Enhanced homing and engraftment of fresh but not ex vivo cultured murine marrow cells in submyeloablated hosts following CD26 inhibition by Diprotin A

Abstract

Objective We recently reported that murine marrow cultured ex vivo for gamma-retrovirus transduction engrafts ~10 fold less well than fresh marrow upon transplantation into submyeloablated hosts. Here, we evaluated homing efficiency as a potential mechanism for this engraftment disparity, and whether CD26 inhibition with the tripeptide Diprotin A (DipA) would enhance engraftment of ex vivo cultured cells in submyeloablated hosts. Methods Homing and engraftment of fresh and ex vivo cultured lineage-negative (lin-) marrow cells in submyeloablated congenic hosts with and without DipA treatment was evaluated. Expression of CXCR4 and CD26 on fresh and cultured lin- marrow cells was compared. Results Homing of lin- cells cultured for gamma-retrovirus transduction was ≥3-fold less than that of fresh lin- cells 20 hours after transplantation into submyeloablated hosts. DipA treatment of fresh lin- cells resulted in ≥-fold increased homing and engraftment in submyeloablated hosts. DipA treatment, however, did not significantly improve homing or engraftment of cells undergoing a three-day culture protocol for gamma-retrovirus transduction in submyeloablated hosts. CXCR4 expression on lin- cells was significantly decreased following three days of culture; CXCR4 expression was not significantly altered following overnight culture. Conclusions Ex vivo culture of lin- cells for gamma-retroviral transduction downregulates CXCR4 expression and markedly impairs homing and engraftment of murine lin- marrow in submyeloablated hosts. While inhibition of CD26 activity with DipA increases homing and engraftment of fresh lin- cells, DipA treatment does not improve homing and engraftment of cultured lin- marrow cells in submyeloablated congenic hosts.

Implications of DPP4 modification of proteins that regulate stem/progenitor and more mature cell types

“…Taking into consideration effects of DPP4 inhibition on enhanced homing and engraftment of mouse HSC 5,6,[26][27][28] and engraftment of human CD34…”

Dipeptidylpeptidase 4 negatively regulates colony-stimulating factor activity and stress hematopoiesis

“…3, also known as CD26) is expressed on HSCs and HPCs; a non–membrane-bound, soluble form of DPP4 is also produced 4 . Genetic deletion of Dpp4 or inhibition of DPP4 activity with diprotin A (Ile-Pro-Ile) or Val-Pyr greatly enhances chemotaxis of HPCs toward SDF-1 (CXCL12) 4 and engraftment of mouse5–8 and human 9–11 HSCs, in part through increasing homing 5 toward endogenous bone marrow SDF-1 (ref. 12).…”

Counteracting the enzymatic activity of dipeptidylpeptidase 4 for potential therapeutic advantage, with an emphasis on cord blood transplantation

“…Thus, deletion of CD26 in CD26 -/- mice or inhibition of DPP4 (with two separate DPP4 inhibitors) demonstrated increased homing of a long-term BM repopulating and self-renewing HSCs [28]. This work was quickly confirmed and extended by others [31-33], followed by reports [34-36] demonstrating that inhibition of DPP4 on CD34 + human CB or human mPB enhanced their engrafting capability in sublethally irradiated mice with nonobese diabetic severe combined immunodeficiency (SCID). This mouse serves as an in vivo model for detecting human HSCs, which are quantitated as SCID-repopulating cells.…”