title: A novel approach for targeted delivery to motoneurons using cholera toxin-B modified protocells.
abstract: Trophic interactions between muscle fibers and motoneurons at the neuromuscular junction (NMJ) play a critical role in determining motor function throughout development, ageing, injury, or disease. Treatment of neuromuscular disorders is hindered by the inability to selectively target motoneurons with pharmacological and genetic interventions.
  
  
  
  We describe a novel delivery system to motoneurons using mesoporous silica nanoparticles encapsulated within a lipid bilayer (protocells) and modified with the atoxic subunit B of the cholera toxin (CTB) that binds to gangliosides present on neuronal membranes.
  
  
  
  CTB modified protocells showed significantly greater motoneuron uptake compared to unmodified protocells after 24h of treatment (60% vs. 15%, respectively). CTB-protocells showed specific uptake by motoneurons compared to muscle cells and demonstrated cargo release of a surrogate drug. Protocells showed a lack of cytotoxicity and unimpaired cellular proliferation. In isolated diaphragm muscle-phrenic nerve preparations, preferential axon terminal uptake of CTB-modified protocells was observed compared to uptake in surrounding muscle tissue. A larger proportion of axon terminals displayed uptake following treatment with CTB-protocells compared to unmodified protocells (40% vs. 6%, respectively).
  
  
  
  Current motoneuron targeting strategies lack the functionality to load and deliver multiple cargos. CTB-protocells capitalizes on the advantages of liposomes and mesoporous silica nanoparticles allowing a large loading capacity and cargo release. The ability of CTB-protocells to target motoneurons at the NMJ confers a great advantage over existing methods.
  
  
  
  CTB-protocells constitute a viable targeted motoneuron delivery system for drugs and genes facilitating various therapies for neuromuscular diseases.
authors.affiliation: Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, United States.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Gonzalez Porras
authors.affiliation: Center for Micro-Engineered Materials, Advanced Materials, University of New Mexico, Albuquerque, NM, United States; Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM, United States.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Durfee
authors.affiliation: Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, United States.
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Gregory
authors.affiliation: Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, United States; Department of Anesthesiology, Mayo Clinic, Rochester, MN, United States.
authors.forename: Gary C
authors.initials: GC
authors.lastname: Sieck
authors.affiliation: Center for Micro-Engineered Materials, Advanced Materials, University of New Mexico, Albuquerque, NM, United States; Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM, United States; Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, NM, United States.
authors.forename: C Jeffrey
authors.initials: CJ
authors.lastname: Brinker
authors.affiliation: Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, United States; Department of Anesthesiology, Mayo Clinic, Rochester, MN, United States. Electronic address: mantilla.carlos@mayo.edu.
authors.forename: Carlos B
authors.initials: CB
authors.lastname: Mantilla
mesh_terms: D000818:Animals; D058045:Artificial Cells / Q000378:metabolism / Q000648:ultrastructure; D001583:Benzoxazoles / Q000378:metabolism; D002478:Cells, Cultured; D055598:Chemical Phenomena; D002772:Cholera Toxin / Q000008:administration & dosage* / Q000378:metabolism / Q000494:pharmacology; D003964:Diaphragm / Q000166:cytology; D016503:Drug Delivery Systems / Q000379:methods*; D066298:In Vitro Techniques; D008051:Lipid Bilayers / Q000378:metabolism; D008297:Male; D009046:Motor Neurons / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D009469:Neuromuscular Junction / Q000378:metabolism* / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000378:metabolism; D011806:Quinolinium Compounds / Q000378:metabolism; D051381:Rats; D012822:Silicon Dioxide; D013997:Time Factors
chemical_list: D001583:Benzoxazoles; D008051:Lipid Bilayers; D011806:Quinolinium Compounds; C089813:YO-PRO 1; D012822:Silicon Dioxide; D002772:Cholera Toxin
keywords: Cholera toxin B; Diaphragm; Drug delivery system; Mesoporous silica nanoparticles; Motoneurons; Nanoparticles; Nanotechnology; Neuromuscular junction; Phrenic nerve