Nanomedicine Center for Nucleoprotein Machines
Gang Bao, Ph.D., Georgia Tech
Matthew Porteus, M.D., Ph.D., Stanford University
David Roth, M.D., Ph.D., University of Pennsylvania
The Nanomedicine Center for Nucleoprotein Machines is developing a gene correction approach for treating sickle cell disease (SCD).
This center began with a strong basic science and engineering focus on better understanding nucleoprotein machines, specifically looking at assembly and function of the non-homologous end joining (NHEJ) molecular complex. The purpose was to use the pathway for genetic therapies. It became apparent that NHEJ could not be understood isolated from homologous recombination (HR), which competes with NHEJ and affords better possibilities for gene correction. The investigators developed protein tagging strategies and imaging methods to study the NHEJ and HR complexes at work in the living cell.
The Nanomedicine program was designed to modulate an intracellular nanoscale complex to treat a specific disease target. The researchers at this center determined that using DNA repair pathways for gene editing is feasible by combining their knowledge about the repair pathways with the newest tools for editing the genome. Activation of gene correction by HR began using Zinc-finger nucleases (ZFNs). Most recently, newly engineered transcription activator-like effector nucleases (TALENs) appear to be more effective and more specific in their ability to snip a specific sequence of DNA. These nucleases, designed to break the DNA and remove the defective gene are introduced into diseased cells along with a corrected donor strand that in theory should replace the defective gene with a normal copy.
The primary translational target of the center is gene correction of the defective beta-globin gene in a mouse model of SCD. The approach is to replace defective cells by isolating hematopoietic stem/progenitor cells (HSPCs) that carry the sickle mutation, correcting this mutation ex vivo, and transplanting the gene-corrected HSPCs back into the SCD patient, thereby supplying healthy red blood cells to ameliorate or even cure the disease. The near-term goal of the center is to lay the foundation for a clinical trial to determine the efficacy of the gene correction approach in treating SCD patients. This strategy includes the following major tasks:
1. Design, validate and optimize nucleases and donor templates
2. Achieve high gene correction rate in HSPCs and optimize their engraftment
3. Optimize nucleases and donor delivery
4. Minimize genomic risk (off-target activity)
5. Control DNA repair pathway choice
CLINICAL CONSULTING BOARD (CCB)
David M. Bodine, Ph.D., National Human Genome Research Institute
Katherine A. High, M.D., Children’s Hospital of Philadelphia
YW Kan, M.D., University of California, San Francisco
David G. Nathan, M.D., Harvard Medical School
Stephen P. Sugrue, Ph.D., University of Florida College of Medicine