STEM CELL PHENOTYPIC AND FUNCTIONAL CHARACTERIZATION

Identification and origin of HSCs can be determined by

Immunophenotypic analysis using flow cytometry.

Earliest identifiable human HSCs capable of initiating long-term cultures

CD34+, CD38−, HLA-DRlow, Thy1low, and Lin−

This population of marrow cells is enriched in primitive progenitors.

Expression of CD38 and HLA-DR is associated with

LOSS OF STEMNESS

Acquisition of CD33 and CD38 is seen on

Committed myeloid progenitors

the expression of CD10 and CD38 is seen on

Committed Lymohoid Progenitors

The expression of CD7 is seen on

T lymphoid progenitor cells and natural killer cells

expression of CD19 is seen on

B Lymphoid Progenitor Cells

Functional characterization of HSCs can be accomplished through

In-vitro techniques using long-term culture assays

-       These involve the enumeration of colony-forming units (e.g., CFU-GEMM) on semisolid media such as methylcellulose.

Ø  Primitive progenitor cells, such as the high proliferative potential colony-forming cell and the long-term colony initiating cell, have also been identified.

Ø  These hematopoietic precursor cells give rise to colonies that can survive for 5 to 8 weeks but can be replated

-       Treatment of hematologic disorders is based on fundamental understanding of the biologic principles of HSC proliferation and maturation.