Transgene expression in various organs post BM-HSC transplantation

• Dual‐promoter lentivirus with EF1a driving the gene of interest (Ii) is efficient.
• After transplantation of transduced HSC, GFP correlates with Ii in myeloid cells.
• Ii levels in splenic APC resemble those in APC in pancreatic LN.
• Ii levels in splenic and PLN APC are not reflected by Ii levels in BM APC.
• Ii function in progeny of transduced HSC develops with APC maturation.

Gene therapy mediated by bone marrow-derived hematopoietic stem cells (BM-HSC) has been widely used in treating genetic deficiencies in both pre-clinical and clinical settings. Using mitotically inactive cell-targeting lentivirus with separate promoters for our gene of interest (the murine MHC class II (MHCII) chaperone, invariant chain (Ii)) and a GFP reporter, we monitored the expression and function of introduced Ii in various types of professional antigen presenting cells (B cells, macrophages and DC) from different organs (spleen, pancreatic lymph nodes (PLN), BM and blood). Ii and GFP were detected. Ii levels correlated with GFP levels only in macrophages and monocytes from spleen, monocytes from PLN and macrophage precursors from blood. By cell type, Ii levels in PLN cells were more similar to those in spleen cells than to those in blood or BM cells. Functionally, Ii expressed in PLN or spleen had more effect on MHCII abundance than Ii expressed in BM or blood. The results have implications for analysis of the outcomes of gene therapy when both therapeutic and reporter genes are introduced. The findings also have implications for understanding the development of immune molecule function.