Clinical Application of Frozen Vitamin D3-Tolerogenic Dendritic Cells (P5.318)

Objective: To analyze the in vivo functionality of frozen vitamin D3 (VitD3)-tolDC in EAE, the animal model of MS. Background: Tolerogenic dendritic cells (tolDC) loaded with autoantigens is a promising specific cell therapy for the attenuation of pathogenic T cells in autoimmune diseases such as multiple sclerosis (MS). The use of frozen tolDC is an attractive strategy to increase the feasibility of the translation of these cells to the clinics. However, some tolDC products have shown to lose their function after cryopreservation. Methods: Bone marrow (BM) cells from C57BL/6 mice donors were cultured in presence of GM-CSF, LPS and vitamin D3 (VitD3) as tolerogenic agent- for 8 days, and pulsed with (MOG)40-55. Finally, VitD3-tolDC were cryopreserved in medium with 50[percnt] FBS+10[percnt] DMSO. A total of 110^6 thawed tolDC-MOG cells or PBS (sham control) were administrated therapeutically (after the onset of clinical signs) on EAE-C57BL/6 induced mice. Mice were monitored daily for clinical signs. Characterization of immune response was determined in splenic cells at the end of the experiments. Results: The treatment of EAE-mice with frozen VitD3-tolDC was able to abrogate clinical progression of the disease (p<0.001) and reduced MOG-specific response (p=0.004) compared to control mice at the same extend than fresh VitD3-tolDC treatment. Furthermore, it was observed that long term treatment with frozen VitD-tolDC (until 74 days of follow-up) was well tolerated and, interestingly, the therapeutic effect of the cells after each administration was progressively increased, extending the interval dosing required. This improvement could be mediated, in part, by an increase of regulatory B cells (Breg, p=0.015) and a reduction of NK cells (p<0.05). Conclusions: Our results show that frozen VitD3-tolDC cells could be a feasible therapy for the treatment for MS patients. Disclosure: Dr. Mansilla has nothing to disclose. Dr. Contreras has nothing to disclose. Dr. Navarro has nothing to disclose. Dr. Teniente-Serra has nothing to disclose. Dr. Quirant-Sanchez has nothing to disclose. Dr. Hervas has nothing to disclose. Dr. Presas has nothing to disclose. Dr. Ramo received research support from Biogen Idec Iberia. Dr. Martinez-Caceres has nothing to disclose.