Nanoparticle Technology: Having Impact, but Needing Further Optimization
Authors: S. Moein Moghimi, Ernst Wagner
Journal: Molecular Therapy (2017)

This year, the American Society of Gene & Cell Therapy (ASGCT) celebrates the 20th anniversary of its founding. During this period, viral vectors have become dominant systems for the delivery of nucleic acid medicines, largely because of their extremely efficient capacity to transfect mammalian cells. However, we have witnessed genotoxicity and immune responses to viral vectors, and this has limited repeated administration. These issues, together with the limited genetic capacity and difficulty of large-scale production of such vectors, have generated interest in the engineering of synthetic nonviral nucleic acid transfer systems. Nonviral systems have been evolving slowly but continuously, addressing safety and efficacy, and are starting to have an impact. Parallel advances in gene silencing, gene editing, and exon skipping technologies have fuelled these developments. As of January 2017, six synthetic oligonucleotide therapeutics have entered the market, and several plasmid DNA (pDNA) vaccine and RNA interference (RNAi) products are currently in advanced-stage clinical trials.1Stein C.A. Castanotto D. FDA-Approved Oligonucleotide Therapies in 2017.Mol. Ther. 2017; 25: 1069-1075Abstract Full Text Full Text PDF PubMed Scopus (430) Google Scholar, 2Titze-de-Almeida R. David C. Titze-de-Almeida S.S. The Race of 10 Synthetic RNAi-Based Drugs to the Pharmaceutical Market.Pharm. Res. 2017; 34: 1339-1363Crossref PubMed Scopus (131) Google Scholar Excellent presentations at the ASGCT 20th annual meeting in Washington, DC addressed recent developments in nucleic acid therapeutics and nonviral vectors. For example, James Dahlman (Georgia Tech) designed a DNA barcode system for simultaneous analysis of the biodistribution of hundreds of different nanoparticles (in situ) within an organism.3Dahlman J.E. Kauffman K.J. Xing Y. Shaw T.E. Mir F.F. Dlott C.C. Langer R. Anderson D.G. Wang E.T. Barcoded nanoparticles for high throughput in vivo discovery of targeted therapeutics.Proc. Natl. Acad. Sci. USA. 2017; 114: 2060-2065Crossref PubMed Scopus (123) Google Scholar This technology opens the door for high-throughput in vivo screening, which is far more informative than in vitro assays. Mano Manoharan (Alnylam) reviewed the development of liver-directed RNAi drugs and their clinical evaluation (three ongoing phase 3 trials with encouraging results), highlighting that further chemical optimization resulted in silencing efficacy at a far lower total dose than previously achieved. This improvement was key to avoiding side effects observed in previous clinical studies using higher doses. A series of presentations suggested that blockade of splice sites, either by Cas9-mediated genome editing at the DNA level or antisense oligonucleotides at the RNA level, is an encouraging therapeutic option for Duchenne muscular dystrophy and related genetic diseases. The exon-skipping phosphorodiamidate morpholino oligomers (PMO) drug eteplirsen (Exondys 51) has reached the market,4Stein C.A. Eteplirsen approved for duchenne muscular dystrophy: The FDA faces a difficult choice.Mol. Ther. 2016; 24: 1884-1885Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar with an outlook on chemical derivatives providing improved preclinical efficacy (Ryszard Kole, Sarepta Therapeutics). Preclinical studies presented by David Morrissey (Intellia) demonstrated robust in vivo knockout of a target gene in mouse liver by CRISPR/Cas9 mRNA and guide RNA (gRNA) lipid nanoparticles as a possible long-term alternative to gene silencing. mRNA lipid nanoparticles have also been recognized as very useful agents for active immunotherapy; Ugur Sahin (Mainz) presented exciting results from clinical studies in melanoma patients.5Kranz L.M. Diken M. Haas H. Kreiter S. Loquai C. Reuter K.C. Meng M. Fritz D. Vascotto F. Hefesha H. et al.Systemic RNA delivery to dendritic cells exploits antiviral defence for cancer immunotherapy.Nature. 2016; 534: 396-401Crossref PubMed Scopus (899) Google Scholar, 6Grabbe S. Haas H. Diken M. Kranz L.M. Langguth P. Sahin U. Translating nanoparticulate-personalized cancer vaccines into clinical applications: case study with RNA-lipoplexes for the treatment of melanoma.Nanomedicine (Lond.). 2016; 11: 2723-2734Crossref PubMed Scopus (66) Google Scholar Sahin described how patient-specific tumor neoantigens were cloned and incorporated into mRNA /lipid vectors, resulting in dendritic cell (DC)-specific expression, and thereby triggering strong specific antitumor immune responses and clinical responses in patients. Collectively, these and other studies illustrate that a good understanding of multifaceted and integrated biological processes and their underlying mechanisms is essential for translational activities and development of novel medicines. This special issue of Molecular Therapy celebrates key developments in the design and engineering of therapeutic nonviral vectors that consider pharmaceutical attributes. The selected papers also focus on structural and biological factors controlling vector performance, including safety. The issue includes six invited reviews that critically discuss developments in vector design, safety, and targeting.7Cullis P.R. Hope M.J. Lipid nanoparticle systems for enabling gene therapies.Mol. Ther. 2017; 25 (this issue): 1467-1475Abstract Full Text Full Text PDF Scopus (407) Google Scholar, 8Hall A. Lächelt U. Bartek J. Wagner E. Moghimi S.M. Polyplex evolution: understanding biology, optimizing performance.Mol. Ther. 2017; 25 (this issue): 1476-1490Abstract Full Text Full Text PDF Scopus (114) Google Scholar, 9Mizrahy S. Hazan-Halevy I. Dammes N. Landesman-Milo D. Peer D. Current progress in non-viral RNAi-based delivery strategies to lymphocytes.Mol. Ther. 2017; 25 (this issue): 1491-1500Abstract Full Text Full Text PDF Scopus (36) Google Scholar, 10Quader S. Kataoka K. Nanomaterial-enabled cancer therapy.Mol. Ther. 2017; 25 (this issue): 1501-1513Abstract Full Text Full Text PDF Scopus (90) Google Scholar, 11Palange A.L. Palomba R. Rizzuti I.F. Ferreira M. Decuzzi P. Deformable discoidal polymeric nanoconstructs for the precise delivery of therapeutic and imaging agents.Mol. Ther. 2017; 25 (this issue): 1514-1521Abstract Full Text Full Text PDF Scopus (30) Google Scholar, 12Mirshafiee V. Jiang W. Sun B. Wang X. Xia T. Facilitating translational nanomedicine via predictive safety assessment.Mol. Ther. 2017; 25 (this issue): 1522-1530Abstract Full Text Full Text PDF Scopus (27) Google Scholar Lipoplexes and polyplexes are among the most intensively studied systems for nucleic acid delivery. Lipid nanoparticles are currently the lead nonviral delivery systems owing to design flexibility, payload capacity, and robust and efficient formulation processing. Cullis and Hope7Cullis P.R. Hope M.J. Lipid nanoparticle systems for enabling gene therapies.Mol. Ther. 2017; 25 (this issue): 1467-1475Abstract Full Text Full Text PDF Scopus (407) Google Scholar elegantly discuss these developments, delineating the importance of biophysical attributes, such as lipid asymmetry and polymorphism, in directing vector engineering. These developments are having a major impact on the silencing of target genes in hepatocytes following systemic administration. Polyethylenimines are among the most successful transfecting polycations. However, their use is associated with serious cytotoxic complications and safety concerns at innate immune levels. Hall and colleagues8Hall A. Lächelt U. Bartek J. Wagner E. Moghimi S.M. Polyplex evolution: understanding biology, optimizing performance.Mol. Ther. 2017; 25 (this issue): 1476-1490Abstract Full Text Full Text PDF Scopus (114) Google Scholar provide a detailed discussion of mechanistic issues underlying polycation toxicity and “safe-by-design” approaches that have been taken to synthesize improved polycation derivatives with superb transfection efficacies. Lymphocytes are among the most notorious cells to transduce with nucleic acid medicines. Mizrahy et al.9Mizrahy S. Hazan-Halevy I. Dammes N. Landesman-Milo D. Peer D. Current progress in non-viral RNAi-based delivery strategies to lymphocytes.Mol. Ther. 2017; 25 (this issue): 1491-1500Abstract Full Text Full Text PDF Scopus (36) Google Scholar focus on the challenges and potential opportunities of targeting and manipulating lymphocyte function with RNAi through the design and engineering of different, yet simple, systemic delivery systems. The main rationale for intravenously injected nanoparticle-targeting solid tumors is based on the “enhanced permeability and retention” effect. Contrary to high expectations, anti-cancer nanomedicines have shown limited therapeutic efficacy in humans.13Anchordoquy T.J. Barenholz Y. Boraschi D. Chorny M. Decuzzi P. Dobrovolskaia M.A. Farhangrazi Z.S. Farrell D. Gabizon A. Ghandehari H. et al.Mechanisms and barriers in cancer nanomedicine: addressing challenges, looking for solutions.ACS Nano. 2017; 11: 12-18Crossref PubMed Scopus (196) Google Scholar, 14Moghimi S.M. Farhangrazi Z.S. Just so stories: the random acts of anti-cancer nanomedicine performance.Nanomedicine. 2014; 10: 1661-1666Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar Many factors could account for this, including tumor heterogeneity as well as disparity between animal models and clinical studies. Quader and Kataoka10Quader S. Kataoka K. Nanomaterial-enabled cancer therapy.Mol. Ther. 2017; 25 (this issue): 1501-1513Abstract Full Text Full Text PDF Scopus (90) Google Scholar discuss these challenges and propose strategies for improved cancer therapy with nucleic acid-based medicines. Parameters such as size, shape, surface properties, and mechanical stiffness of nanoparticles play a crucial role in their biological performance.15Moghimi S.M. Hunter A.C. Andresen T.L. Factors controlling nanoparticle pharmacokinetics: an integrated analysis and perspective.Annu. Rev. Pharmacol. Toxicol. 2012; 52: 481-503Crossref PubMed Scopus (420) Google Scholar Inspired by erythrocyte behavior, Palange et al.11Palange A.L. Palomba R. Rizzuti I.F. Ferreira M. Decuzzi P. Deformable discoidal polymeric nanoconstructs for the precise delivery of therapeutic and imaging agents.Mol. Ther. 2017; 25 (this issue): 1514-1521Abstract Full Text Full Text PDF Scopus (30) Google Scholar review the role of particle shape and deformability in directing particle navigation within the vasculature. Understanding these features will enable efficient targeting of the tortuous angiogenic microvasculature, while minimizing particle sequestration by professional phagocytes. The final review by Mirshafiee et al.12Mirshafiee V. Jiang W. Sun B. Wang X. Xia T. Facilitating translational nanomedicine via predictive safety assessment.Mol. Ther. 2017; 25 (this issue): 1522-1530Abstract Full Text Full Text PDF Scopus (27) Google Scholar discusses our current knowledge of predictive safety and structure-activity relationship analyses that may help to facilitate the design of safer nanomedicines with improved therapeutic efficacy in clinical settings. This special issue also offers a wide range of research papers highlighting state-of-the-art developments in particulate technologies for different routes of administration (e.g., oral, intravenous, intraperitoneal, and subcutaneous) and their characterization in relation to cell and molecular therapy. These technologies address ligand selection, nanoengineering and characterization aspects, biological barriers (e.g., the blood-brain barrier), target recognition processes from an integrative perspective, nucleic acid compaction strategies, and modulation of intracellular release mechanisms, immunization, therapeutic efficacy in cancer, ulcerative colitis, neovascular macular degeneration, and obesity.16Meng Y. Wiseman J.A. Nemtsova Y. Moore D.F. Guevarra J. Reuhl K. Banks W.A. Daneman R. Sleat D.E. Lobel P. A basic apoE-based peptide mediator to deliver proteins across the blood-brain barrier: long-term efficacy, toxicity, and mechanism.Mol. 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Ther. 2017; 25 (this issue): 1567-1579Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar, 20O’Loughlin A.J. Mäger I. de Jong O.G. Varela M.A. Schiffelers R.M. El Andaloussi S. Wood M.J.A. Vader P. Functional delivery of lipid-conjugated siRNA by extracellular vesicles.Mol. Ther. 2017; 25 (this issue): 1580-1587Abstract Full Text Full Text PDF Scopus (109) Google Scholar, 21Oshima G. Guo N. He C. Stack M.E. Poon C. Uppal A. Wightman S.C. Parekh A. Skowron K.B. Posner M.C. et al.In vivo delivery and therapeutic effects of a microRNA on colorectal liver metastases.Mol. Ther. 2017; 25 (this issue): 1588-1595Abstract Full Text Full Text PDF Scopus (37) Google Scholar, 22Sobot D. Mura S. Rouquette M. Vukosavljevic B. Cayre F. Buchy E. Pieters G. Garcia-Argote S. Windbergs M. Desmaële D. Couvreur P. Circulating lipoprotein: a Trojan horse guiding squalenoylated drugs to LDL-accumulating cancer cells.Mol. Ther. 2017; 25 (this issue): 1596-1605Abstract Full Text Full Text PDF Scopus (35) Google Scholar, 23Zhang X. Bohner A. Bhuvanagiri S. Uehara H. Upadhyay A.K. Emerson L.L. Bondalapati S. Muddana S.K. Fang D. Li M. et al.Targeted intraceptor nanoparticle for neovascular macular degeneration: preclinical dose optimization and toxicology assessment.Mol. Ther. 2017; 25 (this issue): 1606-1615Abstract Full Text Full Text PDF Scopus (8) Google Scholar, 24Heun Y. Pogoda K. Anton M. Pircher J. Pfeifer A. Woernle M. Ribeiro A. Kameritsch P. Mykhaylyk O. Plank C. et al.HIF-1α dependent wound healing angiogenesis in vivo can be controlled by site-specific lentiviral magnetic targeting of SHP-2.Mol. Ther. 2017; 25 (this issue): 1616-1627Abstract Full Text Full Text PDF Scopus (22) Google Scholar, 25Xiao B. Xu Z. Viennois E. Zhang Y. Zhang Z. Zhang M. Han M.K. Kang Y. Merlin D. Orally targeted delivery of tripeptide KPV via hyaluronic acid-functionalized nanoparticles efficiently alleviates ulcerative colitis.Mol. Ther. 2017; 25 (this issue): 1628-1640Abstract Full Text Full Text PDF Scopus (111) Google Scholar, 26Deng Z. Rong Y. Teng Y. Mu J. Zhuang X. Tseng M. Samykutty A. Zhang L. Yan J. Miller D. et al.Broccoli-derived nanoparticle inhibits mouse colitis by activating dendritic cell AMP-activated protein kinase.Mol. Ther. 2017; 25 (this issue): 1641-1654Abstract Full Text Full Text PDF Scopus (151) Google Scholar, 27Pearson R.M. Casey L.M. Hughes K.R. Wang L.Z. North M.G. Getts D.R. Miller S.D. Shea L.D. Controlled delivery of single or multiple antigens in tolergenic nanoparticles using peptide-polymer bioconjugates.Mol. Ther. 2017; 25 (this issue): 1655-1664Abstract Full Text Full Text PDF Scopus (61) Google Scholar, 28Cheng L. Wang Y. Huang L. Exosomes from M1-polarized macrophages potentiate the cancer vaccine by creating a pro-inflammatory microenvironment in the lymph node.Mol. Ther. 2017; 25 (this issue): 1665-1675Abstract Full Text Full Text PDF PubMed Scopus (196) Google Scholar, 29Kuo R. Saito E. Miller S.D. Shea L.D. Peptide-conjugated nanoparticles reduce positive co-stimulatory expression and T cell activity to induce tolerance.Mol. Ther. 2017; 25 (this issue): 1676-1685Abstract Full Text Full Text PDF Scopus (65) Google Scholar, 30Garnacho C. Dhami R. Solomon M. Schuchman E.H. Muro S. Enhanced delivery and effects of acid sphingomyelinase by ICAM-1-targeted nanocarriers in type B Niemann-Pick disease mice.Mol. Ther. 2017; 25 (this issue): 1686-1696Abstract Full Text Full Text PDF Scopus (17) Google Scholar, 31Wilson D.R. Routkevitch D. Rui Y. Mosenia A. Wahlin K.J. Quinones-Hinojosa A. Zack D.J. Green J.J. A triple-fluorophore-labeled nucleic acid pH nanosensor to investigate non-viral gene therapy.Mol. Ther. 2017; 25 (this issue): 1697-1709Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar, 32Hvam M.L. Cai Y. Dagnæ-Hansen F. Nielsen J.S. Wengel J. Kjems J. Howard K.A. Fatty acid-modified gapmer antisense oligonucleotide and human serum albumin constructs for pharmacokinetic modulation.Mol. Ther. 2017; 25 (this issue): 1710-1717Abstract Full Text Full Text PDF Scopus (30) Google Scholar, 33Jiang C. Vega M.A.C. Yue F. Kuang L. Narayanan N. Uzunalli G. Merkel M.P. Kuang S. Deng M. Dibenzazepine-loaded nanoparticles induce local browning of white adipose tissue to counteract obesity.Mol. Ther. 2017; 25 (this issue): 1718-1729Abstract Full Text Full Text PDF Scopus (36) Google Scholar Some of the intriguing technologies with respect to nucleic acid medicines include three-way-junction-based RNA nanoparticles,17Lee T.J. Yoo J.Y. Shu D. Li H. Zhang J. Yu J.-G. Jaime-Ramirez A.C. Acunzo M. Romano G. Cui R. et al.RNA nanoparticle-based targeted therapy for glioblastoma through inhibition of oncogenic miR-21.Mol. Ther. 2017; 25 (this issue): 1544-1555Abstract Full Text Full Text PDF Scopus (90) Google Scholar a succinyl-tetraethylene pentamine-histidine oligomer-based nonviral gene delivery system,18Wang S. Reinhard S. Li C. Qian M. Jiang H. Du Y. Lächelt U. Lu W. Wagner E. Huang R. Antitumoral cascade-targeting ligand for IL-6 receptor-mediated gene delivery to glioma.Mol. Ther. 2017; 25 (this issue): 1556-1566Abstract Full Text Full Text PDF Scopus (35) Google Scholar and envelope-type nanoparticles.19Shi K. Zhao Y. Miao L. Satterlee A. Haynes M. Luo C. Musetti S. Huang L. Dual functional LipoMET mediates envelope-type nanoparticles to combinatorial oncogene silencing and tumor growth inhibition.Mol. Ther. 2017; 25 (this issue): 1567-1579Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar There is also an increasing trend toward the use of endogenous materials for nano-construct engineering and manipulation of biological targets. Some of the discussed technologies are based on exosomes,20O’Loughlin A.J. Mäger I. de Jong O.G. Varela M.A. Schiffelers R.M. El Andaloussi S. Wood M.J.A. Vader P. Functional delivery of lipid-conjugated siRNA by extracellular vesicles.Mol. Ther. 2017; 25 (this issue): 1580-1587Abstract Full Text Full Text PDF Scopus (109) Google Scholar, 28Cheng L. Wang Y. Huang L. Exosomes from M1-polarized macrophages potentiate the cancer vaccine by creating a pro-inflammatory microenvironment in the lymph node.Mol. Ther. 2017; 25 (this issue): 1665-1675Abstract Full Text Full Text PDF PubMed Scopus (196) Google Scholar squalene,22Sobot D. Mura S. Rouquette M. Vukosavljevic B. Cayre F. Buchy E. Pieters G. Garcia-Argote S. Windbergs M. Desmaële D. Couvreur P. Circulating lipoprotein: a Trojan horse guiding squalenoylated drugs to LDL-accumulating cancer cells.Mol. Ther. 2017; 25 (this issue): 1596-1605Abstract Full Text Full Text PDF Scopus (35) Google Scholar and serum albumin.32Hvam M.L. Cai Y. Dagnæ-Hansen F. Nielsen J.S. Wengel J. Kjems J. Howard K.A. Fatty acid-modified gapmer antisense oligonucleotide and human serum albumin constructs for pharmacokinetic modulation.Mol. Ther. 2017; 25 (this issue): 1710-1717Abstract Full Text Full Text PDF Scopus (30) Google Scholar For instance, O’Loughlin and colleagues20O’Loughlin A.J. Mäger I. de Jong O.G. Varela M.A. Schiffelers R.M. El Andaloussi S. Wood M.J.A. Vader P. Functional delivery of lipid-conjugated siRNA by extracellular vesicles.Mol. Ther. 2017; 25 (this issue): 1580-1587Abstract Full Text Full Text PDF Scopus (109) Google Scholar have systematically evaluated and optimized methods to load exosomes with cholesterol-conjugated RNAi, while Hvam et al.32Hvam M.L. Cai Y. Dagnæ-Hansen F. Nielsen J.S. Wengel J. Kjems J. Howard K.A. Fatty acid-modified gapmer antisense oligonucleotide and human serum albumin constructs for pharmacokinetic modulation.Mol. Ther. 2017; 25 (this issue): 1710-1717Abstract Full Text Full Text PDF Scopus (30) Google Scholar introduce self-assembled constructs between gapmer antisense oligonucleotides and human serum albumin. Finally, we acknowledge succinct contributions by all authors and hope that this compendium will serve as a platform for accelerating interest in therapeutic nanoparticle engineering with pharmaceutical attributes and diverse applications in cell and molecular therapy through interdisciplinary and integrative engagements.