Reducing hydrophobic drug adsorption in an in-vitro extracorporeal membrane oxygenation model.

Extracorporeal membrane oxygenation (ECMO) is a life-saving cardiopulmonary bypass technology for critically ill patients with heart and lung failure. Patients treated with ECMO receive a range of drugs that are used to treat underlying diseases and critical illnesses. However, the dosing guidelines for these drugs used in ECMO patients are unclear. Mortality rate for patients on ECMO exceeds 40% partly due to inaccurate dosing information, caused in part by the adsorption of drugs in the ECMO circuit and its components. These drugs range in hydrophobicity, electrostatic interactions, and pharmacokinetics. Propofol is commonly administered to ECMO patients and is known to have high adsorption rates to the circuit components due to its hydrophobicity. To reduce adsorption onto the circuit components, we used micellar block copolymers (Poloxamer 188TM and Poloxamer 407TM) and liposomes tethered with poly(ethylene glycol) to encapsulate propofol, provide a hydrophilic shell and prevent its adsorption. Size, polydispersity index (PDI), and zeta potential of the delivery systems were characterized by dynamic light scattering, and encapsulation efficiency was characterized using High Performance Liquid Chromatography (HPLC). All delivery systems used demonstrated colloidal stability at physiological conditions for seven days, cytocompatibility with a human leukemia monocytic cell line, i.e., THP-1 cells, and did not activate the complement pathway in human plasma. We demonstrated a significant reduction in adsorption of propofol in an in-vitro ECMO model upon encapsulation in micelles and liposomes. These results show promise in reducing the adsorption of hydrophobic drugs to the ECMO circuits by encapsulation in nanoscale structures tethered with hydrophilic polymers on the surface.

Vascular permeability in HPV+ oropharyngeal cancers aids in fluorescent image-guided transoral robotic surgery using indocyanine green.

BACKGROUND: Indocyanine green (ICG) fluorescent image (FI)-guided surgery has demonstrated success in improving intraoperative visualization and tumor resections. The objectives were to evaluate the use of IGC in FI-guided transoral robotic surgery (TORS) and the underlying molecular mechanism. METHODS: HPV+ oropharyngeal squamous cell carcinoma (OPSCCa) patient (n = 10) undergoing TORS were enrolled in this prospective study. Participants received intravenous ICG. Excised tissues were evaluated for ICG accumulation, tumor demarcation, and pathological characteristics using In-vivo imaging system (IVIS), histology, and RNA sequencing. RESULTS: ICG accumulation was significantly increased in primary tumor and pathological lymph nodes compared with normal tissues (p < 0.001). IVIS was 91.3% accurate in identifying OPSCCa in excised tissues; the correlation between IVIS- and histologically determined tumor tissues was significant (R2 = 0.8301; p = 0.001). Genes associated with vascular and angiogenic signaling pathways were significantly upregulated in OPSCCa tissues. CONCLUSION: ICG effectively demarcates tumor margins in OPSCCa, due to the increased upregulation of genes associated with vascular permeability.

Micellar Encapsulation of Propofol Reduces its Adsorption on Extracorporeal Membrane Oxygenator (ECMO) Circuit.

Extracorporeal membrane oxygenation (ECMO) is a life-saving cardiopulmonary bypass device used on critically ill patients with refractory heart and lung failure. Patients supported with ECMO receive numerous drugs to treat critical illnesses and the underlying diseases. Unfortunately, most drugs prescribed to patients on ECMO lack accurate dosing information. Dosing can be variable in this patient population because the ECMO circuit components can adsorb drugs and affect drug exposure substantially. Propofol is a widely used anesthetic in ECMO patients and is known to have high adsorption rates in ECMO circuits due to its high hydrophobicity. In an attempt to reduce adsorption, we encapsulated propofol with Poloxamer 407 (Polyethylene-Polypropylene Glycol). Size and polydispersity index (PDI) were characterized using dynamic light scattering. Encapsulation efficiency was analyzed using High performance liquid chromatography. Cytocompatibility of micelles was analyzed against human macrophages and the formulation was finally injected in an ex-vivo ECMO circuit to determine the adsorption of propofol. Size and PDI of micellar propofol were 25.5 ± 0.8 nm and 0.08 ± 0.01, respectively. Encapsulation efficiency of the drug was 96.1 ± 1.3%. Micellar propofol demonstrated colloidal stability at physiological temperature for a period of 7 days, and was cytocompatible with human macrophages. Micellar propofol demonstrated a significant reduction in adsorption of propofol in the ECMO circuit at earlier time points compared to free propofol (Diprivan®). We observed 97 ± 2% recovery of the propofol from the micellar formulation after an infusion. These results demonstrate the potential of micellar propofol to reduce drug adsorption to ECMO circuit.

Inflammation-driven vascular dysregulation in chronic rhinosinusitis.

BACKGROUND: Altered neovascularity is typically observed in chronic inflammatory diseases with overlapping pathophysiology to that observed in chronic rhinosinusitis (CRS). However, characterization of these inflammatory-induced vascular-mediated changes in CRS is limited. Understanding the underlying vascular changes in CRS will allow for strategic design and development of new drug-delivery technologies that exploit vascular permeability for increased extravasation into the target sinonasal tissues. METHODS: Patients with CRS with nasal polyps (CRSwNP) and without nasal polyps (CRSsNP) and non-CRS controls were enrolled in this prospective, observational study. The extent of angiogenesis in tissue was characterized using immunohistochemical and multiplex gene expression analyses. Vascular permeability, interendothelial junction structures, and endothelial barrier morphology were evaluated using transmission electron microscopy. RESULTS: Sinonasal vascularity was increased significantly in CRSsNP and CRSwNP (p < 0.05) when compared with controls, as assessed by enumerating the platelet endothelial cell adhesion molecule (PECAM-1)-positive blood vessels. Pro-angiogenic gene expression, including PECAM1 and platelet-activating factor receptor, was elevated significantly in patients with CRSwNP when compared with controls (p < 0.05). The fenestration sizes between endothelial cells (17-280 nm) were larger in CRSwNP compared with CRSsNP (10-33 nm) patients and controls (4-12 nm). Global thinning of the endothelial cell lining was observed in CRS patients but not in controls. CONCLUSION: Significant increases in vascularity, the pro-angiogenic gene, and protein expression and blood vessel morphogenesis were observed in CRS patients compared with controls. In addition, fenestration sizes between interendothelial junction structures were larger in CRS patients than in controls, suggesting inflammation-driven vascular dysregulation in CRS pathology.

Meta-analysis of global and high throughput public gene array data for robust vascular gene expression discovery in chronic rhinosinusitis: Implications in controlled release.

BACKGROUND: Chronic inflammation is known to cause alterations in vascular homeostasis that directly affects blood vessel morphogenesis, angiogenesis, and tissue permeability. These phenomena have been investigated and exploited for targeted drug delivery applications in the context of cancers and other disease processes. Vascular pathophysiology and its associated genes and signaling pathways, however, have not been systematically investigated in patients with chronic rhinosinusitis (CRS). Understanding the interplay between key vascular signaling pathways and top biomarkers associated with CRS may facilitate the development of new targeted delivery strategies and treatment paradigms. Herein, we report findings from a gene meta-analysis to identify key vascular pathways and top genes involved in CRS. METHODS: Proprietary software (Illumina BaseSpace Correlation Engine) and open-access data sets were used to perform a gene meta-analysis to systematically determine significant differences between key vascular biomarkers and vascular signaling pathways expressed in sinonasal tissue biopsies of controls and patients with CRS. RESULTS: Thirteen studies were initially identified, and then reduced to five after applying exclusion principle algorithms. Genes associated with vasculature development and blood vessel morphogenesis signaling pathways were identified to be overexpressed among the top 15 signaling pathways. Out of many significantly upregulated genes, the levels of pro angiogenic genes such as early growth response (EGR3), platelet endothelial cell adhesion molecule (PECAM1) and L-selectin (SELL) were particularly significant in patients with CRS compared to controls. DISCUSSION: Key vascular biomarkers and signaling pathways were significantly overexpressed in patients with CRS compared to controls, suggesting a contribution of vascular dysfunction in CRS pathophysiology. Vascular dysregulation and permeability may afford opportunities to develop drug delivery systems to improve efficacy and reduce toxicity of CRS treatment.

A dual-functional Embolization-Visualization System for Fluorescence image-guided Tumor Resection.

Rationale: Intraoperative bleeding impairs physicians' ability to visualize the surgical field, leading to increased risk of surgical complications and reduced outcomes. Bleeding is particularly challenging during endoscopic-assisted surgical resection of hypervascular tumors in the head and neck. A tool that controls bleeding while marking tumor margins has the potential to improve gross tumor resection, reduce surgical morbidity, decrease blood loss, shorten procedure time, prevent damage to surrounding tissues, and limit postoperative pain. Herein, we develop and characterize a new system that combines pre-surgical embolization with improved visualization for endoscopic fluorescence image-guided tumor resection. Methods: Silk-elastinlike protein (SELP) polymers were employed as liquid embolic vehicles for delivery of a clinically used near-infrared dye, indocyanine green (ICG). The biophysical properties of SELP, including gelation kinetics, modulus of elasticity, and viscosity, in response to ICG incorporation using rheology, were characterized. ICG release from embolic SELP was modeled in tissue phantoms and via fluorescence imaging. The embolic capability of the SELP-ICG system was then tested in a microfluidic model of tumor vasculature. Lastly, the cytotoxicity of the SELP-ICG system in L-929 fibroblasts and human umbilical vein endothelial cells (HUVEC) was assessed. Results: ICG incorporation into SELP accelerated gelation and increased its modulus of elasticity. The SELP embolic system released 83 ± 8% of the total ICG within 24 hours, matching clinical practice for pre-surgical embolization procedures. Adding ICG to SELP did not reduce injectability, but did improve the gelation kinetics. After simulated embolization, ICG released from SELP in tissue phantoms diffused a sufficient distance to deliver dye throughout a tumor. ICG-loaded SELP was injectable through a clinical 2.3 Fr microcatheter and demonstrated deep penetration into 50-µm microfluidic-simulated blood vessels with durable occlusion. Incorporation of ICG into SELP improved biocompatibility with HUVECs, but had no effect on L-929 cell viability. Principle Conclusions: We report the development and characterization of a new, dual-functional embolization-visualization system for improving fluorescence-imaged endoscopic surgical resection of hypervascular tumors.