Evaluation of paclitaxel-loaded polymeric nanoparticles in 3D tumor model: impact of tumor stroma on penetration and efficacy

Abstract

Since tumor stroma poses as a barrier to achieve efficacy of nanomedicines, it is essential to evaluate nano-chemotherapeutics in stroma-mimicking 3D models that reliably predict their behavior regarding these hurdles limiting efficacy. In this study, we evaluated the effect of paclitaxel-loaded polymeric micelles (PTX-PMCs) and polymeric nanoparticles (PTX-PNPs) in a tumor stroma–mimicking 3D in vitro model. PTX-PMCs (77 nm) based on a amphiphilic block copolymer of mPEG-b-p(HPMAm-Bz) and PTX-PNPs (159 nm) based on poly(lactic-co-glycolic acid) were prepared, which had an encapsulation efficiency (EE%) of 81 ± 15% and 45 ± 8%, respectively. 3D homospheroids of mouse 4T1 breast cancer cells and heterospheroids of NIH3T3 fibroblasts and 4T1 (5:1 ratio) were prepared and characterized with high content two-photon microscopy and immunostaining. Data showed an induction of epithelial-mesenchymal transition (α-SMA) in both homo- and heterospheroids, while ECM (collagen) deposition only in heterospheroids. Two-photon imaging revealed that both fluorescently labeled PMCs and PNPs penetrated into the core of homospheroids and only PMCs penetrated into heterospheroids. Furthermore, PTX-PMCs, PTX-PNPs, and free PTX induced cytotoxicity in tumor cells and fibroblasts grown as monolayer, but these effects were substantially reduced in 3D models, in particular in heterospheroids. Gene expression analysis showed that heterospheroids had a significant increase of drug resistance markers (Bcl2, Abgc2) compared to 2D or 3D monocultures. Altogether, this study shows that the efficacy of nanotherapeutics is challenged by stroma-induced poor penetration and development of resistant phenotype. Therefore, this tumor stroma–mimicking 3D model can provide an excellent platform to study penetration and effects of nanotherapeutics before in vivo studies. Graphical Abstract

Architectural organization and molecular profiling of 3D cancer heterospheroids and their application in drug testing

“…The formation of reproducible 3D cell structures comprising cancer cell lines and the 1BR.3.G fibroblasts indicated dynamic interactions between the two cell populations. We and others have previously reported that fibroblasts support the development of spheroid structures ( 17 , 23 , 25 , 33 , 34 ), but the use of 1BR.3.G in 3D cancer models has not previously been reported. Here, we found that the 1BR.3.G cell line generally supported 3D spheroid structures to a broader extent than the skin fibroblast GM00498, and the more commonly used lung fibroblast MRC-5, as well as the intestinal HIF fibroblasts.…”

“…A variety of heterospheroids, a subgroup of MCTS ( 13 ), have been developed and comprise human cancer cell lines originating from e.g. colon ( 14 , 15 ), breast ( 16 , 17 ), pancreas ( 18 – 21 ), skin ( 22 ) and lung ( 23 – 26 ), combined with fibroblast cell lines often derived from human lung (MRC-5 cells) or from mouse embryo (NIH/3T3 cells).…”

Nitric oxide/paclitaxel micelles enhance anti-liver cancer effects and paclitaxel sensitivity by inducing ferroptosis, endoplasmic reticulum stress and pyroptosis

“…36,37 To enhance the water solubility, bioavailability, and reduce toxicity of taxanes, various pharmaceutical formulation techniques such as liposomes, polymeric micelles, and other carriers have been developed as nanomedicine delivery systems. [38][39][40] Building upon the synergistic anti-tumor effect of NO and PTX and with the goal of improving the pharmacokinetic prole of PTX, we previously designed and synthesized an NO-donating polymer, consisting of monomethoxy poly(ethylene glycol) and polylactic acid (mPEG-PLA-NO). This polymer was used to generate biodegradable polymeric micelles loaded with PTX (NO/ PTX) in a nanoparticle delivery system (Fig.…”

Delivery of Chemotherapy Agents and Nucleic Acids with pH-Dependent Nanoparticles

“…Furthermore, increased protonation of weakly basic carriers/ligands in an acidic tumor matrix leads to greater binding and uptake by tumor cells, which have, in general, a higher negative surface membrane charge. An increase in uptake applies not only to basic carriers such as polyethylenimine (PEI), but also to nanoparticles modified with acidic peptides [ 18 ]. Additional interactions with pH-sensitive peptides/polymers may enhance the nanoparticle’s uptake.…”

“…Unlike Dox and irinotecan, other chemotherapeutic agents, such as cisplatin or paclitaxel (PTX), have not been loaded efficiently into liposomes [ 16 ]. Nonetheless, there are non-liposomal polymeric nanoparticles with high loading capacity for PTX and prolonged half-lives in the bloodstream, which have demonstrated marked antitumor efficacy [ 17 , 18 ]. Although several clinical trials are evaluating the efficacy of polymeric-chemotherapy agents, none of these have been approved for clinical use by regulatory agencies [ 10 , 19 ].…”