Keisuke Nishioka

Hybrid Cell–Gene Therapy for Pulmonary Hypertension Based on Phagocytosing Action of Endothelial Progenitor Cells

Background—Circulating endothelial progenitor cells (EPCs) migrate to injured vascular endothelium and differentiate into mature endothelial cells. We investigated whether transplantation of vasodilator gene-transduced EPCs ameliorates monocrotaline (MCT)-induced pulmonary hypertension in rats. Methods and Results—We obtained EPCs from cultured human umbilical cord blood mononuclear cells and constructed plasmid DNA of adrenomedullin (AM), a potent vasodilator peptide. We used cationic gelatin to produce ionically linked DNA-gelatin complexes. Interestingly, EPCs phagocytosed plasmid DNA-gelatin complexes, which allowed nonviral, highly efficient gene transfer into EPCs. Intravenously administered EPCs were incorporated into the pulmonary vasculature of immunodeficient nude rats given MCT. Transplantation of EPCs alone modestly attenuated MCT-induced pulmonary hypertension (16% decrease in pulmonary vascular resistance). Furthermore, transplantation of AM DNA-transduced EPCs markedly ameliorated pulmonary hypertension in MCT rats (39% decrease in pulmonary vascular resistance). MCT rats transplanted with AM-expressing EPCs had a significantly higher survival rate than those given culture medium or EPCs alone. Conclusions—Umbilical cord blood–derived EPCs had a phagocytosing action that allowed nonviral, highly efficient gene transfer into EPCs. Transplantation of AM gene-transduced EPCs caused significantly greater improvement in pulmonary hypertension in MCT rats than transplantation of EPCs alone. Thus, a novel hybrid cell–gene therapy based on the phagocytosing action of EPCs may be a new therapeutic strategy for the treatment of pulmonary hypertension.

Reduced-Intensity Conditioning Followed by Unrelated Umbilical Cord Blood Transplantation for Advanced Hematologic Malignancies: Rapid Engraftment in Bone Marrow

Reduced-intensity (RI) conditioning followed by cord blood transplantation (CBT) is a new treatment modality, but failure to engraft is a major concern. We describe 12 patients with advanced hematologic malignancies who underwent RI conditioning and CBT with a conditioning regimen consisting of 200 mg/m2 fludarabine (Flu), 50 mg/kg cyclophosphamide (CY), and 3 Gy total body irradiation (TBI). Cyclosporin A and/or methotrexate were used for graft-versus-host disease prophylaxis. Cord blood grafts were not mismatched for more than 2 serologically defined HLA alleles but were later found by high-resolution DNA typing to be mismatched for 2 to 4 alleles in most cases. Short tandem repeat analysis of bone marrow cells at day 14 showed complete donor chimerism in 6 of the patients and mixed chimerism in 5, indicating rapid engraftment in the bone marrow, whereas the remaining patient experienced graft rejection. Neutrophil recovery was achieved at a median of day 17 (range, days 11-24) in 10 of the 11 patients with marrow chimerism at day 14. Of these 10 patients, however, transplantation-related mortality within 100 days occurred in 4 patients who showed failed platelet recovery and a lack of durable engraftment. Overall survival and disease-free survival rates were 41.7% and 33.3%, respectively.These results show that CB mismatched at 2 to 4 HLA alleles and transplanted with the Flu/CY/3 Gy TBI regimen is able to engraft in the bone marrow as early as day 14.

Unrelated umbilical cord blood transplantation using a TBI/FLAG conditioning regimen for adults with hematologic malignancies.

A combined chemotherapy regimen comprising fludarabine, cytosine arabinoside, and granulocyte colony-stimulating factor (FLAG) has been used in the treatment of relapsed or refractory leukemias. We here report 38 patients with hematologic malignancies who underwent single-unit cord blood transplantation (CBT) with a conditioning regimen comprising 12-Gy total-body irradiation (TBI) and FLAG therapy (TBI/FLAG). Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus or cyclosporin A and/or methotrexate. The median nucleated cell dose was 2.43 x 10(7)/kg (range: 1.96-3.55 x 10(7)/kg). Of 34 evaluable recipients, the cumulative incidence of donor engraftment was 97%. The median time to reach an absolute neutrophil count of 500/microL was 23 days (range: 18-35 days). The median time to an untransfused platelet count of 50,000/microL was 45.5 days (range: 28-208 days). Sixteen patients developed grades II-IV of acute GVHD. Fourteen patients were alive at a median follow-up of 46 months (range: 4-77 months). The estimated event-free survival at 3 years for all patients was 33.5%, with 72.7% in the standard-risk group (n = 11) and 17.7% in the high-risk group (n = 27) (P = .0075). These results showed that this novel regimen was well tolerated by patients and able to establish sustained donor cell engraftment, indicating the feasibility of TBI/FLAG as a conditioning regimen for CBT in adults with hematologic malignancies.

Establishment of Mouse Embryonic Fibroblast Cell Lines That Promote Ex Vivo Expansion of Human Cord Blood CD34+ Hematopoietic Progenitors

The development of culture systems that facilitate ex vivo maintenance and expansion of transplantable hematopoietic progenitor cells (HPC) is vital to stem cell transplantation. The use of a monolayer of stromal cells on which to grow HPC in direct contact allows high efficiency ex vivo expansion of HPC. Here, we report an establishment of three murine embryonic fibroblast stromal cell lines from adherent cells of day-12 mouse embryos. Among them, HYMEQ-5 was most efficient in supporting long-term maintenance of human umbilical cord blood (CB) CD34(+) cells. Human CB CD34(+) cells cultured on HYMEQ-5 in the presence of stem cell factor (SCF), thrombopoietin, and flk-ligand (FL) showed high expansion of CD34(+)CD38(-) cells and highly proliferative potential-colony forming cells (HPP-CFC). Direct cell-to-cell contact between CD34(+) cells and HYMEQ-5 was important for this expansion. RT-PCR analysis showed that HYMEQ-5 produced FL, SCF, interleukin-6, and macrophage colony-stimulating factor (M-CSF). Expanded CB CD34(+) cells efficiently reconstituted hematopoiesis in nonobese diabetic/severe combined immunodeficient disease (NOD/SCID) mice. These findings suggest that HYMEQ-5 provides a milieu that supports long-term human hematopoiesis as well as ex vivo expansion of human CB CD34(+) HPC. This cell line may facilitate elucidation of the mechanism of cellular interactions between HPC and stromal cells.