Browsing by Subject "Mixed chimerism"

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    Dualism of mixed chimerism between hematopoiesis and stroma in chronic idiopathic myelofibrosis after allogeneic stem cell transplantation
    (Murcia : F. Hernández, 2007) Thiele, J.; Varus, E.; Siebolts, U.; Kvasnicka, H.M.; Wickenhauser, C.; Metz, K.A.; Beelen, D.W.; Ditschkowski, M.; Zander, A.; Kröger, N.
    Scant knowledge exists concerning lineagerestricted mixed chimerism (mCh) after allogeneic peripheral blood stem cell transplantation (PSCT) in patients with chronic idiopathic myelofibrosis (CIMF). Following a sex-mismatched PSCT, a combined immunopheno- and genotyping by fluorescence in-situ hybridization (FISH) was performed on sequential bone marrow (BM) biopsies at standardized intervals. Results were compared with PCR analysis of corresponding peripheral blood samples in five patients. According to FISH, pretransplant specimens revealed a gender congruence of more than 99%, while in the first three months the total BM exhibited a persistent fraction of host cells (30% to 40%) with a tendency to decline after about one year. It is noteworthy that the majority of endothelial cells maintained a recipient origin, whereas CD34+ progenitors and especially CD61+ megakaryocytes exhibited only very few host-derived cells. In keeping with the prevalence of donor cells in the hematopoietic compartment, PCR analysis of peripheral blood cells displayed a non-significant degree of mCh. In conclusion, according to FISH and PCR analysis, successful PSCT in CIMF results in an almost complete chimeric (donor-derived) state of the hematopoietic cell population. The non-transplantable stromal compartment includes the vascular endothelium with a predominance of recipient cells. The minimal mCh of this population implies probably a donor-derived origin (endothelial progenitor cells).
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    Dynamics of lineage-restricted mixed chimerism following sex-mismatched allogeneic bone marrow transplantation
    (Murcia : F. Hernández, 2003) Thiele, J.; Wickenhauser, C.; Kvasnicka, H.M.; Varus, E.; Beelen, D.W.; Schaefer, U.W.
    Scant knowledge is available about the dynamics of lineage-specific mixed chimerism (Ch) following bone marrow transplantation (BMT). This review is focused on findings derived from bone marrow (BM) biopsies in patients with chronic myeloid leukemia (CML) including a sex-mismatched host/donor constellation. Appropriate techniques involved immunophenotyping by monoclonal antibodies to identify the various cell lineages, dual color fluorescence in situ hybridization (FISH) with x- and y-chromosomespecific DNA-probes and a proper detection system for a simultaneous labeling of the bcr/abl locus. A significant degree of Ch with more than 20% host CD34+ progenitors was found in the early and late (up to 200 days after BMT) posttransplant period. However, only 10% of these cells harbored the bcr/abl translocation gene. This result fits well with corresponding molecularbiological findings of so-called minimal residual disease. Conversion of Ch evolved during leukemic relapse with 90% host progenitors of which 50% revealed the bcr/abl locus. A Ch of nucleated erythroid percursors (5%) and CD68+ macrophages (8%) was expressed to a significantly lower degree. The slightly increased frequency found in CD61+ megakaryocytes (16%) was probably due to the polyploid state of these cells. Similar to the CD34+ progenitor cells abrupt changes from donor to host type was associated with an insidious transformation into recurrent leukemia. The CD34+ endothelial cells showed a minor degree of Ch, because donor-derived elements ranged from 18% to 25%. Leukemic relapse was characterized by an almost complete conversion of the endothelial cells to a host type. These findings point towards a CD34+ progenitor cell origin of the (leukemic) endothelial cell layer and suggests that their dysfunction may contribute to an expansion of the neoplastic clone.