Analysis of copy number change in cord lining epithelial cells after phage integrase mediated genomic integration.

The two obstacles that impede a wider application of genetically modified cells expressing therapeutic transgenes for ex vivo gene therapy are the immune mediated rejection of the transplanted cells, combined with their potential to cause iatrogenic oncogenesis. In this study we describe a new cellular vehicle for this form of therapy, termed the cord lining epithelial cell (CLEC). CLECs are derived from the human amnion and incorporate many of the immunoregulatory functions associated with the fetal/maternal interface. We show that CLECs can be safely transfected by phage φC31 integrase to accomplish site-specific integration of a therapeutic human transgene. We also show that transplanted CLECs are not oncogenic in vivo and can be maintained in immunocompetent mice where acute xeno-rejection rapidly destroys other human cell types. Finally, we demonstrate the utility of CLECs for ex vivo gene therapy by delivering human coagulation factor 8 to mice with Hemophilia A. High-resolution copy number profiling was performed on genomic DNA of untreated (GSM315546 and GSM315713) and phage integrase modified CLECs (GSM315974 and GSM316895) using the Human Mapping 500K Array Set (Affymetrix) and the data analyzed using GeneChip Chromosome Copy Number Analysis Tool. Regions of copy number gain or loss were defined as having 3 consecutive SNPs concordant for significant copy number abnormalities. Log2 signal intensity ratios >0.3 and <-0.3 were criteria for significant copy number gain and loss, respectively.