Endothelial cells in the bone marrow of patients with multiple myeloma.

Endothelial cells (EC) were extracted through a lectin-based method from bone marrow of 57 patients with active multiple myeloma (MM) and compared with their healthy quiescent counterpart, human umbilical vein EC (HUVEC). MMECs exhibit specific antigens that indicate ongoing angiogenesis and embryo vasculogenesis; solid intercellular connections, hence stability of MM neovessels; and frequent interactions with plasma cells, hence tumor dissemination. They show heterogeneous antigen expression, hence existence of subsets. Their main genetic markers are indicative of a vascular phase. They show intrinsic angiogenic ability, because they rapidly form a capillary network in vitro, and extrinsic ability, because they generate numerous new vessels in vivo. They vividly secrete growth and invasive factors for plasma cells. They signal through kinases mandatory for development of neovascularization. Ultrastructurally, they are abnormal and show metabolic activation, like tumor ECs. Thalidomide heavily interferes with their functions. Vasculogenesis and angiogenesis might contribute to the MM vascular tree and progression, in the form of growth, invasion, and dissemination. In view of the heterogeneity of the antigenic phenotype of MMECs, a mixture (or a sequence) of antiangiogenic agents coupled with thalidomide would seem plausible for the biologic management of MM.

Graft engineering for allogeneic haploidentical stem cell transplantation.

Haploidentical stem cell transplantation has became a clinical reality in the last 10 years as it provides the chance of transplant for about 50% of patients with hematological malignancies who do not have a matched related or unrelated donor. Proper graft preparation for this type of transplant is crucial and this paper analyses our work over the past decade in the search for the optimal graft processing procedure moving from E-rosetting and soybean agglutination, through a combination of negative or positive selection of hematopoietic stem cells to the current method of one-step positive selection. In preparing a graft for haploidentical transplant, three essential requisites must be met. It must contain (1) a megadose (>10 x 10(6) x kg recipient b.w.) of hematopoietic stem cells to overcome the HLA histocompatibility barrier; (2) very few T-lymphocytes (CD3+ cells < 3 x 10(4)/kg recipient b.w.) to prevent severe acute and chronic graft-versus-host disease (GvHD); (3) very few B-lymphocytes to prevent Epstein-Barr virus-related lymphoproliferative disorders. With current graft processing technologies based on positive selection of hematopoietic stem cells, these requirements can be met. A 70-80% hematopoietic stem cell recovery ensures the target megadose is achieved in over 70% of cases with a T-cell depletion of more than 4 logs and a B-cell depletion of over 3 logs. Progress in graft processing has ensured primary, sustained engraftment rates of over 90% and has significantly reduced the incidence of severe acute GvHD and EBV-related lymphoproliferative disorders. Modern time-saving automated graft processing devices ensure reproducibility, reliability, and biological safety, which make widespread application of the haploidentical transplant currently feasible.