Biodegradable and Inherently Fluorescent pH-Responsive Nanoparticles for Cancer Drug Delivery.

PURPOSE: The development of two novel pH-only and pH- and thermo-responsive theranostic nanoparticle (NP) formulations to deliver an anticancer drug and track the accumulation and therapeutic efficacy of the formulations through inherent fluorescence. METHODS: A pH-responsive formulation was synthesized from biodegradable photoluminescent polymer (BPLP) and sodium bicarbonate (SBC) via an emulsion technique, while a thermoresponsive BPLP copolymer (TFP) and SBC were used to synthesize a dual-stimuli responsive formulation via free radical co-polymerization. Cisplatin was employed as a model drug and encapsulated during synthesis. Size, surface charge, morphology, pH-dependent fluorescence, lower critical solution temperature (LCST; TFP NPs only), cytocompatibility and in vitro uptake, drug release kinetics and anticancer efficacy were assessed. RESULTS: While all BPLP-SBC and TFP-SBC combinations produced spherical nanoparticles of a size between 200-300 nm, optimal polymer-SBC ratios were selected for further study. Of these, the optimal BPLP-SBC formulation was found to be cytocompatible against primary Type-1 alveolar epithelial cells (AT1) up to 100 µg/mL, and demonstrated sustained drug release over 14 days, dose-dependent uptake, and marked pH-dependent A549 cancer cell killing (72 vs. 24% cell viability, at pH 7.4 vs. 6.0). The optimal TFP-SBC formulation showed excellent cytocompatibility against AT1 cells up to 500 µg/mL, sustained release characteristics, dose-dependent uptake, pH-dependent (78% at pH 7.4 vs. 64% at pH 6.0 at 37°C) and marked temperature-dependent A549 cancer cell killing (64% at 37°C vs. 37% viability at pH 6.0, 41°C). CONCLUSIONS: In all, both formulations hold promise as inherently fluorescent, stimuli-responsive theranostic platforms for passively targeted anti-cancer therapy.

Corrigendum: Notch Intracellular Domain Plasmid Delivery via Poly(Lactic-Co-Glycolic Acid) Nanoparticles to Upregulate Notch Pathway Molecules.

[This corrects the article DOI: 10.3389/fcvm.2021.707897.].

Notch Intracellular Domain Plasmid Delivery via Poly(Lactic-Co-Glycolic Acid) Nanoparticles to Upregulate Notch Pathway Molecules.

Notch signaling is a highly conserved signaling system that is required for embryonic development and regeneration of organs. When the signal is lost, maldevelopment occurs and leads to a lethal state. Delivering exogenous genetic materials encoding Notch into cells can reestablish downstream signaling and rescue cellular functions. In this study, we utilized the negatively charged and FDA approved polymer poly(lactic-co-glycolic acid) to encapsulate Notch Intracellular Domain-containing plasmid in nanoparticles. We show that primary human umbilical vein endothelial cells (HUVECs) readily uptake the nanoparticles with and without specific antibody targets. We demonstrated that our nanoparticles are non-toxic, stable over time, and compatible with blood. We further demonstrated that HUVECs could be successfully transfected with these nanoparticles in static and dynamic environments. Lastly, we elucidated that these nanoparticles could upregulate the downstream genes of Notch signaling, indicating that the payload was viable and successfully altered the genetic downstream effects.

Characterization of Photoluminescent Polylactone-Based Nanoparticles for Their Applications in Cardiovascular Diseases.

Cardiovascular diseases (CVD) affect a large number of the population across the globe and are the leading cause of death worldwide. Nanotechnology-based drug delivery has currently offered novel therapeutic options to treat these diseases, yet combination of both diagnostic and therapeutic abilities is further needed to understand factors and/or mechanisms that affect the treatment in order to design better therapies to challenge CVD. Biodegradable photoluminescent polylactones (BPLPLs) enable to bridge this gap as these materials exhibit a stable, long-term intrinsic fluorescence as well as offers excellent cytocompatibility and biodegradability properties. Herein, we formulated three different BPLPL based nanoparticles (NPs), including BPLP-co-poly (L-lactic acid) (BPLPL-PLLA), BPLP-co-poly (lactic-co-glycolic acid) copolymers with lactic acid and glycolic acid ratios of 75:25 (BPLPL-PLGA75:25) and 50:50 (BPLPL-PLGA50:50), and extensively evaluated their suitability as theranostic nanocarriers for CVD applications. All BPLPL based NPs were <160 nm in size and had photoluminescence characteristics and tunable release kinetics of encapsulated protein model depending on polylactones copolymerized with BPLP materials. Compared to BPLPL-PLLA NPs, BPLPL-PLGA NPs demonstrated excellent stability in various formulations including deionized water, serum, saline, and simulated body fluid over 2 days. In vitro cell studies with human umbilical vein derived endothelial cells showed dose-dependent accumulation of BPLPL-based NPs, and BPLPL-PLGA NPs presented superior compatibility with endothelial cells in terms of viability with minimal effects on cellular functions such as nitric oxide production. Furthermore, all BPLPL NPs displayed hemocompatibility with no effect on whole blood kinetic profiles, were non-hemolytic, and consisted of comparable platelet responses such as platelet adhesion and activation to those of PLGA, an FDA approved material. Overall, our results demonstrated that BPLPL-PLGA based NPs have better physical and biological properties than BPLPL-PLLA; hence they have potential to be utilized as functional nanocarriers for therapy and diagnosis of CVD.

Scaffold-based lung tumor culture on porous PLGA microparticle substrates.

Scaffold-based cancer cell culture techniques have been gaining prominence especially in the last two decades. These techniques can potentially overcome some of the limitations of current three-dimensional cell culture methods, such as uneven cell distribution, inadequate nutrient diffusion, and uncontrollable size of cell aggregates. Porous scaffolds can provide a convenient support for cell attachment, proliferation and migration, and also allows diffusion of oxygen, nutrients and waste. In this paper, a comparative study was done on porous poly (lactic-co-glycolic acid) (PLGA) microparticles prepared using three porogens-gelatin, sodium bicarbonate (SBC) or novel poly N-isopropylacrylamide [PNIPAAm] particles, as substrates for lung cancer cell culture. These fibronectin-coated, stable particles (19-42 µm) supported A549 cell attachment at an optimal cell seeding density of 250,000 cells/ mg of particles. PLGA-SBC porous particles had comparatively larger, more interconnected pores, and favored greater cell proliferation up to 9 days than their counterparts. This indicates that pore diameters and interconnectivity have direct implications on scaffold-based cell culture compared to substrates with minimally interconnected pores (PLGA-gelatin) or pores of uniform sizes (PLGA-PMPs). Therefore, PLGA-SBC-based tumor models were chosen for preliminary drug screening studies. The greater drug resistance observed in the lung cancer cells grown on porous particles compared to conventional cell monolayers agrees with previous literature, and indicates that the PLGA-SBC porous microparticle substrates are promising for in vitro tumor or tissue development.

Nanoparticle eluting-angioplasty balloons to treat cardiovascular diseases.

Nanoparticles (NPs) can be used to locally deliver anti-restenosis drugs when they are infused directly to the injured arteries after intervention procedures such as angioplasty. However, the efficacy of transferring NPs via infusion to the arterial wall is limited, at least partially, due to poor NP retention on the inner artery wall. To improve NP retention, angioplasty balloons coated with drug-loaded NPs were fabricated via either layer-by-layer (LbL) electrostatic coating or acrylic-based hydrogel (AAH) coating techniques. Three types of NPs, namely poly (lactide-co-glycolide) (PLGA), biodegradable photo-luminescent PLGA and urethane doped polyester were studied. The transfer efficacy of NPs from various coatings to the arterial wall were further evaluated to find the optimal coating conditions. The ex vivo NP transfer studies showed significantly more NPs being transferred to the rat arterial wall after the angioplasty procedure by the AAH coating (95% transfer efficiency) compared to that of the LbL technique (60%) and dip coating (20%) under flow conditions (10 dyn/cm2). Our results suggest that the AAH coating of drug-loaded NPs on the angioplasty balloon could potentially provide superior retention of drug-loaded NPs onto the arterial wall for a better local delivery of drug-loaded NPs to effectively treat arterial diseases.

Targeted Ganglionated Plexi Denervation Using Magnetic Nanoparticles Carrying Calcium Chloride Payload.

OBJECTIVES: This study sought to develop a novel targeted delivery therapy to ablate the major atrial ganglionated plexi (GP) using magnetic nanoparticles carrying a CaCl2 payload. BACKGROUND: Prior studies indicated the role of hyperactivity of the cardiac autonomic nervous system in the genesis of atrial fibrillation. METHODS: Twenty-eight male mongrel dogs underwent a bilateral thoracotomy. CaCl2-encapsulated magnetic nanoparticles (Ca-MNP) included magnetite in a sphere of biocompatible, biodegradable poly(lactic-co-glycolic acid). A custom external electromagnet focusing the magnetic field gradient (2,600 G) on the epicardial surface of the targeted GP was used to pull Ca-MNP into and release CaCl2 within the GP. The ventricular rate slowing response to high frequency stimulation (20 Hz, 0.1 ms) of the GP was used to assess the GP function. RESULTS: The minimal effective concentration of CaCl2 to inhibit the GP function was 0.5 mmol/l. Three weeks after CaCl2 (0.5 mmol/l, n = 18 GP) or saline (n = 18 GP) microinjection into GP, the increased GP function, neural activity, and atrial fibrillation inducibility, as well as shortened effective refractory period in response to 6 h of rapid atrial pacing (1,200 beats/min) were suppressed by CaCl2 microinjection. After intracoronary infusion of Ca-MNP, the external electromagnet pulled Ca-MNP to the targeted GP and suppressed the GP function (n = 6 GP) within 15 min. CONCLUSIONS: Ca-MNP can be magnetically targeted to suppress GP function by calcium-mediated neurotoxicity. This novel approach may be used to treat arrhythmias related to hyperactivity of the cardiac autonomic nervous system, such as early stage of atrial fibrillation, with minimal myocardial injury.

Enhancing anti-thrombogenicity of biodegradable polyurethanes through drug molecule incorporation.

Sufficient and sustained anti-thrombogenicity is essential for blood-contacting materials, because blood coagulation and thrombosis caused by platelet adhesion and activation on material surfaces may lead to functional failure and even fatal outcomes. Covalently conjugating antithrombogenic moieties into polymer, instead of surface modifying or blending, can maintain the anti-thrombogenicity of polymer at a high level over a time range. In this study, series of randomly crosslinked, elastic, biodegradable polyurethanes (PU-DPA) were synthesized through a one-pot and one-step method from polycaprolactone (PCL) diol, hexamethylene diisocyanate (HDI) and anti-thrombogenic drug, dipyridamole (DPA). The mechanical properties, hydrophilicity, in vitro degradation, and anti-thrombogenicity of the resultant PU-DPA polymers can be tuned by altering the incorporated DPA amount. The surface and bulk hydrophilicity of the polyurethanes decreased with increasing hydrophobic DPA amount. All PU-DPA polymers exhibited strong mechanical properties and good elasticity. The degradation rates of the PU-DPAs decreased with increasing DPA content in both PBS and lipase/PBS solutions. Covalently incorporating DPA into the polyurethane significantly reduced the platelet adhesion and activation compared to the polyurethane without DPA, and also can achieve sustained anti-thrombogenicity. The PU-DPA films also supported the growth of human umbilical vein endothelial cells. The attractive mechanical properties, blood compatibility, and cell compatibility of this anti-thrombogenic biodegradable polyurethane indicate that it has a great potential to be utilized for blood-contacting devices, and cardiovascular tissue repair and regeneration.

Hybrid Nitric Oxide Donor and its Carrier for the Treatment of Peripheral Arterial Diseases.

Nitric oxide (NO) has been known to promote physiological angiogenesis to treat peripheral arterial diseases (PAD) by increasing the vascular endothelial growth factor (VEGF) level in endothelial cells (ECs) and preventing platelet adherence and leukocyte chemotaxis. However, the ongoing ischemic event during peripheral ischemia produces superoxide and diminishes the NO bioavailability by forming toxic peroxynitrite anion. Here we disclose an efficacious hybrid molecule 4-(5-Amino-1,2,3-oxadiazol-3-yl)-2,2,6,6-tetramethyl-1-piperidinol (SA-2) containing both antioxidant and NO donor functionalities that provide a therapeutic level of NO necessary to promote angiogenesis and to protect ECs against hydrogen peroxide-induced oxidative stress. Compound SA-2 scavenged reactive oxygen species, inhibited proliferation and migration of smooth muscle cells (SMCs) and promoted the tube formation from ECs. Copolymer poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with SA-2 provided a sustained release of NO over days, improved aqueous stability in serum, protected ECs against oxidative stress, and enhanced angiogenesis under stress conditions as compared to that of the control in the in vitro matrigel tube formation assay. These results indicated the potential use of SA-2 nanoparticles as an alternative therapy to treat PAD.