Auditory prostheses can partially restore speech comprehension when hearing fails. Sound coding with current prostheses is based on electrical stimulation of auditory neurons and has limited frequency resolution due to broad current spread within the cochlea. In contrast, optical stimulation can be spatially confined, which may improve frequency resolution. Here, we used animal models to characterize optogenetic stimulation, which is the optical stimulation of neurons genetically engineered to express the light-gated ion channel channelrhodopsin-2 (ChR2). Optogenetic stimulation of spiral ganglion neurons (SGNs) activated the auditory pathway, as demonstrated by recordings of single neuron and neuronal population responses. Furthermore, optogenetic stimulation of SGNs restored auditory activity in deaf mice. Approximation of the spatial spread of cochlear excitation by recording local field potentials (LFPs) in the inferior colliculus in response to suprathreshold optical, acoustic, and electrical stimuli indicated that optogenetic stimulation achieves better frequency resolution than monopolar electrical stimulation. Virus-mediated expression of a ChR2 variant with greater light sensitivity in SGNs reduced the amount of light required for responses and allowed neuronal spiking following stimulation up to 60 Hz. Our study demonstrates a strategy for optogenetic stimulation of the auditory pathway in rodents and lays the groundwork for future applications of cochlear optogenetics in auditory research and prosthetics.
Victor H. Hernandez, Anna Gehrt, Kirsten Reuter, Zhizi Jing, Marcus Jeschke, Alejandro Mendoza Schulz, Gerhard Hoch, Matthias Bartels, Gerhard Vogt, Carolyn W. Garnham, Hiromu Yawo, Yugo Fukazawa, George J. Augustine, Ernst Bamberg, Sebastian Kügler, Tim Salditt, Livia de Hoz, Nicola Strenzke, Tobias Moser
The transcriptome is subject to multiple changes during pathogenesis, including the
use of alternate 5′ start-sites that can affect transcription levels and
output. Current RNA sequencing techniques can assess mRNA levels, but do not robustly
detect changes in 5′ start-site use. Here, we developed a transcriptome
sequencing strategy that detects genome-wide changes in start-site usage
(5′RNA-Seq) and applied this methodology to identify regulatory events that
occur in hypertrophic cardiomyopathy (HCM). Compared with transcripts from WT mice,
92 genes had altered start-site usage in a mouse model of HCM, including
four-and-a-half LIM domains protein 1 (
Danos C. Christodoulou, Hiroko Wakimoto, Kenji Onoue, Seda Eminaga, Joshua M. Gorham, Steve R. DePalma, Daniel S. Herman, Polakit Teekakirikul, David A. Conner, David M. McKean, Andrea A. Domenighetti, Anton Aboukhalil, Stephen Chang, Gyan Srivastava, Barbara McDonough, Philip L. De Jager, Ju Chen, Martha L. Bulyk, Jochen D. Muehlschlegel, Christine E. Seidman, J.G. Seidman
Lysosomal storage disorders (LSDs) occur at a frequency of 1 in every 5,000 live births and are a common cause of pediatric neurodegenerative disease. The relatively small number of patients with LSDs and lack of validated biomarkers are substantial challenges for clinical trial design. Here, we evaluated the use of a commercially available fluorescent probe, Lysotracker, that can be used to measure the relative acidic compartment volume of circulating B cells as a potentially universal biomarker for LSDs. We validated this metric in a mouse model of the LSD Niemann-Pick type C1 disease (NPC1) and in a prospective 5-year international study of NPC patients. Pediatric NPC subjects had elevated acidic compartment volume that correlated with age-adjusted clinical severity and was reduced in response to therapy with miglustat, a European Medicines Agency–approved drug that has been shown to reduce NPC1-associated neuropathology. Measurement of relative acidic compartment volume was also useful for monitoring therapeutic responses of an NPC2 patient after bone marrow transplantation. Furthermore, this metric identified a potential adverse event in NPC1 patients receiving i.v. cyclodextrin therapy. Our data indicate that relative acidic compartment volume may be a useful biomarker to aid diagnosis, clinical monitoring, and evaluation of therapeutic responses in patients with lysosomal disorders.
Danielle te Vruchte, Anneliese O. Speak, Kerri L. Wallom, Nada Al Eisa, David A. Smith, Christian J. Hendriksz, Louise Simmons, Robin H. Lachmann, Alison Cousins, Ralf Hartung, Eugen Mengel, Heiko Runz, Michael Beck, Yasmina Amraoui, Jackie Imrie, Elizabeth Jacklin, Kate Riddick, Nicole M. Yanjanin, Christopher A. Wassif, Arndt Rolfs, Florian Rimmele, Naomi Wright, Clare Taylor, Uma Ramaswami, Timothy M. Cox, Caroline Hastings, Xuntian Jiang, Rohini Sidhu, Daniel S. Ory, Begona Arias, Mylvaganam Jeyakumar, Daniel J. Sillence, James E. Wraith, Forbes D. Porter, Mario Cortina-Borja, Frances M. Platt
The ability to map the functional connectivity of discrete cell types in the intact mammalian brain during behavior is crucial for advancing our understanding of brain function in normal and disease states. We combined
Michael Michaelides, Sarah Ann R. Anderson, Mala Ananth, Denis Smirnov, Panayotis K. Thanos, John F. Neumaier, Gene-Jack Wang, Nora D. Volkow, Yasmin L. Hurd
The use of induced pluripotent stem cells (iPSCs) has been postulated to be the most effective strategy for developing patient-specific respiratory epithelial cells, which may be valuable for lung-related cell therapy and lung tissue engineering. We generated a relatively homogeneous population of alveolar epithelial type II (AETII) and type I (AETI) cells from human iPSCs that had phenotypic properties similar to those of mature human AETII and AETI cells. We used these cells to explore whether lung tissue can be regenerated in vitro. Consistent with an AETII phenotype, we found that up to 97% of cells were positive for surfactant protein C, 95% for mucin-1, 93% for surfactant protein B, and 89% for the epithelial marker CD54. Additionally, exposing induced AETII to a Wnt/β-catenin inhibitor (IWR-1) changed the iPSC-AETII–like phenotype to a predominantly AETI-like phenotype. We found that of induced AET1 cells, more than 90% were positive for type I markers, T1α, and caveolin-1. Acellular lung matrices were prepared from whole rat or human adult lungs treated with decellularization reagents, followed by seeding these matrices with alveolar cells derived from human iPSCs. Under appropriate culture conditions, these progenitor cells adhered to and proliferated within the 3D lung tissue scaffold and displayed markers of differentiated pulmonary epithelium.
Mahboobe Ghaedi, Elizabeth A. Calle, Julio J. Mendez, Ashley L. Gard, Jenna Balestrini, Adam Booth, Peter F. Bove, Liqiong Gui, Eric S. White, Laura E. Niklason
While flow cytometry has been used to analyze the antigenic composition of individual cells, the antigenic makeup of viral particles is still characterized predominantly in bulk. Here, we describe a technology, “flow virometry,” that can be used for antigen detection on individual virions. The technology is based on binding magnetic nanoparticles to virions, staining the virions with monoclonal antibodies, separating the formed complexes with magnetic columns, and characterizing them with flow cytometers. We used this technology to study the distribution of two antigens (HLA-DR and LFA-1) that HIV-1 acquires from infected cells among individual HIV-1 virions. Flow virometry revealed that the antigenic makeup of virions from a single preparation is heterogeneous. This heterogeneity could not be detected with bulk analysis of viruses. Moreover, in two preparations of the same HIV-1 produced by different cells, the distribution of antigens among virions was different. In contrast, HIV-1 of two different HIV-1 genotypes replicating in the same cells became somewhat antigenically similar. This nanotechnology allows the study of virions in bodily fluids without virus propagation and in principle is not restricted to the analysis of HIV, but can be applied to the analysis of the individual surface antigenic makeup of any virus.
Anush Arakelyan, Wendy Fitzgerald, Leonid Margolis, Jean-Charles Grivel
Diabetes is a disorder characterized by loss of β cell mass and/or β cell function, leading to deficiency of insulin relative to metabolic need. To determine whether stem cell–derived β cells recapitulate molecular-physiological phenotypes of a diabetic subject, we generated induced pluripotent stem cells (iPSCs) from subjects with maturity-onset diabetes of the young type 2 (MODY2), which is characterized by heterozygous loss of function of the gene encoding glucokinase (
Haiqing Hua, Linshan Shang, Hector Martinez, Matthew Freeby, Mary Pat Gallagher, Thomas Ludwig, Liyong Deng, Ellen Greenberg, Charles LeDuc, Wendy K. Chung, Robin Goland, Rudolph L. Leibel, Dieter Egli
MicroRNAs (miRNAs) are excellent tumor biomarkers because of their cell-type specificity and abundance. However, many miRNA detection methods, such as real-time PCR, obliterate valuable visuospatial information in tissue samples. To enable miRNA visualization in formalin-fixed paraffin-embedded (FFPE) tissues, we developed multicolor miRNA FISH. As a proof of concept, we used this method to differentiate two skin tumors, basal cell carcinoma (BCC) and Merkel cell carcinoma (MCC), with overlapping histologic features but distinct cellular origins. Using sequencing-based miRNA profiling and discriminant analysis, we identified the tumor-specific miRNAs miR-205 and miR-375 in BCC and MCC, respectively. We addressed three major shortcomings in miRNA FISH, identifying optimal conditions for miRNA fixation and ribosomal RNA (rRNA) retention using model compounds and high-pressure liquid chromatography (HPLC) analyses, enhancing signal amplification and detection by increasing probe-hapten linker lengths, and improving probe specificity using shortened probes with minimal rRNA sequence complementarity. We validated our method on 4 BCC and 12 MCC tumors. Amplified miR-205 and miR-375 signals were normalized against directly detectable reference rRNA signals. Tumors were classified using predefined cutoff values, and all were correctly identified in blinded analysis. Our study establishes a reliable miRNA FISH technique for parallel visualization of differentially expressed miRNAs in FFPE tumor tissues.
Neil Renwick, Pavol Cekan, Paul A. Masry, Sean E. McGeary, Jason B. Miller, Markus Hafner, Zhen Li, Aleksandra Mihailovic, Pavel Morozov, Miguel Brown, Tasos Gogakos, Mehrpouya B. Mobin, Einar L. Snorrason, Harriet E. Feilotter, Xiao Zhang, Clifford S. Perlis, Hong Wu, Mayte Suárez-Fariñas, Huichen Feng, Masahiro Shuda, Patrick S. Moore, Victor A. Tron, Yuan Chang, Thomas Tuschl
Cystic fibrosis (CF) pigs develop disease with features remarkably similar to those in people with CF, including exocrine pancreatic destruction, focal biliary cirrhosis, micro-gallbladder, vas deferens loss, airway disease, and meconium ileus. Whereas meconium ileus occurs in 15% of babies with CF, the penetrance is 100% in newborn CF pigs. We hypothesized that transgenic expression of porcine CF transmembrane conductance regulator (
David A. Stoltz, Tatiana Rokhlina, Sarah E. Ernst, Alejandro A. Pezzulo, Lynda S. Ostedgaard, Philip H. Karp, Melissa S. Samuel, Leah R. Reznikov, Michael V. Rector, Nicholas D. Gansemer, Drake C. Bouzek, Mahmoud H. Abou Alaiwa, Mark J. Hoegger, Paula S. Ludwig, Peter J. Taft, Tanner J. Wallen, Christine Wohlford-Lenane, James D. McMenimen, Jeng-Haur Chen, Katrina L. Bogan, Ryan J. Adam, Emma E. Hornick, George A. Nelson IV, Eric A. Hoffman, Eugene H. Chang, Joseph Zabner, Paul B. McCray Jr., Randall S. Prather, David K. Meyerholz, Michael J. Welsh
During complement activation the C3 protein is cleaved, and C3 activation fragments are covalently fixed to tissues. Tissue-bound C3 fragments are a durable biomarker of tissue inflammation, and these fragments have been exploited as addressable binding ligands for targeted therapeutics and diagnostic agents. We have generated cross-reactive murine monoclonal antibodies against human and mouse C3d, the final C3 degradation fragment generated during complement activation. We developed 3 monoclonal antibodies (3d8b, 3d9a, and 3d29) that preferentially bind to the iC3b, C3dg, and C3d fragments in solution, but do not bind to intact C3 or C3b. The same 3 clones also bind to tissue-bound C3 activation fragments when injected systemically. Using mouse models of renal and ocular disease, we confirmed that, following systemic injection, the antibodies accumulated at sites of C3 fragment deposition within the glomerulus, the renal tubulointerstitium, and the posterior pole of the eye. To detect antibodies bound within the eye, we used optical imaging and observed accumulation of the antibodies within retinal lesions in a model of choroidal neovascularization (CNV). Our results demonstrate that imaging methods that use these antibodies may provide a sensitive means of detecting and monitoring complement activation–associated tissue inflammation.
Joshua M. Thurman, Liudmila Kulik, Heather Orth, Maria Wong, Brandon Renner, Siranush A. Sargsyan, Lynne M. Mitchell, Dennis E. Hourcade, Jonathan P. Hannan, James M. Kovacs, Beth Coughlin, Alex S. Woodell, Matthew C. Pickering, Bärbel Rohrer, V. Michael Holers