Electrospun Fibers Improving Cellular Respiration via Mitochondrial Protection.

Cellular respiration is the prerequisite for cell survival and functions, and mitochondrial function and microcirculation oxygen supply are essential for cellular respiration. However, in diabetic fracture, cellular respiration of bone marrow stem cells (BMSCs) is disrupted because of the dysfunction of mitochondria and microcirculation disorders. Here, the electrospun fibers of GelMA loaded with Hif-1 pathway activator (DFO) are constructed to improve the cellular respiration of BMSCs via protecting mitochondrial function and reconstructing microcirculation. The sequential process of electrospinning and UV crosslinking endowed the electrospun fibers with breathability and the biomechanical properties like the periosteum. In vitro biomolecular experiments showed that by crosslinking grafted polyethylene glycol acrylate liposomes loaded with DFO, the functional electrospun fibers can release DFO locally to activate Hif-1 in BMSCs, which can regulate the balance of Bcl-2/Bax to protect mitochondria and upregulate the expression of VEGF to reconstruct microcirculation. Animal experiments confirmed that the functional electrospun fibers can promote the recovery of diabetic fracture in vivo. These suggested that the functional electrospun fibers can improve cellular respiration for cell survival and functions of BMSCs. This study provides a new treatment strategy for diabetic fracture and other tissue regeneration on basis of cellular respiration improvement.

Effect of Retro-Inverso Isomer of Bradykinin on Size-Dependent Penetration of Blood-Brain Tumor Barrier.

Retro-inverso bradykinin (RI-BK) has better metabolic stability and higher affinity for the BK type 2 (B2) receptor, compared with bradykinin. At low doses, RI-BK can selectively enhance the permeability of the blood-brain tumor barrier (BBTB) without harming normal brain tissue. In this study, gold nanoparticles (GNPs) of size ranging from 5 to 90 nm are synthesized to assess the optimal size of nanocarriers that achieves maximum brain accumulation after the treatment of RI-BK. The ability of the GNPs to cross the BBTB is tested in a rat C6 glioma tumor model. The results of inductively coupled plasma-mass spectrometry and transmission electron microscopy indicate that GNPs with size of 70 nm achieve maximum permeability to the glioma. The present study supports the conclusion that RI-BK can enhance the permeability of BBTB and provides fundamental information for further development of nanomedicines or nanoprobes for glioma therapy.

Enhanced Glioblastoma Targeting Ability of Carfilzomib Enabled by a DA7R-Modified Lipid Nanodisk.

The robust proliferation of tumors relies on a rich neovasculature for nutrient supplies. Therefore, a basic strategy of tumor targeting therapy should include not only killing regular cancer cells but also blocking tumor neovasculature. D-peptide DA7R, which was previously reported to specifically bind vascular endothelial growth factor receptor 2 (VEGFR2) and neuropilin-1 (NRP-1), could achieve the goal of multitarget recognition. Accordingly, the main purposes of this work were to establish a carfilzomib-loaded lipid nanodisk modified with multifunctional peptide DA7R (DA7R-ND/CFZ) and to evaluate its anti-glioblastoma efficacy in vitro and in vivo. It is testified that the DA7R peptide-conjugated lipid nanodisk can be specifically taken up by U87MG cells and HUVECs. Furthermore, DA7R-ND demonstrated a more enhanced penetration than that of the nonmodified formulation on the tumor spheroid model in vitro and more tumor region accumulation in vivo on the subcutaneous and intracranial tumor-bearing nude mice model. DA7R-ND was shown to co-localize with tumor neovasculature in vivo. When loaded with proteasome inhibitor carfilzomib, the DA7R-decorated nanodisk could remarkably suppress tumor proliferation, extend survival time of nude mice bearing an intracranial tumor, and inhibit neovasculature formation with an efficacy higher than that of the nonmodified nanodisk in vitro and in vivo. The present study verified that the heptapeptide DA7R-conjugated nanodisk is a promising nanocarrier for glioblastoma targeting therapy.

Ternary Nanoparticles with a Sheddable Shell Efficiently Deliver MicroRNA-34a against CD44-Positive Melanoma.

PEGylation can stabilize drug delivery systems for cancer therapy by creating repulsive interactions with biological components in vivo. While these interactions reduce nonspecific adsorption of drug-loaded particles onto nontarget surfaces, they also inhibit internalization of particles into target cells. To circumvent this so-called "PEG-dilemma", we have developed nanoparticles with a PEG coating that is shed after arrival in target tissue. Positively charged polycation nanoparticles were assembled with microRNA-34a via electrostatic interactions and then coated again via electrostatic interactions with an anionic PEG derivative that separates from the nanoparticle in the acidic tumor microenvironment. The resulting ternary nanoparticles with a sheddable shell have nearly neutral surface charge, which markedly reduces nonspecific adsorption. Shedding the PEG coat enhanced nanoparticle uptake into CD44-positive melanoma cells and promoted microRNA-34a release, which down-regulated CD44 expression and thereby inhibited tumor growth. We conclude that nanocarriers with a sheddable shell show promise for cancer therapy.

Hydrogen Ion Capturing Hydrogel Microspheres for Reversing Inflammaging.

Inflammaging is deeply involved in aging-related diseases and can be destructive during aging. The maintenance of pH balance in the extracellular microenvironment can alleviate inflammaging and repair aging-related tissue damage. In this study, the hydrogen ion capturing hydrogel microsphere (GMNP) composed of mineralized transforming growth factor-ß (TGF-ß) and catalase (CAT) nanoparticles is developed via biomimetic mineralization and microfluidic technology for blocking the NLRP3 cascade axis in inflammaging. This GMNP can neutralize the acidic microenvironment by capturing excess hydrogen ions through the calcium carbonate mineralization layer. Then, the subsequent release of encapsulated TGF-ß and CAT can eliminate both endogenous and exogenous stimulus of NLRP3, thus suppressing the excessive activation of inflammaging. In vitro, GMNP can suppress the excessive activation of the TXNIP/NLRP3/IL-1ß cascade axis and enhance extracellular matrix (ECM) synthesis in nucleus pulposus cells. In vivo, GMNP becomes a sustainable and stable niche with microspheres as the core to inhibit inflammaging and promote the regeneration of degenerated intervertebral discs. Therefore, this hydrogen ion-capturing hydrogel microsphere effectively reverses inflammaging by interfering with the excessive activation of NLRP3 in the degenerated tissues.

Stem Cells Expansion Vector via Bioadhesive Porous Microspheres for Accelerating Articular Cartilage Regeneration.

Stem cell tissue engineering is a potential treatment for osteoarthritis. However, the number of stem cells that can be delivered, loss of stem cells during injection, and migration ability of stem cells limit applications of traditional stem cell tissue engineering. Herein, kartogenin (KGN)-loaded poly(lactic-co-glycolic acid) (PLGA) porous microspheres is first engineered via emulsification, and then anchored with chitosan through the amidation reaction to develop a new porous microsphere (PLGA-CS@KGN) as a stem cell expansion vector. Following 3D co-culture of the PLGA-CS@KGN carrier with mesenchymal stem cells (MSCs), the delivery system is injected into the capsule cavity in situ. In vivo and in vitro experiments show that PLGA-CS microspheres have a high cell-carrying capacity up to 1 × 104 mm-3 and provide effective protection of MSCs to promote their controlled release in the osteoarthritis microenvironment. Simultaneously, KGN loaded inside the microspheres effectively cooperated with PLGA-CS to induce MSCs to differentiate into chondrocytes. Overall, these findings indicate that PLGA-CS@KGN microspheres held high cell-loading ability, adapt to the migration and expansion of cells, and promote MSCs to express markers associated with cartilage repair. Thus, PLGA-CS@KGN can be used as a potential stem cell carrier for enhancing stem cell therapy in osteoarthritis treatment.

Regulated macrophage immune microenvironment in 3D printed scaffolds for bone tumor postoperative treatment.

The 3D printing technique is suitable for patient-specific implant preparation for bone repair after bone tumor resection. However, improving the survival rate due to tumor recurrence remains a challenge for implants. The macrophage polarization induction to M2-type tumor-associated macrophages (TAMs) by the tumor microenvironment is a key factor of immunosuppression and tumor recurrence. In this study, a regenerative scaffold regulating the macrophage immune microenvironment and promoting bone regeneration in a dual-stage process for the postoperative treatment of bone tumors was constructed by binding a colony-stimulating factor 1 receptor (CSF-1R) inhibitor GW2580 onto in situ cosslinked hydroxybutylchitosan (HBC)/oxidized chondroitin sulfate (OCS) hydrogel layer covering a 3D printed calcium phosphate scaffold based on electrostatic interaction. The hydrogel layer on scaffold surface not only supplied abundant sulfonic acid groups for stable loading of the inhibitor, but also acted as the cover mask protecting the bone repair part from exposure to unhealthy growth factors in the microenvironment at the early treatment stage. With local prolonged release of inhibitor being realized via the functional material design, CSF-1R, the main pathway that induces polarization of TAMs, can be efficiently blocked, thus regulating the immunosuppressive microenvironment and inhibiting tumor development at a low therapeutic dose. At the later stage of treatment, calcium phosphate component of the scaffold can facilitate the repair of bone defects caused by tumor excision. In conclusion, the difunctional 3D printed bone repair scaffold regulating immune microenvironment in stages proposed a novel approach for bone tumor postoperative treatment.

Advances in extracellular vesicle functionalization strategies for tissue regeneration.

Extracellular vesicles (EVs) are nano-scale vesicles derived by cell secretion with unique advantages such as promoting cell proliferation, anti-inflammation, promoting blood vessels and regulating cell differentiation, which benefit their wide applications in regenerative medicine. However, the in vivo therapeutic effect of EVs still greatly restricted by several obstacles, including the off-targetability, rapid blood clearance, and undesired release. To address these issues, biomedical engineering techniques are vastly explored. This review summarizes different strategies to enhance EV functions from the perspective of drug loading, modification, and combination of biomaterials, and emphatically introduces the latest developments of functionalized EV-loaded biomaterials in different diseases, including cardio-vascular system diseases, osteochondral disorders, wound healing, nerve injuries. Challenges and future directions of EVs are also discussed.

Circadian Clock Regulation via Biomaterials for Nucleus Pulposus.

Circadian clock disorder during tissue degeneration has been considered the potential pathogenesis for various chronic diseases, such as intervertebral disc degeneration (IVDD). In this study, circadian clock-regulating biomaterials (ClockMPs) that can effectively activate the intrinsic circadian clock of nucleus pulposus cells (NPCs) in IVDD and improve the physiological function of NPCs for disc regeneration are fabricated via air-microfluidic technique and the chemical cross-linking between polyvinyl alcohol and modified-phenylboronic acid. In vitro experiments verified that ClockMPs can scavenge reactive oxygen species to maintain a stable microenvironment for the circadian clock by promoting the binding of BMAL1 and CLOCK proteins. ClockMPs can regulate the expression of core circadian clock genes by activating the PI3K-AKT pathway in NPCs to remodel the intrinsic circadian clock and promote extracellular matrix synthesis. Furthermore, in vivo experiments of IVDD treated with ClockMPs proved that ClockMPs can promote disc regeneration by regulating the circadian clock of NPCs. In conclusion, ClockMPs provided a novel and promising strategy for circadian clock regulation during tissue regeneration.

Erratum: Inhaled ACE2-engineered microfluidic microsphere for intratracheal neutralization of COVID-19 and calming of the cytokine storm.

[This corrects the article DOI: 10.1016/j.matt.2021.09.022.].

Bio-clickable, small extracellular vesicles-COCKTAIL therapy for ischemic stroke.

Delivering large therapeutic molecules via the blood-brain barrier to treat ischemic stroke remains challenging. NR2B9c is a potent neuroprotective peptide but it's safe and targeted delivery to the brain requires an efficient, natural, and non-immunogenic delivery technique. Small extracellular vesicles (sEVs) have shown great potential as a non-immunogenic, natural cargo delivery system; however, tailoring of its inefficient brain targeting is desired. Here, we coupled rabies virus glycoprotein 29 with sEVs surface via bio-orthogonal click chemistry reactions, followed by loading of NR2B9c, ultimately generating stroke-specific therapeutic COCKTAIL (sEVs-COCKTAIL). Primary neurons and Neuro-2a cells were cultured for in vitro and transient middle cerebral artery occlusion model was used for in vivo studies to evaluate neuron targeting and anti-ischemic stroke potential of the sEVs-COCKTAIL. Bio-clickable sEVs were selectively taken up by neurons but not glial cells. In the in vitro ischemic stroke model of oxygen-glucose deprivation, the sEVs-COCKTAIL exhibited remarkable potential against reactive oxygen species and cellular apoptosis. In vivo studies further demonstrated the brain targeting and increased half-life of bio-clickable sEVs, delivering NR2B9c to the ischemic brain and reducing stroke injury. Treatment with the sEVs-COCKTAIL significantly increased behavioral recovery and reduced neuronal apoptosis after transient middle cerebral artery occlusion. NR2B9c was delivered to neurons binding to post-synaptic density protein-95, inhibiting N-methyl-d-Aspartate receptor-mediated over production of oxidative stress and mitigating protein B-cell lymphoma 2 and P38 proteins expression. Our results provide an efficient and biocompatible approach to a targeted delivery system, which is a promising modality for stroke therapy.

Click chemistry extracellular vesicle/peptide/chemokine nanocarriers for treating central nervous system injuries.

Central nervous system (CNS) injuries, including stroke, traumatic brain injury, and spinal cord injury, are essential causes of death and long-term disability and are difficult to cure, mainly due to the limited neuron regeneration and the glial scar formation. Herein, we apply extracellular vesicles (EVs) secreted by M2 microglia to improve the differentiation of neural stem cells (NSCs) at the injured site, and simultaneously modify them with the injured vascular targeting peptide (DA7R) and the stem cell recruiting factor (SDF-1) on their surface via copper-free click chemistry to recruit NSCs, inducing their neuronal differentiation, and serving as the nanocarriers at the injured site (Dual-EV). Results prove that the Dual-EV could target human umbilical vascular endothelial cells (HUVECs), recruit NSCs, and promote the neuronal differentiation of NSCs in vitro. Furthermore, 10 miRNAs are found to be upregulated in Dual-M2-EVs compared to Dual-M0-EVs via bioinformatic analysis, and further NSC differentiation experiment by flow cytometry reveals that among these miRNAs, miR30b-3p, miR-222-3p, miR-129-5p, and miR-155-5p may exert effect of inducing NSC to differentiate into neurons. In vivo experiments show that Dual-EV nanocarriers achieve improved accumulation in the ischemic area of stroke model mice, potentiate NSCs recruitment, and increase neurogenesis. This work provides new insights for the treatment of neuronal regeneration after CNS injuries as well as endogenous stem cells, and the click chemistry EV/peptide/chemokine and related nanocarriers for improving human health.

Nanoantidote for repression of acidosis pH promoting COVID-19 infection.

Acidosis, such as respiratory acidosis and metabolic acidosis, can be induced by coronavirus disease 2019 (COVID-19) infection and is associated with increased mortality in critically ill COVID-19 patients. It remains unclear whether acidosis further promotes SARS-CoV-2 infection in patients, making virus removal difficult. For antacid therapy, sodium bicarbonate poses great risks caused by sodium overload, bicarbonate side effects, and hypocalcemia. Therefore, new antacid antidote is urgently needed. Our study showed that an acidosis-related pH of 6.8 increases SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) expression on the cell membrane by regulating intracellular microfilament polymerization, promoting SARS-CoV-2 pseudovirus infection. Based on this, we synthesized polyglutamic acid-PEG materials, used complexation of calcium ions and carboxyl groups to form the core, and adopted biomineralization methods to form a calcium carbonate nanoparticles (CaCO3-NPs) nanoantidote to neutralize excess hydrogen ions (H+), and restored the pH from 6.8 to approximately 7.4 (normal blood pH). CaCO3-NPs effectively prevented the heightened SARS-CoV-2 infection efficiency due to pH 6.8. Our study reveals that acidosis-related pH promotes SARS-CoV-2 infection, which suggests the existence of a positive feedback loop in which SARS-CoV-2 infection-induced acidosis enhances SARS-CoV-2 infection. Therefore, antacid therapy for acidosis COVID-19 patients is necessary. CaCO3-NPs may become an effective antacid nanoantidote superior to sodium bicarbonate.

Transcriptome Analysis Revealed the Symbiosis Niche of 3D Scaffolds to Accelerate Bone Defect Healing.

Three dimension (3D) printed scaffolds have been shown to be superior in promoting tissue repair, but the cell-level specific regulatory network activated by 3D printing scaffolds with different material components to form a symbiosis niche have not been systematically revealed. Here, three typical 3D printed scaffolds, including natural polymer hydrogel (gelatin-methacryloyl, GelMA), synthetic polymer material (polycaprolactone, PCL), and bioceramic (ß-tricalcium phosphate, ß-TCP), are fabricated to explore the regulating effect of the symbiotic microenvironment during bone healing. Enrichment analysis show that hydrogel promotes tissue regeneration and reconstruction by improving blood vessel generation by enhancing oxygen transport and red blood cell development. The PCL scaffold regulates cell proliferation and differentiation by promoting cellular senescence, cell cycle and deoxyribonucleic acid (DNA) replication pathways, accelerating the process of endochondral ossification, and the formation of callus. The ß-TCP scaffold can specifically enhance the expression of osteoclast differentiation and extracellular space pathway genes to promote the differentiation of osteoclasts and promote the process of bone remodeling. In these processes, specific biomaterial properties can be used to guide cell behavior and regulate molecular network in the symbiotic microenvironment to reduce the barriers of regeneration and repair.

Inhaled ACE2-engineered microfluidic microsphere for intratracheal neutralization of COVID-19 and calming of the cytokine storm.

The SARS-CoV-2 pandemic spread worldwide unabated. However, achieving protection from the virus in the whole respiratory tract, avoiding blood dissemination, and calming the subsequent cytokine storm remains a major challenge. Here, we develop an inhaled microfluidic microsphere using dual camouflaged methacrylate hyaluronic acid hydrogel microspheres with a genetically engineered membrane from angiotensin-converting enzyme II (ACE2) receptor-overexpressing cells and macrophages. By timely competing with the virus for ACE2 binding, the inhaled microspheres significantly reduce SARS-CoV-2 infective effectiveness over the whole course of the respiratory system in vitro and in vivo. Moreover, the inhaled microspheres efficiently neutralize proinflammatory cytokines, cause an alternative landscape of lung-infiltrated immune cells, and alleviate hyperinflammation of lymph nodes and spleen. In an acute pneumonia model, the inhaled microspheres show significant therapeutic efficacy by regulation of the multisystem inflammatory syndrome and reduce acute mortality, suggesting a powerful synergic strategy for the treatment of patients with severe COVID-19 via non-invasive administration.

Capturing Magnesium Ions via Microfluidic Hydrogel Microspheres for Promoting Cancellous Bone Regeneration.

Metal ions are important trace elements in the human body, which directly affect the human metabolism and the regeneration of damaged tissues. For instance, the advanced combination of magnesium ions (Mg2+) and bone repair materials make the composite materials have the function of promoting vascular repair and enhancing the adhesion of osteoblasts. Herein, inspired by magnets to attract metals, we utilized the coordination reaction of metal ion ligand to construct a bisphosphonate-functionalized injectable hydrogel microsphere (GelMA-BP-Mg) which could promote cancellous bone reconstruction of osteoporotic bone defect via capturing Mg2+. By grafting bisphosphonate (BP) on GelMA microspheres, GelMA-BP microspheres could produce powerful Mg2+ capture ability and sustained release performance through coordination reaction, while sustained release BP has bone-targeting properties. In the injectable GelMA-BP-Mg microsphere system, the atomic percentage of captured Mg2+ was 0.6%, and the captured Mg2+ could be effectively released for 18 days. These proved that the composite microspheres could effectively capture Mg2+ and provided the basis for the composite microspheres to activate osteoblasts and endothelial cells and inhibit osteoclasts. Both in vivo and in vitro experimental results revealed that the magnet-inspired Mg2+-capturing composite microspheres are beneficial to osteogenesis and angiogenesis by stimulating osteoblasts and endothelial cells while restraining osteoclasts, and ultimately effectively promote cancellous bone regeneration. This study could provide some meaningful conceptions for the treatment of osteoporotic bone defects on the basis of metal ions.

Inhibition of post-surgery tumour recurrence via a hydrogel releasing CAR-T cells and anti-PDL1-conjugated platelets.

The immunosuppressive microenvironment of solid tumours reduces the antitumour activity of chimeric antigen receptor T cells (CAR-T cells). Here, we show that the release-through the implantation of a hyaluronic acid hydrogel-of CAR-T cells targeting the human chondroitin sulfate proteoglycan 4, polymer nanoparticles encapsulating the cytokine interleukin-15 and platelets conjugated with the checkpoint inhibitor programmed death-ligand 1 into the tumour cavity of mice with a resected subcutaneous melanoma tumour inhibits the local recurrence of the tumour as well as the growth of distant tumours, through the abscopal effect. The hydrogel, which functions as a reservoir, facilitates the enhanced distribution of the CAR-T cells within the surgical bed, and the inflammatory microenvironment triggers platelet activation and the subsequent release of platelet-derived microparticles. The post-surgery local delivery of combination immunotherapy through a biocompatible hydrogel reservoir could represent a translational route for preventing the recurrence of cancers with resectable tumours.

Mechanical on-off gates for regulation of drug release in cutaneous or musculoskeletal tissue repairs.

Drug release synchronized with tissue motion is attractive to cutaneous or musculoskeletal tissue injury repair. Here, we have developed a method of regulating drug release by mechanical on-off gates for potential treatment of repeated injury in these tissues. The mechanical gates consisted of a multilayer structure: A brittle outmost layer adhered to an elastic middle layer, which wrapped an inmost drug carrier to form the composite multilayer structure. When it was stretched, cracks appeared as mechanical gates due to mechanical performance difference between the outmost layer and the middle layer, leading to the drug release. When the external force disappeared, it recovered to stop the drug release. The controlled drug release would therefore be achieved by changing the status (opening or closure) of mechanical gates through applying this on-off mechanical stretching. A prototype based on the composite multilayer structure of adhesive coating and electrospinning technique realized the controlled release of drug and effectively repaired the incision. More types of composite multilayer structures for mechanical drug release were expected to meet curing requirement in cutaneous or musculoskeletal tissues.

Strategies of Combination Drug Delivery for Immune Checkpoint Blockades.

The past few years have witnessed vast clinical accomplishments of immune checkpoint blockades (ICB), which block the regulatory receptor expressed on immune cells or tumor cells to prevent the suppression of antitumor cytotoxic T-cell responses. Despite this, limitations still exist, such as low objective response rate (ORR) and the risk of immune-related side effects. To address these issues, combination treatment strategies are vastly explored and recommended. This review summarizes recent advances in combination of ICB with therapies that participate in different stages of cancer immune cycle, including tumor antigen release, tumor antigen presentation, T-cell activation, recognition of cancer cells by T-cells, and tumor-killing activity. Challenges and potential opportunities of combination approaches in this field are also discussed.

Advances in drug delivery for post-surgical cancer treatment.

Surgery remains a primary modality of treatment for the majority of solid tumor malignancies. While advancements in surgical technique and instrumentation have improved the quality of life for cancer patients, local tumor recurrence and metastasis after surgery remain challenging and result in a high rate of mortality and decrease quality of life. It is therefore urgent to explore effective methods to eliminate residual microscopic disease in the surgical site and/or circulating tumor cells (CTCs) to inhibit tumor recurrence and minimize the risk of distant metastasis. Recently, advances in bioengineering technology have facilitated the development of drug delivery systems (DDSs) for the release of chemotherapy and immunotherapy agents, which could be used to enhance the effectiveness of surgical resection. In this review, we survey the rapidly evolving fields of local and systemic controlled DDSs, utilizing a variety of formulations and devices, such as implantable wafers, injectable/sprayable hydrogels, micro/nanoparticles, and cellular particles. Opportunities and challenges for the clinical translations of these delivery systems are also discussed.