Spray dried lipid nanoparticle formulations enable intratracheal delivery of mRNA.

RNA therapies have recently taken a giant leap forward with the approval of Onpattro™, a siRNA therapy delivered using a lipid nanoparticle (LNP), and the LNP-enabled mRNA vaccines against COVID-19, which are the first mRNA drugs to reach the marketplace. The latter medicines have illustrated that stability is a significant challenge in the distribution of RNA drugs using non-viral delivery systems, particularly in areas without cold chain storage. Here, we describe a proof-of-concept study on the engineering of an LNP mRNA formulation suitable for spray drying. This process produced a dry powder formulation that maintained stability and preserved mRNA functionality with increased performance compared to liquid formulations stored two weeks at 4 °C. Intratracheal delivery of spray dried LNPs loaded with eGFP mRNA to rats resulted in the production of the eGFP protein in a range of cell types including bronchiolar epithelial cells, macrophages and type II pneumocytes; cell types involved in adaptive immunity and which would be valuable targets for inhaled vaccines against respiratory pathogens. Together, these data show that spray drying of LNPs enhances their stability and may enable RNA delivery to the lung for protein replacement therapy, gene editing, vaccination, and beyond.

Heparin interferes with the uptake of liposomes in glioma.

In glioblastoma, a malignant primary brain tumor, liposomes have shown promise in pre-clinical and early phase clinical trials as delivery vehicles for therapeutics. However, external factors influencing cellular uptake of liposomes in glioma cells are poorly understood. Heparin and heparin analogues are commonly used in glioma patients to decrease the risk of thrombo-embolic events. Our results show that heparin inhibits pegylated liposome uptake by U87 glioma and GL261 cells in a dose dependent manner in vitro, and that heparin-mediated inhibition of uptake required presence of fetal bovine serum in the media. In a subcutaneous model of glioma, Cy5.5 labeled liposomes could be detected with in vivo imaging after direct intra-tumoral injection. Ex-vivo analysis with flow cytometry showed a decreased uptake of liposomes into tumor cells in mice treated systemically with heparin compared to those treated with vehicle only.

Quantification of protein cargo loading into engineered extracellular vesicles at single-vesicle and single-molecule resolution.

Extracellular Vesicles (EVs) have been intensively explored for therapeutic delivery of proteins. However, methods to quantify cargo proteins loaded into engineered EVs are lacking. Here, we describe a workflow for EV analysis at the single-vesicle and single-molecule level to accurately quantify the efficiency of different EV-sorting proteins in promoting cargo loading into EVs. Expi293F cells were engineered to express EV-sorting proteins fused to green fluorescent protein (GFP). High levels of GFP loading into secreted EVs was confirmed by Western blotting for specific EV-sorting domains, but quantitative single-vesicle analysis by Nanoflow cytometry detected GFP in less than half of the particles analysed, reflecting EV heterogeneity. Anti-tetraspanin EV immunostaining in ExoView confirmed a heterogeneous GFP distribution in distinct subpopulations of CD63+, CD81+, or CD9+ EVs. Loading of GFP into individual vesicles was quantified by Single-Molecule Localization Microscopy. The combined results demonstrated TSPAN14, CD63 and CD63/CD81 fused to the PDGFRß transmembrane domain as the most efficient EV-sorting proteins, accumulating on average 50-170 single GFP molecules per vesicle. In conclusion, we validated a set of complementary techniques suitable for high-resolution analysis of EV preparations that reliably capture their heterogeneity, and propose highly efficient EV-sorting proteins to be used in EV engineering applications.

Translating Cell and Gene Biopharmaceutical Products for Health and Market Impact. Product Scaling From Clinical to Marketplace: Lessons Learned and Future Outlook.

Cell and gene therapies have the potential to be curative for severe disease states such as cancer or incurable orphan genetic diseases. Despite the promise, there are only few such therapies available, although more are appearing in pharmaceutical pipelines. A major culprit limiting a fast translation from preclinical research to the clinic and the market is chemistry, manufacturing and control. The root cause is that most cell and gene therapies currently are personalized in form of ex vivo manipulated cells. This approach stands in sharp contrast to the population-based approach seen for small molecules and protein therapeutics. Therefore, it warrants a different approach to product manufacturing, testing, release, regulatory submissions, and product distribution. In this commentary, we highlight opportunities to solve these issues already in progress in industry and at academic institutions, but in addition call for expert contributions to a future cluster of articles in Journal of Pharmaceutical Sciences to illuminate additional solutions. Finally, we are also providing a perspective on future directions including expanding from current approaches of gene modification via viral vectors to for example gene editing, approaches that may lend themselves better toward allogenic and in vivo therapies and more typical chemistry, manufacturing and control approaches.

Extracellular vesicles and intercellular communication within the nervous system.

Extracellular vesicles (EVs, including exosomes) are implicated in many aspects of nervous system development and function, including regulation of synaptic communication, synaptic strength, and nerve regeneration. They mediate the transfer of packets of information in the form of nonsecreted proteins and DNA/RNA protected within a membrane compartment. EVs are essential for the packaging and transport of many cell-fate proteins during development as well as many neurotoxic misfolded proteins during pathogenesis. This form of communication provides another dimension of cellular crosstalk, with the ability to assemble a "kit" of directional instructions made up of different molecular entities and address it to specific recipient cells. This multidimensional form of communication has special significance in the nervous system. How EVs help to orchestrate the wiring of the brain while allowing for plasticity associated with learning and memory and contribute to regeneration and degeneration are all under investigation. Because they carry specific disease-related RNAs and proteins, practical applications of EVs include potential uses as biomarkers and therapeutics. This Review describes our current understanding of EVs and serves as a springboard for future advances, which may reveal new important mechanisms by which EVs in coordinate brain and body function and dysfunction.

Directed Molecular Evolution of an Engineered Gammaretroviral Envelope Protein with Dual Receptor Use Shows Stable Maintenance of Both Receptor Specificities.

UNLABELLED: We have previously reported the construction of a murine leukemia virus-based replication-competent gammaretrovirus (SL3-AP) capable of utilizing the human G protein-coupled receptor APJ (hAPJ) as its entry receptor and its natural receptor, the murine Xpr1 receptor, with equal affinities. The apelin receptor has previously been shown to function as a coreceptor for HIV-1, and thus, adaptation of the viral vector to this receptor is of significant interest. Here, we report the molecular evolution of the SL3-AP envelope protein when the virus is cultured in cells harboring either the Xpr1 or the hAPJ receptor. Interestingly, the dual receptor affinity is maintained even after 10 passages in these cells. At the same time, the chimeric viral envelope protein evolves in a distinct pattern in the apelin cassette when passaged on D17 cells expressing hAPJ in three separate molecular evolution studies. This pattern reflects selection for reduced ligand-receptor interaction and is compatible with a model in which SL3-AP has evolved not to activate hAPJ receptor internalization. IMPORTANCE: Few successful examples of engineered retargeting of a retroviral vector exist. The engineered SL3-AP envelope is capable of utilizing either the murine Xpr1 or the human APJ receptor for entry. In addition, SL3-AP is the first example of an engineered retrovirus retaining its dual tropism after several rounds of passaging on cells expressing only one of its receptors. We demonstrate that the virus evolves toward reduced ligand-receptor affinity, which sheds new light on virus adaptation. We provide indirect evidence that such reduced affinity leads to reduced receptor internalization and propose a novel model in which too rapid receptor internalization may decrease virus entry.