A Clinical Study of Bone Marrow Stromal Cell Therapy in Patients with Refractory Cgvhd by Down-Regulating the Jagged2 Gene

Abstract 4673

Refractory chronic GVHD (cGVHD) is an important complication after allogeneic hematopoietic SCT and is prognostic of poor outcome. Bone Marrow Stromal Cells (MSCs) are involved in tissue repair and modulating immune responses in vitro and in vivo. MSCs as salvage treatment for refractory cGVHD have been reported in our previous study, however, the possible mechanism have yet not to be determined.

Between November 2006 and November 2010, 18 patients were diagnosed with refractory cGVHD, 8 patients were treated with in vitro expanded BM-derived MSCs as a compassionate treatment for refractory cGVHD, 10 patients that did not receive BMSCs treatment were control group. The median MSC dose given was 0.6×10⁶/kg body weight. MSCs were harvested fresh from culture and administered to the patients by intravenous infusions over 30 minutes. The median time of MSC administrations was 3 (range, 2–6). The response was assessed monthly after BMSCs treatment, and the total follow-up period was 6 months. The organ response and the overall response were used to determine the therapeutic efficacies of MSC for refractory cGVHD. The expression of the Jagged2 gene of peripheral blood mononuclear cells in patients at the assessment points were analyzed using the TaqMan real-time polymerase chain reaction, with ABL mRNA expression levels as an internal reference.

After BMSCs treatment, a total of 6 patients (75%) had an overall response (PR n=6), and 2 patients had a minor partial response (mPR n=2). The expression levels of Jagged2 mRNA in these cases at the diagnosis of refractory cGVHD were significantly increased, compared with none cGVHD patients (23.94%±18.68% vs 3.76%±1.50%, P < 0.05), and the copies of Jagged2 mRNA in BMSC treatment responsed patients' peripheral blood were significantly reduced (5.15%±3.25%, P <0.05), while Jagged2 mRNA expression levels of the control group were no significant difference (P> 0.05).

Our pilot study showed that Jagged2 gene reproduction upregulated when the cGVHD is active, so, dynamic monitoring of Jagged2 mRNA expression may have the potential effect on predicting the activity of chronic graft-versus-host disease. Mechanism of Bone marrow stromal cells to treat refractory cGVHD may be related to down-regulation of donor T cells Notch ligand Jagged2 gene expression, which suppression of T cell Notch signaling pathway activation, thus inducing immune tolerance.