No abstract

This study was designed to establish a direct homing assay using purified lineage-negative Sca-1-positive (Lin(-) Sca(+)) murine bone marrow cells and to evaluate the effects of cytokines on homing. C57BL/6 Lin(-) Sca(+) marrow stem cells were labeled with 5-(and 6)-carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) and then injected by tail vein into untreated C57BL/6 mice. Marrow was harvested at various times after cell infusion and analyzed on a high-speed MoFlo cell sorter for fluorescent positive events, using a large event analysis, with at least 16 million total events analyzed. We have shown that homing of Lin(-) Sca(+) cells plateaus by 1 h, and at 3 h post-infusion is linear between 50,000 and 1,000,000 infused cells. This forms a base for a homing assay in which 250,000 CFDA-SE labeled Lin(-) Sca(+) marrow cells are infused and then recovered from marrow 3 h later, followed by a large-event fluorescence-activated cell sorting (FACS) analysis. We found that 7.45-9.32% of infused cells homed and that homing of stem cells cultured for 48 h in interleukin-3 (IL-3), IL-6, IL-11, and steel factor cultured cells was defective when compared to noncultured cells. Exposure of marrow stem cells to IL-3, IL-6, IL-11, and steel factor induces a stem cell homing defect, which probably underlies the engraftment defect previously characterized under these conditions.

Allogeneic stem cell transplantation is curative for certain cancers, but the high doses of chemotherapy/radiotherapy lead to toxicity. Here, we treat patients with refractory cancer with 100 cGy total body irradiation (TBI) followed by infusion of nonmobilized pheresed allogeneic peripheral blood cells. Twenty-five patients, with a median age of 47 years, with refractory cancers were enrolled. Eighteen patients received sibling and 7 received unrelated cord blood cells. Donor chimerism was assessed at weeks 1, 2, 3, 4, and 8 after transplantation. Seven patients with solid tumors received a sibling transplant and 6 received a cord blood transplant; none achieved donor chimerism, but 1 treated at the higher dose level of 1 ؋ 10 8 CD3 ؉ cells/kg had a transient nodal response. Twelve patients with hematologic malignancies were treated; 1 received a cord blood transplant and 11 received sibling donor cells. Nine of these 11 patients achieved donor chimerism, ranging from 5% to 100%. Four patients had sustained complete remission of their cancers, including one patient with transient 5% donor chimerism. The development of chimerism correlated with hematologic malignancy (P < .001), total previous myelotoxic chemotherapy (P < .001), T-cell dose (P ‫؍‬ .03), and graft-versus-host disease (P ‫؍‬ .01). Tumor response correlated with donor chimerism (P ‫؍‬ .01). Engraftment was achieved in patients with hematologic malignancies who had been heavily pretreated, suggesting the degree of immunosuppression may be a determinant of engraftment. Low-dose TBI and allogeneic lymphocyte infusion may induce remission in patients with refractory hematologic malignancy. (Blood. 2002; 100:442-450)