Fusion-dependent formation of lipid nanoparticles containing macromolecular payloads

The success of Onpattro™ (patisiran) clearly demonstrates the utility of lipid nanoparticle (LNP) systems for enabling gene therapies. These systems are composed of ionizable cationic lipids, phospholipid, cholesterol, and polyethylene glycol (PEG)-lipids, and are produced through rapid-mixing of an ethanolic-lipid solution with an acidic aqueous solution followed by dialysis into neutralizing buffer. A detailed understanding of the mechanism of LNP formation is crucial to improving LNP design. Here we use cryogenic transmission electron microscopy and fluorescence techniques to further demonstrate that LNP are formed through the fusion of precursor, pH-sensitive liposomes into large electron-dense core structures as the pH is neutralized. Next, we show that the fusion process is limited by the accumulation of PEG-lipid on the emerging particle. Finally, we show that the fusion-dependent mechanism of formation also applies to LNP containing macromolecular payloads including mRNA, DNA vectors, and gold nanoparticles

Engineering cytokine therapeutics

Cytokines have pivotal roles in immunity, making them attractive as therapeutics for a variety of immune-related disorders. However, the widespread clinical use of cytokines has been limited by their short blood half-lives and severe side effects caused by low specificity and unfavourable biodistribution. Innovations in bioengineering have aided in advancing our knowledge of cytokine biology and yielded new technologies for cytokine engineering. In this Review, we discuss how the development of bioanalytical methods, such as sequencing and high-resolution imaging combined with genetic techniques, have facilitated a better understanding of cytokine biology. We then present an overview of therapeutics arising from cytokine re-engineering, targeting and delivery, mRNA therapeutics and cell therapy. We also highlight the application of these strategies to adjust the immunological imbalance in different immune-mediated disorders, including cancer, infection and autoimmune diseases. Finally, we look ahead to the hurdles that must be overcome before cytokine therapeutics can live up to their full potential

Resolving sepsis-induced immunoparalysis via trained immunity by targeting interleukin-4 to myeloid cells.

Immunoparalysis is a compensatory and persistent anti-inflammatory response to trauma, sepsis or another serious insult, which increases the risk of opportunistic infections, morbidity and mortality. Here, we show that in cultured primary human monocytes, interleukin-4 (IL4) inhibits acute inflammation, while simultaneously inducing a long-lasting innate immune memory named trained immunity. To take advantage of this paradoxical IL4 feature in vivo, we developed a fusion protein of apolipoprotein A1 (apoA1) and IL4, which integrates into a lipid nanoparticle. In mice and non-human primates, an intravenously injected apoA1-IL4-embedding nanoparticle targets myeloid-cell-rich haematopoietic organs, in particular, the spleen and bone marrow. We subsequently demonstrate that IL4 nanotherapy resolved immunoparalysis in mice with lipopolysaccharide-induced hyperinflammation, as well as in ex vivo human sepsis models and in experimental endotoxemia. Our findings support the translational development of nanoparticle formulations of apoA1-IL4 for the treatment of patients with sepsis at risk of immunoparalysis-induced complications.We thank M. Jaeger (Radboudumc) for kindly providing flourescein isothiocyanate-labelled Candida albicans. D. Williams (East Tennessee State University) provided the β-glucan we used in our initial experiments. H. Lemmers (Radboudumc) kindly prepared the purified lipopolysaccharide used for stimulation of primary human monocytes and macrophages. Part of the figures were prepared using (among other software) Biorender.com. B.N. is supported by a National Health and Medical Research Council (Australia) Investigator Grant (APP1173314). This work was supported by National Institutes of Health grants R01 HL144072, R01 CA220234 and P01 HL131478, as well as a Vici grant from the Dutch Research Council NWO and an ERC Advanced Grant (all to W.J.M.M.). M.G.N. was supported by a Spinoza grant from Dutch Research Council NWO and an ERC Advanced Grant (#833247).S

Nanotechnology for organ-tunable gene editing

Lipid nanoparticles containing genetic drugs can be bioengineered to tune their biodistribution and induce organspecifc gene regulation

Cancer nanomedicines: oversold or underappreciated?

Since the approval of liposomal doxorubicin (Doxil) and daunorubicin (DaunoXome) 20 years ago for the treatment of (HIV-related) Kaposi’s sarcoma, significant investment and research efforts have been geared toward the development of nanomedicines for cancer treatment. The benefits of formulating cancer drugs in lipid- and polymer-based nanocarrier systems regarding drug solubility, circulation time, biodistribution, and toxicity while maintaining (or even enhancing) therapeutic efficacy, have led to the approval of about a dozen cancer nanomedicines, including antibody-drug conjugates (ADCs

Cancer nanomedicines : oversold or underappreciated?

Since the approval of liposomal doxorubicin (Doxil) and daunorubicin (DaunoXome) 20 years ago for the treatment of (HIV-related) Kaposi’s sarcoma, significant investment and research efforts have been geared toward the development of nanomedicines for cancer treatment. The benefits of formulating cancer drugs in lipid- and polymer-based nanocarrier systems regarding drug solubility, circulation time, biodistribution, and toxicity while maintaining (or even enhancing) therapeutic efficacy, have led to the approval of about a dozen cancer nanomedicines, including antibody-drug conjugates (ADCs

The EPR effect and beyond: Strategies to improve tumor targeting and cancer nanomedicine treatment efficacy

Following its discovery more than 30 years ago, the enhanced permeability and retention (EPR) effect has become the guiding principle for cancer nanomedicine development. Over the years, the tumor-targeted drug delivery field has made significant progress, as evidenced by the approval of several nanomedicinal anticancer drugs. Recently, however, the existence and the extent of the EPR effect - particularly in patients - have become the focus of intense debate. This is partially due to the disbalance between the huge number of preclinical cancer nanomedicine papers and relatively small number of cancer nanomedicine drug products reaching the market. To move the field forward, we have to improve our understanding of the EPR effect, of its cancer type-specific pathophysiology, of nanomedicine interactions with the heterogeneous tumor microenvironment, of nanomedicine behavior in the body, and of translational aspects that specifically complicate nanomedicinal drug development. In this virtual special issue, 24 research articles and reviews discussing different aspects of the EPR effect and cancer nanomedicine are collected, together providing a comprehensive and complete overview of the current state-of-the-art and future directions in tumor-targeted drug delivery

Lipid nanoparticle technology for clinical translation of siRNA therapeutics

ConspectusDelivering nucleic acid-based therapeutics to cells is an attractive approach to target the genetic cause of various diseases. In contrast to conventional small molecule drugs that target gene products (i.e., proteins), genetic drugs induce therapeutic effects by modulating gene expression. Gene silencing, the process whereby protein production is prevented by neutralizing its mRNA template, is a potent strategy to induce therapeutic effects in a highly precise manner. Importantly, gene silencing has broad potential as theoretically any disease-causing gene can be targeted. It was demonstrated two decades ago that introducing synthetic small interfering RNAs (siRNAs) into the cytoplasm results in specific degradation of complementary mRNA via a process called RNA interference (RNAi). Since then, significant efforts and investments have been made to exploit RNAi therapeutically and advance siRNA drugs to the clinic.Utilizing (unmodified) siRNA as a therapeutic, however, is challenging due to its limited bioavailability following systemic administration. Nuclease activity and renal filtration result in siRNA's rapid clearance from the circulation and its administration induces (innate) immune responses. Furthermore, siRNA's unfavorable physicochemical characteristics largely prevent its diffusion across cellular membranes, impeding its ability to reach the cytoplasm where it can engage the RNAi machinery. The clinical translation of siRNA therapeutics has therefore been dependent on chemical modifications and developing sophisticated delivery platforms to improve their stability, limit immune activation, facilitate internalization, and increase target affinity.These developments have resulted in last year's approval of the first siRNA therapeutic, called Onpattro (patisiran), for treatment of hereditary amyloidogenic transthyretin (TTR) amyloidosis. This disease is characterized by a mutation in the gene encoding TTR, a serum protein that transports retinol in circulation following secretion by the liver. The mutation leads to production of misfolded proteins that deposit as amyloid fibrils in multiple organs, resulting in progressive neurodegeneration. Patisiran's therapeutic effect relies on siRNA-mediated TTR gene silencing, preventing mutant protein production and halting or even reversing disease progression. For efficient therapeutic siRNA delivery to hepatocytes, patisiran is critically dependent on lipid nanoparticle (LNP) technology.In this Account, we provide an overview of key advances that have been crucial for developing LNP delivery technology, and we explain how these developments have contributed to the clinical translation of siRNA therapeutics for parenteral administration. We discuss optimization of the LNP formulation, particularly focusing on the rational design of ionizable cationic lipids and poly(ethylene glycol) lipids. These components have proven to be instrumental for highly efficient siRNA encapsulation, favorable LNP pharmacokinetic parameters, and hepatocyte internalization. Additionally, we pay attention to the development of rapid mixing-based methods that provide robust and scalable LNP production procedures. Finally, we highlight patisiran's clinical translation and LNP delivery technology's potential to enable the development of genetic drugs beyond the current state-of-the-art, such as mRNA and gene editing therapeutics