Nanoliposomes Permeability in a Microfluidic Drug Delivery Platform across a 3D Hydrogel

Abstract

Nanoliposomes are nano-sized vesicles that can be used as drug delivery carriers with the ability to encapsulate both hydrophobic and hydrophilic compounds. Moreover, their lipid compositions facilitate their internalization by cells. However, the interaction between nanoliposomes and the membrane barrier of the human body is not well-known. If cellular tests and animal testing offer a solution, their lack of physiological relevance and ethical concerns make them unsuitable to properly mimic human body complexity. Microfluidics, which allows the environment of the human body to be imitated in a controlled way, can fulfil this role. However, existing models are missing the presence of something that would mimic a basal membrane, often consisting of a simple cell layer on a polymer membrane. In this study, we investigated the diffusion of nanoliposomes in a microfluidic system and found the optimal parameters to maximize their diffusion. Then, we incorporated a custom made GelMA with a controlled degree of substitution and studied the passage of fluorescently labeled nanoliposomes through this barrier. Our results show that highly substituted GelMA was more porous than lower substitution GelMA. Overall, our work lays the foundation for the incorporation of a hydrogel mimicking a basal membrane on a drug delivery microfluidic platform.

Introduction

Nanoliposomes are considered as the most successful drug delivery system, with 15 liposomal drugs approved for clinical uses [1,2]. With a diameter of between 100 and 200 nm, their unique structure confers them the ability to encapsulate both hydrophilic and hydrophobic compounds [3,4,5]. The enhanced permeability and retention (EPR) effect helps nanoliposomes easily deliver their payload intracellularly. For this reason, they have garnered significant attention in recent years in various biomedical applications such as drug delivery and cancer therapy [6,7,8,9].
An important aspect of their utilization lies in comprehending their diffusion pathways through epithelial membranes via the trans- and para-cellular transporter pathway [10,11]. To study the interaction between nanoliposomes and epithelial membranes, there is a wide variety of tools to choose from animal models to Petri dish culture and Transwell® systems [12,13,14,15,16]. However, while cell cultures have a high throughput, they lack physiological relevance and if animal models are more relevant to mimic the in vivo mechanisms, there is an imperative to reduce our reliance on animal experimentation for ethical reasons [17,18,19]. Finally, testing the products from a laboratory scale to clinical trial is a slow process and there is a growing demand for in vitro tools and methodologies that mimic human epithelial tissues. The Transwell® system is a widely used technique that consists of two superimposed compartments that rely on passive particle diffusion. While they can mimic somewhat accurately the diffusion coefficient of drugs compared to in vivo values, their simplified structure, and the lack of active flow rate for compound diffusion, does not thoroughly recapitulate in vivo conditions.

In the last decade, microfluidic systems, more specifically, organ-on-a-chip, have been proposed to address this issue. Organ-on-a-chip microfluidic devices usually consist of two parallel channels representing either side of the epithelium and are separated by a membrane on which cells are cultured [20,21]. Microfluidic devices allow us to mimic the circulation of fluid to mimic blood flow and mechanical contraction of the membrane for a more accurate imitation of the in vivo environment. The addition of mechanical stimuli has been demonstrated to influence cell fate and to help recreate tissue-like structures observed in vivo (e.g., villi for gut) [22,23]. Such models offer a means to probe nanoliposome interactions with epithelial barriers in a controlled and physiologically relevant environment. However, these microfluidic models consist of a single cell layer on top of a polymer membrane, and they lack the presence of a basal membrane for the cells. The latter has been shown to direct cell fate, and its presence could therefore play a role to better mimic biological structures such as epitheliums [24,25]. Therefore, the addition of a hydrogel mimicking the basal membrane would be a step forward in the re-creation of a more physiologically relevant environment, and studying the passage of nanoparticles through them would help in understanding the interaction between nanoliposomes and epitheliums.

Here, we looked at the diffusion of nanoliposomes across a membrane in a microfluidic system. First, we determined the optimum parameters for promoting the passage of nanoliposomes through the system’s membrane. Then, using these parameters, we added a hydrogel membrane made of gelatin methacryloyl and studied the diffusion of nanoliposomes through it, where we found that the addition of the hydrogel did not obstruct the passage of nanoliposomes. This work is the first step toward establishing a more complex system, with the next being the addition of cells on the hydrogel to mimic an epithelium.

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Materials

Gelatin from porcine skin (Type A, 300 bloom), methacrylic anhydride (MA), Irgacure 2959 (PI) (2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone), Dulbecco’s phosphate-buffered saline (DPBS), and hexamethyldisilazane (HMDS) were purchased from Sigma-Aldrich (Saint-Quentin-Fallavier, France). 1,1′-Dioctadecyl-3,3,3′,3′tetramethylindocarbocyanine-perchlorate (Dil stain) was purchased from Thermo Fisher, France (Illkirch-Graffenstaden, France). Deuterium oxide (99.9 atom% D) was purchased from Eurisotop (Saint-Aubin, France).

Peyret, C.; Manousaki, A.; Bouguet-Bonnet, S.; Stratakis, E.; Sanchez-Gonzalez, L.; Kahn, C.J.F.; Arab-Tehrany, E. Nanoliposomes Permeability in a Microfluidic Drug Delivery Platform across a 3D Hydrogel. Pharmaceutics 2024, 16, 765. https://doi.org/10.3390/pharmaceutics16060765

Read also our introduction article on Gelatin here:

excipients formulation