Direct growth suppression of myeloid bone marrow progenitor cells but not cord blood progenitors by human cytomegalovirus in vitro

Recently, considerable interest has arisen as to use cord blood (CB) as a source of hematopoietic stem cells for allogenic transplantation when bone marrow (BM) from a familial HLA-matched donor is not available. Because human cytomegalovirus (HCMV) has been shown to inhibit the proliferation of BM progenitors in vitro, it was important to examine whether similar effect could be observed in HCMV-infected CB cells. Therefore, the effect of HCMV challenge on the proliferation of myeloid progenitors from BM and CB was compared using both mononuclear cells (MNC) and purified CD34+ cells. A clinical isolate of HCMV inhibited the colony formation of myeloid BM progenitors responsive to granulocyte-macrophage colony-stimulating factor (CSF), granulocyte- CSF, macrophage-CSF, interleukin-3 (IL-3) and the combination of IL-3 and stem cell factor (SCF). In contrast, colony growth of CB progenitors was not affected. In addition, HCMV inhibited directly the growth of purified BM CD34+ cells responsive to IL-3 and SCF in single cell assay by 40%, wheras the growth of CD34+ progenitors obtained from CB was not suppressed. The HCMV lower matrix structural protein pp65 and HCMV DNA were detected in both CB and BM CD34+ cells after in vitro challenge. However, neither immediate early (IE)-mRNA nor IE proteins were observed in infected cells. Cell cyclus examination of BM and CB CD34+ cells revealed that 25.7% of BM progenitors were in S + G2/ M phase wheras only 10.7% of the CB progenitors. Thus, a clinical isolate of HCMV directly inhibited the proliferation of myeloid BM progenitors in vitro wheras CB progenitors were not affected. This difference in the susceptibility of CB and BM cells to HCMV may partly be caused by the slow cycling rate of naive CB progenitors compared to BM progenitors at the time of infection.     

Aplastic anemia: presence in human bone marrow of cells that suppress myelopoiesis.

Bone marrow from a patient with aplastic anemia was shown by multiple criteria to have a block in early myeloid differentiation. This block was overcome in vitro by elimination of marrow lymphocytes. Furthermore, this differentiation block was transferred in vitro to normal marrow by coculturing with the patient's marrow. We suggest that some cases of aplastic anemia may be due to an immunologically based suppression of marrow cell differentiation rather than to a defect in stem cells or their necessary inductive environment.     

Abortive human cytomegalovirus infection in patients after allogeneic bone marrow transplantation.

Infection with human cytomegalovirus (HCMV) after allogeneic bone marrow transplantation (BMT) was studied in 12 HCMV seronegative recipients of marrow from seropositive donors by weekly monitoring of cultures, expression of HCMV antigenemia (pp65) in granulocytes, polymerase chain reaction (PCR) on HCMV-DNA in granulocytes and IgM and IgG anti-HCMV antibodies. Eight patients remained negative in all tests as did 33 HCMV seronegative recipients of marrow from seronegative donors. In four patients, a transient expression of HCMV antigen pp65 in granulocytes from peripheral blood, together with a positive PCR on HCMV-DNA from the same samples were found without positive cultures, seroconversion or expression of other HCMV antigens in granulocytes. The data indicate the presence of an abortive HCMV infection in these four patients.     

The synergistic effect of thrombopoietin in erythropoiesis and myelopoiesis from human bone marrow cells

We sought to determine whether recombinant human thrombopoietin (TPO) acts synergistically with recombinant human erythropoietin (EPO) and/or recombinant human interleukin-3 (IL-3) on erythroid burst formation and granulocyte-macrophage colony formation from human bone marrow (BM). BM cells were from 5 adults and 15 children who underwent bone marrow examination because of a clinical suspicion of malignancy; their bone marrows as well as the complete blood counts were normal and were cultured in a methylcellulose system. TPO has a synergistic effect with EPO or EPO + IL-3 on erythropoiesis of human BM, as the addition of TPO to EPO significantly gave rise to more erythroid bursts (p = 0.0001) and the addition of TPO to EPO + IL-3 might give rise to more erythroid bursts (p = 0.05). TPO also has a synergistic effect with recombinant human granulocyte colony-stimulating factor (G-CSF) on myelopoiesis of human BM, since the addition of TPO to G-CSF gave rise to significantly more granulocyte-macrophage colonies (p = 0. 0001). Besides its well-known significant role in megakaryopoiesis, TPO also has synergistic effects on erythropoiesis and myelopoiesis.     

Influence of human cytomegalovirus on immune reconstitution after bone marrow transplantation

HCMV infection diagnosed by the highly sensitive polymerase chain reaction (PCR) technology in blood, urine and skin biopsies of patients after bone marrow transplantation (BMT) correlated with the reconstitution of peripheral blood lymphocytes and dermal immunohistological alterations to evaluate the interaction of viral infection with the recovery of the immune system, as well as with the induction or aggravation of graftversus-host disease (GVHD). In a prospective study 73% of 63 patients showed viremia at a median time of 25 days after BMT. Only 44% of these cases that also presented with a higher frequency of acute GVHD symptoms developed HCMB disease later on. In the skin, similar immunohistological alternations, as well as frequent primary local HCMV infection before the development of cutaneous signs of GVHD, was found, suggesting the direct involvement of anti-HCMV immune responses in the induction of GVHD-associated organ lesions.     

Treatment of cytomegalovirus pneumonia after bone marrow transplantation with cytomegalovirus immunoglobulin combined with ganciclovir

We studied the effect of cytomegalovirus immunoglobulin alone, or combined with ganciclovir, on the outcome of biopsy proven cytomegalovirus pneumonia after bone marrow transplantation. Treatment with cytomegalovirus immunoglobulin alone had no effect on the cytomegalovirus nor on clinical outcome. The combined treatment of cytomegalovirus immunoglobulin with ganciclovir suppressed the cytomegalovirus but all patients died because of ongoing pulmonary deterioration. These results may suggest that this combined treatment has limited value on the outcome of an established cytomegalovirus pneumonia after marrow transplantation.     

Treatment of human bone marrow with recombinant placenta immunoregulator ferritin results in myelopoiesis and T-cell suppression through modulation of the cytokine-chemokine networks

OBJECTIVE: Placenta immunomodulator ferritin (PLIF) is a cloned human chimeric ferritin H chain with a novel non-ferritin C-terminal 48 amino acid sequence (C48). Recombinant PLIF-C48 exhibited cell-mediated immunosuppression. The aim of the current study was to investigate the regulatory effects of native placental ferritin (PLF), recombinant PLIF, and C48 on hematopoiesis of human bone marrow (BM). METHODS: BM mononuclear cells (BM-MNCs) and CD34(+) selected cells were treated in vitro with either PLF, PLIF, or C48 without and in combination with granulocyte (G)-monocyte (M) colony-stimulating factor (GM-CSF) and subjected to hematopoietic progenitor cell assay. Cytokines and chemokines secreted by the treated cells were evaluated in culture supernatant using antibody array assays to determine mechanism of action. RESULTS: In vitro treatment of BM-MNCs with PLF, PLIF, or C48 induced significant growth of myeloid colonies and when mixed with GM-CSF or Granulocyte-Colony Stimulating Factor (G-CSF) exhibited additive enhanced colony forming units-granulocyte monocyte growth. Yet, C48 treatment of selected CD34(+) cells did not yield colony formation and did not affect their response to GM-CSF. Treatment of BM-MNCs with C48 for 48 hours induced secretion of marked levels of GM-CSF, interleukin (IL)-6, IL-1, and IL-10. These cytokines were secreted primarily by C48-treated BM adherent cells and partly by nonadherent cells, whereas the CD34(+) selected cells secreted IL-6 only. CONCLUSION: C48-PLIF enhancement of myelopoiesis resulted from cross talk between BM accessory cells and progenitor cells. The differential PLIF-C48 effects (i.e., myeloid progenitor cell growth and T-cell suppression) are due to their effect on the cytokine-chemokine networks.     

Recovery of normal autologous myelopoiesis after graft rejection following allogeneic bone marrow transplant for agnogenic myeloid metaplasia

Allogeneic hematopoietic transplantation is the only currently available therapy that has the potential to cure agnogenic myeloid metaplasia (AMM) or primary myelofibrosis (PMF). Amelioration of fibrosis and eradication of the abnormal clone is thought to occur through the repopulation of marrow by donor-derived hematopoiesis and graft-vs.-host reaction leading to graft vs. tumor effect. We report here a 50-year-old female with AMM/PMF, conditioned with busulfan and cyclophosphamide, who rejected a single locus (HLA-B) mismatched bone marrow transplant from her daughter, but recovered normal autologous hematopoiesis with disappearance of marrow fibrosis and extramedullary hematopoiesis. Variable number tandem repeats (VNTR) analysis showed a gradual loss of donor-derived hematopoietic cells with recovery of autologous hematopoiesis. This case therefore illustrates that eradication of AMM/PMF in this patient with myeloablative chemotherapy combined with a transient allogeneic effect was sufficient to suppress the abnormal stem cell clone associated with AMM/PMF with subsequent cure.     

Management of human cytomegalovirus infection and disease after allogeneic bone marrow transplantation

BACKGROUND AND OBJECTIVE: Human cytomegalovirus (HCMV) infection and disease remain a major cause of morbidity and mortality after bone marrow transplantation. HCMV disease, especially pneumonitis, may be treated with ganciclovir and immunoglobulin but even so the outcome is poor with mortality rates of 30-70%. It is therefore imperative to treat HCMV infection before it develops into disease. The aim of this article is to describe the main strategies used to prevent HCMV infection and to improve the survival after CMV disease in bone marrow transplant recipients. INFORMATION SOURCES: In the present review, we examined personal papers in this field and articles published in journals covered by the Science Citation Index and Medline. STATE OF THE ART: Major advances have been made in preventing HCMV infection and disease through two different approaches, both of which reduce HCMV induced morbidity and mortality: In pre-emptive therapy, patients are given ganciclovir when HCMV infection is first identified and this is continued 3-4 months after transplantation; in prophylactic therapy ganciclovir is given to all patients at risk of HCMV disease from engraftment up to 3-4 months post transplantation. Each strategy has advantages and disadvantages and there is no evidence for the superiority of one over the other since the overall survival is the same and the incidence of death from HCMV disease is similar. PERSPECTIVES: The use of more sensitive tests such as HCMV PCR or antigenemia may improve the outcome but probably will not eradicate all HCMV disease. Future possible strategies could include adoptive transfer of CD8+ HCMV-specific cytotoxic T lymphocytes clones derived from the donor marrow or boosting donor or patient immunity using subunit anti-HCMV vaccines such as gB or pp65.     

Cytomegalovirus-specific lymphocyte proliferation and in vitro cytomegalovirus IgG synthesis for diagnosis of cytomegalovirus infections after bone marrow transplantation

With new techniques 19 bone marrow transplant (BMT) recipients were monitored for lymphocyte proliferation and specific IgG production in vitro by cytomegalovirus (CMV) antigen in solid phase. Twelve patients got a reactivated CMV infection as defined by virus isolation or serum IgG conversion. Lymphocyte proliferation and in vitro IgG production responses were significantly stronger in these 12 patients than in seven without ongoing CMV infection (P = .02). CMV infection was indicated by the lymphocyte responses at a mean of 45 days after BMT as against a mean of 79 days that passed before CMV growth in culture was detected (P less than .05). Lymphocyte proliferation and in vitro IgG production may thus be used as tools for diagnosis and for monitoring of CMV infections in BMT recipients.     

Enhanced myelopoiesis in long-term cultures of human bone marrow pretreated with recombinant granulocyte-macrophage colony-stimulating factor

Long-term bone marrow culture (LTBMC) for human hemopoiesis supports continuous proliferation and differentiation within the myeloid progenitor population by the formation of an adherent stromal monolayer. LTBMC represents the most suitable in vitro model for the study of regulatory mechanisms in human hemopoiesis. We investigated the effect of recombinant human granulocyte-macrophage colony-stimulating factor (rhuGM-CSF) on bone marrow of normal donors in LTBMC. The cells (2 x 10(6)/ml) were incubated with 100 ng/ml rhuGM-CSF for 24 h in culture medium supplemented with 10% fetal calf serum. After the preincubation, LTBMCs were started and maintained over a period of 10 weeks. After 1 week in culture we observed a statistically significant difference with a 1.5-fold higher number of nonadherent cells in the LTBMCs containing the bone marrow preincubated with rhuGM-CSF (p less than 0.05). This increase was due to an expansion of the mature myeloid cells. At the same time point the number of GM colony-forming units (CFU-GM)/ml in the LTBMCs with rhuGM-CSF-preincubated bone marrow was slightly increased compared to the controls without reaching a statistically significant level. We conclude that rhuGM-CSF at a saturation dose is a potent stimulator of in vitro myelopoiesis stem cell pool. This in vitro result is of relevance for the clinical use of rhuGM-CSF in patients undergoing bone marrow transplantation. The incubation of donor bone marrow prior to transplantation might be a new approach to facilitate the engraftment and to shorten the phase of pancytopenia.     

Direct synergistic effects of interleukin-7 on in vitro myelopoiesis of human CD34+ bone marrow progenitors

Interleukin-7 (IL-7) is an important growth factor in B and T lymphopoiesis in mouse and human, whereas IL-7 has been regarded to lack proliferative effects on cells within the myeloid lineage. However, we have recently reported that IL-7 potently can enhance colony stimulating factor (CSF)-induced myelopoiesis from primitive murine hematopoietic progenitors, showing a novel role of IL-7 in early murine myelopoiesis. Using CD34+ human hematopoietic progenitor cells, we show here a similar role of IL-7 in human myelopoiesis, although interesting differences between the two species were found as well. Although purified recombinant human (rh)IL-7 alone did not induce any proliferation of CD34+ cells, IL-7 in a concentration-dependent manner enhanced the colony formation induced by all four CSFs up to threefold. Furthermore, stem cell factor (SCF)-induced granulocyte-macrophage (GM) colony formation was increased fourfold in the presence of IL-7. Single- cell cloning assays showed that these synergistic effects of IL-7 were directly mediated on the targeted progenitors, and that IL-7 increased the number, as well as the size of the colonies formed. Morphological examination showed that IL-7 affected the progeny developed from CD34+ cells stimulated by G-CSF or IL-3, increasing the number of CFU-M (colony forming unit-macrophage) and CFU-granulocyte-macrophage, whereas the number of CFU-granulocyte were unaltered.     

Polypeptide-specific antibody response to human cytomegalovirus after infection in bone marrow transplant recipients

Human cytomegalovirus (HCMV) infection continues to be the most important infection occurring after allogeneic bone marrow transplantation (BMT). Although T cell-specific antiviral immunity appears to be necessary for control of the infection, the humoral immune reaction also contributes to a complete immune response. In this paper we report our findings concerning the antibody response to the individual polypeptides of HCMV in patients who had undergone BMT and subsequently had displayed evidence of HCMV infection. Sera obtained from the subjects during and after HCMV viremia were studied by using both a radioimmunoprecipitation assay and an immunoblot assay, and the results were compared with the pattern of antibody response in normal individuals. The results show that the BMT patient can make antibodies to individual proteins of HCMV in a pattern similar to that displayed by persons with natural infection. The polypeptide-specific antibody response present most frequently was directed to proteins of 64 kDa, 50 kDa, and 36 kDa. Some BMT recipients also produced antibody to a wide range of HCMV proteins: 183 kDa, 155 kDa, 130 kDa, 110 kDa, 92 kDa, 86 kDa, 74 kDa, 71 kDa, 69 kDa, 39-44 kDa, 33 kDa, and 29 kDa.     

Basic fibroblast growth factor stimulates myelopoiesis in long-term human bone marrow cultures

We previously showed that basic fibroblast growth factor (bFGF) is a potent mitogen for human bone marrow (BM) stromal cells and significantly delays their senescence. In the present study, we demonstrated that low concentrations of bFGF (0.2 to 2 ng/mL) enhance myelopoiesis in long-term human BM culture. Addition of bFGF to long-term BM cultures resulted in an increase in (a) the number of nonadherent cells (sixfold), particularly those of the neutrophil granulocyte series; (b) the number of nonadherent granulocyte colony-stimulating factor (G-CSF)- and granulocyte-macrophage colony-stimulating factor (GM-CSF)-responsive progenitor cells; (c) the number of adherent foci of hematopoietic cells (10-fold); and (d) the number of progenitor cells in the adherent stromal cell layer. These effects were not noted with higher concentrations of bFGF (20 ng/mL). Thus, low concentrations of bFGF effectively augment myelopoiesis in human long-term BM cultures, and bFGF may therefore be a regulator of the hematopoietic system in vitro and in vivo.     

In vitro suppression of bone marrow progenitor cell differentiation by human herpesvirus 6 infection.

Suppression of marrow function may be one of the most serious effects of human herpesvirus 6 (HHV-6) infection in marrow transplant patients. In this study, normal bone marrow mononuclear cells were infected in vitro with HHV-6, and a methylcellulose-based colony formation assay was used to evaluate the impact of the infection on marrow cell differentiation and proliferation. Results demonstrated that the outgrowth of colony-forming units of granulocyte and macrophage lineages (cfu-GM) was decreased by approximately 43%, that growth of cfu of granulocyte, erythrocyte, macrophage, and megakaryocyte lineages (cfu-GEMM) was inhibited by an average of 71%, and that the erythroid burst-forming unit (bfu-E) was decreased by approximately 73%. Further, outgrowth of the marrow stromal layer was reduced 74%. Direct infection of bone marrow monocytes was observed, although cell-free virus could not be detected in infected culture supernatants. Addition of a neutralizing monoclonal antibody specific for interferon-alpha to the infected cultures resulted in an almost complete reversal of the viral suppressive effects.     

Ultrastructural evidence for the origin of mast cells in normal human bone marrow.

Whether the origin of the progenitor of mast cells occurs in the basophil/mast cell system or the myeloid cell system of neutrophils and monocytes/macrophages remains controversial. Lactoferrin or lysozyme is known to be present in the myeloid cell system. By electron microscopy, antibodies against lactoferrin and lysozyme were observed to stain the granules of normal bone marrow mast cells. This supports the proposal that the precursor cell of bone marrow mast cells is nearer to the myeloid cell system than the basophil/mast cell system.     

Trochanter bone marrow: a source of normal human colony forming cells.

In vitro studies of human hemopoiesis are often limited by the availability of normal bone marrow. We have overcome this difficulty by taking advantage of the bone marrow fragments removed during total hip replacement. We report here a comparative study of the colony forming capacity of trochanter and sternal or iliac crest marrow from five hematologically normal donors. Our data indicate that trochanter marrow is a reliable source of normal in vitro granulocyte/macrophage colony forming cells.     

Megakaryocytic differentiation capacity of human pluripotent bone marrow progenitor cells CFU-GEMM in vitro after cryopreservation

The effect of cryopreservation on the pluripotent haemopoietic progenitors CFU-GEMM as well as on the megakaryocytic (CFU-Mk), erythroid (BFU-E) and granulocytic-monocytic (CFU-GM) progenitor cells was analyzed. Progenitor cell recovery after freezing, as determined in 5 experiments, averaged 89% for CFU-GEMM (range: 63% - 194%), 85% for CFU-Mk (range: 62% - 96%), 92% for BFU-E (range: 43% - 174%) and 60% for CFU-GM (range: 31% - 93%). Immunological analysis of individual mixed colonies using a double labelling immunoalkaline phosphatase slide technique and monoclonal antibodies against megakaryocytic and granulocytic cells revealed megakaryocytic cells in more than 79% (range: 73% - 94%) and 84% (range: 75% - 87%) of mixed colonies before and after freezing, respectively. Our results indicate that cryopreservation of human bone marrow cells does not alter the megakaryocytic differentiation capacity of the haemopoietic progenitor cells CFU-GEMM and CFU-Mk in vitro.     

Flow cytometric detection of cytomegalovirus antigen in peripheral blood cells after bone marrow transplantation

We report 13 normal peripheral blood stem cell (PBSC) donors who had a second PBSC collection for allogeneic transplantation performed after the first. The median interval between the first and second collection was 5 months. Mobilization was achieved with filgrastim (12 μg/kg/d). No significant difference was found in the median pre-apheresis leucocyte count (×10⁹/l) between the two donations (40.2 v 38.5; P  = 0.91). The median apheresis yield (×10⁶ CD34⁺ cells/litre blood processed, first apheresis) was also similar (28 v 27.3; P  = 0.91). Filgrastim-related adverse events were comparable. These data suggest that second PBSC collections are feasible, similarly tolerated and provide comparable apheresis yields.