Reversible commitment to differentiation by human multipotent stromal cells in single-cell-derived colonies

Area of Science:

• Cell Biology
• Stem Cell Biology

Background:

• Human multipotent stromal cells form heterogeneous colonies.
• Colony heterogeneity arises from variations in size and differentiation potential upon replating.

Purpose of the Study:

• To test if cells in inner colony regions are partially differentiated and if this differentiation is reversible.
• To investigate the characteristics of inner (IN) versus outer (OUT) region cells within single-cell-derived colonies.

Main Methods:

• Isolating cells from inner (IN) and outer (OUT) regions of colonies.
• Comparing IN and OUT cells using transcriptomic, proteomic, clonogenicity, and differentiation assays.

Main Results:

• IN cells showed reduced cell-cycle gene expression and increased extracellular matrix gene expression compared to OUT cells.
• Differentiation occurred primarily in IN regions when cells were transferred to differentiation medium.
• IN cells were indistinguishable from OUT cells in propagation rates and clonogenicity when replated, forming similar heterogeneous colonies.

Conclusions:

• Cells in the inner regions of single-cell-derived colonies exhibit partial differentiation.
• This partial differentiation is reversible upon replating cells at clonal densities, restoring multipotency.