Organoids direct systemic expression of erythropoietin in mice

Organoids are adenoviral vector transduced cells embedded ex vivo in a collagen-polytetrafluoroethylene lattice that is saturated with angiogenic factors. Organoids provide an alternative method of cell mediated gene transfer following implantation in the donor/recipient. The feasibility of adenovirally mediated delivery via organoids using the erythropoietin (Epo) cDNA was tested. Fibroblasts were transduced by two recombinant adenoviral vectors encoding the Macaca cynomolgus Epo cDNA, driven by a viral (RSV LTR) or a murine housekeeping gene promoter (PGK-1). A functional in vivo assay was used to monitor Epo production via the rise in hematocrit(s) (hct). The hct remained elevated for as long as 6 weeks after implantation. Subcutaneous implants gave consistently higher hct than intraperitoneal implants, while organoids made with a greater number of cells, or an equal number of cells transduced at higher multiplicities of infection (MOI) also produced a larger increase in hct. AdPGKEpo-organoids produced a greater increase in hct than AdRSVEpo-organoids under comparable conditions, but the duration of expression was similar. A 10- to 50-fold lower input of AdRSVEpo using organoids versus direct intravenous injections resulted in an equal to, or greater than hct response in mice. Explanted organoids caused a rapid decrease in the hct of mice. Organoid supernatant had little or no detectable free viral particles making this method safe from unwanted recombinant adenovirus dissemination.