1
|
Underhill HR, Karsy M, Davidson CJ, Hellwig S, Stevenson S, Goold EA, Vincenti S, Sellers DL, Dean C, Harrison BE, Bronner MP, Colman H, Jensen RL. Subclonal Cancer Driver Mutations Are Prevalent in the Unresected Peritumoral Edema of Adult Diffuse Gliomas. Cancer Res 2024; 84:1149-1164. [PMID: 38270917 PMCID: PMC10982644 DOI: 10.1158/0008-5472.can-23-2557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/20/2023] [Accepted: 01/23/2024] [Indexed: 01/26/2024]
Abstract
Adult diffuse gliomas commonly recur regardless of therapy. As recurrence typically arises from the peritumoral edema adjacent to the resected bulk tumor, the profiling of somatic mutations from infiltrative malignant cells within this critical, unresected region could provide important insights into residual disease. A key obstacle has been the inability to distinguish between next-generation sequencing (NGS) noise and the true but weak signal from tumor cells hidden among the noncancerous brain tissue of the peritumoral edema. Here, we developed and validated True2 sequencing to reduce NGS-associated errors to <1 false positive/100 kb panel positions while detecting 97.6% of somatic mutations with an allele frequency ≥0.1%. True2 was then used to study the tumor and peritumoral edema of 22 adult diffuse gliomas including glioblastoma, astrocytoma, oligodendroglioma, and NF1-related low-grade neuroglioma. The tumor and peritumoral edema displayed a similar mutation burden, indicating that surgery debulks these cancers physically but not molecularly. Moreover, variants in the peritumoral edema included unique cancer driver mutations absent in the bulk tumor. Finally, analysis of multiple samples from each patient revealed multiple subclones with unique mutations in the same gene in 17 of 22 patients, supporting the occurrence of convergent evolution in response to patient-specific selective pressures in the tumor microenvironment that may form the molecular foundation of recurrent disease. Collectively, True2 enables the detection of ultralow frequency mutations during molecular analyses of adult diffuse gliomas, which is necessary to understand cancer evolution, recurrence, and individual response to therapy. SIGNIFICANCE True2 is a next-generation sequencing workflow that facilitates unbiased discovery of somatic mutations across the full range of variant allele frequencies, which could help identify residual disease vulnerabilities for targeted adjuvant therapies.
Collapse
Affiliation(s)
- Hunter R. Underhill
- Department of Pediatrics, Division of Medical Genetics, University of Utah, Salt Lake City, Utah
- Department of Radiology, University of Utah, Salt Lake City, Utah
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | - Michael Karsy
- Department of Neurological Surgery, University of Utah, Salt Lake City, Utah
| | | | | | - Samuel Stevenson
- Department of Pediatrics, Division of Medical Genetics, University of Utah, Salt Lake City, Utah
| | - Eric A. Goold
- Department of Pathology, University of Utah, Salt Lake City, Utah
| | | | - Drew L. Sellers
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Charlie Dean
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | - Brion E. Harrison
- Department of Pediatrics, Division of Medical Genetics, University of Utah, Salt Lake City, Utah
| | - Mary P. Bronner
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
- Department of Pathology, University of Utah, Salt Lake City, Utah
| | - Howard Colman
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
- Department of Neurological Surgery, University of Utah, Salt Lake City, Utah
- Department of Internal Medicine, Division of Oncology, University of Utah, Salt Lake City, Utah
| | - Randy L. Jensen
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
- Department of Neurological Surgery, University of Utah, Salt Lake City, Utah
| |
Collapse
|
2
|
Nguyen DC, Song K, Jokonya S, Yazdani O, Sellers DL, Wang Y, Zakaria ABM, Pun SH, Stayton PS. Mannosylated STING Agonist Drugamers for Dendritic Cell-Mediated Cancer Immunotherapy. ACS Cent Sci 2024; 10:666-675. [PMID: 38559305 PMCID: PMC10979423 DOI: 10.1021/acscentsci.3c01310] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/22/2024] [Accepted: 02/06/2024] [Indexed: 04/04/2024]
Abstract
The Stimulator of Interferon Genes (STING) pathway is a promising target for cancer immunotherapy. Despite recent advances, therapies targeting the STING pathway are often limited by routes of administration, suboptimal STING activation, or off-target toxicity. Here, we report a dendritic cell (DC)-targeted polymeric prodrug platform (polySTING) that is designed to optimize intracellular delivery of a diamidobenzimidazole (diABZI) small-molecule STING agonist while minimizing off-target toxicity after parenteral administration. PolySTING incorporates mannose targeting ligands as a comonomer, which facilitates its uptake in CD206+/mannose receptor+ professional antigen-presenting cells (APCs) in the tumor microenvironment (TME). The STING agonist is conjugated through a cathepsin B-cleavable valine-alanine (VA) linker for selective intracellular drug release after receptor-mediated endocytosis. When administered intravenously in tumor-bearing mice, polySTING selectively targeted CD206+/mannose receptor+ APCs in the TME, resulting in increased cross-presenting CD8+ DCs, infiltrating CD8+ T cells in the TME as well as maturation across multiple DC subtypes in the tumor-draining lymph node (TDLN). Systemic administration of polySTING slowed tumor growth in a B16-F10 murine melanoma model as well as a 4T1 murine breast cancer model with an acceptable safety profile. Thus, we demonstrate that polySTING delivers STING agonists to professional APCs after systemic administration, generating efficacious DC-driven antitumor immunity with minimal side effects. This new polymeric prodrug platform may offer new opportunities for combining efficient targeted STING agonist delivery with other selective tumor therapeutic strategies.
Collapse
Affiliation(s)
- Dinh Chuong Nguyen
- Molecular
Engineering & Sciences Institute, University
of Washington, Seattle, Washington 98195, United States
| | - Kefan Song
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| | - Simbarashe Jokonya
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| | - Omeed Yazdani
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| | - Drew L. Sellers
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| | - Yonghui Wang
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| | - ABM Zakaria
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| | - Suzie H. Pun
- Molecular
Engineering & Sciences Institute, University
of Washington, Seattle, Washington 98195, United States
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| | - Patrick S. Stayton
- Molecular
Engineering & Sciences Institute, University
of Washington, Seattle, Washington 98195, United States
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| |
Collapse
|
3
|
Sellers DL, Lee K, Murthy N, Pun SH. TAxI-peptide targeted Cas12a ribonuclease protein nanoformulations increase genome editing in hippocampal neurons. J Control Release 2023; 354:188-195. [PMID: 36596342 PMCID: PMC9975068 DOI: 10.1016/j.jconrel.2022.12.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 12/19/2022] [Accepted: 12/28/2022] [Indexed: 01/05/2023]
Abstract
Gene therapy approaches that utilize Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) ribonucleases have tremendous potential to treat human disease. However, CRISPR therapies delivered by integrating viral vectors are limited by potential off-target genome editing caused by constitutive activation of ribonuclease functions. Thus, biomaterial formulations are being used for the delivery of purified CRISPR components to increase the efficiency and safety of genome editing approaches. We previously demonstrated that a novel peptide identified by phage display, TAxI-peptide, mediates delivery of recombinant proteins into neurons. In this report we utilized NeutrAvidin protein to formulate neuron-targeted genome-editing nanoparticles. Cas12a ribonucleases was loaded with biotinylated guide RNA and biotinylated TAxI-peptide onto NeutrAvidin protein to coordinate the formation a targeted ribonuclease protein (RNP) complex. TAxI-RNP complexes are polydisperse with a 14.3 nm radius. The nanoparticles are stable after formulation and show good stability in the presence of normal mouse serum. TAxI-RNP nanoparticles increased neuronal delivery of Cas12a in reporter mice, resulting in induced tdTomato expression after direct injection into the dentate gyrus of the hippocampus. TAxI-RNP nanoparticles also increased genome editing efficacy in hippocampal neurons versus glia. These studies demonstrate the ability to assemble RNP nanoformulations with NeutrAvidin by binding biotinylated peptides and gRNA-loaded Cas12a ribonucleases into protein nanoparticles that target CRISPR delivery to specific cell-types in vivo. The potential to deliver CRISPR nanoparticles to specific cell-types and control off-target delivery to further reduce deleterious genome editing is essential for the creation of viable therapies to treat nervous system disease.
Collapse
Affiliation(s)
- Drew L Sellers
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, United States; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, United States.
| | - Kunwoo Lee
- GenEdit Inc., Berkeley, CA, United States
| | - Niren Murthy
- Department of Bioengineering, University of California, Berkeley, CA, United States
| | - Suzie H Pun
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, United States.
| |
Collapse
|
4
|
Abstract
Despite the rising global incidence of central nervous system (CNS) disorders, CNS drug development remains challenging, with high costs, long pathways to clinical use and high failure rates. The CNS is highly protected by physiological barriers, in particular, the blood-brain barrier and the blood-cerebrospinal fluid barrier, which limit access of most drugs. Biomaterials can be designed to bypass or traverse these barriers, enabling the controlled delivery of drugs into the CNS. In this Review, we first examine the effects of normal and diseased CNS physiology on drug delivery to the brain and spinal cord. We then discuss CNS drug delivery designs and materials that are administered systemically, directly to the CNS, intranasally or peripherally through intramuscular injections. Finally, we highlight important challenges and opportunities for materials design for drug delivery to the CNS and the anticipated clinical impact of CNS drug delivery.
Collapse
Affiliation(s)
- Elizabeth Nance
- Department of Chemical Engineering, University of Washington, Seattle, WA, USA
- These authors contributed equally: Elizabeth Nance, Suzie H. Pun, Rajiv Saigal, Drew L. Sellers
| | - Suzie H. Pun
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- These authors contributed equally: Elizabeth Nance, Suzie H. Pun, Rajiv Saigal, Drew L. Sellers
| | - Rajiv Saigal
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Department of Neurological Surgery, University of Washington, Seattle, WA, USA
- These authors contributed equally: Elizabeth Nance, Suzie H. Pun, Rajiv Saigal, Drew L. Sellers
| | - Drew L. Sellers
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- These authors contributed equally: Elizabeth Nance, Suzie H. Pun, Rajiv Saigal, Drew L. Sellers
| |
Collapse
|
5
|
Zhao YT, Fallas JA, Saini S, Ueda G, Somasundaram L, Zhou Z, Xavier Raj I, Xu C, Carter L, Wrenn S, Mathieu J, Sellers DL, Baker D, Ruohola-Baker H. F-domain valency determines outcome of signaling through the angiopoietin pathway. EMBO Rep 2021; 22:e53471. [PMID: 34698433 DOI: 10.15252/embr.202153471] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/09/2021] [Accepted: 09/16/2021] [Indexed: 12/14/2022] Open
Abstract
Angiopoietins 1 and 2 (Ang1 and Ang2) regulate angiogenesis through their similar F-domains by activating Tie2 receptors on endothelial cells. Despite the similarity in the underlying receptor-binding interaction, the two angiopoietins have opposite effects: Ang1 induces phosphorylation of AKT, strengthens cell-cell junctions, and enhances endothelial cell survival while Ang2 can antagonize these effects, depending on cellular context. To investigate the molecular basis for the opposing effects, we examined the phenotypes of a series of computationally designed protein scaffolds presenting the Ang1 F-domain in a wide range of valencies and geometries. We find two broad phenotypic classes distinguished by the number of presented F-domains: Scaffolds presenting 3 or 4 F-domains have Ang2-like activity, upregulating pFAK and pERK but not pAKT, while scaffolds presenting 6, 8, 12, 30, or 60 F-domains have Ang1-like activity, upregulating pAKT and inducing migration and vascular stability. The scaffolds with 6 or more F-domains display super-agonist activity, producing stronger phenotypes at lower concentrations than Ang1. Tie2 super-agonist nanoparticles reduced blood extravasation and improved blood-brain barrier integrity four days after a controlled cortical impact injury.
Collapse
Affiliation(s)
- Yan Ting Zhao
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA.,Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA, USA
| | - Jorge A Fallas
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Shally Saini
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - George Ueda
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Logeshwaran Somasundaram
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Ziben Zhou
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Infencia Xavier Raj
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Chunfu Xu
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Lauren Carter
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Samuel Wrenn
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Julie Mathieu
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA.,Department of Comparative Medicine, University of Washington, Seattle, WA, USA
| | - Drew L Sellers
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA.,Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Protein Design, University of Washington, Seattle, WA, USA.,Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Hannele Ruohola-Baker
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA.,Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA, USA.,Department of Bioengineering, University of Washington, Seattle, WA, USA
| |
Collapse
|
6
|
Kacherovsky N, Yang LF, Dang HV, Cheng EL, Cardle II, Walls AC, McCallum M, Sellers DL, DiMaio F, Salipante SJ, Corti D, Veesler D, Pun SH. Discovery and Characterization of Spike N‐Terminal Domain‐Binding Aptamers for Rapid SARS‐CoV‐2 Detection. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202107730] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Nataly Kacherovsky
- Department of Bioengineering University of Washington Seattle WA 98105 USA
| | - Lucy F. Yang
- Department of Bioengineering University of Washington Seattle WA 98105 USA
| | - Ha V. Dang
- Department of Biochemistry University of Washington Seattle WA 98105 USA
| | - Emmeline L. Cheng
- Department of Bioengineering University of Washington Seattle WA 98105 USA
| | - Ian I. Cardle
- Department of Bioengineering University of Washington Seattle WA 98105 USA
| | - Alexandra C. Walls
- Department of Biochemistry University of Washington Seattle WA 98105 USA
| | - Matthew McCallum
- Department of Biochemistry University of Washington Seattle WA 98105 USA
| | - Drew L. Sellers
- Department of Bioengineering University of Washington Seattle WA 98105 USA
| | - Frank DiMaio
- Department of Biochemistry University of Washington Seattle WA 98105 USA
| | | | - Davide Corti
- Humabs BioMed SA, a subsidiary of Vir Biotechnology 6500 Bellinzona Switzerland
| | - David Veesler
- Department of Biochemistry University of Washington Seattle WA 98105 USA
| | - Suzie H. Pun
- Department of Bioengineering University of Washington Seattle WA 98105 USA
| |
Collapse
|
7
|
Kacherovsky N, Yang LF, Dang HV, Cheng EL, Cardle II, Walls AC, McCallum M, Sellers DL, DiMaio F, Salipante SJ, Corti D, Veesler D, Pun SH. Discovery and Characterization of Spike N-Terminal Domain-Binding Aptamers for Rapid SARS-CoV-2 Detection. Angew Chem Int Ed Engl 2021; 60:21211-21215. [PMID: 34328683 PMCID: PMC8426805 DOI: 10.1002/anie.202107730] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Indexed: 12/13/2022]
Abstract
The coronavirus disease 2019 (COVID‐19) pandemic has devastated families and disrupted healthcare, economies and societies across the globe. Molecular recognition agents that are specific for distinct viral proteins are critical components for rapid diagnostics and targeted therapeutics. In this work, we demonstrate the selection of novel DNA aptamers that bind to the SARS‐CoV‐2 spike glycoprotein with high specificity and affinity (<80 nM). Through binding assays and high resolution cryo‐EM, we demonstrate that SNAP1 (SARS‐CoV‐2 spike protein N‐terminal domain‐binding aptamer 1) binds to the S N‐terminal domain. We applied SNAP1 in lateral flow assays (LFAs) and ELISAs to detect UV‐inactivated SARS‐CoV‐2 at concentrations as low as 5×105 copies mL−1. SNAP1 is therefore a promising molecular tool for SARS‐CoV‐2 diagnostics.
Collapse
Affiliation(s)
- Nataly Kacherovsky
- Department of Bioengineering, University of Washington, Seattle, WA, 98105, USA
| | - Lucy F Yang
- Department of Bioengineering, University of Washington, Seattle, WA, 98105, USA
| | - Ha V Dang
- Department of Biochemistry, University of Washington, Seattle, WA, 98105, USA
| | - Emmeline L Cheng
- Department of Bioengineering, University of Washington, Seattle, WA, 98105, USA
| | - Ian I Cardle
- Department of Bioengineering, University of Washington, Seattle, WA, 98105, USA
| | - Alexandra C Walls
- Department of Biochemistry, University of Washington, Seattle, WA, 98105, USA
| | - Matthew McCallum
- Department of Biochemistry, University of Washington, Seattle, WA, 98105, USA
| | - Drew L Sellers
- Department of Bioengineering, University of Washington, Seattle, WA, 98105, USA
| | - Frank DiMaio
- Department of Biochemistry, University of Washington, Seattle, WA, 98105, USA
| | - Stephen J Salipante
- Department of Laboratory Medicine, University of Washington, Seattle, WA, 98105, USA
| | - Davide Corti
- Humabs BioMed SA, a subsidiary of, Vir Biotechnology, 6500, Bellinzona, Switzerland
| | - David Veesler
- Department of Biochemistry, University of Washington, Seattle, WA, 98105, USA
| | - Suzie H Pun
- Department of Bioengineering, University of Washington, Seattle, WA, 98105, USA
| |
Collapse
|
8
|
Cardle II, Jensen MC, Pun SH, Sellers DL. Optimized serum stability and specificity of an αvβ6 integrin-binding peptide for tumor targeting. J Biol Chem 2021; 296:100657. [PMID: 33857478 PMCID: PMC8138772 DOI: 10.1016/j.jbc.2021.100657] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/06/2021] [Accepted: 04/09/2021] [Indexed: 12/03/2022] Open
Abstract
The integrin αvβ6 is an antigen expressed at low levels in healthy tissue but upregulated during tumorigenesis, which makes it a promising target for cancer imaging and therapy. A20FMDV2 is a 20-mer peptide derived from the foot-and-mouth disease virus that exhibits nanomolar and selective affinity for αvβ6 versus other integrins. Despite this selectivity, A20FMDV2 has had limited success in imaging and treating αvβ6+ tumors in vivo because of its poor serum stability. Here, we explore the cyclization and modification of the A20FMDV2 peptide to improve its serum stability without sacrificing its affinity and specificity for αvβ6. Using cysteine amino acid substitutions and cyclization by perfluoroarylation with decafluorobiphenyl, we synthesized six cyclized A20FMDV2 variants and discovered that two retained binding to αvβ6 with modestly improved serum stability. Further d-amino acid substitutions and C-terminal sequence optimization outside the cyclized region greatly prolonged peptide serum stability without reducing binding affinity. While the cyclized A20FMDV2 variants exhibited increased nonspecific integrin binding compared with the original peptide, additional modifications with the non-natural amino acids citrulline, hydroxyproline, and d-alanine were found to restore binding specificity, with some modifications leading to greater αvβ6 integrin selectivity than the original A20FMDV2 peptide. The peptide modifications detailed herein greatly improve the potential of utilizing A20FMDV2 to target αvβ6 in vivo, expanding opportunities for cancer targeting and therapy.
Collapse
Affiliation(s)
- Ian I Cardle
- Department of Bioengineering, University of Washington, Seattle, Washington, USA; Seattle Children's Therapeutics, Seattle, Washington, USA
| | - Michael C Jensen
- Department of Bioengineering, University of Washington, Seattle, Washington, USA; Seattle Children's Therapeutics, Seattle, Washington, USA; Department of Pediatrics, University of Washington, Seattle, Washington, USA; Program in Immunology, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Suzie H Pun
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Drew L Sellers
- Department of Bioengineering, University of Washington, Seattle, Washington, USA.
| |
Collapse
|
9
|
Zhao YT, Fallas JA, Saini S, Ueda G, Somasundaram L, Zhou Z, Xavier I, Ehnes D, Xu C, Carter L, Wrenn S, Mathieu J, Sellers DL, Baker D, Ruohola-Baker H. F-domain valency determines outcome of signaling through the angiopoietin pathway. bioRxiv 2020. [PMID: 33501432 PMCID: PMC7836102 DOI: 10.1101/2020.09.19.304188] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Angiopoietin 1 and 2 (Ang1 and Ang2) modulate angiogenesis and vascular homeostasis through engagement of their very similar F-domain modules with the Tie2 receptor tyrosine kinase on endothelial cells. Despite this similarity in the underlying receptor binding interaction, the two angiopoietins have opposite effects: Ang1 induces phosphorylation of protein kinase B (AKT), strengthens cell-cell junctions and enhances endothelial cell survival while Ang2 antagonizes these effects1–4. To investigate the molecular basis for the opposing effects, we examined the protein kinase activation and morphological phenotypes produced by a series of computationally designed protein scaffolds presenting the Ang1 F-domain in a wide range of valencies and geometries. We find two broad phenotypic classes distinguished by the number of presented F-domains: scaffolds presenting 4 F-domains have Ang2 like activity, upregulating pFAK and pERK but not pAKT, and failing to induce cell migration and tube formation, while scaffolds presenting 6 or more F-domains have Ang1 like activity, upregulating pAKT and inducing migration and tube formation. The scaffolds with 8 or more F-domains display superagonist activity, producing stronger phenotypes at lower concentrations than Ang1. When examined in vivo, superagonist icosahedral self-assembling nanoparticles caused significant revascularization in hemorrhagic brains after a controlled cortical impact injury.
Collapse
|
10
|
Lee DC, Sellers DL, Liu F, Boydston AJ, Pun SH. Synthesis and Characterization of Anionic Poly(cyclopentadienylene vinylene) and Its Use in Conductive Hydrogels. Angew Chem Int Ed Engl 2020; 59:13430-13436. [PMID: 32378290 PMCID: PMC7485123 DOI: 10.1002/anie.202004098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Indexed: 11/08/2022]
Abstract
The use of π-conjugated polymers (CPs) in conductive hydrogels remains challenging due to the water-insoluble nature of most CPs. Conjugated polyelectrolytes (CPEs) are promising alternatives because they have tunable electronic properties and high water-solubility, but they are often difficult to synthesize and thus have not been widely adopted. Herein, we report the synthesis of an anionic poly(cyclopentadienylene vinylene) (aPCPV) from an insulating precursor under mild conditions and in high yield. Functionalized aPCPV is a highly water-soluble CPE that exhibits low cytotoxicity, and we found that doping hydrogels with aPCPV imparts conductivity. We also anticipate that this synthetic strategy, due to its ease and high efficiency, will be widely used to create families of not-yet-explored π-conjugated vinylene polymers.
Collapse
Affiliation(s)
- Daniel C Lee
- Molecular Engineering and Sciences Institute, University of Washington, 3946 W Stevens Way NE, Seattle, WA, 98105, USA
| | - Drew L Sellers
- Department of Bioengineering, University of Washington, 3720 15th Avenue NE, Seattle, WA, 98195, USA
| | - Fan Liu
- Department of Bioengineering, University of Washington, 3720 15th Avenue NE, Seattle, WA, 98195, USA
| | - Andrew J Boydston
- Department of Chemistry, Department of Materials Science and Engineering, Department of Chemical and Biological Engineering, University of Wisconsin, Madison, WI, 53706, USA
| | - Suzie H Pun
- Molecular Engineering and Sciences Institute, University of Washington, 3946 W Stevens Way NE, Seattle, WA, 98105, USA
- Department of Bioengineering, University of Washington, 3720 15th Avenue NE, Seattle, WA, 98195, USA
| |
Collapse
|
11
|
Lee DC, Sellers DL, Liu F, Boydston AJ, Pun SH. Synthesis and Characterization of Anionic Poly(cyclopentadienylene vinylene) and Its Use in Conductive Hydrogels. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Daniel C. Lee
- Molecular Engineering and Sciences Institute University of Washington 3946 W Stevens Way NE Seattle WA 98105 USA
| | - Drew L. Sellers
- Department of Bioengineering University of Washington 3720 15th Avenue NE Seattle WA 98195 USA
| | - Fan Liu
- Department of Bioengineering University of Washington 3720 15th Avenue NE Seattle WA 98195 USA
| | - Andrew J. Boydston
- Department of Chemistry Department of Materials Science and Engineering Department of Chemical and Biological Engineering University of Wisconsin Madison WI 53706 USA
| | - Suzie H. Pun
- Molecular Engineering and Sciences Institute University of Washington 3946 W Stevens Way NE Seattle WA 98105 USA
- Department of Bioengineering University of Washington 3720 15th Avenue NE Seattle WA 98195 USA
| |
Collapse
|
12
|
Lee J, Zhao T, Peeler DJ, Lee DC, Pichon TJ, Li D, Weigandt KM, Horner PJ, Pozzo LD, Sellers DL, Pun SH. Formulation of thrombin-inhibiting hydrogels via self-assembly of ionic peptides with peptide-modified polymers. Soft Matter 2020; 16:3762-3768. [PMID: 32239011 PMCID: PMC7204513 DOI: 10.1039/d0sm00209g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Cell therapy for spinal cord injuries offers the possibility of replacing lost cells after trauma to the central nervous system (CNS). In preclinical studies, synthetic hydrogels are often co-delivered to the injury site to support survival and integration of the transplanted cells. These hydrogels ideally mimic the mechanical and biochemical features of a healthy CNS extracellular matrix while also providing the possibility of localized drug delivery to promote healing. In this work, we synthesize peptide-functionalized polymers that contain both a peptide sequence for incorporation into self-assembled peptide hydrogels along with bioactive peptides that inhibit scar formation. We demonstrate that peptide hydrogels formulated with the peptide-functionalized polymers possess similar mechanical properties (soft and shear-thinning) as peptide-only hydrogels. Small angle neutron scattering analysis reveals that polymer-containing hydrogels possess larger inhomogeneous domains but small-scale features such as mesh size remain the same as peptide-only hydrogels. We further confirm that the integrated hydrogels containing bioactive peptides exhibit thrombin inhibition activity, which has previously shown to reduce scar formation in vivo. Finally, while the survival of encapsulated cells was poor, cells cultured on the hydrogels exhibited good viability. Overall, the described composite hydrogels formed from self-assembling peptides and peptide-modified polymers are promising, user-friendly materials for CNS applications in regeneration.
Collapse
Affiliation(s)
- Jason Lee
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA.
| | - Tianyu Zhao
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA.
| | - David J Peeler
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA.
| | - Daniel C Lee
- Molecular Engineering and Sciences, University of Washington, Seattle, WA 98195, USA
| | - Trey J Pichon
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA.
| | - David Li
- Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Kathleen M Weigandt
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Philip J Horner
- Center for Neuroregeneration and Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Lilo D Pozzo
- Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Drew L Sellers
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA.
| | - Suzie H Pun
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA. and Molecular Engineering and Sciences, University of Washington, Seattle, WA 98195, USA
| |
Collapse
|
13
|
Peeler DJ, Luera N, Horner PJ, Pun SH, Sellers DL. Polyplex transfection from intracerebroventricular delivery is not significantly affected by traumatic brain injury. J Control Release 2020; 322:149-156. [PMID: 32198024 DOI: 10.1016/j.jconrel.2020.03.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/09/2020] [Accepted: 03/16/2020] [Indexed: 10/24/2022]
Abstract
Traumatic brain injury (TBI) is largely non-preventable and often kills or permanently disables its victims. Because current treatments for TBI merely ameliorate secondary effects of the initial injury like swelling and hemorrhaging, strategies for the induction of neuronal regeneration are desperately needed. Recent discoveries regarding the TBI-responsive migratory behavior and differentiation potential of neural progenitor cells (NPCs) found in the subventricular zone (SVZ) have prompted strategies targeting gene therapies to these cells to enhance neurogenesis after TBI. We have previously shown that plasmid polyplexes can non-virally transfect SVZ NPCs when directly injected in the lateral ventricles of uninjured mice. We describe the first reported intracerebroventricular transfections mediated by polymeric gene carriers in a murine TBI model and investigate the anatomical parameters that dictate transfection through this route of administration. Using both luciferase and GFP plasmid transfections, we show that the time delay between injury and polyplex injection directly impacts the magnitude of transfection efficiency, but that overall trends in the location of transfection are not affected by injury. Confocal microscopy of quantum dot-labeled plasmid uptake in vivo reveals association between our polymers and negatively charged NG2 chondroitin sulfate proteoglycans of the SVZ extracellular matrix. We further validate that glycosaminoglycans but not sulfate groups are required for polyplex uptake and transfection in vitro. These studies demonstrate that non-viral gene delivery is impacted by proteoglycan interactions and suggest the need for improved polyplex targeting materials that penetrate brain extracellular matrix to increase transfection efficiency in vivo.
Collapse
Affiliation(s)
- David J Peeler
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, United States
| | - Nicholas Luera
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, United States
| | - Philip J Horner
- Center for Neuroregeneration and Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX, United States
| | - Suzie H Pun
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, United States.
| | - Drew L Sellers
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, United States.
| |
Collapse
|
14
|
Sellers DL, Tan JKY, Pineda JMB, Peeler DJ, Porubsky VL, Olden BR, Salipante SJ, Pun SH. Targeting Ligands Deliver Model Drug Cargo into the Central Nervous System along Autonomic Neurons. ACS Nano 2019; 13:10961-10971. [PMID: 31589023 PMCID: PMC7651855 DOI: 10.1021/acsnano.9b01515] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
While biologic drugs such as proteins, peptides, or nucleic acids have shown promise in the treatment of neurodegenerative diseases, the blood-brain barrier (BBB) severely limits drug delivery to the central nervous system (CNS) after systemic administration. Consequently, drug delivery challenges preclude biological drug candidates from the clinical armamentarium. In order to target drug delivery and uptake into to the CNS, we used an in vivo phage display screen to identify peptides able to target drug-uptake by the vast array of neurons of the autonomic nervous system (ANS). Using next-generation sequencing, we identified 21 candidate targeted ANS-to-CNS uptake ligands (TACL) that enriched bacteriophage accumulation and delivered protein-cargo into the CNS after intraperitoneal (IP) administration. The series of TACL peptides were synthesized and tested for their ability to deliver a model enzyme (NeutrAvidin-horseradish peroxidase fusion) to the brain and spinal cord. Three TACL-peptides facilitated significant active enzyme delivery into the CNS, with limited accumulation in off-target organs. Peptide structure and serum stability is increased when internal cysteine residues are cyclized by perfluoroarylation with decafluorobiphenyl, which increased delivery to the CNS further. TACL-peptide was demonstrated to localize in parasympathetic ganglia neurons in addition to neuronal structures in the hindbrain and spinal cord. By targeting uptake into ANS neurons, we demonstrate the potential for TACL-peptides to bypass the blood-brain barrier and deliver a model drug into the brain and spinal cord.
Collapse
Affiliation(s)
- Drew L. Sellers
- Department of Bioengineering, University of Washington, Seattle, Washington, 98195, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, 98195, USA
| | - James-Kevin Y. Tan
- Department of Bioengineering, University of Washington, Seattle, Washington, 98195, USA
| | - Julio Marco B. Pineda
- Department of Bioengineering, University of Washington, Seattle, Washington, 98195, USA
| | - David J. Peeler
- Department of Bioengineering, University of Washington, Seattle, Washington, 98195, USA
| | - Veronica L. Porubsky
- Department of Bioengineering, University of Washington, Seattle, Washington, 98195, USA
| | - Brynn R. Olden
- Department of Bioengineering, University of Washington, Seattle, Washington, 98195, USA
| | - Stephen J. Salipante
- Department of Laboratory Medicine, University of Washington, Seattle, Washington 98195, United States
| | - Suzie H. Pun
- Department of Bioengineering, University of Washington, Seattle, Washington, 98195, USA
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, Washington, 98195, USA
| |
Collapse
|
15
|
Abstract
The nonviral delivery of exogenous nucleic acids (NA) into cells for therapeutic purposes has rapidly matured into tangible clinical impact. Synthetic polymers are particularly attractive vectors for NA delivery due to their relatively inexpensive production compared to viral alternatives and their highly tailorable chemical properties; indeed, many preclinical investigations have revealed the primary biological barriers to nonviral NA delivery by systematically varying polymeric material properties. This review focuses on applications of pH-sensitive chemistries that enable polymeric vectors to serially address multiple biological barriers to NA delivery. In particular, we focus on recent innovations with in vivo evaluation that dynamically enable colloidal stability, cellular uptake, endosomal escape, and nucleic acid release. We conclude with a summary of successes to date and projected areas for impactful future research.
Collapse
Affiliation(s)
- David J Peeler
- Department of Bioengineering and Molecular Engineering and Sciences Institute , University of Washington , Seattle , Washington 98195 , United States
| | - Drew L Sellers
- Department of Bioengineering and Molecular Engineering and Sciences Institute , University of Washington , Seattle , Washington 98195 , United States
| | - Suzie H Pun
- Department of Bioengineering and Molecular Engineering and Sciences Institute , University of Washington , Seattle , Washington 98195 , United States
| |
Collapse
|
16
|
Peeler DJ, Thai SN, Cheng Y, Horner PJ, Sellers DL, Pun SH. pH-sensitive polymer micelles provide selective and potentiated lytic capacity to venom peptides for effective intracellular delivery. Biomaterials 2018; 192:235-244. [PMID: 30458359 DOI: 10.1016/j.biomaterials.2018.11.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 10/31/2018] [Accepted: 11/03/2018] [Indexed: 01/12/2023]
Abstract
Endocytosed biomacromolecule delivery systems must escape the endosomal trafficking pathway in order for their cargo to exert effects in other cellular compartments. Although endosomal release is well-recognized as one of the greatest barriers to efficacy of biologic drugs with intracellular targets, most drug carriers have relied on cationic materials that passively induce endosomal swelling and membrane rupture with low efficiency. To address the endosome release challenge, our lab has developed a diblock copolymer system for nucleic acid delivery that selectively displays a potent membrane-lytic peptide (melittin) in response to the pH drop during the endosomal maturation. To further optimize this system, we evaluated a panel of peptides with reported lytic activity in comparison to melittin. Nineteen different lytic peptides were synthesized and their membrane-lytic properties at both neutral and acidic pH characterized using a red blood cell hemolysis assay. The top five performing peptides were then conjugated to our pH-sensitive diblock copolymer via disulfide linkers and used to deliver a variety of nucleic acids to cultured mammalian cells as well as in vivo to the mouse brain. We demonstrate that the sharp pH-transition of VIPER compensates for potential advantages from pH-sensitive peptides, such that polymer-peptide conjugates with poorly selective but highly lytic peptides achieve safe and effective transfection both in vitro and in vivo. In addition, peptides that require release from polymer backbones for lysis were less effective in the VIPER system, likely due to limited endosomal reducing power of target cells. Finally, we show that certain peptides are potentiated in lytic ability by polymer conjugation and that these peptide-polymer constructs are most effective in vivo.
Collapse
Affiliation(s)
- David J Peeler
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, 98195, United States
| | - Salina N Thai
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, 98195, United States
| | - Yilong Cheng
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, 98195, United States
| | - Philip J Horner
- Center for Neuroregeneration and Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX, United States
| | - Drew L Sellers
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, 98195, United States.
| | - Suzie H Pun
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, 98195, United States.
| |
Collapse
|
17
|
Rosenberg AB, Roco CM, Muscat RA, Kuchina A, Sample P, Yao Z, Graybuck LT, Peeler DJ, Mukherjee S, Chen W, Pun SH, Sellers DL, Tasic B, Seelig G. Single-cell profiling of the developing mouse brain and spinal cord with split-pool barcoding. Science 2018; 360:176-182. [PMID: 29545511 DOI: 10.1126/science.aam8999] [Citation(s) in RCA: 726] [Impact Index Per Article: 121.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 09/30/2017] [Accepted: 02/26/2018] [Indexed: 12/11/2022]
Abstract
To facilitate scalable profiling of single cells, we developed split-pool ligation-based transcriptome sequencing (SPLiT-seq), a single-cell RNA-seq (scRNA-seq) method that labels the cellular origin of RNA through combinatorial barcoding. SPLiT-seq is compatible with fixed cells or nuclei, allows efficient sample multiplexing, and requires no customized equipment. We used SPLiT-seq to analyze 156,049 single-nucleus transcriptomes from postnatal day 2 and 11 mouse brains and spinal cords. More than 100 cell types were identified, with gene expression patterns corresponding to cellular function, regional specificity, and stage of differentiation. Pseudotime analysis revealed transcriptional programs driving four developmental lineages, providing a snapshot of early postnatal development in the murine central nervous system. SPLiT-seq provides a path toward comprehensive single-cell transcriptomic analysis of other similarly complex multicellular systems.
Collapse
Affiliation(s)
| | - Charles M Roco
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Richard A Muscat
- Department of Electrical Engineering, University of Washington, Seattle, WA, USA
| | - Anna Kuchina
- Department of Electrical Engineering, University of Washington, Seattle, WA, USA
| | - Paul Sample
- Department of Electrical Engineering, University of Washington, Seattle, WA, USA
| | - Zizhen Yao
- Allen Institute for Brain Science, Seattle, WA, USA
| | | | - David J Peeler
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Sumit Mukherjee
- Department of Electrical Engineering, University of Washington, Seattle, WA, USA
| | - Wei Chen
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA
| | - Suzie H Pun
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Drew L Sellers
- Department of Bioengineering, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, Seattle, WA, USA
| | | | - Georg Seelig
- Department of Electrical Engineering, University of Washington, Seattle, WA, USA. .,Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA.,Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA, USA
| |
Collapse
|
18
|
Zhao T, Sellers DL, Cheng Y, Horner PJ, Pun SH. Tunable, Injectable Hydrogels Based on Peptide-Cross-Linked, Cyclized Polymer Nanoparticles for Neural Progenitor Cell Delivery. Biomacromolecules 2017; 18:2723-2731. [DOI: 10.1021/acs.biomac.7b00510] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Tianyu Zhao
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| | - Drew L. Sellers
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
- Institute
for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington 98195, United States
| | - Yilong Cheng
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
| | - Philip J. Horner
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
- Institute
for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington 98195, United States
- Center
for Neuroregeneration and Department of Neurosurgery, Houston Methodist Research Institute, Houston, Texas 77030, United States
| | - Suzie H. Pun
- Department
of Bioengineering, University of Washington, Seattle, Washington 98195, United States
- Molecular
Engineering and Sciences Institute, University of Washington, Seattle, Washington 98195, United States
| |
Collapse
|
19
|
Cheng Y, Sellers DL, Tan JKY, Peeler DJ, Horner PJ, Pun SH. Development of switchable polymers to address the dilemma of stability and cargo release in polycationic nucleic acid carriers. Biomaterials 2017; 127:89-96. [PMID: 28284104 DOI: 10.1016/j.biomaterials.2017.02.036] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 02/15/2017] [Accepted: 02/26/2017] [Indexed: 10/20/2022]
Abstract
Cationic polymer gene delivery vehicles that effectively resist premature serum degradation often have difficulty releasing their nucleic acid cargoes. In this work, we report a pH-sensitive polymer (SP), poly(oligo(ethylene glycol) monomethyl ether methacrylate)-co-poly(2-(dimethylamino)ethyl methacrylate)-block- poly(propargyl methacrylate-graft-propyl-(4-methoxy-benzylidene)-amine) (p(PMA-PMBA)-b-(p(OEGMA-DMAEMA)), for successful in vitro and in vivo gene transfer. In the physiological condition, the hydrophobization of p(OEGMA-DMAEMA) polycations by p(PMA-PMBA) significantly enhanced the stability of its polyplexes counterpart. In endosomes, the polymer undergoes an acid-triggered hydrophilic transition through the cleavage of benzoic imines, thus allowing the vector to quickly release nucleic acid cargo due to the loss of hydrophobic functionalization. Compared to a pH-insensitive polymer (IP), SP exhibited more significant luciferase plasmid delivery efficiency with HeLa cells in vitro and with in vivo intraventricular brain injections. Therefore, the polymer designed here is a good solution to address the dilemma of stability and cargo release in gene delivery, and may have broad potential applications in therapeutic agent delivery.
Collapse
Affiliation(s)
- Yilong Cheng
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA 98195, United States
| | - Drew L Sellers
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA 98195, United States
| | - James-Kevin Y Tan
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA 98195, United States
| | - David J Peeler
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA 98195, United States
| | - Philip J Horner
- Center for Neuroregeneration and Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, United States.
| | - Suzie H Pun
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA 98195, United States.
| |
Collapse
|
20
|
Chu DS, Sellers DL, Bocek MJ, Fischedick AE, Horner PJ, Pun SH. MMP9-sensitive polymers mediate environmentally-responsive bivalirudin release and thrombin inhibition. Biomater Sci 2016; 3:41-5. [PMID: 25589953 DOI: 10.1039/c4bm00259h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
MMP9-responsive bivalirudin-HPMA copolymers were synthesized for direct, local administration in rat spinal cord contusion injury models. Polymer-conjugated bivalirudin peptides maintained activity while demonstrating enzyme-mediated release upon MMP9 exposure and prolonged release from hyaluronic acid/methylcellulose (HAMC) hydrogels compared to free bivalirudin peptide. Localized administration of bivalirudin copolymers in vivo at the site of rat spinal cord injury decreased cellular proliferation and astrogliosis, suggesting the bivalirudin copolymer and HAMC hydrogel system are a promising therapeutic intervention for reducing immediate inflammatory responses and long term scarring.
Collapse
Affiliation(s)
- D S Chu
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - D L Sellers
- Department of Neurological Surgery and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98195, USA
| | - M J Bocek
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - A E Fischedick
- Department of Neurological Surgery and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98195, USA
| | - P J Horner
- Department of Neurological Surgery and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98195, USA
| | - S H Pun
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| |
Collapse
|
21
|
Tan JKY, Sellers DL, Pham B, Pun SH, Horner PJ. Non-Viral Nucleic Acid Delivery Strategies to the Central Nervous System. Front Mol Neurosci 2016; 9:108. [PMID: 27847462 PMCID: PMC5088201 DOI: 10.3389/fnmol.2016.00108] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/11/2016] [Indexed: 12/11/2022] Open
Abstract
With an increased prevalence and understanding of central nervous system (CNS) injuries and neurological disorders, nucleic acid therapies are gaining promise as a way to regenerate lost neurons or halt disease progression. While more viral vectors have been used clinically as tools for gene delivery, non-viral vectors are gaining interest due to lower safety concerns and the ability to deliver all types of nucleic acids. Nevertheless, there are still a number of barriers to nucleic acid delivery. In this focused review, we explore the in vivo challenges hindering non-viral nucleic acid delivery to the CNS and the strategies and vehicles used to overcome them. Advantages and disadvantages of different routes of administration including: systemic injection, cerebrospinal fluid injection, intraparenchymal injection and peripheral administration are discussed. Non-viral vehicles and treatment strategies that have overcome delivery barriers and demonstrated in vivo gene transfer to the CNS are presented. These approaches can be used as guidelines in developing synthetic gene delivery vectors for CNS applications and will ultimately bring non-viral vectors closer to clinical application.
Collapse
Affiliation(s)
- James-Kevin Y Tan
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington Seattle, WA, USA
| | - Drew L Sellers
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington Seattle, WA, USA
| | - Binhan Pham
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington Seattle, WA, USA
| | - Suzie H Pun
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington Seattle, WA, USA
| | - Philip J Horner
- Center for Neuroregenerative Medicine, Houston Methodist Research Institute Houston, TX, USA
| |
Collapse
|
22
|
Cheng Y, Wei H, Tan JKY, Peeler DJ, Maris DO, Sellers DL, Horner PJ, Pun SH. Nano-Sized Sunflower Polycations As Effective Gene Transfer Vehicles. Small 2016; 12:2750-8. [PMID: 27061622 PMCID: PMC5052141 DOI: 10.1002/smll.201502930] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Revised: 01/07/2016] [Indexed: 06/05/2023]
Abstract
The architecture of polycations plays an important role in both gene transfection efficiency and cytotoxicity. In this work, a new polymer, sunflower poly(2-dimethyl amino)ethyl methacrylate) (pDMAEMA), is prepared by atom transfer radical polymerization and employed as nucleic acid carriers compared to linear pDMAEMA homopolymer and comb pDMAEMA. The sunflower pDMAEMAs show higher IC50 , greater buffering capacity, and stronger binding capacity toward plasmid DNA than their linear and comb counterparts. In vitro transfection studies demonstrate that sunflower pDMAEMAs exhibit high transfection efficiency as well as relatively low cytotoxicity in complete growth medium. In vivo gene delivery by intraventricular injection to the brain shows that sunflower polymer delivers plasmid DNA more effectively than comb polymer. This study provides a new insight into the relationship between polymeric architecture and gene delivery capability, and as well as a useful means to design potent vectors for successful gene delivery.
Collapse
Affiliation(s)
- Yilong Cheng
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington, Seattle, Washington 98195, United States (USA)
| | - Hua Wei
- Department of Chemistry, Lanzhou University, Lanzhou 730000, China
| | - James-Kevin Y. Tan
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington, Seattle, Washington 98195, United States (USA)
| | - David J. Peeler
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington, Seattle, Washington 98195, United States (USA)
| | - Don O. Maris
- Department of Neurological Surgery, University of Washington Seattle, WA 98195, (USA)
| | - Drew L. Sellers
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington, Seattle, Washington 98195, United States (USA)
| | - Philip J. Horner
- Department of Neurological Surgery, University of Washington Seattle, WA 98195, (USA)
| | - Suzie H. Pun
- Department of Bioengineering and Molecular Engineering & Sciences Institute, University of Washington, Seattle, Washington 98195, United States (USA)
| |
Collapse
|
23
|
Tan JKY, Pham B, Zong Y, Perez C, Maris DO, Hemphill A, Miao CH, Matula TJ, Mourad PD, Wei H, Sellers DL, Horner PJ, Pun SH. Microbubbles and ultrasound increase intraventricular polyplex gene transfer to the brain. J Control Release 2016; 231:86-93. [PMID: 26860281 DOI: 10.1016/j.jconrel.2016.02.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 01/22/2016] [Accepted: 02/02/2016] [Indexed: 12/16/2022]
Abstract
Neurons in the brain can be damaged or lost from neurodegenerative disease, stroke, or traumatic injury. Although neurogenesis occurs in mammalian adult brains, the levels of natural neurogenesis are insufficient to restore function in these cases. Gene therapy has been pursued as a promising strategy to induce differentiation of neural progenitor cells into functional neurons. Non-viral vectors are a preferred method of gene transfer due to potential safety and manufacturing benefits but suffer from lower delivery efficiencies compared to viral vectors. Since the neural stem and progenitor cells reside in the subventricular zone of the brain, intraventricular injection has been used as an administration route for gene transfer to these cells. However, the choroid plexus epithelium remains an obstacle to delivery. Recently, transient disruption of the blood-brain barrier by microbubble-enhanced ultrasound has been used to successfully improve drug delivery to the brain after intravenous injection. In this work, we demonstrate that microbubble-enhanced ultrasound can similarly improve gene transfer to the subventricular zone after intraventricular injection. Microbubbles of different surface charges (neutral, slightly cationic, and cationic) were prepared, characterized by acoustic flow cytometry, and evaluated for their ability to increase the permeability of immortalized choroid plexus epithelium monolayers in vitro. Based on these results, slightly cationic microbubbles were evaluated for microbubble and ultrasound-mediated enhancement of non-viral gene transfer in vivo. When coupled with our previously reported gene delivery vehicles, the slightly cationic microbubbles significantly increased ultrasound-mediated transfection of the murine brain when compared to commercially available Definity® microbubbles. Temporary disruption of the choroid plexus by microbubble-enhanced ultrasound is therefore a viable way of enhancing gene delivery to the brain and merits further research.
Collapse
Affiliation(s)
- James-Kevin Y Tan
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - Binhan Pham
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - Yujin Zong
- Center for Industrial and Medical Ultrasound, University of Washington, Seattle, WA 98195, USA; Department of Biomedical Engineering, Xian Jiaotong University, Xi'an, 710049, China
| | - Camilo Perez
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Center for Industrial and Medical Ultrasound, University of Washington, Seattle, WA 98195, USA
| | - Don O Maris
- Department of Neurological Surgery, University of Washington, Seattle, WA 98109, USA
| | - Ashton Hemphill
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - Carol H Miao
- Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Thomas J Matula
- Center for Industrial and Medical Ultrasound, University of Washington, Seattle, WA 98195, USA
| | - Pierre D Mourad
- Department of Neurological Surgery, University of Washington, Seattle, WA 98109, USA
| | - Hua Wei
- Department of Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Drew L Sellers
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - Philip J Horner
- Department of Neurological Surgery, University of Washington, Seattle, WA 98109, USA.
| | - Suzie H Pun
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA.
| |
Collapse
|
24
|
Choi JL, Tan JKY, Sellers DL, Wei H, Horner PJ, Pun SH. Guanidinylated block copolymers for gene transfer: A comparison with amine-based materials for in vitro and in vivo gene transfer efficiency. Biomaterials 2015; 54:87-96. [PMID: 25907042 DOI: 10.1016/j.biomaterials.2015.03.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 02/26/2015] [Accepted: 03/04/2015] [Indexed: 11/29/2022]
Abstract
There is currently no cure for neuron loss in the brain, which can occur due to traumatic injury or neurodegenerative disease. One proposed method to enhance brain neurogenesis is gene transfer to neural progenitor cells. In this work, a guanidine-based copolymer was synthesized and compared to an amine-based copolymer analog previously shown to effectively deliver genes in the murine brain. The guanidine-based copolymer was more efficient at gene transfer to immortalized, cultured cell lines; however, the amine-based copolymer was more effective at gene transfer in the brain. DNA condensation studies revealed that the nucleic acid complexes formed with the guanidine-based copolymer were more susceptible to unpackaging in the presence of anionic proteoglycans compared to complexes formed with the amine-based copolymer. Therefore, polyplexes formed from the amine-based copolymer may be more resistant to destabilization by the heparan sulfate proteoglycans present in the stem cell niches of the brain.
Collapse
Affiliation(s)
- Jennifer L Choi
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - James-Kevin Y Tan
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - Drew L Sellers
- Department of Neurological Surgery, University of Washington, Seattle, WA 98104, USA
| | - Hua Wei
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - Philip J Horner
- Department of Neurological Surgery, University of Washington, Seattle, WA 98104, USA.
| | - Suzie H Pun
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA.
| |
Collapse
|
25
|
Wei H, Volpatti LR, Sellers DL, Maris DO, Andrews IW, Hemphill AS, Chan LW, Chu DSH, Horner PJ, Pun SH. Dual responsive, stabilized nanoparticles for efficient in vivo plasmid delivery. Angew Chem Int Ed Engl 2013; 52:5377-81. [PMID: 23592572 DOI: 10.1002/anie.201301896] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Hua Wei
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Wei H, Volpatti LR, Sellers DL, Maris DO, Andrews IW, Hemphill AS, Chan LW, Chu DSH, Horner PJ, Pun SH. Dual Responsive, Stabilized Nanoparticles for Efficient In Vivo Plasmid Delivery. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201301896] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
27
|
Brackett DM, Qing F, Amieux PS, Sellers DL, Horner PJ, Morris DR. FMR1 transcript isoforms: association with polyribosomes; regional and developmental expression in mouse brain. PLoS One 2013; 8:e58296. [PMID: 23505481 PMCID: PMC3591412 DOI: 10.1371/journal.pone.0058296] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 02/01/2013] [Indexed: 12/31/2022] Open
Abstract
The primary transcript of the mammalian Fragile X Mental Retardation-1 gene (Fmr1), like many transcripts in the central nervous system, is alternatively spliced to yield mRNAs encoding multiple proteins, which can possess quite different biochemical properties. Despite the fact that the relative levels of the 12 Fmr1 transcript isoforms examined here vary by as much as two orders of magnitude amongst themselves in both adult and embryonic mouse brain, all are associated with polyribosomes, consistent with translation into the corresponding isoforms of the protein product, FMRP (Fragile X Mental Retardation Protein). Employing the RiboTag methodology developed in our laboratory, the relative proportions of the 7 most abundant transcript isoforms were measured specifically in neurons and found to be similar to those identified in whole brain. Measurements of isoform profiles across 11 regions of adult brain yielded similar distributions, with the exceptions of the hippocampus and the olfactory bulb. These two regions differ from most of the brain in relative amounts of transcripts encoding an alternate form of one of the KH RNA binding domains. A possible relationship between patterns of expression in the hippocampus and olfactory bulb and the presence of neuroblasts in these two regions is suggested by the isoform patterns in early embryonic brain and in cultured neural progenitor cells. These results demonstrate that the relative levels of the Fmr1 isoforms are modulated according to developmental stage, highlighting the complex ramifications of losing all the protein isoforms in individuals with Fragile X Syndrome. It should also be noted that, of the eight most prominent FMRP isoforms (1–3, 6–9 and 12) in mouse, only two have the major site of phosphorylation at Ser-499, which is thought to be involved in some of the regulatory interactions of this protein.
Collapse
Affiliation(s)
- David M. Brackett
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Feng Qing
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Paul S. Amieux
- Department of Pharmacology; University of Washington, Seattle, Washington, United States of America
| | - Drew L. Sellers
- Department of Neurological Surgery, University of Washington, Seattle, Washington, United States of America
| | - Philip J. Horner
- Department of Neurological Surgery, University of Washington, Seattle, Washington, United States of America
| | - David R. Morris
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| |
Collapse
|
28
|
Schellinger JG, Pahang JA, Johnson RN, Chu DSH, Sellers DL, Maris DO, Convertine AJ, Stayton PS, Horner PJ, Pun SH. Melittin-grafted HPMA-oligolysine based copolymers for gene delivery. Biomaterials 2012; 34:2318-26. [PMID: 23261217 DOI: 10.1016/j.biomaterials.2012.09.072] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 09/28/2012] [Indexed: 10/27/2022]
Abstract
Non-viral gene delivery systems capable of transfecting cells in the brain are critical in realizing the potential impact of nucleic acid therapeutics for diseases of the central nervous system. In this study, the membrane-lytic peptide melittin was incorporated into block copolymers synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The first block, designed for melittin conjugation, was composed of N-(2-hydroxypropyl)methacrylamide (HPMA) and pyridyl disulfide methacrylamide (PDSMA) and the second block, designed for DNA binding, was composed of oligo-l-lysine (K10) and HPMA. Melittin modified with cysteine at the C-terminus was conjugated to the polymers through the pyridyl disulfide pendent groups via disulfide exchange. The resulting pHgMelbHK10 copolymers are more membrane-lytic than melittin-free control polymers, and efficiently condensed plasmid DNA into salt-stable particles (~100-200 nm). The melittin-modified polymers transfected both HeLa and neuron-like PC-12 cells more efficiently than melittin-free polymers although toxicity associated with the melittin peptide was observed. Optimized formulations containing the luciferase reporter gene were delivered to mouse brain by intraventricular brain injections. Melittin-containing polyplexes produced about 35-fold higher luciferase activity in the brain compared to polyplexes without melittin. Thus, the melittin-containing block copolymers described in this work are promising materials for gene delivery to the brain.
Collapse
Affiliation(s)
- Joan G Schellinger
- Department of Bioengineering, Univeristy of Washington, Seattle, WA 98195, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Abstract
Cellullar deficits are replenished within the central nervous system (CNS) by progenitors to maintain integrity and recover function after injury. NG2 proteoglycan-expressing progenitors replenish oligodendrocyte populations, but the nature of NG2 proteoglycan may not indicate a restricted population of progenitors. After injury, restorative spatiotemporal cues have the potential ability to regulate divergent fate-choices for NG2 progenitors, and NG2 progenitors are known to produce multiple cell types in vitro. Recent data suggest that NG2 expression is attenuated while protein levels remain high within injurious tissue; thus, NG2 expression is not static but transiently controlled in response to a dynamic interplay of environmental cues. Therefore, NG2 proteoglycan expression could label newly generated cells or be inherited by resident cell populations that produce oligodendrocytes for remyelination, astrocytes that provide trophic support and other cells that contribute to CNS function.
Collapse
Affiliation(s)
- Drew L Sellers
- Department of Neurosurgery, University of Washington, Seattle, WA 98105, USA.
| | | |
Collapse
|