Further insight in selecting the ideal vein for lymphaticovenous anastomosis: utilizing the anatomy and Venturi effect of a small vein/venule draining into the main vein.

INTRODUCTION: The functional and dilated lymphatic vessel and veins with minimal backflow and pressure are considered ideal for lymphaticovenous anastomsosis (LVA). However, how to select the ideal vein remains to be determined. This study aims to provide further insight in selecting the ideal vein. MATERIAL AND METHODS: This is a retrospective study evaluating 166 limbs with lymphedema with a minimal follow-up period of 12 months. The surgical approach included side-to-end LVA where one group used a non-Venturi LVA and the other used a small branch draining into a major vein (Venturi LVA). Preoperative, postoperative 1, 3, 6, 12 months limb volume, circumference, reduction volume and ratio were evaluated. RESULTS: The postoperative volume reduction was significant for both groups when compared to their respective preoperative volume. When compared between the 2 groups, the Venturi LVA had a significantly higher reduction volume and ratio at postoperative 1 month (240.82±260.73 cm³ vs 364.27±364.08 cm³, 6.13±5.62% vs 8.77±6.64%; p<0.05) and at 3 months (289.19±291.42 cm³ vs 432.50±395.04cm³, 7.31 ± 6.39% vs 10.55 ± 6.88%; p<0.05) However, the reduction volume and ratio was not significant towards month 6 and 12. CONCLUSION: This study provides further insight in selecting the ideal vein for LVA. By using a small vein draining into the main vein, valves play a role in reducing backflow. Furthermore, the Venturi effect allows significantly enhanced drainage especially in the initial period after surgery. The effect slowly plateaus after few months ultimately having a similar outcome of reduction at 12 months.

Macrophage-reprogramming upconverting nanoparticles for enhanced TAM-mediated antitumor therapy of hypoxic breast cancer.

In an attempt to achieve antitumor effects by switching the phenotype of macrophages from the tumor-promoting M2 type to the tumor-suppressing M1 type, we fabricated mannose-decorated/macrophage membrane-coated, silica-layered NaErF4@NaLuF4 upconverting nanoparticles (UCNPs) co-doped with perfluorocarbon (PFC)/chlorin e6 (Ce6) and loaded with paclitaxel (PTX) (UCNP@mSiO2-PFC/Ce6@RAW-Man/PTX: ∼61 nm; -11.6 mV). These nanoparticles were designed to have two major functionalities, (i) efficient singlet oxygen generation aided by an oxygen supply and (ii) good targeting to tumor-associated macrophage (TAMs) (M2-type), to induce polarization to M1 type macrophages that release proinflammatory cytokines and suppress breast cancers. The primary UCNPs consisted of lanthanide elements (erbium and lutetium) in a core@shell structure, and they facilely emitted 660 nm light in response to a deep-penetrating 808 nm near-infrared laser. Moreover, the UCNPs@mSiO2-PFC/Ce6@RAW-Man/PTX were able to release O2 and generate 1O2 because of the co-doped PFC/Ce6 and upconversion. Our nanocarriers' excellent uptake to RAW 264.7 macrophage cells (M2 type) and efficient M1-type polarization activity were clearly demonstrated using qRT-PCR and immunofluorescence-based confocal laser scanning microscopy. Our nanocarriers displayed significant cytotoxicity to 4T1 cells in 2D culture and 3D co-culture systems of 4T1/RAW 264.7 cells. More importantly, UCNPs@mSiO2-PFC/Ce6@RAW-Man/PTX (+808 nm laser) noticeably suppressed tumor growth in 4T1-xenografted mice, compared with the other treatment groups (332.4 vs. 709.5-1185.5 mm3). We attribute this antitumor efficacy to the prominent M1-type macrophage polarization caused by our nanocarriers through efficient ROS/O2 generation and targeting of M2-type TAMs via mannose ligands on coated macrophage-membrane.

Upconverting nanoparticle-containing erythrocyte-sized hemoglobin microgels that generate heat, oxygen and reactive oxygen species for suppressing hypoxic tumors.

Inspired by erythrocytes that contain oxygen-carrying hemoglobin (Hb) and that exhibit photo-driven activity, we introduce homogenous-sized erythrocyte-like Hb microgel (µGel) systems (5-6 µm) that can (i) emit heat, (ii) supply oxygen, and (iii) generate reactive oxygen species (ROS; 1O2) in response to near-infrared (NIR) laser irradiation. Hb µGels consist of Hb, bovine serum albumin (BSA), chlorin e6 (Ce6) and erbium@lutetium upconverting nanoparticles (UCNPs; ∼35 nm) that effectively convert 808 nm NIR light to 660 nm visible light. These Hb µGels are capable of releasing oxygen to help generate sufficient reactive oxygen species (1O2) from UCNPs/Ce6 under severely hypoxic condition upon NIR stimulation for efficient photodynamic activity. Moreover, the Hb µGels emit heat and increase surface temperature due to NIR light absorption by heme (iron protoporphyrin IX) and display photothermal activity. By changing the Hb/UCNP/Ce6 ratio and controlling the amount of NIR laser irradiation, it is possible to formulate bespoke Hb µGels with either photothermal or photodynamic activity or both in the context of combined therapeutic effect. These Hb µGels effectively suppress highly hypoxic 4T1 cell spheroid growth and xenograft mice tumors in vivo.

Combined Antitumor Therapy Using In Situ Injectable Hydrogels Formulated with Albumin Nanoparticles Containing Indocyanine Green, Chlorin e6, and Perfluorocarbon in Hypoxic Tumors.

Combined therapy using photothermal and photodynamic treatments together with chemotherapeutic agents is considered one of the most synergistic treatment protocols to ablate hypoxic tumors. Herein, we sought to fabricate an in situ-injectable PEG hydrogel system having such multifunctional effects. This PEG hydrogel was prepared with (i) nabTM-technique-based paclitaxel (PTX)-bound albumin nanoparticles with chlorin-e6 (Ce6)-conjugated bovine serum albumin (BSA-Ce6) and indocyanine green (ICG), named ICG/PTX/BSA-Ce6-NPs (~175 nm), and (ii) an albumin-stabilized perfluorocarbon (PFC) nano-emulsion (BSA-PFC-NEs; ~320 nm). This multifunctional PEG hydrogel induced moderate and severe hyperthermia (41-42 °C and >48 °C, respectively) at the target site under two different 808 nm laser irradiation protocols, and also induced efficient singlet oxygen (1O2) generation under 660 nm laser irradiation supplemented by oxygen produced by ultrasound-triggered PFC. Due to such multifunctionality, our PEG hydrogel formula displayed significantly enhanced killing of three-dimensional 4T1 cell spheroids and also suppressed the growth of xenografted 4T1 cell tumors in mice (tumor volume: 47.7 ± 11.6 and 63.4 ± 13.0 mm3 for photothermal and photodynamic treatment, respectively, vs. PBS group (805.9 ± 138.5 mm3), presumably based on sufficient generation of moderate heat as well as 1O2/O2 even under hypoxic conditions. Our PEG hydrogel formula also showed excellent hyperthermal efficacy (>50 °C), ablating the 4T1 tumors when the irradiation duration was extended and output intensity was increased. We expect that our multifunctional PEG hydrogel formula will become a prototype for ablation of otherwise poorly responsive hypoxic tumors.