local inflammation, enhancing the release of pro-healing factors, and improving osteogenesis. Overall, this innovative scaffold is a promising and efficient treatment for filling irregular bone defects after bone tumor surgery.

An Integrated Virtual Screening Platform to Identify Potent Co-Assembled Nanodrugs for Cancer Treatment

Co-assembled nanodrugs provide significant advantages in cancer treatment and drug delivery, yet effective screening methods to identify molecular combinations for co-assembly are lacking. This study presents a screening strategy integrating ligand-based virtual screening (LBVS) and density functional theory (DFT) calculations to explore new molecular combinations with co-assembly capabilities. The accuracy of this screening was validated by synthesizing various co-assembled nanodrugs under mild conditions. Vinpocetine (Vin) and lenvatinib (Len) are representative co-assembly combinations that can directly co-assemble into nanoparticles (NPs) through hydrogen bonding, van der Waals forces, and π-π interactions. These NPs were further functionalized with polyethylene glycol (PEG), resulting in PEG-L/V NPs that exhibited enhanced stability and biocompatibility. In addition, PEG-L/V NPs can respond to acidic conditions and release Vin and Len, working synergistically to induce cell cycle arrest and apoptosis in tumor cells in vitro while also inhibiting xenograft tumor growth in vivo. RNA sequencing (RNA-seq) analysis revealed that the co-assembled nanodrugs exhibited mechanisms that are distinct from those of single drugs. This study demonstrates the feasibility of utilizing a computational approach combining LBVS and DFT to identify small molecules with co-assembly capabilities, leading to innovative anticancer strategies.

Rapid angiogenic hydrogel nanofiber scaffold promotes random flap regeneration and modulates inflammation

Random skin flaps are commonly used to cover thick skin wounds. However, necrosis frequently occurs when the flap's aspect ratio exceeds 2:1. Promoting angiogenesis and regulating inflammation are essential for treating ischemia-reperfusion injury in random flaps. In this study, calcium-doped silica nanoparticles loaded with deferoxamine (CD) were created through physical adsorption by rapidly mixing biodegradable calcium-doped silica nanoparticles (CS) with deferoxamine (DFO). A gelatin methacryloyl (GM) hydrogel nanofiber scaffold containing 1% (w/v) CD (GM/CD-1) was subsequently produced using electrospinning technology. The GM/CD-1 scaffold showed excellent biocompatibility and significantly promoted flap regeneration in mice, achieving a 96.17 ± 3.17% flap survival rate at 14 days. Additionally, it effectively stimulated hair follicle growth and exhibited an inflammatory-modulating effect. These features suggest that the GM/CD-1 scaffold could be valuable for clinical applications in flap regeneration and other tissue engineering fields.

Localized COUP-TFII pDNA Delivery Modulates Stem/Progenitor Cell Differentiation to Enhance Endothelialization and Inhibit Calcification of Decellularized Allografts

Decellularized allografts have emerged as promising candidates for vascular bypass grafting, owing to their inherent bioactivity and minimal immunogenicity. However, graft failure that results from suboptimal regeneration and pathological remodeling has hindered their clinical adoption. Recent advances in vascular biology highlight the pivotal role of COUP-TFII in orchestrating endothelial identity, angiogenesis, safeguarding against atherosclerosis, and mitigating vascular calcification. Here, plasmid DNA (pDNA) encoding COUP-TFII is incorporated into decellularized allografts to realize localized delivery. Comprehensive in vitro investigation complemented by a bone marrow transplantation model on genetic-lineage-tracing mouse revealed the underlying mechanisms of COUP-TFII in regulating vascular regeneration and remodeling. COUP-TFII augmented endothelialization and inhibited calcification in decellularized allografts by modulating the Ang1/Tie2/PI3K/AKT signaling pathway that dictates the fate of Sca-1+ stem/progenitor cells. Heparin-polyethyleneimine nanoparticles (HEPI) are prepared as COUP-TFII pDNA nanocarriers (COUP-TFII@HPEI) and used to modify decellularized allografts, achieving long-term and stable overexpression of COUP-TFII. Functionalized grafts are evaluated in rat abdominal artery replacement models, demonstrating enhanced neo-artery regeneration without calcification. The study provides an effective strategy to enhance the applicability of decellularized allograft and illustrates their translational prospects for vascular bypass grafting.

Transition from Procoagulation to Antiplatelet Effect: Application and Mechanism of Aspirin-Modified Chitosan in Small-Diameter Vascular Grafts

Chitosan is generally considered to be a procoagulant effect, which may cause adverse phenomena such as blood clotting when used in small-diameter vascular grafts. However, it also shows good biocompatibility and anti-inflammatory properties, which can facilitate vascular reconstruction. Therefore, it is significant to transition the effect of chitosan from coagulation promotion to antiplatelet while still harnessing its bioactivity. The procoagulant mechanism of chitosan is primarily attributed to the presence of protonated amino groups in the molecular chain. If the number of amino groups in chitosan is reduced, the procoagulant effect will be diminished as well. Aspirin has a strong antiplatelet function, and its molecular structure contains numerous active carboxyl groups, which can couple with the amino groups in chitosan. Aspirin-modified chitosan retains the biological activity of chitosan while also imparting an antiplatelet effect. In our study, we used a heparinized electrospun graft as the substrate and coated it with aspirin-modified chitosan to create a functional vascular graft. The blood clotting index of the graft remained above 80% after 45 min, and the platelet activation degree was only 4.03%. Additionally, the graft maintained complete patency with stable blood flow after 4 weeks of implantation and the vascular structure was largely rebuilt.

Tailored endothelialization enabled by engineered endothelial cell vesicles accelerates remodeling of small-diameter vascular grafts

Current gold standard for the replacement of small-diameter blood vessel (ID < 4 mm) is still to utilize the autologous vessels of patients due to the limitations of small-diameter vascular grafts (SDVG) on weak endothelialization, intimal hyperplasia and low patency. Herein, we create the SDVG with the tailored endothelialization by applying the engineered endothelial cell vesicles to camouflaging vascular grafts for the enhancement of vascular remodeling. The engineered endothelial cell vesicles were modified with azide groups (ECVs-N3) through metabolic glycoengineering to precisely link the vascular graft made of PCL-DBCO via click chemistry, and thus fabricating ECVG (ECVs-N3 modified SDVG), which assists inhibition of platelet adhesion and activation, promotion of ECs adhesion and enhancement of anti-inflammation. Furthermore, In vivo single-cell transcriptome analysis revealed that the proportion of ECs in the cell composition of ECVG surpassed that of PCL, and the tailored endothelialization enabled to convert endothelial cells (ECs) into some specific ECs clusters. One of the specific cluster, Endo_C5 cluster, was only detected in ECVG. Consequently, our study integrates the engineered membrane vesicles of ECVs-N3 from native ECs for tailored endothelialization on SDVG by circumventing the limitations of living cells, and paves a new way to construct the alternative endothelialization in vessel remodeling following injury.

Small diameter vascular grafts: progress on electrospinning matrix/stem cell blending approach

The exploration of the next-generation small diameter vascular grafts (SDVGs) will never stop until they possess high biocompatibility and patency comparable to autologous native blood vessels. Integrating biocompatible electrospinning (ES) matrices with highly bioactive stem cells (SCs) provides a rational and promising solution. ES is a simple, fast, flexible and universal technology to prepare extracellular matrix-like fibrous scaffolds in large scale, while SCs are valuable, multifunctional and favorable seed cells with special characteristics for the emerging field of cell therapy and regenerative medicine. Both ES matrices and SCs are advanced resources with medical application prospects, and the combination may share their advantages to drive the overcoming of the long-lasting hurdles in SDVG field. In this review, the advances on SDVGs based on ES matrices and SCs (including pluripotent SCs, multipotent SCs, and unipotent SCs) are sorted out, and current challenges and future prospects are discussed.

Development of stem cell therapy for atherosclerosis

Cardiovascular disease (CVD) has a high incidence and low cure rate worldwide, and atherosclerosis (AS) is the main factor inducing cardiovascular disease, of which lipid deposition in the vessel wall is the main marker of AS. Currently, although statins can be used to lower lipids and low-density lipoprotein (LDL) in AS, the cure rate for AS remains low. Therefore, there is an urgent need to develop new therapeutic approaches, and stem cells are now widely studied, while stem cells are a class of cell types that always maintain the ability to differentiate and can differentiate to form other cells and tissues, and stem cell transplantation techniques have shown efficacy in the treatment of other diseases. With the establishment of cellular therapies and continued research in stem cell technology, stem cells are also being used to address the problem of AS. In this paper, we focus on recent research advances in stem cell therapy for AS and briefly summarize the relevant factors that induce the formation of AS. We mainly discuss the efficacy and application prospects of mesenchymal stem cells (MSCs) for the treatment of AS, in addition to the partial role and potential of exosomes in the treatment of AS. Further, provide new ideas for the clinical application of stem cells.

Long-term observation of polycaprolactone small-diameter vascular grafts with thickened outer layer and heparinized inner layer in rabbit carotid arteries

In our previous study, the pristine bilayer small-diameterin situtissue engineered vascular grafts (pTEVGs) were electrospun from a heparinized polycaprolactone (PCL45k) as an inner layer and a non-heparinized PCL80k as an outer layer in the thickness of about 131 μm and 202 μm, respectively. However, the hydrophilic enhancement of inner layer stemmed from the heparinization accelerated the degradation of grafts leading to the early formation of arterial aneurysms in a period of 3 months, severely hindering the perennial observation of the neo-tissue regeneration, host cell infiltration and graft remodeling in those implanted pTEVGs. Herein to address this drawback, the thickness of the outer layers was increased with PCL80k to around 268 μm, while the inner layer remained unchangeable. The thickened TEVGs named as tTEVGs were evaluated in six rabbits via a carotid artery interpositional model for a period of 9 months. All the animals kept alive and the grafts remained patent until explantation except for one whose one side of arterial blood vessels was occluded after an aneurysm occurred at 6 months. Although a significant degradation was observed in the implanted grafts at 9 month, the occurrence of aneurysms was obviously delayed compared to pTEVGs. The tissue stainings indicated that the endothelial cell remodeling was substantially completed by 3 months, while the regeneration of elastin and collagen remained smaller and unevenly distributed in comparison to autologous vessels. Additionally, the proliferation of macrophages and smooth muscle cells reached the maximum by 3 months. These tTEVGs possessing a heparinized inner layer and a thickened outer layer exhibited good patency and significantly delayed onset time of aneurysms.

Red blood cell-derived materials for cancer therapy: Construction, distribution, and applications

Cancer has become an increasingly important public health issue owing to its high morbidity and mortality rates. Although traditional treatment methods are relatively effective, they have limitations such as highly toxic side effects, easy drug resistance, and high individual variability. Meanwhile, emerging therapies remain limited, and their actual anti-tumor effects need to be improved. Nanotechnology has received considerable attention for its development and application. In particular, artificial nanocarriers have emerged as a crucial approach for tumor therapy. However, certain deficiencies persist, including immunogenicity, permeability, targeting, and biocompatibility. The application of erythrocyte-derived materials will help overcome the above problems and enhance therapeutic effects. Erythrocyte-derived materials can be acquired via the application of physical and chemical techniques from natural erythrocyte membranes, or through the integration of these membranes with synthetic inner core materials using cell membrane biomimetic technology. Their natural properties such as biocompatibility and long circulation time make them an ideal choice for drug delivery or nanoparticle biocoating. Thus, red blood cell-derived materials are widely used in the field of biomedicine. However, further studies are required to evaluate their efficacy, in vivo metabolism, preparation, design, and clinical translation. Based on the latest research reports, this review summarizes the biology, synthesis, characteristics, and distribution of red blood cell-derived materials. Furthermore, we provide a reference for further research and clinical transformation by comprehensively discussing the applications and technical challenges faced by red blood cell-derived materials in the treatment of malignant tumors.

Adventitial delivery of miR-145 to treat intimal hyperplasia post vascular injuries through injectable and in-situ self-assembling peptide hydrogels

Intimal hyperplasia is a common lesion that can be observed in diverse vascular diseases. Drug-eluting stents and drug-coated balloons, which can release anti-proliferative agents to inhibit smooth muscle cell (SMC) proliferation, are developed to prevent intimal hyperplasia. However, these intervention devices still cannot achieve satisfactory clinical outcomes. In contrast to endovascular drug delivery, vascular adventitial drug delivery is a new strategy. To develop a vascular adventitial drug delivery system to treat intimal hyperplasia post vascular injuries, we loaded miR-145-5p-agomir (miR-145) into an injectable and in-situ self-assembling RAD peptide hydrogel. In vitro data showed that the miR-145 could be well incorporated into the RAD peptide hydrogels and released in a slow and controlled manner. The released miR-145 could transfect SMCs successfully, and the transfected SMCs exhibited a reduced migration capacity and higher expressions of SMC contractile biomarkers as compared to the non-transfected SMCs. In vivo data showed that the retention of the miR-145 was greatly elongated by the RAD peptide hydrogels. In addition, the application of the miR-145-loaded RAD peptide hydrogels surrounding injured arteries decreased the proliferative SMCs, promoted the regeneration of endothelium, reduced the macrophage infiltration, inhibited the neointimal formation and prevented adverse ECM remodeling via downregulation of KLF4 expression. The RAD peptide hydrogels loaded with miR-145 can successfully inhibit intimal hyperplasia after vascular injuries and thus hold great potential as an innovative extravascular drug delivery approach to treat vascular diseases. STATEMENT OF SIGNIFICANCE: Intimal hyperplasia is a common lesion that can be observed in diverse vascular diseases. Drug-eluting stents and drug-coated balloons, which can release anti-proliferative agents to inhibit smooth muscle cell (SMC) proliferation, are developed to prevent intimal hyperplasia. However, these intervention devices still cannot achieve satisfactory clinical outcomes. In contrast to endovascular drug delivery, vascular adventitial drug delivery is a new strategy. Our work here demonstrates that the RAD peptide hydrogels loaded with miR-145-5p-agomir (miR-145) can successfully reverse intimal hyperplasia after vascular injuries and thus hold great potential as an innovative vascular adventitial drug delivery approach to treat vascular diseases. Our work proposes a possible paradigm shift from endovascular drug delivery to extravascular drug delivery for vascular disorder treatment.

Surface Functionalization of Electrospun Scaffolds by QK-AG73 Peptide for Enhanced Interaction with Vascular Endothelial Cells

Rapid endothelialization still remains challenging for blood-contacting biomaterials, especially for long-term, functional, small-diameter vascular grafts. The vascular endothelial growth factor (VEGF)-mimicking QK peptide holds great promise in promoting vascular endothelial cellular activities such as adhesion, spreading, proliferation, and migration. Syndecans are transmembrane proteoglycans that are highly expressed on cell surfaces, including vascular endothelial cells, which can act as docking receptors to provide binding sites for a variety of cellular growth and signaling molecules. Herein, a novel peptide QK-AG73 that coupled the QK domain with the syndecan binding peptide AG73 was proposed, aiming to synergistically enhance the interaction with vascular endothelial cells. In addition, mechanically matched bioactive scaffolds based on poly(l-lactide-co-ε-caprolactone) were successfully prepared by surface functionalization of the covalently combined QK-AG73 peptide. The result showed that the adhesion of human umbilical vein endothelial cells (HUVECs) was increased by approximately 2-fold on QK-AG73-modified surface compared with those modified with a single QK or AG73 peptide. Moreover, surface functionalization of electrospun scaffolds by this QK-AG73 peptide was more efficient in specifically promoting the proliferation of HUVECs and allowing them to grow with an elongated cobblestone-like cell morphology. It was hypothesized that both VEGF receptors and transmembrane syndecan receptors were involved in cellular regulation by the QK-AG73 peptide, which resulted in synergistic improvement of the interactions with vascular endothelial cells and provided a promising strategy to promote endothelialization of small-diameter vascular grafts.

Injectable Antibacterial Hydrogel with Asiaticoside-Loaded Liposomes and Ultrafine Silver Nanosilver Particles Promotes Healing of Burn-Infected Wounds

Post-injury infection and wound healing are recurrent daily life problems. Therefore, the necessity of developing a biomaterial with antibacterial and wound-healing properties is paramount. Based on the special porous structure of hydrogel, this work modifies recombinant collagen and quaternary ammonium chitosan and fused them with silver nanoparticles (Ag@mental-organic framework (Ag@MOF)) with antibacterial properties, and asiaticoside-loaded liposomes (Lip@AS) with anti-inflammatory/vascularization effects to form the rColMA/QCSG/LIP@AS/Ag@MOF (RQLAg) hydrogel. The prepared hydrogel possesses good sustainable release capabilities of Ag+ and AS and exhibits concentration-dependent swelling properties, pore size, and compressive strength. Cellular experiments show that the hydrogel exhibits good cell compatibility and promote cell migration, angiogenesis, and M1 macrophage polarization. Additionally, the hydrogels exhibit excellent antibacterial activity against Escherichia coli and Staphylococcus aureus in vitro. In vivo, Sprague Dawley rats burn-wound infection model showed that the RQLAg hydrogel could efficiently promote wound healing and has stronger healing promoting abilities than those of Aquacel Ag. In summary, the RQLAg hydrogel is expected to be an excellent material for accelerating open wound healing and preventing bacterial infections.

Immunomodulatory hybrid micro-nanofiber scaffolds enhance vascular regeneration

The inertness of synthetic polymer materials and the insufficient mechanical strength of reprocessed decellularized extracellular matrix (dECM) limited their promotive efforts on tissue regeneration. Here, we prepared a hybrid scaffold composed of PCL microfibers and human placental extracellular matrix (pECM) nanofibers by co-electrospinning, which was grafted with heparin and further absorbed with IL-4. The hybrid scaffold with improved hemocompatibility firstly switched macrophages to anti-inflammatory phenotype (increased by 18.1%) and then promoted migration, NO production, tube formation of endothelial cells (ECs), and migration and maturation of vascular smooth muscle cells (VSMCs), and ECM deposition in vitro and in vivo. ECs coverage rate increased by 8.6% and the thickness of the smooth muscle layer was 1.8 times more than PCL grafts at 12 wks. Our study realized the complementary advantages of synthetic polymer materials and dECM materials, and opened intriguing perspectives for the design and construction of small-diameter vascular grafts (SDVGs) and immune-regulated materials for other tissue regeneration.

Quercetin improves rapid endothelialization and inflammatory microenvironment in electrospun vascular grafts

There is a great need for small diameter vascular grafts among patients with cardiovascular diseases annually. However, continuous foreign body reactions and fibrosis capsules brought by biomaterials are both prone to poor vascular tissue regeneration. To address this problem, we fabricated a polycaprolactone (PCL) vascular graft incorporated with quercetin (PCL/QCT graft) in this study. In vitro cell assay showed that quercetin reduced the expressions of pro-inflammatory genes of macrophages while increased the expressions of anti-inflammatory genes. Furthermore, in vivo implantation was performed in a rat abdominal aorta replacement model. Upon implantation, the grafts exhibited sustained quercetin release and effectively enhanced the regeneration of vascular tissue. The results revealed that quercetin improved endothelial layer formation along the lumen of the vascular grafts at 4 weeks. Furthermore, the thickness of vascular smooth muscle layers significantly increased in PCL/QCT group compared with PCL group. More importantly, the presence of quercetin stimulated the infiltration of a large amount of M2 phenotype macrophages into the grafts. Collectively, the above data reinforced our hypothesis that the incorporation of quercetin may be in favor of modulating the inflammatory microenvironment and improving vascular tissue regeneration and remodeling in vascular grafts.

Recent advances of natural and bioengineered extracellular vesicles and their application in vascular regeneration

The progression of cardiovascular diseases such as atherosclerosis and myocardial infarction leads to serious vascular injury, highlighting the urgent need for targeted regenerative therapy. Extracellular vesicles (EVs) composed of a lipid bilayer containing nuclear and cytosolic materials are relevant to the progression of cardiovascular diseases. Moreover, EVs can deliver bioactive cargo in pathological cardiovascular and regulate the biological function of recipient cells, such as inflammation, proliferation, angiogenesis and polarization. However, because the targeting and bioactivity of natural EVs are subject to several limitations, bioengineered EVs have achieved wide advancements in biomedicine. Bioengineered EVs involve three main ways to acquire including (i) modification of the EVs after isolation; (ii) modification of producer cells before EVs’ isolation; (iii) synthesize EVs using natural or modified cell membranes, and encapsulating drugs or bioactive molecules into EVs. In this review, we first summarize the cardiovascular injury-related disease and describe the role of different cells and EVs in vascular regeneration. We also discuss the application of bioengineered EVs from different producer cells to cardiovascular diseases. Finally, we summarize the surface modification on EVs which can specifically target abnormal cells in injured vascular.

Small Diameter Cell-Free Tissue-Engineered Vascular Grafts: Biomaterials and Manufacture Techniques to Reach Suitable Mechanical Properties

Vascular grafts (VGs) are medical devices intended to replace the function of a blood vessel. Available VGs in the market present low patency rates for small diameter applications setting the VG failure. This event arises from the inadequate response of the cells interacting with the biomaterial in the context of operative conditions generating chronic inflammation and a lack of regenerative signals where stenosis or aneurysms can occur. Tissue Engineered Vascular grafts (TEVGs) aim to induce the regeneration of the native vessel to overcome these limitations. Besides the biochemical stimuli, the biomaterial and the particular micro and macrostructure of the graft will determine the specific behavior under pulsatile pressure. The TEVG must support blood flow withstanding the exerted pressure, allowing the proper compliance required for the biomechanical stimulation needed for regeneration. Although the international standards outline the specific requirements to evaluate vascular grafts, the challenge remains in choosing the proper biomaterial and manufacturing TEVGs with good quality features to perform satisfactorily. In this review, we aim to recognize the best strategies to reach suitable mechanical properties in cell-free TEVGs according to the reported success of different approaches in clinical trials and pre-clinical trials.