Post-remission treatment with allogeneic stem cell transplantation in patients aged 60 years and older with acute myeloid leukaemia: a time-dependent analysis

BACKGROUND Acute myeloid leukaemia mainly affects elderly people, with a median age at diagnosis of around 70 years. Although about 50-60% of patients enter first complete remission upon intensive induction chemotherapy, relapse remains high and overall outcomes are disappointing. Therefore, effective post-remission therapy is urgently needed. Although often no post-remission therapy is given to elderly patients, it might include chemotherapy or allogeneic haemopoietic stem cell transplantation (HSCT) following reduced-intensity conditioning. We aimed to assess the comparative value of allogeneic HSCT with other approaches, including no post-remission therapy, in patients with acute myeloid leukaemia aged 60 years and older. METHODS For this time-dependent analysis, we used the results from four successive prospective HOVON-SAKK acute myeloid leukaemia trials. Between May 3, 2001, and Feb 5, 2010, a total of 1155 patients aged 60 years and older were entered into these trials, of whom 640 obtained a first complete remission after induction chemotherapy and were included in the analysis. Post-remission therapy consisted of allogeneic HSCT following reduced-intensity conditioning (n=97), gemtuzumab ozogamicin (n=110), chemotherapy (n=44), autologous HSCT (n=23), or no further treatment (n=366). Reduced-intensity conditioning regimens consisted of fludarabine combined with 2 Gy of total body irradiation (n=71), fludarabine with busulfan (n=10), or other regimens (n=16). A time-dependent analysis was done, in which allogeneic HSCT was compared with other types of post-remission therapy. The primary endpoint of the study was 5-year overall survival for all treatment groups, analysed by a time-dependent analysis. FINDINGS 5-year overall survival was 35% (95% CI 25-44) for patients who received an allogeneic HSCT, 21% (17-26) for those who received no additional post-remission therapy, and 26% (19-33) for patients who received either additional chemotherapy or autologous HSCT. Overall survival at 5 years was strongly affected by the European LeukemiaNET acute myeloid leukaemia risk score, with patients in the favourable risk group (n=65) having better 5-year overall survival (56% [95% CI 43-67]) than those with intermediate-risk (n=131; 23% [19-27]) or adverse-risk (n=444; 13% [8-20]) acute myeloid leukaemia. Multivariable analysis with allogeneic HSCT as a time-dependent variable showed that allogeneic HSCT was associated with better 5-year overall survival (HR 0·71 [95% CI 0·53-0·95], p=0·017) compared with non-allogeneic HSCT post-remission therapies or no post-remission therapy, especially in patients with intermediate-risk (0·82 [0·58-1·15]) or adverse-risk (0.39 [0·21-0·73]) acute myeloid leukaemia. INTERPRETATION Collectively, the results from these four trials suggest that allogeneic HSCT might be the preferred treatment approach in patients 60 years of age and older with intermediate-risk and adverse-risk acute myeloid leukaemia in first complete remission, but the comparative value should ideally be shown in a prospective randomised study. FUNDING None.

Stem cell mobilization chemotherapy with gemcitabine is effective and safe in myeloma patients with bortezomib-induced neurotoxicity.

Vinorelbine chemotherapy with granulocyte-colony stimulating factor (G-CSF) stimulation is a widely applied non-myelosuppressive mobilization regimen in Switzerland for myeloma patients, but its neurotoxic potential limits its use in patients with bortezomib-induced polyneuropathy. In this single-center study, we alternatively evaluated safety and effectiveness of gemcitabine chemotherapy with G-CSF for mobilization of autologous stem cells. Between March 2012 and February 2013, all bortezomib-pretreated myeloma patients planned to undergo first-line high-dose melphalan chemotherapy received a single dose of 1250 mg/m(2) gemcitabine, with G-CSF started on day 4. The 24 patients in this study had received a median of four cycles of bortezomib-dexamethason-based induction. Bortezomib-related polyneuropathy was identified in 21 patients (88%) by clinical evaluation and a standardized questionnaire. Administration of gemcitabine mobilization did not induce new or aggravate pre-existing neuropathy. Stem cell mobilization was successful in all 24 patients, with a single day of apheresis being sufficient in 19 patients (78%). The median yield was 9.51 × 10(6) CD34+ cells/kg. Stem collection could be accomplished at day 8 in 67%. Our data suggest that single-dose gemcitabine together with G-CSF is an effective mobilization regimen in myeloma patients and a safe alternative non-myelosuppressive mobilization chemotherapy for myeloma patients with bortezomib-induced polyneuropathy.

Neurotoxicity of stem cell mobilization chemotherapy with vinorelbine in myeloma patients after bortezomib treatment.

Vinorelbine chemotherapy with G-CSF stimulation is the standard mobilization regimen in Switzerland for multiple myeloma patients. However, with the increasing use of bortezomib during induction treatment, adding the neurotoxic compound vinorelbine for mobilization may aggravate bortezomib-induced polyneuropathy. In this retrospective single-center study, we aimed to explore vinorelbine mediated neuropathy in 106 consecutive bortezomib pretreated myeloma patients. We confirmed that vinorelbine with G-CSF represents a reliable and effective regimen for mobilization of autologous stem cells. However, the single administration of 35 mg/m(2) vinorelbine added significant neurotoxicity. We found that 24 patients (24%) reported vinorelbine mediated neurotoxicity: Aggravation of bortezomib-induced neuropathy was observed in 17 patients (17%), and vinorelbine mobilization induced first occurrence of polyneuropathy in additional 7 patients (7%). We observed that development of polyneuropathy was not associated with differing survival rates. Finally, affected patients reported polyneuropathy associated disease burden as "very high" in 13% and "high" in 50%. Our data indicate that a single administration of vinorelbine to mobilize autologous stem cells is associated with significant additional polyneuropathy in bortezomib pretreated myeloma patients. The efficacy of vinorelbine mobilization should be balanced against its neurotoxic potential.

CD34+ selected versus unselected autologous stem cell transplantation in patients with advanced-stage mantle cell and diffuse large B-cell lymphoma

Novel strategies aiming to increase survival rates in patients with advanced-stage mantle cell lymphoma (MCL) and relapsing diffuse large B-cell lymphoma (DLBCL) are a clinical need. High-dose chemotherapy (HDCT) with autologous stem cell transplantation (ASCT) has improved progression-free (PFS) and overall survival (OS) in MCL and relapsed DLBCL. However, the role of CD34+ cell selection before ASCT in MCL and DLBCL is unclear. We retrospectively analyzed the outcome of 62 consecutive patients with advanced-stage MCL or relapsed DLBCL undergoing ASCT with (n=31) or without (n=31) prior CD34+ selection. All patients had stage III or IV disease, with 47% having DLBCL and 53% MCL. The median duration for neutrophil and platelet recovery was 12 and 16 days in CD34+ selected patients, and 11 (P<.001) and 14 days (P=.012) in the group without selection, respectively. No differences in toxicities were observed. The 5-year PFS for CD34+ selected versus not selected patients was 67% and 39% (P=.016), and the 5-year OS was 86% and 54% (P=.007). Our data suggest that using CD34+ selected autografts for ASCT in advanced stage MCL and DLBCL is associated with longer PFS and OS without increased toxicity.

Human lung-derived mesenchymal stem cell-conditioned medium exerts in vitro antitumor effects in malignant pleural mesothelioma cell lines.

BACKGROUND The soluble factors secreted by mesenchymal stem cells are thought to either support or inhibit tumor growth. Herein, we investigated whether the human lung-derived mesenchymal stem cell-conditioned medium (hlMSC-CM) exerts antitumor activity in malignant pleural mesothelioma cell lines H28, H2052 and Meso4. METHODS hlMSC-CM was collected from the human lung-derived mesenchymal stem cells. Inhibition of tumor cell growth was based on the reduction of cell viability and inhibition of cell proliferation using the XTT and BrdU assays, respectively. Elimination of tumor spheroids was assessed by the anchorage-independent sphere formation assay. The cytokine profile of hlMSC-CM was determined by a chemiluminescence-based cytokine array. RESULTS Our data showed that hlMSC-CM contains a broad range of soluble factors which include: cytokines, chemokines, hormones, growth and angiogenic factors, matrix metalloproteinases, metalloproteinase inhibitors and cell-cell mediator proteins. The 48- and 72-hour hlMSC-CM treatments of H28, H2052 and Meso4 cell lines elicited significant decreases in cell viability and inhibited cell proliferation. The 72-hour hlMSC-CM incubation of H28 cells completely eliminated the drug-resistant sphere-forming cells, which is more potent than twice the half maximal inhibitory concentration of cisplatin. CONCLUSIONS Our findings indicate that the cell-free hlMSC-CM confers in vitro antitumor activities via soluble factors in the tested mesothelioma cells and, hence, may serve as a therapeutic tool to augment the current treatment strategies in malignant pleural mesothelioma.

Spatial Distribution of Stem Cell-Like Keratinocytes in Dissected Compound Hair Follicles of the Dog

Hair cycle disturbances are common in dogs and comparable to some alopecic disorders in humans. A normal hair cycle is maintained by follicular stem cells which are predominately found in an area known as the bulge. Due to similar morphological characteristics of the bulge area in humans and dogs, the shared particularity of compound hair follicles as well as similarities in follicular biomarker expression, the dog is a promising model to study human hair cycle and stem cell disorders. To gain insight into the spatial distribution of follicular keratinocytes with stem cell potential in canine compound follicles, we microdissected hair follicles in anagen and telogen from skin samples of freshly euthanized dogs. The keratinocytes isolated from different locations were investigated for their colony forming efficiency, growth and differentiation potential as well as clonal growth. Our results indicate that i) compound and single hair follicles exhibit a comparable spatial distribution pattern with respect to cells with high growth potential and stem cell-like characteristics, ii) the lower isthmus (comprising the bulge) harbors most cells with high growth potential in both, the anagen and the telogen hair cycle stage, iii) unlike in other species, colonies with highest growth potential are rather small with an irregular perimeter and iv) the keratinocytes derived from the bulbar region exhibit characteristics of actively dividing transit amplifying cells. Our results now provide the basis to conduct comparative studies of normal dogs and those with hair cycle disorders with the possibility to extend relevant findings to human patients.

Differentiation of Human Embryonic Stem Cell (hESC) Derived Pyramidal Neurons

The mammalian cerebral neocortex is a complex six-layered structure containing multiple types of neurons. Pyramidal neurons of the neocortex are formed during development in an inside-out manner, by which deep layer (DL) neurons are generated first, and upper layer (UL) neurons are generated last. Neurons within the six-layered neocortex express unique markers for their position, showing whether they are subplate, deep layer, upper layer, or Cajal-Retzius neurons. The sequential generation of cortical layers, which exists in vivo, has been partially recapitulated in vitro by differentiation of mouse embryonic stem cells (Gaspard et al., 2008) and human embryonic stem cells (hESC) (Eiraku et al., 2008). The timeline of generation of cortical neurons from hESC is still not well defined, and could be very important in the future of cell therapy. In this study we will define timeline for UL and DL neurons for our experimental paradigm as well as test the effects of fibroblast growth factors (FGF) 2 and 8 on this neuronal differentiation. Recent papers suggest that FGFs are critical for forebrain patterning (Storm et al., 2003). Neuronal differentiation after treatment with either FGF2 or FGF8 from hESCs will be examined and the proportion of specific neuronal markers will be analyzed using immunocytochemistry. Our results show that the generated pyramidal neurons will express DL and UL laminar markers in vitro as they do in vivo and that the presence of FGF8 in induction media creates a proliferative effect, while FGF2 induces hESC to differentiate at a higher rate.

Determination of the Myogenic Potential of Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells

Human embryonic stem cells (hESCs) have the potential to differentiate to all adult somatic cells. This property makes hESCs a very promising area of research for the treatment of disorders in which specific cell populations need to be restored. Despite this potential, research that focuses on producing mesodermally derived cell populations from hESCs is decidedly limited, notwithstanding the prevalence of disorders involving mesodermal tissues for which treatment options are limited. Skeletal muscle myoblasts are derivatives of mesodermal cells and are characterized by the expression of the MyoD gene. These cells are difficult to obtain from hESCs in a reproducible and efficient manner. Recent developments in the field have showed some success in obtaining myogenic cells from hESCs through a mesenchymal stem cell (MSC)-like intermediate population. MSCs, which are an adult stem cell population typically derived from the bone marrow, are capable of generating multiple cell types including skeletal muscle. The aim of this study was to develop an efficient method that derives myoblasts from an MSC-like intermediate. To accomplish this goal, we first set out to isolate and expand the MSC-like intermediate from hESCs differentiated in vitro. Difficulties in reproducing published cell-differentiation methodologies, which represent a significant and familiar challenge in hESC research, are highlighted in this report.

The roles of costimulatory molecules in the cooperative effects of combination epinephrine and dexamethasone on type-1/type-2 cytokine production in tetanus-toxoid specific stimulated human peripheral blood mononuclear cells

A growing number of studies show strong associations between stress and altered immune function. In vivo studies of chronic and acute stress have demonstrated that cognitive stressors are strongly correlated with high circulating levels of catecholamines (CT) and corticosteroids (CS) that are associated with changes in type-1/type-2 cytokine expression. Although individual pharmacologic doses of CS and CT can inhibit the expression of T-helper 1 (Th1, type-1 like) and promote the production of T-helper 2 (Th2, type-2 like) cytokines in antigen-specific and mitogen stimulated human leukocyte cultures in vitro, little attention has been focused on the effects of combination physiologic-stress doses of CT and CS that may be more physiologically relevant. In addition, both in-vivo and in-vitro studies suggest that the differential expression of the B7 family of costimulatory molecules CD80 and CD86 may promote the expression of type-1 or type-2 cytokines, respectively. Furthermore, corticosteroids can influence the expression of β2-adrenergic receptors in various human tissues. We therefore investigated the combined effects of physiologic-stress doses of in vitro CT and CS upon the type-1/type-2 cytokine balance and expression of B7 costimulatory molecules of human peripheral blood mononuclear cells (PBMC) as a model to study the immunomodulatory effects of physiologic stress. Results demonstrated a significant decrease in type-1 cytokine expression and a significant increase in type-2 cytokine production in our CS+CT incubated cultures when compared to either CT or CS agents alone. In addition, we demonstrated the differential expression of CD80/CD86 in favor of CD86 at the cellular and population level as determined by flow cytometry in lipopolysaccharide stimulated human Monocytes. Furthermore, we developed flow cytometry based assays to detect total β2AR in human CD4+ T-lymphocytes that demonstrated decreased expression of β2AR in mitogen stimulated CD4+ T-lymphocytes in the presence of physiologic stress levels of CS and CT as single in vitro agents, however, when both CS and CT were combined, significantly higher expression of β2AR was observed. In summary, our in vitro data suggest that both CS and CT work cooperatively to shift immunity towards type-2 responses. ^

Current United States stem cell policy considerations and a recommendation for an alternative policy based on guidelines from existing international policies

Embryonic stem cell research is a widely debated topic in modern politics and religion. Differing views on the fetal rights conflict with the rights of an embryo. Those who believe an embryo has the same human qualities as a fetus accordingly believe embryonic stem cell research is unethical because it destroys a potential human life. However, scientists advocate the embryo does not have human qualities and should be used for valuable research in the stem cell field. Stem cell research may lead to vast developments in medical treatments, including cancer and brain conditions and injuries that are currently incurable. ^ The current stem cell policy introduced by President Bush in 2001 in an attempt to balance the moral issues with the need for scientific research has broad negative implications on the furthering of stem cell research. There is a limited diversity of available stem cell lines, there may be constitutional issues, there is an increasing disparity between the public and private research spheres, and the U.S. is struggling to maintain its scientific community. The U.S. must develop a new stem cell research policy that will balance the interest of science and public health with the moral issues that concern the public. ^ The United Kingdom allows researchers great liberty in conducting research, permitting the creation of embryos for the sole purpose of research, while Germany is equally conservative in their laws, as their policies support the philosophy that all embryos deserve the protection of full life. The United States should adopt a policy that takes the "middle ground" approach and permit research on excess embryos created for IVF purposes, rather than simply discarding those potentially valuable research tools. ^

Federal regulation of human embryonic stem cell research

President George W. Bush's 2001 statement, which laid out guidelines for research that uses human embryonic stem cells to qualify for federal funding, intends to prevent new embryonic stem cell lines from being developed, by prohibiting the federal funding of research that uses embryonic stem cell lines other than those that existed at the time of the policy's inception and were approved by the National Institutes of Health. This policy raises questions of medical and technological ethics and the governments' role in making decisions regarding the advancement of science based on moral and political opinions. Federal stem cell usage policy directly affects scientific research efforts that are currently on the path to understanding the mechanisms of cell differentiation and could potentially offer answers and therapies for disabilities and many chronic diseases. By reviewing the current literature on the background information on human embryonic stem cells, including what they are, where they come from, how they are used for research purposes, and the ethical controversy surrounding their use, I have researched and reported the impact of the 2001 policy on medical research. ^ Both those who support the current policy on human embryonic stem cell research and those who are advocates for policy change have relevant arguments and varying opinions on human embryonic stem cell usage itself. The ethical implication of how embryonic stem cells are obtained has led to fierce debate. This paper presents many arguments for and against hESC research in addition to the policy governing their use. This analysis concludes that the current policy on federal funding of human embryonic stem cell research should be revised to allow research using new stem lines to be eligible for federal funding under specific guidelines. Supporting evidence for this recommendation is provided.^

Connexin-43 prevents hematopoietic stem cell senescence through transfer of reactive oxygen species to bone marrow stromal cells

Hematopoietic stem cell (HSC) aging has become a concern in chemotherapy of older patients. Humoral and paracrine signals from the bone marrow (BM) hematopoietic microenvironment (HM) control HSC activity during regenerative hematopoiesis. Connexin-43 (Cx43), a connexin constituent of gap junctions (GJs) is expressed in HSCs, down-regulated during differentiation, and postulated to be a self-renewal gene. Our studies, however, reveal that hematopoietic-specific Cx43 deficiency does not result in significant long-term competitive repopulation deficiency. Instead, hematopoietic Cx43 (H-Cx43) deficiency delays hematopoietic recovery after myeloablation with 5-fluorouracil (5-FU). 5-FU-treated H-Cx43-deficient HSC and progenitors (HSC/P) cells display decreased survival and fail to enter the cell cycle to proliferate. Cell cycle quiescence is associated with down-regulation of cyclin D1, up-regulation of the cyclin-dependent kinase inhibitors, p21cip1. and p16INK4a, and Forkhead transcriptional factor 1 (Foxo1), and activation of p38 mitogen-activated protein kinase (MAPK), indicating that H-Cx43-deficient HSCs are prone to senescence. The mechanism of increased senescence in H-Cx43-deficient HSC/P cells depends on their inability to transfer reactive oxygen species (ROS) to the HM, leading to accumulation of ROS within HSCs. In vivo antioxidant administration prevents the defective hematopoietic regeneration, as well as exogenous expression of Cx43 in HSC/P cells. Furthermore, ROS transfer from HSC/P cells to BM stromal cells is also rescued by reexpression of Cx43 in HSC/P. Finally, the deficiency of Cx43 in the HM phenocopies the hematopoietic defect in vivo. These results indicate that Cx43 exerts a protective role and regulates the HSC/P ROS content through ROS transfer to the HM, resulting in HSC protection during stress hematopoietic regeneration.

Direct visualization of antigen-specific T cells: HTLV-1 Tax11–19- specific CD8+ T cells are activated in peripheral blood and accumulate in cerebrospinal fluid from HAM/TSP patients

Human T lymphotropic virus type 1 (HTLV-1) -associated myelopathy/tropic spastic paraparesis is a demyelinating inflammatory neurologic disease associated with HTLV-1 infection. HTLV-1 Tax11–19-specific cytotoxic T cells have been isolated from HLA-A2-positive patients. We have used a peptide-loaded soluble HLA-A2–Ig complex to directly visualize HTLV-1 Tax11–19-specific T cells from peripheral blood and cerebrospinal fluid without in vitro stimulation. Five of six HTLV-1-associated myelopathy/tropic spastic paraparesis patients carried a significant number (up to 13.87%) of CD8+ lymphocytes specific for the HTLV-1 Tax11–19 peptide in their peripheral blood, which were not found in healthy controls. Simultaneous comparison of peripheral blood and cerebrospinal fluid from one patient revealed 2.5-fold more Tax11–19-specific T cells in the cerebrospinal fluid (23.7% vs. 9.4% in peripheral blood lymphocyte). Tax11–19-specific T cells were seen consistently over a 9-yr time course in one patient as far as 19 yrs after the onset of clinical symptoms. Further analysis of HTLV-1 Tax11–19-specific CD8+ T lymphocytes in HAM/TSP patients showed different expression patterns of activation markers, intracellular TNF-α and γ-interferon depending on the severity of the disease. Thus, visualization of antigen-specific T cells demonstrates that HTLV-1 Tax11–19-specific CD8+ T cells are activated, persist during the chronic phase of the disease, and accumulate in cerebrospinal fluid, showing their pivotal role in the pathogenesis of this neurologic disease.

Chymase cleavage of stem cell factor yields a bioactive, soluble product

Stem cell factor (SCF) is produced by stromal cells as a membrane-bound molecule, which may be proteolytically cleaved at a site close to the membrane to produce a soluble bioactive form. The proteases producing this cleavage are unknown. In this study, we demonstrate that human mast cell chymase, a chymotrypsin-like protease, cleaves SCF at a novel site. Cleavage is at the peptide bond between Phe-158 and Met-159, which are encoded by exon 6 of the SCF gene. This cleavage results in a soluble bioactive product that is 7 amino acids shorter at the C terminus than previously identified soluble SCF. This research shows the identification of a physiologically relevant enzyme that specifically cleaves SCF. Because mast cells express the KIT protein, the receptor for SCF, and respond to SCF by proliferation and degranulation, this observation identifies a possible feedback loop in which chymase released from mast cell secretory granules may solubilize SCF bound to the membrane of surrounding stromal cells. The liberated soluble SCF may in turn stimulate mast cell proliferation and differentiated functions; this loop could contribute to abnormal accumulations of mast cells in the skin and hyperpigmentation at sites of chronic cutaneous inflammation.