Microparticle Depots for Controlled and Sustained Release of Endosomolytic Nanoparticles



Nucleic acids have gained recognition as promising immunomodulatory therapeutics. However, their potential is limited by several drug delivery barriers, and there is a need for technologies that enhance intracellular delivery of nucleic acid drugs. Furthermore, controlled and sustained release is a significant concern, as the kinetics and localization of immunomodulators can influence resultant immune responses. Here, we describe the design and initial evaluation of poly(lactic-co-glycolic) acid (PLGA) microparticle (MP) depots for enhanced retention and sustained release of endosomolytic nanoparticles that enable the cytosolic delivery of nucleic acids.


Endosomolytic p[DMAEMA]10kD-bl-[PAA0.3-co-DMAEMA0.3-co-BMA0.4]25kD diblock copolymers were synthesized by reversible addition-fragmentation chain transfer polymerization. Polymers were electrostatically complexed with nucleic acids and resultant nanoparticles (NPs) were encapsulated in PLGA MPs. To modulate release kinetics, ammonium bicarbonate was added as a porogen. Release profiles were quantified in vitro and in vivovia quantification of fluorescently-labeled nucleic acid. Bioactivity of released NPs was assessed using small interfering RNA (siRNA) targeting luciferase as a representative nucleic acid cargo. MPs were incubated with luciferase-expressing 4T1 (4T1-LUC) breast cancer cells in vitro or administered intratumorally to 4T1-LUC breast tumors, and silencing via RNA interference was quantified via longitudinal luminescence imaging.


Endosomolytic NPs complexed to siRNA were effectively loaded into PLGA MPs and release kinetics could be modulated in vitro and in vivovia control of MP porosity, with porous MPs exhibiting faster cargo release. In vitro, release of NPs from porous MP depots enabled sustained luciferase knockdown in 4T1 breast cancer cells over a five-day treatment period. Administered intratumorally, MPs prolonged the retention of nucleic acid within the injected tumor, resulting in enhanced and sustained silencing of luciferase relative to a single bolus administration of NPs at an equivalent dose.


This work highlights the potential of PLGA MP depots as a platform for local release of endosomolytic polymer NPs that enhance the cytosolic delivery of nucleic acid therapeutics.

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Butyl methacrylate




Dimethylaminoethyl methacrylate




4-Cyano-4-(ethylsulfanylthiocarbonyl)sulfanylpentanoic acid






Propylacrylic acid


Poly(lactic-co-glycolic) acid


Polyvinyl alcohol


Scanning electron microscopy


2,2′-Azobis(4-methoxy-2,4-dimethyl valeronitrile)


  1. 1.

    Ahn, J., T. Xia, A. Rabasa Capote, D. Betancourt, and G. N. Barber. Extrinsic phagocyte-dependent STING signaling dictates the immunogenicity of dying cells. Cancer Cell 33(5):862–873e5, 2018.

    Google Scholar 

  2. 2.

    Ali, O. A., N. Huebsch, L. Cao, G. Dranoff, and D. J. Mooney. Infection-mimicking materials to program dendritic cells in situ. Nat. Mater. 8(2):151–158, 2009.

    Google Scholar 

  3. 3.

    Ali, O. A., C. Verbeke, C. Johnson, R. W. Sands, S. A. Lewin, D. White, E. Doherty, G. Dranoff, and D. J. Mooney. Identification of immune factors regulating antitumor immunity using polymeric vaccines with multiple adjuvants. Cancer Res. 74(6):1670–1681, 2014.

    Google Scholar 

  4. 4.

    Aliabadi, H. M. Natural polymers in nucleic acid delivery. In: Polymers and Nanomaterials for Gene Therapy, edited by R. Narain. Cambridge: Woodhead Publishing, 2016, pp. 55–80.

    Google Scholar 

  5. 5.

    Aliru, M. L., J. E. Schoenhals, B. P. Venkatesulu, C. C. Anderson, H. B. Barsoumian, A. I. Younes, K. M. Ls, M. Soeung, K. E. Aziz, J. W. Welsh, and S. Krishnan. Radiation therapy and immunotherapy: what is the optimal timing or sequencing? Immunotherapy 10(4):299–316, 2018.

    Google Scholar 

  6. 6.

    Amar-Lewis, E., A. Azagury, R. Chintakunta, R. Goldbart, T. Traitel, J. Prestwood, D. Landesman-Milo, D. Peer, and J. Kost. Quaternized starch-based carrier for siRNA delivery: from cellular uptake to gene silencing. J. Control. Release 185:109–120, 2014.

    Google Scholar 

  7. 7.

    Arany, S., D. S. Benoit, S. Dewhurst, and C. E. Ovitt. Nanoparticle-mediated gene silencing confers radioprotection to salivary glands in vivo. Mol. Ther. 21(6):1182–1194, 2013.

    Google Scholar 

  8. 8.

    Aznar, M. A., N. Tinari, A. J. Rullan, A. R. Sanchez-Paulete, M. E. Rodriguez-Ruiz, and I. Melero. Intratumoral delivery of immunotherapy-act locally, think globally. J. Immunol. 198(1):31–39, 2017.

    Google Scholar 

  9. 9.

    Bartlett, D. W., and M. E. Davis. Insights into the kinetics of siRNA-mediated gene silencing from live-cell and live-animal bioluminescent imaging. Nucleic Acids Res. 34(1):322–333, 2006.

    Google Scholar 

  10. 10.

    Beyranvand Nejad, E., M. J. Welters, R. Arens, and S. H. van der Burg. The importance of correctly timing cancer immunotherapy. Expert Opin. Biol. Ther. 17(1):87–103, 2017.

    Google Scholar 

  11. 11.

    Bobbin, M. L., and J. J. Rossi. RNA Interference (RNAi)-Based Therapeutics: delivering on the Promise? Annu. Rev. Pharmacol. Toxicol. 56:103–122, 2016.

    Google Scholar 

  12. 12.

    Brody, J. D., W. Z. Ai, D. K. Czerwinski, J. A. Torchia, M. Levy, R. H. Advani, Y. H. Kim, R. T. Hoppe, S. J. Knox, L. K. Shin, I. Wapnir, R. J. Tibshirani, and R. Levy. In situ vaccination with a TLR9 agonist induces systemic lymphoma regression: a phase I/II study. J. Clin. Oncol. 28(28):4324–4332, 2010.

    Google Scholar 

  13. 13.

    Broz, P., and D. M. Monack. Newly described pattern recognition receptors team up against intracellular pathogens. Nat. Rev. Immunol. 13(8):551–565, 2013.

    Google Scholar 

  14. 14.

    Brudno, Y., and D. J. Mooney. On-demand drug delivery from local depots. J. Control. Release 219:8–17, 2015.

    Google Scholar 

  15. 15.

    Chang, E., A. J. McClellan, W. J. Farley, D. Q. Li, S. C. Pflugfelder, and C. S. De Paiva. Biodegradable PLGA-based drug delivery systems for modulating ocular surface disease under experimental murine dry eye. J. Clin. Exp. Ophthalmol. 2(11):191, 2011.

    Google Scholar 

  16. 16.

    Chen, Q., C. Wang, X. Zhang, G. Chen, Q. Hu, H. Li, J. Wang, D. Wen, Y. Zhang, Y. Lu, G. Yang, C. Jiang, J. Wang, G. Dotti, and Z. Gu. In situ sprayed bioresponsive immunotherapeutic gel for post-surgical cancer treatment. Nat. Nanotechnol. 14(1):89–97, 2019.

    Google Scholar 

  17. 17.

    Cohen, H., R. J. Levy, J. Gao, I. Fishbein, V. Kousaev, S. Sosnowski, S. Slomkowski, and G. Golomb. Sustained delivery and expression of DNA encapsulated in polymeric nanoparticles. Gene Ther. 7(22):1896–1905, 2000.

    Google Scholar 

  18. 18.

    Convertine, A. J., D. S. Benoit, C. L. Duvall, A. S. Hoffman, and P. S. Stayton. Development of a novel endosomolytic diblock copolymer for siRNA delivery. J. Control. Release 133(3):221–229, 2009.

    Google Scholar 

  19. 19.

    Convertine, A. J., C. Diab, M. Prieve, A. Paschal, A. S. Hoffman, P. H. Johnson, and P. S. Stayton. pH-Responsive polymeric micelle carriers for siRNA drugs. Biomacromolecules 11(11):2904–2910, 2010.

    Google Scholar 

  20. 20.

    Cooper, C., and D. Mackie. Hepatitis B surface antigen-1018 ISS adjuvant-containing vaccine: a review of HEPLISAV safety and efficacy. Expert Rev. Vaccines 10(4):417–427, 2011.

    Google Scholar 

  21. 21.

    Cun, D., C. Foged, M. Yang, S. Frokjaer, and H. M. Nielsen. Preparation and characterization of poly(d,l-lactide-co-glycolide) nanoparticles for siRNA delivery. Int. J. Pharm. 390(1):70–75, 2010.

    Google Scholar 

  22. 22.

    Cun, D., D. K. Jensen, M. J. Maltesen, M. Bunker, P. Whiteside, D. Scurr, C. Foged, and H. M. Nielsen. High loading efficiency and sustained release of siRNA encapsulated in PLGA nanoparticles: quality by design optimization and characterization. Eur. J. Pharm. Biopharm. 77(1):26–35, 2011.

    Google Scholar 

  23. 23.

    Danhier, F., E. Ansorena, J. M. Silva, R. Coco, A. Le Breton, and V. Preat. PLGA-based nanoparticles: an overview of biomedical applications. J. Control. Release 161(2):505–522, 2012.

    Google Scholar 

  24. 24.

    Elion, D. L., M. E. Jacobson, D. J. Hicks, B. Rahman, V. Sanchez, P. I. Gonzales-Ericsson, O. Fedorova, A. M. Pyle, J. T. Wilson, and R. S. Cook. Therapeutically active RIG-I agonist induces immunogenic tumor cell killing in breast cancers. Cancer Res. 78(21):6183–6195, 2018.

    Google Scholar 

  25. 25.

    Ferritto, M. S., and D. A. Tirrell. Photoregulation of the binding of an azobenzene-modified poly(methacrylic acid) to phosphatidylcholine bilayer membranes. Biomaterials 11(9):645–651, 1990.

    Google Scholar 

  26. 26.

    Fire, A., S. Xu, M. K. Montgomery, S. A. Kostas, S. E. Driver, and C. C. Mello. Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. Nature 391(6669):806–811, 1998.

    Google Scholar 

  27. 27.

    Frauke Pistel, K., A. Breitenbach, R. Zange-Volland, and T. Kissel. Brush-like branched biodegradable polyesters, part III. Protein release from microspheres of poly(vinyl alcohol)-graft-poly(d,l-lactic-co-glycolic acid). J. Control. Release 73(1):7–20, 2001.

    Google Scholar 

  28. 28.

    Hammerich, L., A. Binder, and J. D. Brody. In situ vaccination: cancer immunotherapy both personalized and off-the-shelf. Mol Oncol 9(10):1966–1981, 2015.

    Google Scholar 

  29. 29.

    Han, F. Y., K. J. Thurecht, A. K. Whittaker, and M. T. Smith. Bioerodable PLGA-based microparticles for producing sustained-release drug formulations and strategies for improving drug loading. Front Pharmacol. 7:185, 2016.

    Google Scholar 

  30. 30.

    Ishihara, J., K. Fukunaga, A. Ishihara, H. M. Larsson, L. Potin, P. Hosseinchi, G. Galliverti, M. A. Swartz, and J. A. Hubbell. Matrix-binding checkpoint immunotherapies enhance antitumor efficacy and reduce adverse events. Sci. Transl. Med. 9(415):eaan0401, 2017.

    Google Scholar 

  31. 31.

    Jacobson, M. E., L. Wang-Bishop, K. W. Becker, and J. T. Wilson. Delivery of 5′-triphosphate RNA with endosomolytic nanoparticles potently activates RIG-I to improve cancer immunotherapy. Biomater. Sci. 7(2):547–559, 2019.

    Google Scholar 

  32. 32.

    Jewell, C. M., S. C. B. López, and D. J. Irvine. In situ engineering of the lymph node microenvironment via intranodal injection of adjuvant-releasing polymer particles. Proc. Natl. Acad. Sci. USA 108(38):15745–15750, 2011.

    Google Scholar 

  33. 33.

    Jiang, W., F. G. Zhu, L. Bhagat, D. Yu, J. X. Tang, E. R. Kandimalla, N. La Monica, and S. Agrawal. A toll-like receptor 7, 8, and 9 antagonist inhibits Th1 and Th17 responses and inflammasome activation in a model of IL-23-induced psoriasis. J. Invest. Dermatol. 133(7):1777–1784, 2013.

    Google Scholar 

  34. 34.

    Johannes, L., and M. Lucchino. Current challenges in delivery and cytosolic translocation of therapeutic RNAs. Nucleic Acid Ther. 28(3):178–193, 2018.

    Google Scholar 

  35. 35.

    Khan, A., M. Benboubetra, P. Z. Sayyed, K. W. Ng, S. Fox, G. Beck, I. F. Benter, and S. Akhtar. Sustained polymeric delivery of gene silencing antisense ODNs, siRNA, DNAzymes and ribozymes: in vitro and in vivo studies. J. Drug Target. 12(6):393–404, 2004.

    Google Scholar 

  36. 36.

    Krhac Levacic, A., S. Morys, and E. Wagner. Solid-phase supported design of carriers for therapeutic nucleic acid delivery. Biosci. Rep. 37(5):BSR20160617, 2017.

    Google Scholar 

  37. 37.

    Kwong, B., S. A. Gai, J. Elkhader, K. D. Wittrup, and D. J. Irvine. Localized immunotherapy via liposome-anchored Anti-CD137 + IL-2 prevents lethal toxicity and elicits local and systemic antitumor immunity. Can. Res. 73(5):1547–1558, 2013.

    Google Scholar 

  38. 38.

    Kwong, B., H. Liu, and D. J. Irvine. Induction of potent anti-tumor responses while eliminating systemic side effects via liposome-anchored combinatorial immunotherapy. Biomaterials 32(22):5134–5147, 2011.

    Google Scholar 

  39. 39.

    Langer, R. Drug delivery and targeting. Nature 392(6679 Suppl):5–10, 1998.

    Google Scholar 

  40. 40.

    Langer, R., and D. A. Tirrell. Designing materials for biology and medicine. Nature 428(6982):487–492, 2004.

    Google Scholar 

  41. 41.

    Luby, T. M., G. Cole, L. Baker, J. S. Kornher, U. Ramstedt, and M. L. Hedley. Repeated immunization with plasmid DNA formulated in poly(lactide-co-glycolide) microparticles is well tolerated and stimulates durable T cell responses to the tumor-associated antigen cytochrome P450 1B1. Clin. Immunol. 112(1):45–53, 2004.

    Google Scholar 

  42. 42.

    Lurescia, S., D. Fioretti, and M. Rinaldi. Targeting cytosolic nucleic acid-sensing pathways for cancer immunotherapies. Front. Immunol. 9:711, 2018.

    Google Scholar 

  43. 43.

    Lurescia, S., D. Fioretti, and M. Rinaldi. Nucleic acid sensing machinery: targeting innate immune system for cancer therapy. Recent Pat. Anticancer Drug Discov. 13(1):2–17, 2018.

    Google Scholar 

  44. 44.

    Luten, J., C. F. van Nostrum, S. C. De Smedt, and W. E. Hennink. Biodegradable polymers as non-viral carriers for plasmid DNA delivery. J. Control. Release 126(2):97–110, 2008.

    Google Scholar 

  45. 45.

    Makadia, H. K., and S. J. Siegel. Poly lactic-co-glycolic acid (PLGA) as biodegradable controlled drug delivery carrier. Polymers (Basel) 3(3):1377–1397, 2011.

    Google Scholar 

  46. 46.

    Malcolm, D. W., M. A. T. Freeberg, Y. Wang, K. R. Sims, H. A. Awad, and D. S. W. Benoit. Diblock copolymer hydrophobicity facilitates efficient gene silencing and cytocompatible nanoparticle-mediated siRNA delivery to musculoskeletal cell types. Biomacromolecules 18(11):3753–3765, 2017.

    Google Scholar 

  47. 47.

    Mao, S., J. Xu, C. Cai, O. Germershaus, A. Schaper, and T. Kissel. Effect of WOW process parameters on morphology and burst release of FITC-dextran loaded PLGA microspheres. Int. J. Pharm. 334(1–2):137–148, 2007.

    Google Scholar 

  48. 48.

    Marabelle, A., H. Kohrt, C. Caux, and R. Levy. Intratumoral immunization: a new paradigm for cancer therapy. Clin. Cancer Res. 20(7):1747–1756, 2014.

    Google Scholar 

  49. 49.

    Marabelle, A., L. Tselikas, T. de Baere, and R. Houot. Intratumoral immunotherapy: using the tumor as the remedy. Ann. Oncol. 28(suppl 12):xii33–xii43, 2017.

    Google Scholar 

  50. 50.

    Martin, J. R., C. E. Nelson, M. K. Gupta, F. Yu, S. M. Sarett, K. M. Hocking, A. C. Pollins, L. B. Nanney, J. M. Davidson, S. A. Guelcher, and C. L. Duvall. Local delivery of PHD2 siRNA from ROS-degradable scaffolds to promote diabetic wound healing. Adv. Healthc. Mater. 5(21):2751–2757, 2016.

    Google Scholar 

  51. 51.

    McGinity, J. W., and P. B. O’Donnell. Preparation of microspheres by the solvent evaporation technique. Adv. Drug Deliv. Rev. 28(1):25–42, 1997.

    Google Scholar 

  52. 52.

    Milling, L., Y. Zhang, and D. J. Irvine. Delivering safer immunotherapies for cancer. Adv. Drug Deliv. Rev. 114:79–101, 2017.

    Google Scholar 

  53. 53.

    National Center for Immunization and Respiratory Diseases. General recommendations on immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm. Rep. 60(2):1–64, 2011.

    Google Scholar 

  54. 54.

    Nelson, C. E., M. K. Gupta, E. J. Adolph, J. M. Shannon, S. A. Guelcher, and C. L. Duvall. Sustained local delivery of siRNA from an injectable scaffold. Biomaterials 33(4):1154–1161, 2012.

    Google Scholar 

  55. 55.

    Nishikawa, M., Y. Mizuno, K. Mohri, N. Matsuoka, S. Rattanakiat, Y. Takahashi, H. Funabashi, D. Luo, and Y. Takakura. Biodegradable CpG DNA hydrogels for sustained delivery of doxorubicin and immunostimulatory signals in tumor-bearing mice. Biomaterials 32(2):488–494, 2011.

    Google Scholar 

  56. 56.

    Ogawa, Y., M. Yamamoto, H. Okada, T. Yashiki, and T. Shimamoto. A new technique to efficiently entrap leuprolide acetate into microcapsules of polylactic acid or copoly(lactic/glycolic) acid. Chem. Pharm. Bull. (Tokyo) 36(3):1095–1103, 1988.

    Google Scholar 

  57. 57.

    Ozcan, G., B. Ozpolat, R. L. Coleman, A. K. Sood, and G. Lopez-Berestein. Preclinical and clinical development of siRNA-based therapeutics. Adv. Drug Deliv. Rev. 87:108–119, 2015.

    Google Scholar 

  58. 58.

    Pannier, A. K., and L. D. Shea. Controlled release systems for DNA delivery. Mol. Ther. 10(1):19–26, 2004.

    Google Scholar 

  59. 59.

    Pantazis, P., K. Dimas, J. H. Wyche, S. Anant, C. W. Houchen, J. Panyam, and R. P. Ramanujam. Preparation of siRNA-encapsulated PLGA nanoparticles for sustained release of siRNA and evaluation of encapsulation efficiency. Methods Mol. Biol. 906:311–319, 2012.

    Google Scholar 

  60. 60.

    Park, C. G., C. A. Hartl, D. Schmid, E. M. Carmona, H. J. Kim, and M. S. Goldberg. Extended release of perioperative immunotherapy prevents tumor recurrence and eliminates metastases. Sci. Transl. Med. 10(433):eear1916, 2018.

    Google Scholar 

  61. 61.

    Patil, Y., and J. Panyam. Polymeric nanoparticles for siRNA delivery and gene silencing. Int. J. Pharm. 367(1–2):195–203, 2009.

    Google Scholar 

  62. 62.

    Poeck, H., R. Besch, C. Maihoefer, M. Renn, D. Tormo, S. S. Morskaya, S. Kirschnek, E. Gaffal, J. Landsberg, J. Hellmuth, A. Schmidt, D. Anz, M. Bscheider, T. Schwerd, C. Berking, C. Bourquin, U. Kalinke, E. Kremmer, H. Kato, S. Akira, R. Meyers, G. Häcker, M. Neuenhahn, D. Busch, J. Ruland, S. Rothenfusser, M. Prinz, V. Hornung, S. Endres, T. Tüting, and G. Hartmann. 5′-Triphosphate-siRNA: turning gene silencing and RIG-I activation against melanoma. Nat. Med. 14(11):1256–1263, 2008.

    Google Scholar 

  63. 63.

    Radovic-Moreno, A. F., N. Chernyak, C. C. Mader, S. Nallagatla, R. S. Kang, L. Hao, D. A. Walker, T. L. Halo, T. J. Merkel, C. H. Rische, S. Anantatmula, M. Burkhart, C. A. Mirkin, and S. M. Gryaznov. Immunomodulatory spherical nucleic acids. Proc. Natl. Acad. Sci. USA 112(13):3892–3897, 2015.

    Google Scholar 

  64. 64.

    Rathbone, M. J., J. Hadgraft, and M. S. Roberts. Modified-release drug delivery technology. London: Taylor & Francis, 2002.

    Google Scholar 

  65. 65.

    Rothschilds, A. M., and K. D. Wittrup. What, why, where, and when: bringing timing to immuno-oncology. Trends Immunol. 40(1):12–21, 2019.

    Google Scholar 

  66. 66.

    Sarett, S. M., C. E. Nelson, and C. L. Duvall. Technologies for controlled, local delivery of siRNA. J. Control. Release 218:94–113, 2015.

    Google Scholar 

  67. 67.

    Senti, G., A. U. Freiburghaus, D. Larenas-Linnemann, H. J. Hoffmann, A. M. Patterson, L. Klimek, D. Di Bona, O. Pfaar, L. Ahlbeck, M. Akdis, D. Weinfeld, F. A. Contreras-Verduzco, A. Pedroza-Melendez, S. H. Skaarup, S. M. Lee, L. O. Cardell, J. M. Schmid, U. Westin, R. Dollner, and T. M. Kundig. Intralymphatic immunotherapy: update and unmet needs. Int. Arch. Allergy Immunol. 178(2):141–149, 2019.

    Google Scholar 

  68. 68.

    Sioud, M. RNA interference: mechanisms, technical challenges, and therapeutic opportunities. Methods Mol. Biol. 1218:1–15, 2015.

    Google Scholar 

  69. 69.

    Smith, S. A., L. I. Selby, A. P. R. Johnston, and G. K. Such. The endosomal escape of nanoparticles: towards more efficient cellular delivery. Bioconjug. Chem. 30(2):263–272, 2018.

    Google Scholar 

  70. 70.

    van den Boorn, J. G., W. Barchet, and G. Hartmann. Nucleic acid adjuvants: toward an educated vaccine. Adv. Immunol. 114:1–32, 2012.

    Google Scholar 

  71. 71.

    van den Boorn, J. G., and G. Hartmann. Turning tumors into vaccines: co-opting the innate immune system. Immunity 39(1):27–37, 2013.

    Google Scholar 

  72. 72.

    Wang, L. L., and J. A. Burdick. Engineered hydrogels for local and sustained delivery of RNA-interference therapies. Adv. Healthc. Mater. 6(1):1601041, 2017.

    Google Scholar 

  73. 73.

    Wang, Y., D. W. Malcolm, and D. S. W. Benoit. Controlled and sustained delivery of siRNA/NPs from hydrogels expedites bone fracture healing. Biomaterials 139:127–138, 2017.

    Google Scholar 

  74. 74.

    Wang, D., D. R. Robinson, G. S. Kwon, and J. Samuel. Encapsulation of plasmid DNA in biodegradable poly(d,l-lactic-co-glycolic acid) microspheres as a novel approach for immunogene delivery. J. Control. Release 57(1):9–18, 1999.

    Google Scholar 

  75. 75.

    Wang, C., W. Sun, G. Wright, A. Z. Wang, and Z. Gu. Inflammation-triggered cancer immunotherapy by programmed delivery of CpG and anti-PD1 antibody. Adv. Mater. 28(40):8912–8920, 2016.

    Google Scholar 

  76. 76.

    Whitehead, K. A., R. Langer, and D. G. Anderson. Knocking down barriers: advances in siRNA delivery. Nat. Rev. Drug Discov. 8(2):129–138, 2009.

    Google Scholar 

  77. 77.

    Wilson, J. T., S. Keller, M. J. Manganiello, C. Cheng, C.-C. Lee, C. Opara, A. Convertine, and P. S. Stayton. pH-Responsive nanoparticle vaccines for dual-delivery of antigens and immunostimulatory oligonucleotides. ACS Nano. 7(5):3912–3925, 2013.

    Google Scholar 

  78. 78.

    Woodrow, K. A., Y. Cu, C. J. Booth, J. K. Saucier-Sawyer, M. J. Wood, and W. M. Saltzman. Intravaginal gene silencing using biodegradable polymer nanoparticles densely loaded with small-interfering RNA. Nat. Mater. 8(6):526–533, 2009.

    Google Scholar 

  79. 79.

    Wu, S. Y., G. Lopez-Berestein, G. A. Calin, and A. K. Sood. RNAi therapies: drugging the undruggable. Sci. Transl. Med. 6(240):240, 2014.

    Google Scholar 

  80. 80.

    Wu-Pong, S., and Y. Rojanasakul. Biopharmaceutical Drug Design and Development (2nd ed.). Totowa: Humana Press, p. 375, 2008.

    Google Scholar 

  81. 81.

    Yan, J., Z.-Y. Wang, H.-Z. Yang, H.-Z. Liu, S. Mi, X.-X. Lv, X.-M. Fu, H.-M. Yan, X.-W. Zhang, Q.-M. Zhan, and Z.-W. Hu. Timing is critical for an effective anti-metastatic immunotherapy: the decisive role of IFNγ/STAT1-mediated activation of autophagy. PLoS ONE 6(9):e24705, 2011.

    Google Scholar 

  82. 82.

    Young, K. H., J. R. Baird, T. Savage, B. Cottam, D. Friedman, S. Bambina, D. J. Messenheimer, B. Fox, P. Newell, K. S. Bahjat, M. J. Gough, and M. R. Crittenden. Optimizing timing of immunotherapy improves control of tumors by hypofractionated radiation therapy. PLoS ONE 11(6):e0157164, 2016.

    Google Scholar 

  83. 83.

    Zhang, L., W. Wang, and S. Wang. Effect of vaccine administration modality on immunogenicity and efficacy. Expert Rev. Vaccines 14(11):1509–1523, 2015.

    Google Scholar 

  84. 84.

    Zhu, F. G., W. Jiang, L. Bhagat, D. Wang, D. Yu, J. X. Tang, E. R. Kandimalla, N. La Monica, and S. Agrawal. A novel antagonist of Toll-like receptors 7, 8 and 9 suppresses lupus disease-associated parameters in NZBW/F1 mice. Autoimmunity 46(7):419–428, 2013.

    Google Scholar 

  85. 85.

    Zhu, X., F. Nishimura, K. Sasaki, M. Fujita, J. E. Dusak, J. Eguchi, W. Fellows-Mayle, W. J. Storkus, P. R. Walker, A. M. Salazar, and H. Okada. Toll like receptor-3 ligand poly-ICLC promotes the efficacy of peripheral vaccinations with tumor antigen-derived peptide epitopes in murine CNS tumor models. J. Transl. Med. 5:10, 2007.

    Google Scholar 

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We gratefully acknowledge Dr. Bob Weinberg and Dr. Didier Trono for gifts of plasmids via Addgene.org. We thank Dr. Steven Goodbred Jr. and his laboratory for use of the Mastersizer 2000 (Malvern, USA). We thank Kyle Becker for his assistance with the orthotopic tumor inoculations. We thank the core facilities of Vanderbilt, including the Vanderbilt Institute of Nanoscale Sciences and Engineering (VINSE) for the use of both the Zetasizer Nano ZS Instrument (Malvern, USA) and the Zeiss Merlin SEM (Carl Zeiss Microscopy, LLC, ZEISS Group, Thornwood, NY), the Vanderbilt Translational Pathology Shared Resource (supported in part by the NCI/NIH Cancer Center Support Grant 5P30 CA684850-19) for cryosectioning of tumor samples, and Vanderbilt University Medical Center Flow Cytometry Shared Resource (supported by the Vanderbilt Ingram Cancer Center P30 CA68485) and the Vanderbilt Digestive Disease Research Center (DK058404) for cell sorting. This research was supported by grants from Alex’s Lemonade Stand Foundation ‘A’ Award SID924 (JTW) and Pediatric Oncology Student Training (POST) Award cosponsored by Love Your Mellon (KMG), the American Cancer Society Institutional Research Grant IRG-58-009-56 (JTW), the Congressionally-Directed Medical Research Program W81XWH-161-0063 (JTW) and W81XWH-161-0063 (RSC), the National Institutes of Health R01CA224241 (CLD) and R01EB019409 (CLD), and the National Science Foundation Graduate Research Fellowship Program 0909667 and 1445197 (KVK).

Conflict of interest

The authors declare no conflicts of interest.

Ethical approval

All animal experiments were approved by the Vanderbilt University Institutional Animal Care and Use Committee (IACUC), and all surgical and experimental procedures were performed in accordance with the regulations and guidelines of the Vanderbilt University IACUC. Female BALB/cJ mice (6–8 weeks old; The Jackson Laboratory, Bar Harbor, ME) were maintained at the animal facilities of Vanderbilt University under specific pathogen-free conditions. Tumor volume, total mass, and animal well-being were monitored every other day.

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Correspondence to John T. Wilson.

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John T. Wilson is an Assistant Professor of Chemical and Biomolecular Engineering and Biomedical Engineering at Vanderbilt University. He received his B.S. in Bioengineering from Oregon State University and his Ph.D. from the Georgia Institute of Technology in the laboratory of Professor Elliot L. Chaikof, where he was awarded a Whitaker Foundation Graduate Fellowship. He then joined the laboratory of Professor Patrick Stayton at the University of Washington with support of a Cancer Research Institute Postdoctoral Fellowship. He started his independent laboratory at Vanderbilt in January of 2014, where his group works at the interface of molecular engineering and immunology to innovate technologies to improve human health. His multidisciplinary research program is supported by productive and synergistic collaborations with oncologists, cancer biologists, immunologists, chemists, and other engineers. Since establishing his lab at Vanderbilt, he has been awarded the NSF CAREER Award, an ‘A’ Award from Alex’s Lemonade Stand Foundation, a Melanoma Research Alliance Young Investigator Award, an Innovative Research Grant from Stand Up To Cancer, and has been named an Emerging Investigator by Biomaterials Science.


This article is part of the 2019 CMBE Young Innovators special issue.

Associate Editor Michael R. King oversaw the review of this article.

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Garland, K.M., Sevimli, S., Kilchrist, K.V. et al. Microparticle Depots for Controlled and Sustained Release of Endosomolytic Nanoparticles. Cel. Mol. Bioeng. 12, 429–442 (2019). https://doi.org/10.1007/s12195-019-00571-6

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