Hiroyuki Nakai, MD, PhD

RESEARCH

The major focuses of our laboratory are the elucidation of the biology of recombinant adeno-associated virus (rAAV) vectors and cellular biology associated with rAAV infection/transduction, and development of new rAAV vector-mediated gene and cell therapies to treat various human diseases. This new lab in the department has just relocated from University of Pittsburgh in August 2011.

AAV is a non-pathogenic single-stranded DNA virus with the simplest viral structure and provides a promising and powerful tool for gene delivery. Recent studies have shown that single intravenous injection of rAAV serotype 8 or 9 vectors into experimental animals can efficiently deliver genetic materials to many types of cells in the body, including the liver, heart, muscle and brain cells.  However, despite the structural simplicity, the biology of this virus is very complicated and is not well understood. Due to the lack of profound understanding of the in vivo AAV biology, potentially significant issues remain in rAAV vectors. The issues include:  (1) there remain a number of extracellular and intracellular barriers (physical and biological) that hinder efficient gene delivery to target cells/tissues, necessitating administration of high vector doses; (2) efficient in vivo gene delivery with current rAAV vectors results in substantial vector spillover to non-target cells/tissues; (3) studies have shown a potential risk of AAV-mediated insertional mutagenesis causing malignancy; and (4) acquired immune responses against AAV capsid proteins or transgene products limit the efficiency of gene delivery. The challenge in our laboratory has been to overcome these issues toward successful rAAV-mediated human gene and cell therapies by substantially understanding the AAV biology and host responses.

In our laboratory, we have been studying AAV genome biology for many years. In this project, we focus on the interactions between viral genomes, host chromosomal DNA and host cellular DNA repair machinery in the in vivo context of various tissues to understand the post-uncoating events in AAV vector transduction. The AAV capsid biology project is aimed at mechanistically understanding how biological properties of different types of AAV capsids are determined based on their amino acid sequences, which vary between different AAV serotypes, naturally occurring variants, and capsid-engineered artificial variants. AAV capsid VP protein is a multifunctional protein that manifests an array of biological phenotypes. The phenotypes include efficiency of capsid assembly, ability to interact with components in body fluid and ECM, blood clearance rates, vascular permeability, antigenicity, reactivity to neutralizing antibodies, tissue/organ/cell type tropism, efficiency of cell attachment and internalization, intracellular trafficking routes, virion uncoating rates, and so on. Many of these phenotypes have significant influences on how efficiently or inefficiently AAV overcomes various barriers toward establishing infection/transduction. Therefore, the elucidation of the molecular mechanisms underlying AAV phenotypes is very important to understand the AAV biology and develop next generation vectors with the most desirable properties. In this project, to achieve the goal, we will take a novel high-throughput approach that we have recently established, which integrates Illumina deep sequencing and the concept of systems biology and bioinformatics. Our AAV translational research has so far focused on AAV-mediated gene therapy for heart and liver diseases. It is expected that our focus will also be directed to gene / cell therapy for genetic diseases in children and CNS diseases at OHSU.

 
SELECT PUBLICATIONS

Adachi, K., Nakai, H. 2011 "The Roles of DNA Repair Pathways in Adeno-Associated Virus Infection and Viral Genome Replication / Recombination / Integration" In Sofya Vengrova (ed), DNA Repair/ Book 3, InTech (accepted for publication).

Kotchey, N., Adachi, K., Zahid, M., Inagaki, K., Charan, R., Parker, P., Nakai, H. 2011 “A potential role of distinctively delayed blood clearance of recombinant adeno-associated virus serotype 9 in robust cardiac transduction“ Mol. Ther. 19, 1079-89| Abstract

Adachi, K., Nakai, H. 2010 “A new recombinant adeno-associated virus (AAV)-based random peptide display library system: infection-defective AAV1.9-3 as a novel detargeted platform for vector evolution” Gene Ther. Regulation 5, 31-55| Abstract

Dong, B., Nakai, H., Xiao, W. 2010. “Characterization of genome integrity for oversized recombinant AAV vector” Mol. Ther. 18, 87-92 | Abstract
Miyagi N, Rao VP, Ricci D, Du Z, Byrne GW, Bailey KR, Nakai H, Russell SJ, McGregor CG. 2008. "Efficient and durable gene transfer to transplanted heart using adeno-associated virus 9 vector" J. Heart Lung Transplant. 27: 554-60 | Abstract

Inagaki, K., Piao, C., Kotchey, N., Wu, X., Nakai, H. 2008. "Frequency and spectrum of genomic integration of recombinant adeno-associated virus serotype 8 vector in neonatal mouse liver" J. Virol. 82: 9513-9524 | Abstract

Inagaki, K., Ma, C., Storm, T.A., Kay, M. A., Nakai, H. 2007. "A Role of DNA-PKcs and Artemis in opening viral DNA hairpin termini in various tissues in mice" J. Virol. 81: 11304-11321 | Abstract

Inagaki, K., Lewis, S.M., Wu, X., Ma, C., Munroe, D.J., Fuess, S., Storm, T.A., Kay, M. A., Nakai, H. 2007. "DNA palindromes with a modest arm length of >~20 bp are a significant target for rAAV vector integration in the liver, muscle and heart in mice" J. Virol. 81: 11290-11303 | Abstract
Inagaki, K., Fuess, S., Storm, T.A., Gibson, G. A., Mctiernan, C. F., Kay, M. A., Nakai, H. 2006. "Robust systemic transduction with AAV9 vectors in mice: efficient global cardiac gene transfer superior to that of AAV8" Mol. Ther. 14:45-53 | Abstract

Nakai, H., Montini, E., Fuess, S., Storm, T. A., Grope, M., Kay, M. A. 2003. "AAV serotype 2 vectors preferentially integrate into active genes in mice" Nat. Genet. 34:297-302 | Abstract