Osmotic selection of human mesenchymal stem/progenitor cells from umbilical cord blood.
The isolation of undifferentiated adult stem/progenitor cells remains a challenging task primarily due to the rare quantity of these cells in biological samples and the lack of unique markers. Herein, we report a relatively straightforward method for isolation of human mesenchymal stem cells (MSCs) based on their unusual resistance to osmotic lysis, which we term "osmotic selection" (OS). MSCs can remarkably withstand significant exposure to hypotonic conditions (> 30 min) with only a reversible impairment in cell proliferation and with no loss of stem cell potential after exposure. Comparison of MSCs to other circulating nonhematopoietic cells revealed a time regime, by which purification of these cells would be attainable without considerable cell loss. OS showed a 50-fold enrichment of fibroblast colony-forming units from umbilical cord blood samples when compared to commonly employed techniques. After upstream processing, isolated cells using OS were immunophenotyped to be CD14-, CD34-, CD45-, CD44+, CD105+, and CD106+, and displayed multipotent differentiation. Preliminary investigations to determine mechanisms responsible for osmolytic resistance revealed MSCs to have an ineffective volume of 59%, with the ability to double cell volume at infinite dilution. Disruption of filamentous actin polymerization by cytochalasin D sensitized MSCs to osmotic lysis, which suggests a cytoskeletal element involved in osmolytic resistance.
Parekkadan
Biju
B
Center for Engineering in Medicine and Surgical Services, BioMEMS Resource Center, Harvard Medical School, Massachusetts General Hospital and the Shriners Hospitals for Children, Boston, MA, USA.
Sethu
Palaniappan
P
van Poll
Daan
D
Yarmush
Martin L
ML
Toner
Mehmet
M
D002469:Cell Separation / Q000379:methods*; D002478:Cells, Cultured; D005312:Fetal Blood / Q000166:cytology*; D017022:Flow Injection Analysis / Q000379:methods*; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D009995:Osmosis