IL-17 is a novel cytokine produced by T-eell subsets which are beleived to facilitate CD34+ stem cell engraftment. We have shown that gene transfer of the II-17 cDN A enhances hematopoietic progenitor cell production in mice. In this study we examined whether IL17 enhanced the engraftment potential of highly purified CD34+ cells on individual mesenchymal / stromal progenitor derived stromal cell colonies from human marrow in vitro. The number of Cobblestone Areas (CA) or nests of more than 50 blasts per individual stromal cell colony was used to measure the engraftment potential of CD34+ cells at weekly intervals for 4 weeks post seeding of CD34+ cells with IL-17 @ 50 ng/ml (5X104CD34+ cells per 30 stromal cell colonies per culture plate). Hematopoietic progenitors in both adherent and non-adherent cell populations were also measured weekly by standard methylcellulose assay. The number (M +/- SEM) of CA or nests of CD34+ cells were assesssed on both pure fibroblast-like stromal cell colonies, CFU-F; and stromal cell colonies containing fibroblst-like cells and adipocytes, CFU-FA. Control cultures of CFU-F and CFU-FA had similar cumulative numbers of CA frequency. CA frequency range was 1-CA/ CFU-F to 8-CA/CFU-F and 1-CA/CFU-FA to 8-CA/CFU-FA by the end of 4 weeks. While IL-17 continuously increased the frequency of CA or blast cell nests from 1 -CA/CFU-F to 13-CA/CFU-F and 2-CA/CFU-FA to 17-CA/CFU-FA by the end of the 4 week culture period. The enhanced engrfatment potential of CD34+ cells resulted in more than a 2x increase in proliferation of non-adherent cells and l .5X increase in adherent cells. While cumulative production of all hematopoietic progenitors (CFU-GEMM, CFU-GM, and BFU-E)were also incresaed by more than 2X. These data indicate that IL-17 enhances the freqency of C A formation or engraftment potential of hihgly purified CD34+ cells when seeded on individual stromal cell colonies. Stromal cell colonies which contain adipocytes and beleived to be derived from an earlier or multipotential stromal progenitor may have functionally diverse populations of stromal cells which may accelerate the rate of engrfatment. They appear to have a greater responce to IL-17 signaling and support a significantly higher frequency of CA/CFU-FA at earlier time post CD34+ cell seeding than CFU-F. These data suggest the IL17 may facilitate engraftment by targeting stromal colony niches which lead to local expansion of early CD34+ hematopietic stem cells and CA formation.
|Original language||English (US)|
|Issue number||11 PART II|
|State||Published - Dec 1 2000|
ASJC Scopus subject areas
- Cell Biology