title: Generation of human adult mesenchymal stromal/stem cells expressing defined xenogenic vascular endothelial growth factor levels by optimized transduction and flow cytometry purification.
abstract: Adult mesenchymal stromal/stem cells (MSCs) are a valuable source of multipotent progenitors for tissue engineering and regenerative medicine, but may require to be genetically modified to widen their efficacy in therapeutic applications. For example, overexpression of the angiogenic factor vascular endothelial growth factor (VEGF) at controlled levels is an attractive strategy to overcome the crucial bottleneck of graft vascularization and to avoid aberrant vascular growth. Since the regenerative potential of MSCs is rapidly lost during in vitro expansion, we sought to develop an optimized technique to achieve high-efficiency retroviral vector transduction of MSCs derived from both adipose tissue (adipose stromal cells, ASCs) or bone marrow (BMSCs) and rapidly select cells expressing desired levels of VEGF with minimal in vitro expansion. The proliferative peak of freshly isolated human ASCs and BMSCs was reached 4 and 6 days after plating, respectively. By performing retroviral vector transduction at this time point, >90% efficiency was routinely achieved before the first passage. MSCs were transduced with vectors expressing rat VEGF(164) quantitatively linked to a syngenic cell surface marker (truncated rat CD8). Retroviral transduction and VEGF expression did not affect MSC phenotype nor impair their in vitro proliferation and differentiation potential. Transgene expression was also maintained during in vitro differentiation. Furthermore, three subpopulations of transduced BMSCs homogeneously producing specific low, medium, and high VEGF doses could be prospectively isolated by flow cytometry based on the intensity of their CD8 expression already at the first passage. In conclusion, this optimized platform allowed the generation of populations of genetically modified MSCs, expressing specific levels of a therapeutic transgene, already at the first passage, thereby minimizing in vitro expansion and loss of regenerative potential.
authors: Cell and Gene Therapy, Department of Biomedicine, Basel University Hospital, Basel, Switzerland.
authors: Uta
authors: U
authors: Helmrich
authors: Anna
authors: A
authors: Marsano
authors: Ludovic
authors: L
authors: Melly
authors: Thomas
authors: T
authors: Wolff
authors: Liliane
authors: L
authors: Christ
authors: Michael
authors: M
authors: Heberer
authors: Arnaud
authors: A
authors: Scherberich
authors: Ivan
authors: I
authors: Martin
authors: Andrea
authors: A
authors: Banfi
mesh_terms: D000328:Adult; D053687:Adult Stem Cells / Q000166:cytology*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D002469:Cell Separation / Q000379:methods*; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D005434:Flow Cytometry / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D012190:Retroviridae / Q000235:genetics; D014161:Transduction, Genetic; D019076:Transgenes / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D042461:Vascular Endothelial Growth Factor A