Expression and role of the cytokine tyrosine kinase receptor flt3 in early hematopoiesis

Mature blood cells are crucial for life, but they have a short lifetime and thus have to be replaced. These mature blood cells are produced by lineage restricted progenitors, which themselves are generated by rare multipotent hematopoietic stem cells (HSCs) in a highly dynamic process called hematopoiesis. In addition to the ability of HSCs to generate all blood cell lineages, they possess the unique property of self-renewal, a process in which a HSC, during a cell division generate at least one daughter cell identical to the parental cell. The maintenance and regulation of HSCs and earliest stages of lineage development are partly controlled by soluble and membrane bound regulators called cytokines. The focus in this thesis has been on the cytokine tyrosine kinase receptor flt3 and its ligand and their role in regulating HSCs and the earliest progenitors in adult murine bone marrow (BM). Earlier studies had implicated a role for flt3 and its ligand in the maintenance of HSCs. When studying mice with targeted deletion of the flt3 ligand (FL), we failed to find any role of flt3 and its ligand in HSC regulation. However, the generation of the common lymphoid progenitor (CLP) and earliest stages of B- and T cell development were severely affected, but not myeloid progenitors or later stages of lymphoid development. Based on flt3 expression, we subfractionated the Lin(-)Sca-1(+)c-kit(+) (LSK) stem cell pool in mouse bone marrow. In contrast to LSKflt3- cells, which sustained multilineage long-term reconstitution, LSKflt3+ cells generated only short-term lymphoid dominated reconstitution when injected into lethally ablated recipients. We also demonstrated the hierarchical relationship at the earliest stages of hematopoiesis, in that LSKflt3- HSCs generate LSKflt3+ cells, which generate the CLP but not the LSKflt3- cells. In the classical model of the hematopoietic hierarchy, the first lineage commitment step of HSCs results in a strict separation into distinct lymphoid and myeloid pathways, generating the recently identified CLP and the common myeloid progenitor (CMP). However, in sharp contrast to LSKflt3-, cells which could generate all blood cell lineages, LSK cells expressing flt3 could not generate megakaryocytes or erythroid cells. Thus, these finding together with the above mentioned relationship between the LSKflt3-, LSKflt3+ and CLP do not support the classical hematopoietic hierarchy model depicting the first lineage commitment generating a strict separation of lymphoid and myeloid pathways. The LSK population contains all LT-HSC activity. However, this population is not homogenous neither in phenotype or function and it has been proposed to contain at least two populations, one with long-term reconstitution (LTR) potential and one with short-term reconstitution potential. Based on the expression of CD34 and flt3 within the adult LSK stem cell pool we were able to subfractionate short-term hematopoietic stem cells (ST-HSC) from the LT-HSCs. In contrast to the LSKCD34-flt3- and LSKCD34+flt3+ cells, the LSKCD34+flt3- is highly enriched for CFU-S activity and capable of rescuing lethally irradiated recipients, fulfilling the criteria of ST-HSCs

(O)vetenskap i dagens gymnasieskola? : En kvalitativ studie om elevers och lärares syn på naturvetenskap.

Syftet med denna uppsats är undersöka elevers och lärares syn på vetenskap kontra ickevetenskap eller pseudovetenskap. Detta har vi ju gjort genom en kvalitativ undersökning där vi intervjuat fem elever och fyra lärare. Elever anser att det är viktigt att veta vad vetenskap är och de anser att de kommer ha nytta av denna kunskap även utanför skolans dörrar. Anledningen till att det är obligatoriskt att läsa naturkunskap på gymnasiet är att eleverna skall få ett vetenskapligt synsätt. Med hjälp av läraren skall eleverna kunna inhämta den kunskap som behövs för att få rätt uppfattning gällande vetenskapsbegreppet. Enligt både elever och lärare så tas inte vetenskapsbegrepp upp i undervisningen. Lärarna tar för givet att eleverna redan innan de kommer till naturkunskap lektion har den här kunskapen. Den kunskap som eleverna fått gällande vetenskap har de inhämtat genom det samhälle de lever i t.ex. genom medierna. Men det är inte säkert att medierna ger rätt bild av vetenskap och då är det risk för att eleverna inte får den korrekta synen på vetenskap. Förstår man inte den korrekta innebörden i vetenskap är det även lätt att blanda ihop tro och vetenskap, som är två skilda saker. Som lärare får man inte ta förgivet att eleverna har en viss kunskap. Eleverna förstår inte heller det egentliga syftet med det laborativa arbetet under naturkunskapslektionerna. Det laborativa arbetet är en del av det naturvetenskapliga tänkandet. Det är en brist hos lärarna att de inte tar upp grundläggande begrepp, risken blir den att eleverna inte ser syftet med varför de läser naturkunskap. Följden blir den att ämnet anses svårt och komplicerat

Multiplexed single-cell mass cytometry reveals distinct inhibitory effects on intracellular phosphoproteins by midostaurin in combination with chemotherapy in AML cells

BackgroundFms-related tyrosine kinase 3 (FLT3) receptor serves as a prognostic marker and therapeutic target in acute myeloid leukemia (AML). Approximately one-third of AML patients carry mutation in FLT3, associated with unfavourable prognosis and high relapse rate. The multitargeted kinase inhibitor midostaurin (PKC412) in combination with standard chemotherapy (daunorubicin and cytarabine) was recently shown to increase overall survival of AML patients. For that reason, PKC412 has been approved for treatment of AML patients with FLT3-mutation. PKC412 synergizes with standard chemotherapy, but the mechanism involved is not fully understood and the risk of relapse is still highly problematic.MethodsBy utilizing the unique nature of mass cytometry for single cell multiparameter analysis, we have explored the proteomic effect and intracellular signaling response in individual leukemic cells with internal tandem duplication of FLT3 (FLT3-ITD) after midostaurin treatment in combination with daunorubicin or cytarabine.ResultsWe have identified a synergistic inhibition of intracellular signaling proteins after PKC412 treatment in combination with daunorubicin. In contrast, cytarabine antagonized phosphorylation inhibition of PKC412. Moreover, we found elevated levels of FLT3 surface expression after cytarabine treatment. Interestingly, the surface localization of FLT3 receptor increased in vivo on the blast cell population of two AML patients during day 3 of induction therapy (daunorubicin; once/day from day 1-3 and cytarabine; twice/day from day 1-7). We found FLT3 receptor expression to correlate with intracellular cytarabine (AraC) response. AML cell line cultured with AraC with or without PKC412 had an antagonizing phosphorylation inhibition of pAKT (p=0.042 and 0.0261, respectively) and pERK1/2 (0.0134 and 0.0096, respectively) in FLT3(high) compared to FLT3(low) expressing cell populations.ConclusionsOur study provides insights into how conventional chemotherapy affects protein phosphorylation of vital signaling proteins in human leukemia cells. The results presented here support further investigation of novel strategies to treat FLT3-mutated AML patients with PKC412 in combination with chemotherapy agents and the potential development of novel treatment strategies.Funding Agencies|Linkoping University; Swedish Research CouncilSwedish Research CouncilEuropean Commission; Swedish Cancer Society (Cancerfonden)Swedish Cancer Society; Swedish Childhood Cancer Fund (Barncancerfonden); Lions Research Fund against Non-communicable Diseases (Lions Forskningsfond mot folksjukdomar); Linkoping University Hospital</p

Immunocyte single cell analysis of vaccine-induced narcolepsy

n/aFunding Agencies|Alfred osterlunds Stiftelse; Anna och Edwin Bergers Stiftelse; Magnus Bergvalls Stiftelse; Crafoord Foundation; Filip Lundbergs Stiftelse; Fredrik och Ingrid Thurings Stiftelse; Royal Physiographic Society of Lund- Hedda; John Forssmans Foundation; Gunvor och Josef Aners Stiftelse; Gyllenstiernska Krapperupsstiftelsen; Jerringfonden; Kronprinsessan Lovisas Forening For Barnasjukvard/Stiftelsen Axel Tielmans Minnesfond; Linnea och Josef Carlssons Stiftelse; Neuro Sweden; Rune Ljungdahls Stiftelse; Stiftelsen Samariten; Stiftelsen till minne av Personalforeningarna i Holmia Forsakring AB; The Gun and Bertil Stohnes Foundation; Segerfalk Foundation; Svenska Lakaresallskapet; Tage Bluchers Stiftelse; Region Skane FoU; ALF grants; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [IRC15-0067]; Swedish Research Council, Linnaeus grantSwedish Research Council [349-2006-237]</p

Immunocyte single cell analysis of vaccine-induced narcolepsy

Increased incidence of narcolepsy type 1 (NT1) was observed following Pandemrix®-vaccination, initiated as a preventive measure against the 2009 Influenza pandemic. Here, single cell analysis was conducted to suggest a lower number of CD8+CD27+ T cells among these patients. These findings provide understanding into the autoimmune pathogenesis of NT1

Direct observation of lateral carrier diffusion in ridge waveguide 1.3 um GaInNAs-GaAs lasers using scanning near-field optical microscopy

Scanning near-field optical microscopy measurements of the lateral spontaneous emission profile for narrow ridge waveguide 1.3 um GaInNAs-GaAs lasers reveal significant lateral carrier diffusion, which can explain the high characteristic temperature of the threshold current

Key Role of flt3 Ligand in Regulation of the Common Lymphoid Progenitor but Not in Maintenance of the Hematopoietic Stem Cell Pool

AbstractThe first lineage commitment step of hematopoietic stem cells (HSC) results in separation into distinct lymphoid and myeloid differentiation pathways, reflected in the generation of common lymphoid and myeloid progenitors (CLP and CMP, respectively). In this report we present the first evidence for a nonredundant regulator of this process, in that adult mice deficient in expression of the flt3 ligand (FL) have severely (10-fold) reduced levels of the CLP, accompanied by reductions in the earliest identifiable B and T cell progenitors. In contrast, CMP and HSC are unaffected in FL-deficient mice. Noteworthy, CLP express high levels of both the flt3 receptor and ligand, indicating a potential autocrine role of FL in regulation of the earliest lymphoid commitment step from HSC