Electrophysiological and arrhythmogenic effects of intramyocardial bone marrow cell injection in patients with chronic ischemic heart disease

BACKGROUND: Bone marrow cell injection has been introduced to treat patients with ischemic heart disease. However, focal application of bone marrow cells may generate an arrhythmogenic substrate. OBJECTIVES: To assess the electrophysiological and arrhythmogenic effects of intramyocardial bone marrow cell injection in patients with chronic myocardial ischemia. METHODS: Bone marrow was aspirated in 20 patients (65+/-11 years, 19 male) with drug-refractory angina and myocardial ischemia. Electroanatomical mapping (NOGA, Biosense-Webster, Waterloo, Belgium) was performed during mononuclear cell isolation. Areas for cell injection were selected based on the localization of ischemia on SPECT. These areas were mapped in detail to evaluate local bipolar electrogram duration, amplitude and fragmentation. Mononuclear cells were injected in the ischemic area with the NOGA system. SPECT and electroanatomical mapping were repeated at 3 months. Holter monitoring was repeated at 3 and 6 months. RESULTS: SPECT revealed a decrease in the number of segments with ischemia (3.5+/-2.5 vs. 1.1+/-1.0 at 3 months; P<0.01) and an increased left ventricular ejection fraction (44+/-13% vs. 49+/-17% at 3 months; P=0.02). The number of ventricular premature beats remained unchanged (10+/-24x10(2)/24h vs. 8+/-23x10(2)/24h at 3 months (P=NS) and 12+/-30x10(2)/24h at 6 months (P=NS)). At 3 months follow-up, bone marrow cell injection did not prolong electrogram duration (15.9+/-4.6 ms vs. 15.6+/-4.0 ms; P=NS), decrease electrogram amplitude (3.8+/-1.5 mV vs. 3.8+/-1.5 mV; P=NS), or increase fragmentation (2.0+/-0.5 vs. 1.9+/-0.4; P=NS). CONCLUSION: Intramyocardial bone marrow cell injection does not increase the incidence of ventricular arrhythmias and does not alter the electrophysiological properties of the injected myocardium.     

Clonal involvement of granulocytes and monocytes, but not of T and B lymphocytes and natural killer cells in patients with myelodysplasia: analysis by X-linked restriction fragment length polymorphisms and polymerase chain reaction of the phosphoglycerate kinase gene.

To determine the clonal nature of hematopoiesis and to assess lineage involvement in patients with myelodysplastic syndromes (MDS), we used restriction fragment length polymorphisms of the X-linked genes phosphoglycerate kinase (PGK1) and hypoxanthine phosphoribosyltransferase (HPRT) and the X-linked probe M27 beta. Eleven female MDS patients heterozygous for at least one of these probes were studied: 3 with refractory anemia (RA), 2 with RA with ringed sideroblasts (RARS), 2 with chronic myelomonocytic leukemia (CMML), and 4 with RA with excess of blasts in transformation (RAEB-t). All exhibited clonal hematopoiesis as determined by Southern analysis of DNA prepared from peripheral blood (PB) and/or bone marrow (BM) cells. In three of the six patients heterozygous for the PGK1 gene, purified cell suspensions of polymorphonuclear cells (PMN), monocytes, lymphocytes, and/or T cells prepared from PB were tested. In addition, five of these patients were analyzed by a polymerase chain reaction (PCR)-based procedure as described recently. This method was slightly adapted to facilitate the analysis of cell lysates of fluorescence-activated cell sorted (FACS) monocytes, T and B lymphocytes, and natural killer (NK) cells. The outcome of Southern and PCR analysis was concordant, showing that PMN and monocytes were clonally derived, whereas circulating T and B lymphocytes and NK cells exhibited random X-chromosome inactivation compatible with a polyclonal pattern. To address the question of whether T cells are derived from unaffected progenitor cells or that their origin had antedated the onset of MDS, naive and memory T cells were analyzed separately. Both subsets showed a polyclonal pattern. However, in one patient analysis of constitutive DNA suggested a skewed methylation, and the presence of clonal lymphocytes against a background of polyclonal lymphoid cells cannot be ruled out in this patient. PCR analysis of PB and BM cells showed a nonrandom, unilateral pattern of X-inactivation, compatible with a mixture of clonally (myeloid) and polyclonally (lymphoid) derived cells. In conclusion, in some patients, MDS represents a disorder with clonal hematopoiesis restricted to cells of myeloid origin, whereas a random X-inactivation pattern is found in lymphoid cells.     

The stem cell mobilizing capacity of patients with acute myeloid leukemia in complete remission correlates with relapse risk: results of the EORTC-GIMEMA AML-10 trial.

Variable numbers of CD34+ cells can be harvested from the blood of AML patients in CR after G-CSF supported mobilization following consolidation chemotherapy. We hypothesized that a decreased ability to mobilize stem cells reflects a chemotherapy-induced reduction in the number of normal and leukemic stem cells. We therefore analyzed whether the mobilizing capacity of these patients was of prognostic significance. 342 AML-patients in first CR received daily G-CSF from day 20 of the consolidation course and underwent 1-6 aphereses to obtain a minimum dose of 2 x 10(6) CD34+ cells/kg. Afterwards they were randomized for autologous bone marrow (BM) or blood SCT. As a surrogate marker for the mobilizing capacity, the highest yield of CD34+ cells of a single apheresis was adopted. Patients could be categorized into four groups: no harvest (n = 76), low yield (<1 x 10(6) CD34+/kg; n = 50), intermediate yield (1-6.9 x 10(6) CD34+ cells/kg; n = 128) and high yield (> or = 7 x 10(6) CD34+ cells/kg; n = 88). The median follow-up was 3.4 years; 163 relapses and 16 deaths in CR were reported. Autologous blood or BM SCT was performed in 36%, 64%, 81% and 88%, respectively, of the patients assigned to the no harvest, low, intermediate and high CD34+ yield group. The 3-year disease-free survival rate was 46.7%, 65.0%, 50.4% and 26.9% (P = 0.0002) and the relapse incidence was 47.5%, 30.1%, 43.1% and 71.9% (P < 0.0001). Multivariate Cox's proportional hazards model showed that the CD34+ yield was the most important independent prognostic variable (P = 0.005) after cytogenetics. Patients with the highest mobilizing capacity have a poor prognosis due to an increased relapse incidence.     

Effect of mast cell growth factor (c-kit ligand) on clonogenic leukemic precursor cells.

Mast cell growth factor (MGF), the ligand for the c-kit receptor, has been shown to be a hematopoietic growth factor that preferentially stimulates the proliferation of immature hematopoietic progenitor cells (HPC). We studied the effect of MGF on the in vitro growth of clonogenic leukemic precursor cells in the presence or absence of interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), and/or erythropoietin (EPO). Leukemic blood and bone marrow cells from patients with various types of acute myeloid leukemia (AML), chronic myeloid leukemia (CML) in chronic phase, as well as bone marrow samples from patients with myelodysplastic syndromes (MDS) were studied. MGF as a single factor did not induce significant colony formation by clonogenic leukemic precursor cells. In the presence of IL-3 and/or GM-CSF, MGF weakly stimulated the colony formation by clonogenic precursor cells from patients with AML. In contrast, in the presence of IL-3 and/or GM-CSF, MGF strongly induced both size and number of leukemic colonies from patients with CML in chronic phase. Furthermore, in the presence of EPO, MGF strongly stimulated erythroid colony formation by CML precursor cells. Cytogenetic analysis of the colonies showed that all metaphases after 1 week of culture were derived from the leukemic clone. In patients with MDS, MGF strongly stimulated myeloid colony formation in the presence of IL-3 and/or GM-CSF (up to fourfold), and erythroid colony formation in the presence of EPO (up to eightfold). Not only the number, but also the size of the colonies increased. In the presence of MGF, the percentage of normal metaphases increased in three patients tested after 1 week of culture compared with the initial suspension, suggesting that the normal HPC were preferentially stimulated compared with the preleukemic precursor cells. In the absence of exogenous EPO and in the presence of 10% human AB serum, MGF in the presence of IL-3 and/or GM-CSF induced erythroid colony formation from normal bone marrow and patients with MDS or CML, illustrating that MGF greatly diminished the EPO requirement for erythroid differentiation. These results indicate that MGF may be a candidate as a hematopoietic growth factor to stimulate normal hematopoiesis in patients with acute myeloid leukemia, or with myelodysplastic syndromes.     

Bone marrow transplantation or chemotherapy as post-remission treatment of adult acute myelogenous leukemia

Summary We compared three consolidation regimens in patients with acute myelogenous leukemia in first remission. Thirty-four patients received only intensive consolidation chemotherapy (SIC); 28 patients were scheduled to undergo an autologous bone marrow transplant (auto-BMT) and 44 patients an allogeneic BMT (allo-BMT). Twenty-seven of them were referred in first remission for allo-BMT. Nineteen patients achieved a complete remission after salvage treatment. All other patients obtained a remission after one or two courses of a standard combination of cytosine arabinoside and daunorubicin. Except for the patients who were referred in remission, all patients received intermediate dose cytosine arabinoside and amsacrine as a first consolidation treatment. The median ages of the three groups were 48 (SIC), 39 (auto-BMT) and 33 years (allo-BMT). Two patients relapsed before auto-BMT and 1 before allo-BMT. The median interval from the date of complete remission to the auto- or allo-BMT was 3 months. In total, 80% of the patients of the SIC group relapsed, compared to 50% of the patients belonging to the auto-BMT group and 35% of the 44 patients who were scheduled to receive an allo-BMT. The overall median disease-free survival was 14 months, 30% of the patients being alive and disease-free at 3 years. The disease-free survival rate at three years was 25% for the SIC group, 30% for the allo-BMT group and 40% for the ABMT group (P=0.45). Our study shows no benefit for bone marrow transplantation over intensive consolidation treatment. However, large randomized trials are required to define the real value of these treatment modalities.     

Human adult bone marrow mesenchymal stem cells repair experimental conduction block in rat cardiomyocyte cultures.

OBJECTIVES: We evaluated whether human adult bone marrow-derived mesenchymal stem cells (hMSCs) could repair an experimentally induced conduction block in cardiomyocyte cultures. BACKGROUND: Autologous stem cell therapy is a novel treatment option for patients with heart disease. However, detailed electrophysiological characterization of hMSCs is still lacking. METHODS: Neonatal rat cardiomyocytes were seeded on multi-electrode arrays. After 48 h, abrasion of a 200- to 450-microm-wide channel caused conduction block. Next, we applied adult hMSCs (hMSC group, n = 8), human skeletal myoblasts (myoblast group, n = 7), rat cardiac fibroblasts (fibroblast group, n = 7), or no cells (control group, n = 7) in a channel-crossing pattern. Cross-channel electrical conduction was analyzed after 24 and 48 h. Intracellular action potentials of hMSCs and cardiomyocytes were recorded. Immunostaining for connexins and intercellular dye transfer (calcein) assessed the presence of functional gap junctions. RESULTS: After creation of conduction block, two asynchronously beating fields of cardiomyocytes were present. Application of hMSCs restored synchronization between the two fields in five of eight cultures after 24 h. Conduction velocity across hMSCs (0.9 +/- 0.4 cm/s) was approximately 11-fold slower than across cardiomyocytes (10.4 +/- 5.8 cm/s). No resynchronization occurred in the myoblast, fibroblast, or control group. Intracellular action potential recordings indicated that conduction across the channel presumably occurred by electrotonic impulse propagation. Connexin-43 was present along regions of hMSC-to-cardiomyocyte contact, but not along regions of cardiomyocyte-to-myoblast or cardiomyocyte-to-fibroblast contact. Calcein transfer from cardiomyocytes to hMSCs was observed within 24 h after co-culture initiation. CONCLUSIONS: Human mesenchymal stem cells are able to repair conduction block in cardiomyocyte cultures, probably through connexin-mediated coupling.     

CD52 antibodies for prevention of graft-versus-host disease and graft rejection following transplantation of allogeneic peripheral blood stem cells

Graft-versus-host disease (GVHD) is a major cause of mortality and morbidity after allogeneic bone marrow transplantation, but can be avoided by removing T lymphocytes from the donor bone marrow. However, T cell depletion increases the risk of graft rejection. In this study, two strategies are used to overcome rejection: (1) use of high doses of stem cells obtained from peripheral blood (PBSC), (2) admixture with a CD52 monoclonal antibody in order to deplete both donor and residual recipient lymphocytes. Two antibodies are compared: CAMPATH-1G (rat IgG2b) and its humanized equivalent CAMPATH-1H (human IgG1). A total of 187 consecutive patients at six centers received PBSC transplants from HLA-matched siblings between 1997 and 1999. A wide spectrum of diseases, both malignant and non-malignant, was included. The recovery of CD34+ cells after antibody treatment was close to 100%. The risk of acute GVHD (grade 2 to 4) was 11% in the CAMPATH-1G group and 4% in the CAMPATH-1H group (P = NS). The risk of chronic GVHD (any grade) was 11% in the CAMPATH-1G group and 24% in the CAMPATH-1H group (P = 0.03) but the risk of extensive chronic GVHD was only 2%. The overall risk of graft failure/rejection was 2%, not significantly different between the two antibodies. Antibody treatment was equally effective at concentrations between 10 microg/ml and 120 microg/ml and it made no significant difference to the outcome whether the patients received post-transplant immunosuppression or not (87% did not). Transplant-related mortality in this heterogenous group of patients (including high-risk and advanced disease) was 22% at 12 months. It is proposed that treatment of peripheral blood stem cells with CAMPATH-1H is a simple and effective method for depleting T cells which may be applicable to both autologous and allogeneic transplants from related or unrelated donors. Special advantages of this approach are the simultaneous depletion of donor B cells (which reduces the risk of EBV-associated lymphoproliferative disease) and the concomitant infusion of CAMPATH-1H to deplete residual recipient T cells and thus prevent graft rejection.     

Rituximab improves the treatment results of DHAP-VIM-DHAP and ASCT in relapsed/progressive aggressive CD20+ NHL: a prospective randomized HOVON trial

We evaluated the role of rituximab during remission induction chemotherapy in relapsed aggressive CD20+ non-Hodgkin lymphoma. Of 239 patients, 225 were evaluable for analysis. Randomized to DHAP (cisplatin-cytarabine-dexamethasone)-VIM (etoposide-ifosfamide-methotrexate)-DHAP (cisplatin-cytarabine-dexamethasone) chemotherapy with rituximab (R; R-DHAP arm) were 119 patients (113 evaluable) and to chemotherapy without rituximab (DHAP arm) 120 patients (112 evaluable). Patients in complete remission (CR) and partial remission (PR) after 2 chemotherapy courses were eligible for autologous stem-cell transplantation. After the second chemotherapy cycle, 75% of the patients in the R-DHAP arm had responsive disease (CR or PR) versus 54% in the DHAP arm (P=.01). With a median follow-up of 24 months, there was a significant difference in failure-free survival (FFS24; 50% vs 24% vs, P<.001), and progression free survival (PFS24; 52% vs 31% P<.002) in favor of the R-DHAP arm. Cox-regression analysis demonstrated a significant effect of rituximab treatment on FFS24 (HR 0.41, 95% confidence interval [CI] 0.29-0.57 versus 0.51, 95% CI 0.37-0.70) and overall-survival (OS24: HR 0.60 [0.41-0.89] vs 0.76 [0.52-1.10]) when adjusted for time since upfront treatment, age, World Health Organization performance status, and secondary age-adjusted international prognostic index. These results demonstrate improved FFS and PFS for relapsed aggressive B-cell NHL if rituximab is added to the re-induction chemotherapy regimen.     

Control of systemic B cell-mediated autoimmune disease by nonmyeloablative conditioning and major histocompatibility complex-mismatched allogeneic bone marrow transplantation

Systemic autoimmune disease (AID) can be controlled with conventional therapies in most patients. However, relapses are common, leading to progressive disability and premature death. Nonmyeloablative conditioning and allogeneic bone marrow transplantation (BMT) could be an effective treatment for severe AID, because of mild toxicity of the conditioning and the potential benefits of donor chimerism. We examined the effects of this treatment in experimental autoimmune arthritis. Our results demonstrate the induction of complete donor chimerism and significant suppression of disease activity. No clinical graft-versus-host disease (GVHD) was observed. The beneficial effects were most likely caused by the elimination of plasma cells producing pathogenic autoantibodies, because these antibodies disappeared rapidly after BMT. Although this type of treatment was effective in organ-specific T-cell-mediated AID, the present study provides convincing evidence that nonmyeloablative conditioning and allogeneic BMT can effectively treat severe B-cell-mediated AID with a systemic inflammatory component.     

Interleukin 1 and poly(rI).poly(rC) induce production of granulocyte CSF, macrophage CSF, and granulocyte-macrophage CSF by human endothelial cells

Electrophoretically pure human interleukin 1 (IL-1) beta was found to stimulate human endothelial cells in monolayer culture to elaborate colony-stimulating activity (CSA). Supernatant fluids from cultures stimulated with increasing concentrations of IL-1 were found to stimulate colony formation of myeloid (CFU-GM), erythroid (BFU-E), and multipotent (CFU-GEMM) progenitor cells in a dose-dependent fashion. The effect on mixed colony formation, however, was less than on CFU-GM and BFU-E growth. Similar to IL-1, the double-stranded RNA polyriboinosinic-polyribocytidilic acid (poly[rI].poly[rC]) also stimulated release of CSA by endothelial cells in a dose-dependent manner. The kinetics of IL-1-induced CSA release as opposed to poly(rI).poly(rC)-induced release were found to be different, in that poly(rI).poly(rC)-induced CSA production occurred more slowly. An anti-IL-1 beta antiserum was able to completely neutralize the IL-1-induced CSA release, but had no effect on poly(rI).poly(rC)-dependent CSA production, indicating that the latter effect was mediated by other mechanisms than intermediate production of IL-1 beta. Using specific immunologic assays, IL-1- as well as poly(rI).poly(rC)-inducible production of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF, and macrophage CSF was found. The release of CSF from endothelial cells in response to IL-1 may be a mechanism for stimulating production of neutrophils and mononuclear phagocytes, and for attracting and activating these cells at sites of inflammation.