Umbilical cord blood transplantation using nonmyeloablative conditioning is currently considered by many as a valid potential alternative for any patient who requires an unrelated donor allograft and who is without a suitably matched and readily available volunteer. Dimethyl sulfoxide (DMSO) has been used for years as a cryoprotectant agent; it acts by penetrating the cell and binding water molecules and it has been described as harmless for the individual who receives it in limited amounts. In this paper, we describe 3 cases of DMSO-induced toxicities and briefly review the most common adverse reactions of the DMSO when used as a cryopreservation agent for the long-term storage of cord blood cells. Two of the 3 cases had a dismal prognosis. A brief review of the literature is presented.

The flow-cytometric DNA content in the plasma cells of patients with multiple myeloma has been studied as a prognostic factor and contrasting results have been found. In a group of 45 patients with myeloma from a single institution, the DNA content of the malignant plasma cells was studied by means of flow cytometry: no patients were found to have hypodiploid DNA content, 14 patients had hyperdiploid DNA, and 31 patients were found to have diploid DNA. The overall survival of patients with hyperdiploid DNA was better than that of patients with diploid DNA: 93% at 85 months and 79% at 89 months, respectively; in both groups, the median overall survival has not been reached. No correlation was found between the DNA content and the International Staging System and the discriminatory effect of the DNA content was apparent only in the patients who were not autografted. It is concluded that the flow-cytometric DNA content of the plasma cells of patients with multiple myeloma may be a prognostic factor independent of others already identified and that myeloma patients with hyperdiploid DNA content in the plasma cells may have a better prognosis than those with a normal DNA content.

The low engraftment rate should be improved by selecting better cord blood units; additional studies are needed to define if non-myeloablative conditioning is preferable over conventional conditioning.

In a single institution, in a group of 28 myeloma patients deemed eligible for autologous transplant, stem cell mobilization was attempted using filgrastim: 26 individuals were given 31 autografts employing 1–4 (median three) apheresis sessions, to obtain a target stem cell dose of 1 x 106 CD34 +ve viable cells / Kg of the recipient. The median number of grafted CD34 cells was 7.56 x 106 / Kg of the recipient; the range being 0.92 to 14.8. By defining as poor mobilizers individuals in which a cell collection of < 1 x 106 CD34 viable cells / Kg was obtained, a subset of eight poor mobilizers was identified; in two patients the autograft was aborted because of an extremely poor CD34 +ve cell yield (< 0.2 x 106 CD34 +ve viable cells / Kg of the recipient) after four apheresis sessions. The long-term overall survival of the patients grafted with > 1 x 106 CD34 +ve viable cells / Kg was better (80% at 80 months) than those grafted with < 1 x 106 CD34 +ve viable cells / Kg (67% at 76 months). Methods to improve stem cell mobilization are needed and may result in obtaining better results when autografting multiple myeloma patients.

4237 High-dose chemotherapy rescued by autologous peripheral blood stem cell transplantation is considered standard of care for patients with multiple myeloma. Hematopoietic stem cell mobilization is accomplished by administration of hematopoietic growth factors combined or not with myelosuppressive chemotherapy. In a single institution, in a group of twenty eight myeloma patients deemed eligible for autologous transplant, stem cell mobilization was attempted using only filgrastim: Twenty six individuals were given 31 autografts employing one to four (median three) apheresis sessions, to obtain a target stem cell dose of 1 × 106 CD34 viable cells / Kg of the recipient. The median number of grafted cells was 7.56 × 106 CD34 viable cells / Kg of the recipient; the range being 0.92 to 14.8. By defining as poor mobilizers individuals in which a cell collection of less than 1 × 106 CD34 viable cells / Kg was obtained, a subset of eight poor mobilizers was identified; in two patients the autograft was aborted because of an extremely poor CD34 cell yield (less than 0.2 × 106 CD34 viable cells / Kg of the recipient) after four apheresis sessions. The long-term overall survival of the patients grafted with more than 1 × 106 CD34 viable cells / Kg was better (80% at 80 months) than those grafted with less than 1 × 106 CD34 viable cells / Kg (67% at 76 months). Methods to improve stem cell mobilization are needed and may result in obtaining better results when autografting multiple myeloma patients. Disclosures: No relevant conflicts of interest to declare.