Visualization of immune response kinetics in full allogeneic chimeras.

Background: Donor Lymphocyte Infusion (DLI) is a well-recognized tool for augmentation of the anti-leukemia effect after mismatched bone marrow transplantation. Experimental results show, however, that DLI efficacy is strongly dependent on the number of donor hematopoietic cells persisting in recipient after transplantation. It is strong in mixed chimeras and relatively weak in full chimeras (FC) that replace host antigen-presenting cells by donor antigen-presenting cells.

Mesenchymal progenitor cells in red and yellow bone marrow.

Marrow cavities in all bones of newborn mammals contain haematopoietic tissue and stromal microenvironment that support haematopoiesis (haematopoietic microenvironment), known as red bone marrow (BM). From the early postnatal period onwards, the haematopoietic microenvironment, mainly in tubular bones of the extremities, is replaced by mesenchymal cells that accumulate lipid drops, known as yellow BM, whereas haematopoietic tissue gradually disappears. We analysed the ability of mesenchymal cell progenitors in red and yellow BM to produce bone and haematopoietic microenvironment in vivo after transplantation into normal or haematopoietically deficient (irradiated and old) recipients.

Prevention of acute graft-vs-host disease by a single low-dose cyclophosphamide injection following allogeneic bone marrow transplantation.

Objective: Previously, we documented that conditioning based on donor-specific cell transfusion (DST) and subsequent selective depletion of activated donor-reactive cells by cyclophosphamide (CY) facilitates alloengraftment in a murine transplantation model. Transplantation event represents a strong immunogenic stimulus for host-reactive donor T cells that induce graft-vs-host disease (GVHD). Therefore, in this study, we addressed the question of whether a single posttransplantation CY administration (CY2) can prevent acute GVHD-related mortality without compromising engraftment of allogeneic transplant.

Mesenchymal stromal cells lose their immunosuppressive potential after allotransplantation.

Objective: The stem cell fraction of mesenchymal stromal cells (MSCs) is capable of self-renewal and under inductive conditions differentiates into bone, cartilage, hematopoietic stroma, and other mesenchymal tissues. Therefore, MSCs represent a promising source for hard tissue repair therapies. MSCs are also immunosuppressive and prevent activation of allogeneic lymphocytes in vitro.

Osteoporosis of hematologic etiology.

Objective: Here we present evidence that overexertion of the hematopoietic system following chronic bleeding plays an important role in the etiology of osteoporosis.

Materials And Methods: C57BL/6 mice were exposed to chronic bloodletting (0.2 mL twice per month for 10 months), total body irradiation (900 cGy), or aging (20-30 months old).