Expansion on stromal cells preserves the undifferentiated state of human hematopoietic stem cells despite compromised reconstitution ability

• Published in: PloS one Vol. 8; no. 1; p. e53912
• Main Authors: Magnusson, Mattias, Sierra, Maria I, Sasidharan, Rajkumar, Prashad, Sacha L, Romero, Melissa, Saarikoski, Pamela, Van Handel, Ben, Huang, Andy, Li, Xinmin, Mikkola, Hanna K A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 16.01.2013; Public Library of Science (PLoS)
• Subjects: Analysis; Antigens, CD - metabolism; Apoptosis; Biology; Bone marrow; CD34 antigen; CD38 antigen; CD90 antigen; Cell Adhesion Molecules - metabolism; Cell culture; Cell cycle; Cell Differentiation; Cell Line; Cell Lineage; Cell Proliferation; Cells (biology); Coculture Techniques - methods; Developmental biology; DNA-Binding Proteins - metabolism; Down-Regulation; Expansion; Gene expression; Gene Expression Profiling; Health aspects; Hematological diseases; Hematopoietic Stem Cell Transplantation; Hematopoietic stem cells; Hematopoietic Stem Cells - cytology; Hematopoietic Stem Cells - metabolism; Histocompatibility antigen HLA; Humans; Laboratory animals; Liver transplants; Medicine; Mesenchyme; Pre-B-Cell Leukemia Transcription Factor 1; Progenitor cells; Proto-Oncogene Proteins - metabolism; Regulators; Regulatory mechanisms (biology); Rodents; Stem cells; Stromal cells; Stromal Cells - cytology; Stromal Cells - metabolism; Transcription; Transcription factors; Transplantation; Los Angeles California; United States > US; California
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0053912

Lack of HLA-matched hematopoietic stem cells (HSC) limits the number of patients with life-threatening blood disorders that can be treated by HSC transplantation. So far, insufficient understanding of the regulatory mechanisms governing human HSC has precluded the development of effective protocols for culturing HSC for therapeutic use and molecular studies. We defined a culture system using OP9M2 mesenchymal stem cell (MSC) stroma that protects human hematopoietic stem/progenitor cells (HSPC) from differentiation and apoptosis. In addition, it facilitates a dramatic expansion of multipotent progenitors that retain the immunophenotype (CD34+CD38-CD90+) characteristic of human HSPC and proliferative potential over several weeks in culture. In contrast, transplantable HSC could be maintained, but not significantly expanded, during 2-week culture. Temporal analysis of the transcriptome of the ex vivo expanded CD34+CD38-CD90+ cells documented remarkable stability of most transcriptional regulators known to govern the undifferentiated HSC state. Nevertheless, it revealed dynamic fluctuations in transcriptional programs that associate with HSC behavior and may compromise HSC function, such as dysregulation of PBX1 regulated genetic networks. This culture system serves now as a platform for modeling human multilineage hematopoietic stem/progenitor cell hierarchy and studying the complex regulation of HSC identity and function required for successful ex vivo expansion of transplantable HSC.