title: Transfection of pancreatic islets using polyvalent DNA-functionalized gold nanoparticles.
abstract: BACKGROUND
  Transplantation of pancreatic islets is an effective treatment for select patients with type 1 diabetes. Improved cellular therapy results may be realized by altering the gene expression profile of transplanted islets. Current viral and nonviral vectors used to introduce nucleic acids for gene regulation hold promise, but safety and efficacy shortcomings motivate the development of new transfection strategies. Polyvalent gold nanoparticles (AuNPs) densely functionalized with covalently immobilized DNA oligonucleotides (AuNP-DNA) are new single entity transfection and gene regulating agents (ie, not requiring lipids, polymers, or viral vectors for cell entry) able to enter cells with high efficiency and no evidence of toxicity. We hypothesize that AuNP-DNA conjugates can efficiently transfect pancreatic islets with no impact on viability or functionality, and can function to regulate targeted gene expression.
  
  
  METHODS
  AuNPs were surface-functionalized with control and antisense DNA oligonucleotides. Purified murine and human islets were exposed to AuNP-DNA conjugates for 24 hours. Islet AuNP-DNA uptake, cell viability, and functionality were measured. Furthermore, the ability of antisense AuNP-DNA conjugates to regulate gene expression was measured using murine islets expressing eGFP.
  
  
  RESULTS
  Collectively, fluorescent confocal microscopy, transmission electron microscopy, mass spectrometry, and flow cytometry revealed substantial penetration of the AuNP-DNA conjugates into the inner core of the islets and within islet cells. No change in cellular viability occurred and the insulin stimulation index was unchanged in treated versus untreated islets. Transplantation of AuNP-DNA treated islets cured diabetic nude mice. Functionally, antisense eGFP AuNP-DNA conjugates reduced eGFP expression in MIP-eGFP islets.
  
  
  CONCLUSIONS
  Polyvalent AuNP-DNA conjugates may represent the next generation of nucleic acid-based therapeutic agents for improving pancreatic islet engraftment, survival, and long-term function.
authors.affiliation: Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Rink
authors.forename: Kaylin M
authors.initials: KM
authors.lastname: McMahon
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Chen
authors.forename: Chad A
authors.initials: CA
authors.lastname: Mirkin
authors.forename: C Shad
authors.initials: CS
authors.lastname: Thaxton
authors.forename: Dixon B
authors.initials: DB
authors.lastname: Kaufman
mesh_terms: D000818:Animals; D001483:Base Sequence; D002470:Cell Survival; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism / Q000601:surgery / Q000628:therapy; D003922:Diabetes Mellitus, Type 1 / Q000601:surgery / Q000628:therapy; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D015316:Genetic Therapy / Q000379:methods; D006046:Gold; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D016381:Islets of Langerhans Transplantation / Q000379:methods; D053768:Metal Nanoparticles / Q000008:administration & dosage* / Q000648:ultrastructure; D051379:Mice; D008819:Mice, Nude; D046529:Microscopy, Electron, Transmission; D020319:Oligodeoxyribonucleotides, Antisense / Q000008:administration & dosage* / Q000235:genetics* / Q000493:pharmacokinetics; D011994:Recombinant Proteins / Q000235:genetics; D014162:Transfection / Q000379:methods*; D014183:Transplantation, Heterologous
chemical_list: D007328:Insulin; D020319:Oligodeoxyribonucleotides, Antisense; D011994:Recombinant Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D006046:Gold