Short telomeres on human chromosome 17p.

Human chromosomes terminate in a series of T2AG3 repeats, which, together with associated proteins, are essential for chromosome stability. In somatic cells, these sequences are known to be gradually lost through successive cells divisions; however, information about changes on specific chromosomes is not available. Individual telomeres could mediate important biological effects as was shown in yeast, in which loss of a single telomere results in cell-cycle arrest and chromosome loss. We now demonstrate by quantitative fluorescence in situ hybridization (Q-FISH; ref. 7) that the number of T2AG3 repeats on specific chromosome arms is very similar in different tissues from the same donor and varies only to some extent between donors. In all sixteen individuals studied, telomeres on chromosome 17p were shorter than the median telomere length--a finding confirmed by analysis of terminal restriction fragments from sorted chromosomes. These observations provide evidence of chromosome-specific factors regulating the number of T2AG3 repeats in individual telomeres and raise the possibility that the relatively short telomeres on chromosome 17p contribute to the frequent loss of 17p alleles in human cancers.

Extramedullary relapses after allogeneic non-myeloablative stem cell transplantation in multiple myeloma patients do not negatively affect treatment outcome.

Recent literature suggests that after non-myeloablative allogeneic (NMA) stem cell transplantation (SCT), the incidence of extramedullary (EM) relapse in multiple myeloma (MM) patients is increased and that these relapses have a poor prognosis. However, numbers on incidence and treatment outcome are scarce. We collected data from 54 relapsed MM patients from a total group of 172 treated with sequential autologous and allogeneic NMA SCT at seven transplantation centres. There were 43 (79.6%) systemic relapses, including 6 with concurrent EM localisation. Five patients had a local EM relapse only. Six patients relapsed with only bone involvement. Patients with deletion of chromosome 13 had a higher incidence of EM relapse (30.8 versus 5.6%, P=0.06). EM relapses were treated with donor lymphocyte infusion, radiotherapy, or chemotherapy, especially with novel agents. The response rate was 45.5%, which was not different when compared to patients without EM disease (54.1%). Overall survival and progression-free survival were not significantly different in patients with EM disease, when compared to those without EM disease. In conclusion, the incidence of relapse with EM disease following allogeneic NMA SCT was 20.4%. There was no negative impact of EM relapse on response rate, overall survival and progression-free survival.

Analysis of gene expression in subpopulations of murine hematopoietic stem and progenitor cells.

OBJECTIVE: The aim of the present work was to study how functional differences between subsets of the murine hematopoietic stem/progenitor cell compartment are manifested on the level of different patterns of gene expression in these subsets. MATERIALS AND METHODS: Amplified 3' terminal total cDNA fragment populations from four stem and progenitor cell fractions sorted using differential staining with Rhodamine 123 were prepared, and gene expression patterns were analyzed by Southern hybridization with a panel of gene markers. RESULTS: For the vast majority of lineage-specific markers, no expression was detected in the long-term repopulating stem cell fraction. Expression of a number of key genes positively regulating entry and progression through the cell cycle was down-regulated in long-term repopulating cells, in accordance with the quiescent state of the latter. In contrast, certain but not all cell division kinase inhibitors were significantly up-regulated in long- and short-term repopulating stem cell fractions. Expression of several genes important for entry into the apoptotic pathway was moderately reduced in long-term repopulating cells. Messenger RNA levels of the transcription factors GATA-1, GATA-2, c-Myb and SCL were down-regulated in long-term repopulating cells, as compared to more mature stem/progenitor cells. Finally, expression of the MDR1a gene encoding the Pgp efflux pump was highest in long-term repopulating cells, and progressively decreased with maturation. CONCLUSION: The patterns of gene expression in the stem/progenitor cell fractions are in good correlation with the known properties of adult hematopoietic stem/progenitor cells and may provide insight into molecular mechanisms underlying stem cell physiology.

Improved survival of lethally irradiated recipient mice transplanted with circulating progenitor cells mobilized by IL-8 after pretreatment with stem cell factor.

We have demonstrated previously that a single bolus-injection of interleukin (IL)-8 induces instant mobilization of hematopoietic progenitor cells (HPC) in mice and primates. To further improve the mobilization of HPC, we treated mice with hematopoietic growth factors (HGF) before IL-8-administration. The mobilized HPC were transplanted into lethally irradiated recipient mice to study the effects on survival. Male donor mice (age 8-12 weeks, weight 20-25 grams) were pretreated intraperitoneally (ip) with a fixed dose of 2.5 micrograms of either granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-3, stem cell factor (SCF), or saline administered twice daily for 2 to 4 days. Then a fixed dose of 30 micrograms of IL-8 was administered ip at various time intervals before harvesting blood, bone marrow, and spleen. Cell counts and numbers of colony-forming units granulocyte/macrophage (CFU-GM) of these organs were assessed. Donor mice pretreated with HGF for 2 days and subsequently injected with IL-8 showed an increase in the numbers of circulating CFU-GM per mL blood from 168 +/- 98 to 402 +/- 201 (mean +/- SD, CFU-GM/mL blood) when GM-CSF was used, 314 +/- 133 to 2502 +/- 513 with G-CSF, and 27 +/- 15 to 524 +/- 339 with SCF compared with saline-pretreated controls (28 +/- 17 to 462 +/- 335 CFU-GM/mL blood, mean +/- SD; n = 42 and 40 per interval). Donor-mice pretreated for 4 days with IL-3 or GM-CSF showed an increase in the numbers of circulating HPC from 62 +/- 52 to 368 +/- 118 and 859 +/- 387 to 1034 +/- 421, respectively (CFU-GM/mL, mean +/- SD, n = 4 per group). Lethally irradiated (8.5 Gy) female Balb/c mice were then injected with decreasing numbers of peripheral blood mononuclear cells (PBMNC). Transplantation of 1.5 x 10(5) MNC obtained from donors pretreated with SCF for 2 days prior to IL-8 mobilization resulted in a significantly enhanced survival of 100% of the recipients, whereas recipients of PBM-NCs derived from donors treated with SCF only or IL-8 as a single injection had a survival rate at day 60 of only 50% and 60% respectively. When equal numbers of IL-8 mobilized MNCs from G-CSF, GM-CSF, or IL-3 pretreated donors were transplanted into lethally irradiated recipients, no such survival-advantage was observed. We conclude that pretreatment with SCF for 2 days improves the mobilizing effect induced by IL-8 and that transplantation of these cells enhances survival of lethally irradiated recipients.

A novel murine cathelin-like protein expressed in bone marrow.

A novel cDNA encoding a putative secreted protein was isolated from murine bone marrow. The encoded protein named MCLP (murine cathelin-like protein) was found to be highly homologous to the pig cathelin, and to four neutrophil antimicrobial polypeptides: CAP 18, indolicidin, Bac 5 and FALL-39. Secondary structure prediction studies identified a highly cationic region in the C-terminal part of prepro-MCLP with a tendency to adopt an amphipathic alpha-helical conformation, as observed in many antimicrobial peptides. However, no antibacterial activity was observed with the synthetic peptide corresponding to this region of MCLP.

Disseminated histoplasmosis. Typical presentation with involvement of the adrenal glands.

A 67-yr-old Indonesian patient with disseminated histoplasmosis is described. He had general malaise and fever for 6 months; an oral ulcer, bilateral adrenal gland enlargement and partial adrenal insufficiency were found. An adrenal aspirate contained Histoplasma capsulatum. The literature on adrenal involvement in disseminated histoplasmosis is reviewed and it is concluded that bilateral enlargement, demonstrated by sonography or computed tomography, in a patient with general malaise is an important clue to the diagnosis.

Differential short-term and long-term repopulating ability of stem cell subsets in mice.

Hematopoietic reconsitution after transplantation requires the presence of cells with early and late repopulating ability. To determine the contribution of relatively immature and mature hematopoietic progenitor cells in engraftment, we used a modified rhodamine staining procedure to purify populations of rhodamine 123 (Rho)bright, Rhodull and Rho- cells from mouse steady-state bone marrow. Following transplantation of these subsets of stem cells in lethally irradiated mice, marrow repopulating cells were mainly present in the small fraction of Rho- cells, indicating that hematopoietic stem cells have a relatively high expression of P-glycoprotein. Similar cell populations could be purified from cytokine-mobilized blood following treatment with cyclophosphamide and G-CSF. The Rho- cell population contained the majority of hematopoietic stem cells with in vivo marrow repopulating ability. In methylcellulose colony assays, the majority of the committed progenitor cells were present in Rhodull and Rhobright fractions. These results indicate that relatively primitive populations of hematopoietic stem cells that lack colony-forming capacity in vitro mediate the early phase of engraftment following syngeneic stem cell transplantation.

Respiratory syncytial virus, a rare cause of severe pneumonia following bone marrow transplantation.

Mixed alveolar interstitial pneumonia is a much-feared complication in bone marrow transplant recipients because it carries a high mortality. Many cases in which an etiological agent is identified are due to fungi or cytomegalovirus; rarely, other infectious agents such as Pneumocystis carinii or (para)influenzavirus are involved. In this report we describe a patient who received intense chemotherapy followed by autologous bone marrow transplantation for relapse of testis seminoma and who developed a severe alveolar interstitial pneumonia caused by respiratory syncytial virus in the early posttransplant period. The patient fully recovered after treatment with ribavirin.

Accelerated platelet reconstitution following transplantation of bone marrow cells derived from IL-6-treated donor mice.

We transplanted bone marrow cells derived from normal donor mice treated with IL-6 to study the effect on the hematopoietic recovery of lethally irradiated (8.5 Gy) recipients. Male Balb/C mice were treated for 7 days by continuous infusion of IL-6 (10 micrograms/day). Not only did these donor mice have increased numbers of circulating platelets as was previously shown; the numbers of circulating progenitor cells also increased more than 25-fold. Transplantation of nucleated bone marrow cells derived from these donor mice into lethally irradiated female recipients resulted in increased platelet nadir counts in comparison to recipients of normal bone marrow cells and similar to nadir counts of recipients of normal donor bone marrow treated with IL-6 for 7 days after transplantation. Combination of transplantation of bone marrow derived from IL-6 treated donors with post-transplantation treatment of the recipients with IL-6 resulted in a further increase in nadir counts, although it did not cause a further acceleration of platelet reconstitution. We conclude that transplantation of bone marrow cells modified in vivo by IL-6 results in significantly accelerated reconstitution of platelets, to a degree similar to that observed following treatment with IL-6 after transplantation.

Modification of rhodamine staining allows identification of hematopoietic stem cells with preferential short-term or long-term bone marrow-repopulating ability.

We have developed a modified rhodamine (Rho) staining procedure to study uptake and efflux in murine hematopoietic stem cells. Distinct populations of Rho++ (bright), Rho+ (dull), and Rho- (negative) cells could be discriminated. Sorted Rho- cells were subjected to a second Rho staining procedure with the P-glycoprotein blocking agent verapamil (VP). Most cells became Rho positive [Rho-/Rho(VP)+ cells] and some remained Rho negative [Rho-/Rho(VP)- cells]. These cell fractions were characterized by their marrow-repopulating ability in a syngeneic, sex-mismatch transplantation model. Short-term repopulating ability was determined by recipient survival for at least 6 weeks after lethal irradiation and transplantation--i.e., radioprotection. Long-term repopulating ability at 6 months after transplantation was measured by fluorescence in situ hybridization with a Y-chromosome-specific probe, by graft function and recipient survival. Marrow-repopulating cells were mainly present in the small Rho- cell fraction. Transplantation of 30 Rho- cells resulted in 50% radioprotection and > 80% donor repopulation in marrow, spleen, and thymus 6 months after transplantation. Cotransplantation of cells from both fractions in individual mice directly showed that within this Rho- cell fraction, the Rho-/Rho(VP)+ cells exhibited mainly short-term and the Rho-/Rho(VP)- cells exhibited mainly long-term repopulating ability. Our results indicate that hematopoietic stem cells have relatively high P-glycoprotein expression and that the cells responsible for long-term repopulating ability can be separated from cells exhibiting short-term repopulating ability, probably by a reduced mitochondrial Rho-binding capacity.

Haemolytic uraemic syndrome following bone marrow transplantation. Case report and review of the literature.

Thrombotic microangiopathy (TMA) can be a late complication of bone marrow transplantation (BMT). A patient is described in whom the haemolytic uraemic syndrome developed 10 months after BMT and who died of E. coli sepsis while on maintenance haemodialysis. The literature is reviewed, regarding clinical presentation, incidence, pathogenesis and therapy. TMA can be observed, after an interval of 3-12 months, in about 6-26% of patients following BMT. Reported cases vary considerably in clinical severity, from mild presentations to severe TMA with high mortality rates despite intensive therapy. Important pathogenetic roles are ascribed to the conditioning total body irradiation and the use of cyclosporin A, but other factors may be involved as well. Next to supportive therapy, plasma exchange and the use of ACE inhibitors may be of value in treating BMT-associated TMA.

Telomeres in the mouse have large inter-chromosomal variations in the number of T2AG3 repeats.

The ultra-long telomeres that have been observed in mice are not in accordance with the concept that critical telomere shortening is related to aging and immortalization. Here, we have used quantitative fluorescence in situ hybridization to estimate (T2AG3)n lengths of individual telomeres in various mouse strains. Telomere lengths were very heterogeneous, but specific chromosomes of bone marrow cells and skin fibroblasts from individual mice had similar telomere lengths. We estimate that the shortest telomeres are around 10 kb in length, indicating that each mouse cell has a few telomeres with (T2AG3)n lengths within the range of human telomeres. These short telomeres may be critical in limiting the replicative potential of murine cells.

Separation, enrichment, and characterization of human hematopoietic progenitor cells from umbilical cord blood.

Human umbilical cord blood (UCB) may be used as an alternative source of bone marrow repopulating cells in allogeneic bone marrow transplantation in children. It has been reported that high numbers of hematopoietic progenitor cells (HPC) from umbilical cord blood may be lost during simple cell-separation techniques. This may seriously hamper the use of UCB as an alternative source of bone marrow repopulating cells. In this study we demonstrate that UCB can be separated into various cell fractions using several cell-separation methods including red blood cell lysis, methylcellulose sedimentation, and density gradients without significant loss of HPC, when cell separations are initiated within 8 h. We demonstrate that UCB contains a high concentration of immature HPC as compared with bone marrow grafts. Using FACS analysis of cells harvested from single colonies derived from single cell- single well-sorted CD34++ CD33- UCB cells, the high frequency of multipotential HPC was illustrated. These results suggest that UCB may contain sufficient HPC for hematopoietic stem cell transplantation in adults.

Molecular remission of Philadelphia/bcr-abl-positive acute myeloid leukaemia after treatment with anti-CD33 calicheamicin conjugate (gemtuzumab ozogamicin, CMA-676).

The anti-CD33 monoclonal antibody linked to NAc-gamma calicheamicin gemtuzumab ozogamicin (CMA-676) was used to treat a patient with Philadelphia/bcr-abl-positive acute myeloid leukaemia. We report a morphological and cytogenetic complete remission after treatment with two doses of gemtuzumab ozogamicin as a single agent. Using real-time polymerase chain reaction (PCR), gemtuzumab ozogamicin treatment resulted in a 3-log tumour mass reduction in bone marrow.

The early phase of engraftment after murine blood cell transplantation is mediated by hematopoietic stem cells.

Blood cells transplantation is largely replacing bone marrow transplantation because engraftment is more rapid. This accelerated engraftment is thought to be mediated by relatively mature committed hematopoietic progenitor cells. Herein, we have used a modified rhodamine (Rho) staining procedure to identify and purify Rho+/++ (dull/bright) and Rho- (negative) subpopulations of hematopoietic progenitor cells in murine cytokine-mobilized blood. The Rho+/++ cell population contained > 99% of committed progenitor cells with in vitro colony-forming ability. The Rho- cell population contained the majority of hematopoietic stem cells with in vivo marrow repopulating ability. The rate of hematopoietic reconstitution was identical in recipients of grafts containing only purified Rho- stem cells or purified Rho- stem cells in combination with large numbers of Rho+/++ committed progenitor cells. In contrast, transplantation of 3-fold more hematopoietic stem cells resulted in accelerated reconstitution, indicating that the reconstitution rate was determined by the absolute numbers of Rho- stem cells in the graft. In addition, we observed a 5- to 8-fold reduced frequency of the subset of hematopoietic stem cells with long-term repopulating ability in cytokine-mobilized blood in comparison to steady-state bone marrow. Our results indicate that hematopoietic stem cells and not committed progenitor cells mediate early hematopoietic reconstitution after blood cell transplantation and that relative to bone marrow, the frequency of stem cells with long-term repopulating ability is reduced in mobilized blood.

High-dose Ara-C for remission induction and consolidation of previously untreated adults with ALL or lymphoblastic lymphoma.

Thirty-two patients with untreated ALL (n = 26) or lymphoblastic lymphoma (n = 6) between 17 and 65 years of age were treated with a short remission induction course with VP16-213, amsacrine, intermediate dose Ara-C for 6 days, prednisone and intrathecal methotrexate, followed by a consolidation course with vincristine, amsacrine, high dose Ara-C for 4 days, prednisone and intrathecal methotrexate. After subsequent cranial irradiation, no further maintenance was planned. However, some patients underwent an allogenic (n = 5) or autologous (n = 5) bone marrow transplantation after the consolidation treatment. Twenty-three of 32 patients (72%) achieved a complete remission. Ten of 13 patients with T-ALL or lymphoma, six of eight patients with pre-B or common ALL, and seven of 11 patients with B-ALL or Burkitt's lymphoma achieved a complete remission. The median duration of remission was 24 months. Overall survival for the whole group was 35% at 5 years. The disease-free survival was 45% at 5 years. Long-term survival for patients with B or T-ALL was approximately 60%, compared with 15% for those with common or pre B-ALL. Short term intensive courses including intermediate or high dose Ara-C during remission and consolidation treatment lead to results comparable to those obtained with long-term maintenance regimens. Our regimen may be sufficient for patients with T or B-ALL. Larger randomized studies are needed to investigate the relative importance of our observations.

Normal viability and altered pharmacokinetics in mice lacking mdr1-type (drug-transporting) P-glycoproteins.

The mdr1-type P-glycoproteins (P-gps) confer multidrug resistance to cancer cells by active extrusion of a wide range of drugs from the cell. To study their physiological roles, we have generated mice genetically deficient in the mdr1b gene [mdr1b (-/-) mice] and in both the mdr1a and mdr1b genes [mdr1a/1b (-/-) mice]. In spite of the host of functions speculatively attributed to the mdrl-type P-gps, we found no physiological abnormalities in either strain. Viability, fertility, and a range of histological, hematological, serum-chemical, and immunological parameters were not abnormal in mdr1a/1b (-/-) mice. The high level of mdrlb P-gp normally present in the pregnant uterus did not protect fetuses from a drug (digoxin) in the bloodstream of the mother, although the protein did reduce drug accumulation in the adrenal gland and ovaries. Pharmacologically, mdr1a/1b (-/-) mice behaved similarly to the previously analyzed mdr1a (-/-) mice, displaying, for instance, increased brain penetration and reduced elimination of digoxin. However, both mdr1a and mdr1b P-gps contributed to the extrusion of rhodamine from hematopoietic progenitor cells, suggesting a potential role for the endogenous mdr1-type P-gps in protection of bone marrow against cytotoxic anticancer drugs. This, and the normal viability of mdr1a/1b (-/-) mice, has implications for the use of P-gp-blocking agents in cancer and other chemotherapy. mdr1a/1b (-/-) mice should provide a useful model system to further test the pharmacological roles of the drug-transporting P-gps and to analyze the specificity and effectivity of P-gp-blocking drugs.