How to study dendriplexes II: Transfection and cytotoxicity

How to screen non-viral gene delivery systems in vitro?

Screening of new gene delivery candidates regarding transfection efficiency and toxicity is usually performed by reading out transgene expression levels relative to a reference formulation after in vitro transfection. However, over the years and among different laboratories, this screening has been performed in a variety of cell lines, using a variety of conditions and read-out systems, and by comparison to a variety of reference formulations. This makes a direct comparison of results difficult, if not impossible. Reaching a consensus would enable placing new results into context of previous findings and estimate the overall contribution to the improvement of non-viral gene delivery. In this paper we illustrate the sensitivity of transfection outcomes on testing conditions chosen, and propose a screening protocol with the aim of standardization within the field.

Advances in using chitosan-based nanoparticles for in vitro and in vivo drug and gene delivery

IMPORTANCE OF THE FIELD

This review aims to provide an overview of state-of-the-art chitosan-based nanosized carriers for the delivery of therapeutic agents. Chitosan nanocarriers are smart delivery systems owing to the possibility of their property alterations with various approaches, which would confer them with the possibility of spatiotemporal delivery features.

AREAS COVERED IN THIS REVIEW

The focus of this review is principally on those aspects that have not often been addressed in other reviews. These include the influence of physicochemical properties of chitosan on delivery mechanisms and chitosan modification with a variety of ligand moieties specific for cell surface receptors to increase recognition and uptake of nanocarriers into cells through receptor-mediated endocytosis. Multiple examples that demonstrate the advantages of chitosan-based nanocarriers over other delivery systems of therapeutic agents are highlighted. Particular emphasis is given to the alteration of material properties by functionalization or combination with other polymers for their specific applications. Finally, structural and experimental parameters influencing transfection efficiency of chitosan-based nanocarriers are presented for both in vitro and in vivo gene delivery.

WHAT THE READER WILL GAIN

The readers will acquire knowledge of parameters influencing the properties of the chitosan-based nanocarriers for delivery of therapeutic agents (genetic material or drugs) in vitro and in vivo. They will get a better idea of the strategies to be adapted to tune the characteristics of chitosan and chitosan derivatives for specific delivery applications.

TAKE HOME MESSAGE

Chitosan is prone to chemical and physical modifications, and is very responsive to environmental stimuli such as temperature and pH. These features make chitosan a smart material with great potential for developing multifunctional nanocarrier systems to deliver large varieties of therapeutic agents administrated in multiple ways with reduced side effects.

Alkyl sulfonyl derivatized PAMAM-G2 dendrimers as nonviral gene delivery vectors with improved transfection efficiencies

Amphiphilic dendrimer-based gene delivery vectors bearing peripheral alkyl sulfonyl hydrophobic tails were constructed using low-generation PAMAM-G2 as the core and functionalized by means of the aza-Michael type addition of its primary amino groups to vinylsulfone derivatives as an efficient tool for surface engineering. While the unmodified PAMAM-G2 was unable to efficiently transfect eukaryotic cells, functionalized PAMAM-G2 dendrimers were able to bind DNA at low N/P ratios, protect DNA from digestion with DNase I and showed high transfection efficiencies and low cytotoxicity. Dendrimers with a C18 alkyl chain produced transfection efficiencies up to 3.1 fold higher than LipofectAMINE™ 2000 in CHO-k1 cells. The dendriplexes based in functionalized PAMAM-G2 also showed the ability to retain their transfection properties in the presence of serum and the ability to transfect different eukaryotic cell lines such as Neuro-2A and RAW 264.7. Taking advantage of the vinylsulfone chemistry, fluorescent PAMAM-G2 derivatives of these vectors were prepared as molecular probes to determine cellular uptake and internalization through a clathrin-independent mechanism.

Dynamic and cellular interactions of nanoparticles in vascular-targeted drug delivery

Vascular-targeted drug delivery systems could provide more efficient and effective pharmaceutical interventions for treating a variety of diseases including cardiovascular, pulmonary, inflammatory, and malignant disorders. However, several factors must be taken into account when designing these systems. The diverse blood hemodynamics and rheology, and the natural clearance process that tend to decrease the circulation time of foreign particles all lessen the probability of successful carrier interaction with the vascular wall. An effective vascular-targeted drug delivery system must be able to navigate through the bloodstream while avoiding immune clearance, attach to the vascular wall, and release its therapeutic cargo at the intended location. This review will summarize and analyze current literature reporting on (1) nanocarrier fabrication methods and materials that allow for optimum therapeutic encapsulation, protection, and release; (2) localization and binding dynamics of nanocarriers as influenced by hemodynamics and blood rheology in medium-to-large vessels; (3) blood cells' responses to various types of nanocarrier compositions and its effects on particle circulation time; and (4) properties that affect nanocarrier internalization at the target site.

Dynamic and cellular interactions of nanoparticles in vascular-targeted drug delivery (review)

Vascular-targeted drug delivery systems could provide more efficient and effective pharmaceutical interventions for treating a variety of diseases including cardiovascular, pulmonary, inflammatory, and malignant disorders. However, several factors must be taken into account when designing these systems. The diverse blood hemodynamics and rheology, and the natural clearance process that tend to decrease the circulation time of foreign particles all lessen the probability of successful carrier interaction with the vascular wall. An effective vascular-targeted drug delivery system must be able to navigate through the bloodstream while avoiding immune clearance, attach to the vascular wall, and release its therapeutic cargo at the intended location. This review will summarize and analyze current literature reporting on (1) nanocarrier fabrication methods and materials that allow for optimum therapeutic encapsulation, protection, and release; (2) localization and binding dynamics of nanocarriers as influenced by hemodynamics and blood rheology in medium-to-large vessels; (3) blood cells' responses to various types of nanocarrier compositions and its effects on particle circulation time; and (4) properties that affect nanocarrier internalization at the target site.