Objective. To find evidence for the presence of endothelial precursor cells, which can induce new vessel formation, in the synovial tissue of patients with rheumatoid arthritis (RA) and osteoarthritis (OA).Methods. Precursor cells in the synovial tissue of 18 RA patients and 15 OA patients were identified by immunohistochemistry, morphometric analysis, and confocal laser scanning microscopy using the following phenotype markers: CD31, CD34, STRO-1, CD133, vascular endothelial growth factor receptor 2 (VEGFR-2), and CXCR4. The presence of CD31, CD34, CD133, VEGFR-2, and CXCR4 messenger RNA in the synovial tissue was determined by reverse transcriptasepolymerase chain reaction, and the message for CXCR4 was quantified by an RNase protection assay.Results. A population of cells that expressed CD34 on their surface but lacked the endothelial cell marker CD31 was found in the synovial tissue of RA and OA patients. CD34؉,CD31؊ cells were detected in close proximity to STRO-1؉ and CD133؉ cells, forming cell clusters in the sublining area of the synovial membrane. Within these cell clusters, CD34؉,CD31؊ precursor cells were located on the inside surrounded by STRO-1؉ cells and with CD133؉ cells on the outside. CD34؉ precursor cells in the cell layer expressed high levels of the chemokine receptor CXCR4, while VEGFR-2 was expressed on CD34؉ and CD133؉ cells, and ␣-smooth muscle actin was expressed on STRO-1؉ cells.Conclusion. The presence of endothelial precursor cells in the synovial tissue of RA and OA patients provides evidence for vasculogenesis induced by precursor cells that arise in situ or from circulating progenitors.

Mobilized allogeneic PBPC are increasingly used instead of BM for allogeneic stem cell grafting. Although the short-term safety profile of recombinant human (rh)G-CSF seems acceptable, only minimal data on long-term safety are available. We therefore reviewed data on 171 sibling donors (M/F: 98/73) with respect to side effects of rhG-CSF and PBPC collection and impact on quality of life (QoL) and health status. In a cross-sectional study, we investigated the actual QoL and health status of the donors as well as the need for medical treatment since PBPC donation by a questionnaire that was sent to 151 donors. Ninety-five (64%) of the addressed donors responded to the questionnaire, but only 69 (46%) of them reported on their actual health status and QoL, which was good to very good in the majority of them. Two donors developed malignancies in the post-donation course. In general, PBPC collection after rhG-CSF mobilization was well tolerated by the responding donors. Although the reported events in medical history after PBPC donation do not seem to be associated with rhG-CSF administration or the collection procedure, a lifelong follow-up of donors should be obligatory.

We assessed the chimerism of CD34+ bone marrow cells before donor leukocyte infusion (DLI) on nine occasions in seven patients with leukemic relapse after allogeneic marrow transplantation. The patients suffered from acute lymphoblastic leukemia (n = 1), acute myeloid leukemia (n = 3), and chronic myeloid leukemia (CML; n = 3). Two patients received a second DLI because of disease progression after the first one. The origin of the CD34+ cells was determined by analyzing variable number of tandem repeats with polymerase chain reaction and, in sex-mismatched cases, by fluorescence in situ hybridization. Before DLI CD34+ cells were exclusively of donor origin in four patients. In another patient 41% of CD34+ cells were derived from the donor. No aplasia occurred in these patients after DLI, whereas in the two patients with exclusively recipient hematopoiesis severe aplasia lasting for 5 and 13 weeks necessitated hematopoietic stem cell support. One patient who had only 5% CD34+ donor cells before DLI recovered without stem cell support after 10 days. Two patients in relapse of CML showed a high percentage of BCR-ABL− CD34+ cells of recipient origin before DLI. These BCR-ABL− cells of recipient type did not prevent severe aplasia which indicates that the assessment of BCR-ABL+ hematopoiesis alone is insufficient for predicting aplasia. Our data indicate that in case of sufficient donor hematopoiesis before DLI no persistent aplasia will occur. Thus, evaluation of donor hematopoiesis allows prediction of aplasia after DLI and makes early therapeutic interventions possible.