Research

The unifying goal of the Sinn Lab is to explore mechanisms of viral entry in the lungs for disease prevention or gene therapy applications. 

Patrick Sinn, PhD

Gene therapy for cystic fibrosis (CF) using integrating vectors

The lungs have evolved many barriers to keep foreign DNA out of its cells. Our goal is to override these barriers and get therapeutic genes into the lungs. CF is a common genetic multi-organ system disorder, but most people with CF die of progressive lung disease. We know that delivering the CFTR gene to enough airway cells will correct CF lung disease.

To this end, a cornerstone of our research deals with modifying and optimizing gene delivery reagents. In particular, we have advanced lentiviral vector design for gene transfer to the airways. We engineered a feline immunodeficiency virus (FIV)-based vector. This delivery vehicle:

1) can efficiently infect multiple airway cell types;
2) can be delivered multiple times without blocking immune responses; and
3) achieve persistent correction of human CF airway epithelia in vitro.

We are now focused on large animal preclinical models of CF. There are still many exciting questions to be answered concerning how gene therapy can be used to correct CF and how to improve vector design.
 

Engineering novel gene delivery tools

The aim of gene therapy vector development for life-long genetic diseases such as CF is to create a vehicle with the ability to efficiently, safely, and persistently express a transgene in the appropriate cell types. There are multiple viral based vectors for delivering genes to the airways. Each system has its pros and cons. Non-viral vectors, such as DNA transposons provide an expanded tool-set for gene transfer to cells. In particular, the recombinant DNA transposon, piggyBac, achieves efficient genomic integration of a transgene when transposase is supplied in trans. Recombinant piggyBac transposon and transposase are typically co-delivered by plasmid transfection; however, the greatest barrier to any plasmid based vector is inefficient delivery. We have shown the potential for using viral vectors (both Ad and AAV) to deliver piggyBac components to cells and achieve transposase mediated genomic integration of the transposon. A hybrid piggyBac/viral vector has the combined advantage of a very efficient gene transfer reagent with life-long expression. This novel hybrid vector system provides a valuable additional tool for in vivo gene transfer. 
 

Measles virus (MV) entry and spread in airway cells

Despite an effective vaccine, MV remains a world wide health burden and is resurging in the US. Medical texts teach that MV initially infects and replicates locally in respiratory cells and subsequently spreads to the lymphatic system. However, we challenged this dogma. Prior to our study in 2002, MV was thought to enter the apical surface of airway epithelia. By using well-differentiated primary cultures of airway epithelia from human donors, we were the first to demonstrate that MV has an overwhelming preference for the basolateral surface. At the time, this result was very unexpected. We subsequently demonstrated in our 2008 and 2011 publications that MV uses an epithelial specific cellular receptor, Nectin-4, to enter airway cells. Another important observation from our 2002 study was MV infection of primary airway cells is non-cytopathic, as is typically observed with MV infected immortalized cells. MV infected airway cells form infectious centers that retain individual nuclei, plasma membranes, and transepithelial resistance. One of the critical challenges for the field of cell-to-cell transmission is a model system that mirrors how viruses actually spread in living organisms. Primary airway cells are the best models for studying cell-to-cell transmission of MV in epithelia. There are so many questions that wait to be answered about an extremely (perhaps most) contagious human virus. 
 

The University of Iowa Viral Vector Core
www.medicine.uiowa.edu/vectorcore

Dr. Sinn is the director of the Viral Vector Core at the University of Iowa. The core serves investigators world-wide and produces viral vectors for studies in the lung, eye, brain, liver, heart, muscle, cardiovascular, and neuromuscular systems. As such, the Viral Vector Core staff members are active participants in the development of gene transfer technologies in the cancer, neurobiology, cardiovascular, macular degeneration, and cystic fibrosis centers. The overall objective of the vector core is to support investigators in gene transfer technologies. This includes consultation, development of novel vectors, collaborative testing of vectors for function and purity, and routine vector preparations.

Viral Vector Core Services
  • Construct, purify, and perform quality control of: recombinant adenovirus; helper-dependent adenovirus; adeno-associated virus; lentivirus; moloney murine retrovirus; baculovirus; vaccinia virus
  • Consultations for individual project requirements
  • Design, build, and produce novel vectors
  • Maintain and distribute stocks of recombinant reporter viruses
  • Cloning expression cassettes into vector shuttles