Distribution of PLGA-modified nanoparticles in 3D cell culture models of hypo-vascularized tumor tissue

Abstract

BackgroundAdvanced stage cancer treatments are often invasive and painful—typically comprised of surgery, chemotherapy, and/or radiation treatment. Low transport efficiency during systemic chemotherapy may require high chemotherapeutic doses to effectively target cancerous tissue, resulting in systemic toxicity. Nanotherapeutic platforms have been proposed as an alternative to more safely and effectively deliver therapeutic agents directly to tumor sites. However, cellular internalization and tumor penetration are often diametrically opposed, with limited access to tumor regions distal from vasculature, due to irregular tissue morphologies. To address these transport challenges, nanoparticles (NPs) are often surface-modified with ligands to enhance transport and longevity after localized or systemic administration. Here, we evaluate stealth polyethylene–glycol (PEG), cell-penetrating (MPG), and CPP-stealth (MPG/PEG) poly(lactic-co-glycolic-acid) (PLGA) NP co-treatment strategies in 3D cell culture representing hypo-vascularized tissue.ResultsSmaller, more regularly-shaped avascular tissue was generated using the hanging drop (HD) method, while more irregularly-shaped masses were formed with the liquid overlay (LO) technique. To compare NP distribution differences within the same type of tissue as a function of different cancer types, we selected HeLa, cervical epithelial adenocarcinoma cells; CaSki, cervical epidermoid carcinoma cells; and SiHa, grade II cervical squamous cell carcinoma cells. In HD tumors, enhanced distribution relative to unmodified NPs was measured for MPG and PEG NPs in HeLa, and for all modified NPs in SiHa spheroids. In LO tumors, the greatest distribution was observed for MPG and MPG/PEG NPs in HeLa, and for PEG and MPG/PEG NPs in SiHa spheroids.ConclusionsPre-clinical evaluation of PLGA-modified NP distribution into hypo-vascularized tumor tissue may benefit from considering tissue morphology in addition to cancer type.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-017-0298-x) contains supplementary material, which is available to authorized users.

A High‐Throughput Automated Confocal Microscopy Platform for Quantitative Phenotyping of Nanoparticle Uptake and Transport in Spheroids

“…With the intent to reduce the amount of data acquired, we next determined an appropriate image acquisition regime in the xyz dimensions ( Figure A; Supporting Information). We used this as a strategy to identify the widest cross‐section or equatorial (EQ) plane of individual 3D structures (Figure B), which can then be used for assessment of nanoparticle penetration to the center of the spheroid . An initial series of 70 z ‐planes with 0.5 µm spacing was acquired in a 10.4 mm 2 of the well area (≈ 30% of the total surface).…”

“…Based on this feature, we implemented a protocol to streamline in situ fluorescence processing and imaging, thereby avoiding manually‐intensive procedures (e.g., steps such as transfer of spheroids, embedding, cryosectioning, etc.) typically adopted in many 3D drug‐screening assays and studies assessing NP‐mediated drug penetration using fluorescence microscopy . The 3D cell culture approach described in this study enables the positioning of spheroids, once fixed, on a common optical plane .…”

“…Owing to the relevance of NPs as medical devices for targeted drug delivery, studies have been directed at visualizing uptake of various types of nanocarriers into multicellular structures, and in a few instances, investigating pathways of NP transport within the spheroid . In striking contrast to studies conducted in monolayer cell culture, the assessment of NP uptake and/or the molecular dissection of cellular pathways responsible for endocytosis and secretion into or from cells, have been interrogated in extremely low‐detail and low‐throughput fashion in 3D cell culture.…”

“…This information is essential to inform improvement of NP design in the context of nanomedicine development . Spheroid systems have been used to investigate the effect of shape, size, and composition of model NPs on their ability to penetrate and distribute inside a multicellular context using confocal, two‐photon or light‐sheet microscopy . However, quantitative fluorescent imaging of NP penetration that has the potential to be applied in large‐scale studies has not been reported.…”

Surface-Modified Melphalan Nanoparticles for Intravitreal Chemotherapy of Retinoblastoma

“…[9][10][11] In contrast, small (<500 nm) or neutrally charged ''stealth'' carriers more rapidly and effectively penetrate the tightly spaced and negatively charged vitreous or mucosal environments. [12][13][14] In previous work, we have assessed the binding and internalization mechanisms of unmodified, MPG, and poly(ethylene glycol) (PEG)-modified NPs in cells [15][16][17] and found that surface-modification with MPG results in higher cell association and binding, likely due to the positive zeta-potential, relative to more negatively charged unmodified and neutrally charged PEG NPs. Regardless of surface-modification (unmodified, MPG-modified, or PEG-modified), cell internalization occurred via clathrin-mediated endocytosis.…”