bims-limsir 2022-05-29 papers

Nucleic Acid Ther. 2022 May 24.

Delivery of RNA Therapeutics: The Great Endosomal Escape!

Steven F Dowdy, Ryan L Setten, Xian-Shu Cui, Satish G Jadhav.

RNA therapeutics, including siRNAs, antisense oligonucleotides, and other oligonucleotides, have great potential to selectively treat a multitude of human diseases, from cancer to COVID to Parkinson's disease. RNA therapeutic activity is mechanistically driven by Watson-Crick base pairing to the target gene RNA without the requirement of prior knowledge of the protein structure, function, or cellular location. However, before widespread use of RNA therapeutics becomes a reality, we must overcome a billion years of evolutionary defenses designed to keep invading RNAs from entering cells. Unlike small-molecule therapeutics that are designed to passively diffuse across the cell membrane, macromolecular RNA therapeutics are too large, too charged, and/or too hydrophilic to passively diffuse across the cellular membrane and are instead taken up into cells by endocytosis. However, similar to the cell membrane, endosomes comprise a lipid bilayer that entraps 99% or more of RNA therapeutics, even in semipermissive tissues such as the liver, central nervous system, and muscle. Consequently, before RNA therapeutics can achieve their ultimate clinical potential to treat widespread human disease, the rate-limiting delivery problem of endosomal escape must be solved in a clinically acceptable manner.

Keywords: ASO; RNA therapeutics; delivery; endosomal escape; siRNA

DOI: https://doi.org/10.1089/nat.2022.0004

Biomaterials. 2022 Apr 05. pii: S0142-9612(22)00149-1. [Epub ahead of print]286 121510

Non-viral siRNA delivery to T cells: Challenges and opportunities in cancer immunotherapy.

Jelter Van Hoeck, Kevin Braeckmans, Stefaan C De Smedt, Koen Raemdonck.

T lymphocytes are the major drivers of antitumor immunity. The recent clinical success of adoptive T cell therapies and immune checkpoint inhibitors has demonstrated the strength of modulating T cell function in fighting cancer. Nonetheless, a significant fraction of patients remain unresponsive largely due to the immunosuppressive tumor environment that blunts T cell activity. Small interfering RNAs (siRNAs) offer the potential to sequence-specifically silence the expression of negative regulator genes in T cells in a transient manner, thereby releasing the block on anti-tumor responses. Despite the current focus on small molecule- and antibody-based immune checkpoint inhibitors as well as T cell-directed delivery of mRNA and genome editing machinery, the application of siRNA involves important clinical advantages. The recent surge of adoptive cell therapies and development of new and potent delivery approaches has enabled efficient siRNA delivery to T cells both ex vivo and in vivo. As such, siRNA molecules have a newfound potential to improve the proliferation, survival, tumor infiltration and potency of T cells in cancer immunotherapy. In this review, we briefly discuss the extracellular and intracellular delivery hurdles associated with siRNA therapy, in particular with regard to T cell targeting. We provide a timely and comprehensive overview of current and emerging delivery technologies used for siRNA transfection, discussing their strengths and weaknesses from a clinical as well as a manufacturing point-of-view. Finally, we critically review the current status and new potential avenues for modulating T cell function in cancer immunotherapy using siRNA.

Keywords: Cell engineering; Cell therapy; Immunotherapy; T cell reprogramming; T cell targeting; siRNA delivery

DOI: https://doi.org/10.1016/j.biomaterials.2022.121510

Bioeng Transl Med. 2022 May;7(2): e10280

Macrophage-targeted delivery of siRNA to silence Mecp2 gene expression attenuates pulmonary fibrosis.

Yong Mou, Guo-Rao Wu, Qi Wang, Ting Pan, Lei Zhang, Yongjian Xu, Weining Xiong, Qing Zhou, Yi Wang.

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease characterized by the infiltration of macrophages in the fibrotic region. Currently, no therapeutic strategies effectively control disease progression, and the 5-year mortality of patients after diagnosis is unacceptably high. Thus, developing an effective and safe treatment for IPF is urgently needed. The present study illustrated that methyl-CpG-binding protein 2 (MECP2), a protein responsible for the interpretation of DNA methylome-encoded information, was abnormally expressed in lung and bronchoalveolar lavage fluid samples of IPF patients and mice with onset of pulmonary fibrosis. And further studies verified that the overexpression of MECP2 occurred mainly in macrophages. Inhibition of Mecp2 expression in macrophages robustly abrogated alternatively activated macrophage (M2) polarization by regulating interferon regulatory factor 4 expression. Accordingly, cationic liposomes loading Mecp2 small interfering RNA (siRNA) were raised for the treatment of pulmonary fibrosis. It was noted that the liposomes accumulated in the fibrotic region after intratracheal injection, especially in macrophages. In addition, intratracheal administration of Mecp2 siRNA-loaded liposomes significantly reversed the established pulmonary fibrosis with few side-effects and high safety coefficients. Collectively, these results are essential not only for further understanding the DNA methylation in pathogenesis of IPF but also for providing a potent therapeutic strategy for IPF treatment in the clinic practice.

Keywords: Mecp2; alternatively activated macrophages; idiopathic pulmonary fibrosis; liposomes; macrophages

DOI: https://doi.org/10.1002/btm2.10280

Pharmaceuticals (Basel). 2022 May 05. pii: 575. [Epub ahead of print]15(5):

Biotechnological Evolution of siRNA Molecules: From Bench Tool to the Refined Drug.

Danielle de Brito E Cunha, Ana Beatriz Teixeira Frederico, Tamiris Azamor, Juliana Gil Melgaço, Patricia Cristina da Costa Neves, Ana Paula Dinis Ano Bom, Tatiana Martins Tilli, Sotiris Missailidis.

The depth and versatility of siRNA technologies enable their use in disease targets that are undruggable by small molecules or that seek to achieve a refined turn-off of the genes for any therapeutic area. Major extracellular barriers are enzymatic degradation of siRNAs by serum endonucleases and RNAases, renal clearance of the siRNA delivery system, the impermeability of biological membranes for siRNA, activation of the immune system, plasma protein sequestration, and capillary endothelium crossing. To overcome the intrinsic difficulties of the use of siRNA molecules, therapeutic applications require nanometric delivery carriers aiming to protect double-strands and deliver molecules to target cells. This review discusses the history of siRNAs, siRNA design, and delivery strategies, with a focus on progress made regarding siRNA molecules in clinical trials and how siRNA has become a valuable asset for biopharmaceutical companies.

Keywords: biopharmaceutical company; performance of siRNA in clinical trials; personalized medicine; siRNA delivery

DOI: https://doi.org/10.3390/ph15050575

Mol Ther. 2022 May 20. pii: S1525-0016(22)00316-1. [Epub ahead of print]

Precision Medicine: In Vivo CAR Therapy as a Showcase for Receptor-Targeted Vector Platforms.

Alexander Michels, Naphang Ho, Christian J Buchholz.

Chimeric antigen receptor (CAR) T cells are a cancer immunotherapy of extremes: Unprecedentedly effective, but complex and costly to manufacture, they are not yet a therapeutic option for all who would benefit. This disparity has motivated worldwide efforts to simplify treatment. Among the proposed solutions, the generation of CAR T cells directly in the patient, i.e. in vivo, is arguably simultaneously the most technically challenging and clinically useful approach to convert CAR therapy from a cell-based autologous medicinal product into a universally applicable off-the-shelf treatment. Here we review the current state-of-the-art of in vivo CAR therapy, focusing especially on the vector technologies used. These cover lentiviral vectors, adenovirus-associated vectors as well as synthetic polymer nanocarriers and lipid nanoparticles. Proof-of-concept, i.e. the generation of CAR cells directly in mouse models, has been demonstrated for all vector platforms. Receptor-targeting of vector particles is crucial, as it can prevent CAR gene delivery into off-target cells, thus reducing toxicities. We discuss the properties of the vector platforms, such as their immunogenicity, potency, and modes of CAR delivery (permanent versus transient). Finally, we outline the work required to advance in vivo CAR therapy from proof-of-concept to a robust, scalable technology for clinical testing.

DOI: https://doi.org/10.1016/j.ymthe.2022.05.018