Highly Efficient mRNA- and cDNA-Based Transient Gene Delivery into Human Progenitor Cells.

The method of gene transfer into progenitor cells is critical as viral vector transduction involves the risk of tumor induction by non-specific genomic integration. Non-viral transfection systems often fail due to low transfection efficiency. However, gene transfer into human CD34+ hematopoietic progenitor (HPC) and mesenchymal stem cells (MSC) is an essential tool for in vitro- and in vivo-applications and therapeutic strategies such as tissue engineering and gene therapy. We recently reported an transient genetic labelling of human CD34+ HPC with deltaLNGFR-plasmid-DNA for in vivo application: Transient transfection was efficient for both, CD34+ HSC (41% ± 2%) and leukemia cell lines (55% ± 4.9%) using the method of nucleofection. Moreover, mature myeloid cells (CD66b+) derived from transfected human CD34+ HPC and leukemia cells maintained deltaLNGFR expression at a high percentage (70% ± 1.6% and 58% ± 2% respectively). In this work, we investigated labelling of CD34+ HPC with mRNA. Human CD34+ HPC and human MSC were transfected with in vitro-transcribed mRNA for deltaLNGFR, a marker gene approved for human in vivo-application, using nucleofection. EGFP was used as a control. 24h after nucleofection, FACS-analysis showed a higher transfection efficiency compared to plasmid transfected CD34+ HPC and MSC: A high transfection frequency was found for mRNA-transfected HPCs using deltaLNGFR (82.4±9.7%) and EGFP (88.7±2.6%). We found also a high transfection rate for MSC using the marker genes deltaLNGFR (92.4±3.6%) and EGFP (83.3±4.1%). Cell viability was not affected by mRNA-transfection. Moreover, differentiation assays of deltaLNGFR-selected MSC after transfection, showed that differentiation of MSC into mesenchymal cells like chondrocytes, adipocytes and osteoblasts was not affected by mRNA nucleofection. Taken together, mRNA based nucleofection is a powerful, highly efficient and non-toxic approach for transient labelling of human progenitor cells or, via transfection of selective proteins, for transient manipulation of stem cell function. It may thus be useful to transiently manipulate stem cell characteristics and combine principles of gene therapy and tissue engineering.