Successful expansion of bone marrow (BM) hematopoietic stem and progenitor cells (HSPCs) would benefit many HSPC transplantation and gene therapy/editing applications. However, current expansion technologies have been limited by a loss of multipotency and self-renewal properties ex vivo.We hypothesized that an ex vivo vascular niche would provide prohematopoietic signals to expand HSPCs while maintaining multipotency and self-renewal. To test this hypothesis, BM autologous CD34+ cells were expanded in endothelial cell (EC) coculture and transplanted in nonhuman primates. CD34+C382 HSPCs cocultured with ECs expanded up to 17-fold, with a significant increase in hematopoietic colony-forming activity compared with cells cultured with cytokines alone (colony-forming unit-granulocyte-erythroid-macrophage-monocyte; p < .005). BM CD34+ cells that were transduced with green fluorescent protein lentivirus vector and expanded on ECs engrafted long term with multilineage polyclonal reconstitution. Gene marking was observed in granulocytes, lymphocytes, platelets, and erythrocytes. Whole transcriptome analysis indicated that EC coculture altered the expression profile of 75 genes in the BM CD34+ cells without impeding the long-term engraftment potential. These findings show that an ex vivo vascular niche is an effective platform for expansion of adult BM HSPCs.

Stem Cells Transl Med. 2016;5:1-13 (14 October 2016) DOI: 10.5966/sctm.2016-0240


Jennifer L. Gori,a Jason M. Butler,b,c,d,e Balvir Kunar,b,c,d,e,f Michael G. Poulos,b,c,d,e Michael Ginsberg,g Daniel J. Nolan,g Zachary K. Norgaard,a Jennifer E. Adair,a Shahin Rafii,b,c,d Hans-Peter Kiema,h,i

aClinical Research Division,Fred Hutchinson Cancer Research Center, Seattle, Washington, USA; bHoward Hughes Medical Institute, Chevy Chase, Maryland, USA; cAnsary Stem Cell Institute and Departments of dGenetic Medicine, eSurgery, and fPhysiology, Biophysics, and Systems Biology, Weill Cornell Medical College, New York, New York, USA; gAngiocrine Bioscience, New York, New York, USA; Departments of hMedicine and iPathology, University of Washington, Seattle, Washington, USA