Generation of Human Regulatory Dendritic Cells from Cryopreserved Healthy Donor Cells and Hematopoietic Stem Cell Transplant Recipients

Acute graft versus host disease (GVHD) remains a significant complication following hematopoietic stem cell transplant (HSCT), despite improved human leukocyte antigen (HLA) matching and advances in prophylactic treatment regimens. Previous studies have shown promising results for future regulatory dendritic cell (DCreg) therapies in the amelioration of GVHD. This study evaluates the effects of cryopreservation on DCreg generation, generation of young and older DCreg in serum-free media, and the feasibility of DCreg generated from young and older HSCT donor monocytes. DCreg were generated in X-vivo 15 serum-free media from donor monocytes. Donors included young and older individuals, either healthy donors or HSCT patients. Phenotypic differences in cell populations were assessed via flow cytometry while pro-inflammatory and anti-inflammatory cytokine production was evaluated in culture supernatants. The number of DCreg generated from cryopreserved monocytes of healthy donors was not significantly different from freshly isolated monocytes. DCreg generated from cryopreserved monocytes had similar levels of co-stimulatory molecule expression, inhibitory molecule expression, and cytokine production as freshly isolated monocytes. Young and older healthy donor monocytes generated similar numbers of DCreg with similar cytokine production and phenotype. Although monocytes from older HSCT patients produced significantly fewer DCreg, DCreg from young and older HSCT patients have a comparable phenotype and cytokine production. Monocytes from young and older myelodysplastic syndrome (MDS) patients generated reduced numbers of DCreg compared to non-MDS monocytes. Results suggest cryopreservation of monocytes from many HSCT patients allows for cost effective generation of DCreg for the prevention and treatment of GVHD on an as needed basis. Although generation of DCreg from MDS patients require further assessment, these data support the possibility of in vitro generated DCreg as a therapy to reduce GVHD-associated morbidity and morbidity in young and older HSCT recipients.