Mesenchymal stromal cell supported umbilical cord blood ex vivo expansion enhances regulatory T cells and reduces graft versus host disease.

Double cord blood transplantation (DCBT) may shorten neutrophil and platelet recovery times compared with standard umbilical cord blood transplantation. However, DCBT may be associated with a higher incidence of graft versus host disease (GVHD). In this study, we explored the effect of ex vivo expansion of a single cord blood unit (CBU) in a DCBT setting on GVHD and engraftment. Post-thaw cryopreserved CBUs from cord blood banks, hereinafter termed "banked" CBUs, were co-cultured with confluent bone marrow mesenchymal stromal cells (MSCs) supplemented with a cytokine cocktail comprising 100 ng/mL stem cell factor, 50 ng/mL flt3-ligand, 100 ng/mL thrombopoietin and 20 ng/mL insulin-like growth factor binding protein 2 for 12 days. When DCBT of one unexpanded and one expanded CBU was performed in non-obese diabetic/severe combined immunodeficient-IL2Rgamma(null) (NOD/SCID-IL2γ(-/-), NSG) mice, the expanded CBU significantly boosted in vivo hematopoiesis of the unexpanded CBU. The median survival of NSG mice was significantly improved from 63.4% (range, 60.0-66.7%) for mice receiving only unexpanded units to 86.5% (range, 80.0-92.9%) for mice receiving an expanded unit (P < 0.001). The difference in survival appeared to be due to a lower incidence of GVHD in the mice receiving expanded cells. This effect on GVHD was mediated by a significant increase in regulatory T cells seen in the presence of MSC co-culture. MSC-supported ex vivo expansion of "banked" CBU boosted unexpanded CBU hematopoiesis in vivo, increased regulatory T cell content and decreased the incidence of GVHD.

Fan X ，Gay FP ，Ong SY ，Ang JM ，Chu PP ，Bari S ，Lim TK ，Hwang WY ... -  《-》

Cotransplantation of ex vivo expanded and unexpanded cord blood units in immunodeficient mice using insulin growth factor binding protein-2-augmented mesenchymal cell cocultures.

Ex vivo expansion of cord blood (CB) hematopoietic stem cells and cotransplantation of 2 CB units (CBUs) could enhance the applicability of CB transplantation in adult patients. We report an immunodeficient mouse model for cotransplantation of ex vivo expanded and unexpanded human CB, showing enhanced CB engraftment and provide proof of concept for this transplantation strategy as a means of overcoming the limiting cell numbers in each CBU. CBUs were expanded in serum-free medium supplemented with stem cell factor, Flt-3 ligand, thrombopoietin, and insulin growth factor binding protein-2 together with mesenchymal stromal cell coculture. Unexpanded and expanded CB cells were cotransplanted by tail vein injection into 45 sublethally irradiated nonobese diabetic SCID-IL2γ(-/-) (NSG) mice. Submandibular bleeding was performed monthly, and mice were sacrificed 4 months after transplantation to analyze for human hematopoietic engraftment. Expansion of non-CD34(+) selected CB cells yielded 40-fold expansion of CD34(+) cells and 3.1-fold expansion of hematopoietic stem cells based on limiting dilution analysis of NSG engraftment. Mice receiving expanded grafts exhibited 4.30% human cell repopulation, compared with 0.92% in mice receiving only unexpanded grafts at equivalent starting cell doses, even though the unexpanded graft predominated in long-term hematopoiesis (P = .07). Ex vivo expanded grafts with lower initiating cell doses also showed equivalent engraftment to unexpanded grafts with higher cell dose (8.0% versus 7.9%; P = .93). In conclusion, ex vivo expansion resulted in enhanced CB engraftment despite eventual rejection by the unexpanded CBU.

Ong LM ，Fan X ，Chu PP ，Gay FP ，Bari S ，Ang JM ，Li Z ，Chen J ，Lim SK ，Bunte RM ，Hwang WY ... -  《-》

Effects of bone marrow mesenchymal stem cells on hematopoietic recovery and acute graft-versus-host disease in murine allogeneic umbilical cord blood transplantation model.

Li ZY ，Wang CQ ，Lu G ，Pan XY ，Xu KL ... -  《-》

Co-culture of cord blood CD34(+) cells with human BM mesenchymal stromal cells enhances short-term engraftment of cord blood cells in NOD/SCID mice.

Fei XM ，Wu YJ ，Chang Z ，Miao KR ，Tang YH ，Zhou XY ，Wang LX ，Pan QQ ，Wang CY ... -  《CYTOTHERAPY》

Optimization of the therapeutic efficacy of human umbilical cord blood-mesenchymal stromal cells in an NSG mouse xenograft model of graft-versus-host disease.

Although in vitro studies have demonstrated the immunosuppressive capacity of mesenchymal stromal cells (MSCs), most in vivo studies on graft-versus-host disease (GVHD) have focused on prevention, and the therapeutic effect of MSCs is controversial. Moreover, optimal time intervals for infusing MSCs have not been established. We attempted to evaluate whether human umbilical cord blood-MSCs (hUCB-MSCs) could either prevent or treat GVHD in an NSG mouse xenograft model by injection of MSCs before or after in vivo clearance. Mice were infused with either a single dose or multiple doses of 5 × 10(5) hUCB-MSCs (3- or 7-day intervals) before or after GVHD onset. Before onset, hUCB-MSCs significantly improved the survival rate only when repeatedly injected at 3-day intervals. In contrast, single or repeated injections after GVHD onset significantly increased the survival rate and effectively attenuated tissue damage and inflammation. Furthermore, the levels of prostaglandin E2 and transforming growth factor-β1 increased significantly, whereas the level of interferon-γ decreased significantly in all MSC treatment groups. These data establish the optimal time intervals for preventing GVHD and show that hUCB-MSCs effectively attenuated symptoms and improved survival rate when administered after the onset of GVDH.

Jang YK ，Kim M ，Lee YH ，Oh W ，Yang YS ，Choi SJ ... -  《-》