155specimens have been well described [ 15 – 17 ]. Briefly, endometrial tissue biopsies
were subjected to enzymatic and mechanical dissociations and diluted into single-
cell suspensions of stromal and epithelial cells. The dissociated cells were further
filtered through sterile 40-μm cell strainers to separate stromal cells that consist of
mainly the flow through and the undigested epithelial glandular clumps were
retained in the strainer. Regenerating stem cell clones were developed from both
stromal and epithelial cells [ 15 ]. Endometrial MSC clones were generated by either
direct dilution of pure stromal cell isolates using serial dilution techniques [ 15 ] or
by single cell cloning of culture grown stromal cells following five repeated pas-
sages ([ 17 ]; Fig. 10.2). Endometrial MSCs can be grown extensively both in vivo
and in vitro and maintained in culture for up to 40 passages. They exhibit a diverse
differentiation potential on specific induction conditions such as chondrogenic,
osteogenic, adipogenic, angiogenic and myogenic lineages [ 1 , 17 ].
10.2.3 Endothelial Progenitor Cells
The progenitor cells in the endometrium are reported to have high proliferative
potential and can generate upto 6 × 10^11 cells from a single cell [ 15 ]. These cells
were able to differentiate into large cytokeratin-expressing structures when cultured
in matrigel and were used as a substitute for mouse embryonic fibroblast feeder lay-
ers in embryonic stem cell cultures [ 15 ].
10.2.4 Endometrial Side Population (SP) Cells
A number of studies suggest that endometrial stem cells possess side population
(SP) phenotype that is characterized by their ability to exclude the DNA-binding
dye Hoechst 33343 due to presence of ATP-binding cassette transporter proteins
[ 18 ]. Endometrial SP cells were identified both in the epithelial and stromal
Fig. 10.1 Localisation of endometrial stem cells in human endometrium
10 Uterine Stem Cells and Their Future Therapeutic Potential in Regenerative Medicine