Development of CD4+CD25+FoxP3+ regulatory T cells from cord blood hematopoietic progenitor cells

Abstract

Adult stem cells are capable of generating all of the cells of the hematopoietic system, and this process is orchestrated in part by the interactions between these cells and the stroma. T cell progenitors emerge from the stem cell compartment and migrate to the thymus, where their terminal differentiation and maturation occur, and it is during this phase that selection shapes the immune repertoire. Notch ligands, including Delta-like 1 (DL1), play a critical role in this lymphoid differentiation. To mimic this in vitro, stroma-expressing DL1 have been used to generate CD4(+)CD8(+) double-positive and single-positive T cells from hematopoietic stem/progenitor cells. This system provides a robust tool to investigate thymopoiesis; however, its capacity to generate regulatory T cells (Tregs) has yet to be reported. Natural Tregs (nTregs) develop in the thymus and help maintain immune homeostasis and have potential clinical use as a cell therapy for modulation of autoimmune disease or for transplant tolerization. Here, we describe for the first time the development of a population of CD4(+)CD25(+) CD127(lo)FoxP3(+) cells that emerge in coculture of cord blood (CB) CD34(+) progenitors on OP9-DL1 stroma. These hematopoietic progenitor-derived CD4(+)CD25(+) Tregs have comparable suppressor function with CB nTregs in vitro. The addition of IL-2 to the coculture enhanced the expansion and survival of this population significantly. This manipulable culture system, therefore, generates functional Tregs and provides a system to elucidate the mechanism of Treg development.

Functionally Mature CD4 and CD8 TCRαβ Cells Are Generated in OP9-DL1 Cultures from Human CD34+ Hematopoietic Cells

“…ϩ TCR␣␤ ϩ natural regulatory T cell (nTreg) population from human cord blood CD34 ϩ cells was reported on OP9-DL1 stromal cells (49). These cells were CD25 ϩ FoxP3 ϩ and appeared as early as day 7 after the initiation of culture.…”

Combination of HOXB4 and Delta-1 ligand improves expansion of cord blood cells

“…Delaney et al 9 showed that there is a dose-depended effect of DL on differentiation and in vivo repopulating ability of human cord blood cells cultured on an immobilized layer of DL. Recently, Hutton et al 10 were able to generate a population of regulatory T cells from human cord blood by adding interleukin (IL)-2 to cord blood cells cocultured on DL-expressing OP9 cells. In addition, clinical trials conducted by Delaney et al 5 have recently shown increased kinetics of neutrophil engraftment when cord blood progenitors were expanded in the presence of DL.…”

Delta-like 1–Mediated Notch Signaling Enhances the In Vitro Conversion of Human Memory CD4 T Cells into FOXP3-Expressing Regulatory T Cells

“…A role for Notch signaling in human Treg development and expansion has been previously suggested (20,21,23). In fact, human cord blood CD34 + cells differentiate into mature Treg upon coculture with OP9-DL1, suggesting that Notch is involved in human thymic Treg development (21).…”

“…In fact, human cord blood CD34 + cells differentiate into mature Treg upon coculture with OP9-DL1, suggesting that Notch is involved in human thymic Treg development (21). Moreover, APCs overexpressing human Jag1 promoted the expansion of alloantigenspecific cells with regulatory properties from human naive CD4 cells (20).…”

“…There is solid experimental data in mice demonstrating a crucial role for Notch signaling in the thymic generation of Treg, their peripheral expansion and function, as well as in the in vitro conversion of conventional T cells into iTreg (15)(16)(17)(18)(19). In humans, there is evidence suggesting a role of Notch signaling in thymic Treg development as well as in peripheral Treg expansion (20)(21)(22)(23), although the putative role of Notch signaling in iTreg conversion has never been formally assessed.…”