Nano delivery systems for siRNA

Abstract

The present invention makes use of a unique methodology of double nano-encapsulation for protecting and controlling the release of active agents, either hydrophobic or hydrophilic, from stable nanoparticles of opposite characteristics. The protection of the active agent was achieved by loading the agent to be protected, into nanocarriers, which were subsequently encapsulated into sub-micron nanoparticles. The sub-micron nanoparticles formation has been successfully achieved by the use of novel nano spray techniques.

Description

FIELD OF THE INVENTION[0001]This invention generally relates to nano delivery systems.BACKGROUND[0002]The discovery of RNA interference (RNAi) has opened up an entirely new field of biology and medicine. The ability of RNAi to specifically silence target genes has yielded not only a new tool for basic research but also raised the concept of developing medicines based on RNAi. RNAi works through the targeting of mRNA via sequence-specific matches and results in degradation of target mRNA or its translational inhibition, leading to the loss of protein expression. This is pharmacologically achieved via the introduction of small 19-21 bp dsRNA molecules called small interfering RNA (siRNA). Since its discovery 10 years ago, siRNA has been widely investigated in vitro for its utility in treating various diseases, such as cancer, neurodegenerative and infectious diseases.[0003]A major barrier to further development of siRNA has been the inability to effectively deliver siRNA in vivo due t...

AI Technical Summary

Benefits of technology

[0032]The delivery systems of the invention provide a platform for systemic delivery of hydrophilic bio-macromolecules (such as siRNA) or hydrophobic bio-macromolecules improving the drug's half-life, biodistribution and pharmacokinetics.

[0138]Depending on the final application and / or the nature of the delivery system, whether the active agent is hydrophobic or hydrophilic, it can be associated to the primary nanocarrier (being hydrophobic or hydrophilic), via chemical bonds (as defined hereinabove, e.g., polar, ionic, van der Waals, etc) and for polyanionic macromolecules, via the addition of a ‘helper lipid’ (such as DOTAP). This chemical association of the active agent to the nanocarriers or nanoparticles prevents leaking of the active agent and the efficacy of encapsulation process is maintained or secured (this approach may be useful depending on the final application and / or particular delivery system).

[0164]The pharmaceutical composition of the present invention may be selected to treat, prevent or diagnose any pathology or condition, depending on the active material contained within the nanoparticles. The term “treatment” or any lingual variation thereof, as used herein, refers to the administering of a therapeutic amount of the composition or system of the present invention which is effective to ameliorate undesired symptoms associated with a disease, to prevent the manifestation of such symptoms before they occur, to slow down the progression of the disease, slow down the deterioration of symptoms, to enhance the onset of remission period, slow down the irreversible damage caused in the progressive chronic stage of the disease, to delay the onset of said progressive stage, to lessen the severity or cure the disease, to improve survival rate or more rapid recovery, or to prevent the disease from occurring or a combination of two or more of the above.

Problems solved by technology

RNAi works through the targeting of mRNA via sequence-specific matches and results in degradation of target mRNA or its translational inhibition, leading to the loss of protein expression.

A major barrier to further development of siRNA has been the inability to effectively deliver siRNA in vivo due to the large molecular weight (for example, 13 kDa) and polyanionic nature (e.g. 40 negative phosphate charges).

Furthermore, unmodified, naked siRNAs are relatively unstable in blood and serum, as they are rapidly degraded by endo- and exonucleases, meaning that they have short half-lives in vivo.

However, the ability of these cationic particles to deliver siRNA systemically is often poor due to rapid uptake by reticuloendothelial (RES) organs [5], thereby hindering the delivery of these particles to the site of interest.

However, most of these methods, though effective, require relatively complicated and lengthy formulation procedures with the resulting particles suspended in an aqueous state.

This has led to long-term storage issues including aggregation and / or fusion of the particles, hydrolysis of the lipids, and instability of siRNA nucleotides in an aqueous environment.

Moreover, these formulations are also prone to be affected by stresses occurring during transport, such as agitation or temperature fluctuation [11].

These problems, along with the significantly increased effort required for large-scale production of these particles using the existing formulation procedures will limit the widespread adoption of siRNA-containing lipid-based products in the clinics.

However, the number of clinically relevant nanocarriers used for such a purpose is scarce, and major challenges still remain to be solved, especially for their efficient delivery via the parenteral route of administration. siRNAs represent a class of hydrophilic bio-macromolecules where the application of appropriate nanocarriers is most needed to exploit their full therapeutic potential.