A pro-angiogenic degradable Mg-poly(lactic-co-glycolic acid) implant combined with rhbFGF in a rat limb ischemia model

ROS-responsive nanoparticle-mediated delivery of CYP2J2 gene for therapeutic angiogenesis in severe hindlimb ischemia

With critical limb ischemia (CLI) being a multi-factorial disease, it is becoming evident that gene therapy with a multiple bio-functional growth factor could achieve better therapeutic outcomes. Cytochrome P450 epoxygenase-2J2 (CYP2J2) and its catalytic products epoxyeicosatrienoic acids (EETs) exhibit pleiotropic biological activities, including pro-angiogenic, anti-inflammatory and cardiovascular protective effects, which are considerably beneficial for reversing ischemia and restoring local blood flow in CLI. Here, we designed a nanoparticle-based pcDNA3.1-CYP2J2 plasmid DNA (pDNA) delivery system (nanoparticle/pDNA complex) composed of a novel three-arm star block copolymer (3S-PLGA-po-PEG), which was achieved by conjugating three-armed PLGA to PEG via the peroxalate ester bond. Considering the multiple bio-functions of CYP2J2-EETs and the sensitivity of the peroxalate ester bond to H₂O₂, this nanoparticle-based gene delivery system is expected to exhibit excellent pro-angiogenic effects while improving the high oxidative stress and inflammatory micro-environment in ischemic hindlimb. Our study reports the first application of CYP2J2 in the field of therapeutic angiogenesis for CLI treatment and our findings demonstrated good biocompatibility, stability and sustained release properties of the CYP2J2 nano-delivery system. In addition, this nanoparticle-based gene delivery system showed high transfection efficiency and efficient VEGF expression in vitro and in vivo. Intramuscular injection of nanoparticle/pDNA complexes into mice with hindlimb ischemia resulted in significant rapid blood flow recovery and improved muscle repair compared to mice treated with naked pDNA. In summary, 3S-PLGA-po-PEG/CYP2J2-pDNA complexes have tremendous potential and provide a practical strategy for the treatment of limb ischemia. Moreover, 3S-PLGA-po-PEG nanoparticles might be useful as a potential non-viral carrier for other gene delivery applications.

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Cytochrome P450 epoxygenase-2J2 (CYP2J2) was first applied in the field of therapeutic angiogenesis for critical limb ischemia treatment.

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The ROS-responsive three-arm star block copolymer (3S-PLGA-po-PEG) was synthesized with peroxalate ester as H₂O₂-responsive linkages through the esterification reaction of oxalyl chloride and hydroxyl group.

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The CYP2J2 nano-delivery system achieved high transfection efficiency and significant therapeutic angiogenesis effect.

Biofunctional magnesium coated Ti6Al4V scaffold enhances osteogenesis and angiogenesis in vitro and in vivo for orthopedic application

The insufficient osteogenesis and osseointegration of porous titanium based scaffold limit its further application. Early angiogenesis is important for scaffold survival. It is necessary to develop a multifunctional surface on titanium scaffold with both osteogenic and angiogenic properties. In this study, a biofunctional magnesium coating is deposited on porous Ti6Al4V scaffold. For osseointegration and osteogenesis analysis, in vitro studies reveal that magnesium-coated Ti6Al4V co-culture with MC3T3-E1 cells can improve cell proliferation, adhesion, extracellular matrix (ECM) mineralization and ALP activity compared with bare Ti6Al4V cocultivation. Additionally, MC3T3-E1 cells cultured with magnesium-coated Ti6Al4V show significantly higher osteogenesis-related genes expression. In vivo studies including fluorochrome labeling, micro-computerized tomography and histological examination of magnesium-coated Ti6Al4V scaffold reveal that new bone regeneration is significantly increased in rabbits after implantation. For angiogenesis studies, magnesium-coated Ti6Al4V improve HUVECs proliferation, adhesion, tube formation, wound-healing and Transwell abilities. HUVECs cultured with magnesium-coated Ti6Al4V display significantly higher angiogenesis-related genes (HIF-1α and VEGF) expression. Microangiography analysis reveal that magnesium-coated Ti6Al4V scaffold can significantly enhance the blood vessel formation. This study enlarges the application scope of magnesium and provides an optional choice to the conventional porous Ti6Al4V scaffold with enhanced osteogenesis and angiogenesis for further orthopedic applications.

Icariin/Aspirin Composite Coating on TiO2 Nanotubes Surface Induce Immunomodulatory Effect of Macrophage and Improve Osteoblast Activity

Surface coating modification of titanium-based alloys is an efficient way to accelerate early osseointegration in dental implant fields. Icariin (ICA) is a traditional Chinese medicine that has bone activating functions, while aspirin (ASP) is a classical non-steroidal anti-inflammatory drug with good antipyretic and analgesic capabilities. Moreover, poly(lactic–co–glycolic acid) (PLGA) has attracted great attention due to its excellent biocompatibility and biodegradability. We superimposed an ASP/PLGA coating onto ICA loaded TiO2 nanotubes structure so as to establish an icariin/aspirin composite coating on TiO2 nanotubes surface. Scanning electron microscopy, X-ray photoelectron spectroscopy, a contact angle test and a drug release test confirmed the successful preparation of the NT–ICA–ASP/PLGA substrate, with a sustained release pattern of both ICA and ASP. Compared to those cultured on the Ti surface, macrophage cells on the NT-ICA-ASP/PLGA substrate displayed decreased M1 proinflammatory and enhanced M2 proregenerative genes and proteins expression, which implied activated immunomodulatory effect. Moreover, when cultured with conditioned medium from macrophages, osteoblast cells on the NT-ICA-ASP/PLGA substrate revealed improved cell proliferation, adhesion and osteogenic genes and proteins expression, compared with those on the Ti surface. The abovementioned results suggest that the established NT-ICA-ASP/PLGA substrate is a promising candidate for functionalized coating material in Ti implant surface modification.

MicroRNA‑93 regulates angiogenesis in peripheral arterial disease by targeting CDKN1A

MicroRNAs (miRNAs) are considered to be critical mediators of gene expression with respect to tumor progression, although their role in ischemia-induced angiogenesis is poorly characterized, including in peripheral arterial disease (PAD). Furthermore, the underlying mechanism of action of specific miRNAs in PAD remains unknown. Reverse transcription-quantitative polymerase chain reaction analysis revealed that microRNA-93 (miR-93) was significantly upregulated in patients with PAD and in the EA.hy926 endothelial cells in response to hypoxia. Additionally, miRNA (miR)-93 promoted angiogenesis by enhancing proliferation, migration and tube formation. Cyclin dependent kinase inhibitor 1A (CDKN1A), verified as a potential target gene of miR-93, was inhibited by overexpressed miR-93 at the protein and mRNA expression levels. Furthermore, a hind-limb ischemia model served to evaluate the role of miR-93 in angiogenesis in vivo, and the results demonstrated that miR-93 overexpression enhanced capillary density and perfusion recovery from hind-limb ischemia. Taken together, miR-93 was indicated to be a promising target for pharmacological regulation to promote angiogenesis, and the miR-93/CDKN1A pathway may function as a novel therapeutic approach in PAD.

Sustained delivery of vascular endothelial growth factor using a dextran/poly(lactic-co-glycolic acid)-combined microsphere system for therapeutic neovascularization

We hypothesize that the controlled delivery of vascular endothelial growth factor (VEGF) using a novel protein sustained-release system based on the combination of protein-loaded dextran microparticles and PLGA microspheres could be useful to achieve mature vessel formation in a rat hind-limb ischemic model. VEGF-loaded dextran microparticles were fabricated and then encapsulated into poly(lactic-co-glycolic acid) (PLGA) microspheres to prepare VEGF-dextran-PLGA microspheres. The release behavior and bioactivity in promoting endothelial cell proliferation of VEGF from PLGA microspheres were monitored in vitro. VEGF-dextran-PLGA microsphere-loaded fibrin gel was injected into an ischemic rat model, and neovascularization at the ischemic site was evaluated. The release of VEGF from PLGA microspheres was in a sustained manner for more than 1 month in vitro with low level of initial burst release. The released VEGF enhanced the proliferation of endothelial cells in vitro, and significantly promoted the capillaries and smooth muscle α-actin positive vessels formation in vivo. The retained bioactivity of VEGF released from VEGF-dextran-PLGA microspheres potentiated the angiogenic efficacy of VEGF. This sustained-release system may be a promising vehicle for delivery of multiple angiogenic factors for therapeutic neovascularization.