搜索结果: 'stemprep kits'

Implanted materials,such as medical devices,provoke the body to initiate an inflammatory reaction,known as the foreign body reaction (FBR),which causes several complications for example in hip prostheses,silicone implants,peritoneal dialysis catheters and left ventricular assist devices. FBR is initiated by macrophage adherence and results in granulation tissue formation. The early immunobiology and development of this tissue is not completely understood,but there are indications from related myofibroblast-forming diseases such as vascular repair and fibrosis that primitive stem cells also play a role in the formation of FBR-tissue. To investigate this,acellular photo-oxidized bovine pericardium patches were implanted intraperitoneally in rats and retrieved at time-points ranging from 6h to 7 days. A significant fraction of Sca-1(+) (6h-2 days),c-kit(+),CD34(+) and CD271(+) (2-3 days) stem/progenitor cells were detected. Colony-forming and differentiation capacity of the primitive stem cells into adipo-,osteo-,and myofibroblasts were shown. The presence of these primitive cells and their myofibroblastic differentiation potential were also confirmed at RNA level. The identification of specific primitive cells during FBR may have important implications for the inflammatory responses to inert materials and their use in tissue prostheses. View Publication

SU5416 is a multi-targeted kinase inhibitor that potentially has the ability to directly block tumor growth by inhibiting Kit signaling,as well as blocking angiogenesis by inhibiting vascular endothelial growth factor receptor (VEGFR) signaling. Previous work has demonstrated that SU5416 efficiently blocks Kit-mediated growth of small cell lung cancer (SCLC) in vitro. To determine the drug's effect on in vivo growth of SCLC,we studied its activity,alone and in combination with carboplatin,in chemotherapy-resistant H526,and chemotherapy-sensitive H209 murine xenograft models. SU5416 efficiently inhibited Kit activity in vivo when administered on a twice-weekly schedule. When administered over a 3-week period to animals bearing established tumors,it inhibited growth by at least 70%. It was at least as effective as carboplatin in suppressing growth of H526 xenografts. However,the combination with carboplatin was not superior to the most active single agent in either xenograft model at the doses and schedule utilized. SU5416 clearly inhibited growth in part by inhibiting angiogenesis,with microvessel density dropping by approximately 50% in treated xenografts. In addition to the recognized mechanism of inhibition of VEGFR,we uncovered a novel mechanism of angiogenesis suppression by demonstrating reduced VEGF expression in SU5416-treated xenografts. In vitro,stem cell factor treatment of the H526 cell line enhanced expression of VEGF,which was efficiently blocked with SU5416. Thus,we have demonstrated that SU5416 can inhibit SCLC growth by directly inhibiting tumor cell proliferation and by inhibiting angiogenesis,in part by inhibiting Kit-mediated VEGF expression. These data suggest that kinase inhibitors that target both Kit and VEGFR could play an important role in the treatment of SCLC,as well as other malignancies that express Kit. View Publication

Systemic mastocytosis (SM) is a myeloid neoplasm involving mast cells (MCs) and their progenitors. In most cases,neoplastic cells display the D816V-mutated variant of KIT. KIT D816V exhibits constitutive tyrosine kinase (TK) activity and has been implicated in increased survival and growth of neoplastic MCs. Recent data suggest that the proapoptotic BH3-only death regulator Bim plays a role as a tumor suppressor in various myeloid neoplasms. We found that KIT D816V suppresses expression of Bim in Ba/F3 cells. The KIT D816-induced down-regulation of Bim was rescued by the KIT-targeting drug PKC412/midostaurin. Both PKC412 and the proteasome-inhibitor bortezomib were found to decrease growth and promote expression of Bim in MC leukemia cell lines HMC-1.1 (D816V negative) and HMC-1.2 (D816V positive). Both drugs were also found to counteract growth of primary neoplastic MCs. Furthermore,midostaurin was found to cooperate with bortezomib and with the BH3-mimetic obatoclax in producing growth inhibition in both HMC-1 subclones. Finally,a Bim-specific siRNA was found to rescue HMC-1 cells from PKC412-induced cell death. Our data show that KIT D816V suppresses expression of proapoptotic Bim in neoplastic MCs. Targeting of Bcl-2 family members by drugs promoting Bim (re)-expression,or by BH3-mimetics such as obatoclax,may be an attractive therapy concept in SM. View Publication

Olfactory epithelium (OE) has a lifelong capacity for neurogenesis due to the presence of basal stem cells. Despite the ability to generate short-term cultures,the successful in vitro expansion of purified stem cells from adult OE has not been reported. We sought to establish expansion-competent OE stem cell cultures to facilitate further study of the mechanisms and cell populations important in OE renewal. Successful cultures were prepared using adult mouse basal cells selected for expression of c-KIT. We show that c-KIT signaling regulates self-renewal capacity and prevents neurodifferentiation in culture. Inhibition of TGFβ family signaling,a known negative regulator of embryonic basal cells,is also necessary for maintenance of the proliferative,undifferentiated state in vitro Characterizing successful cultures,we identified expression of BMI1 and other Polycomb proteins not previously identified in olfactory basal cells but known to be essential for self-renewal in other stem cell populations. Inducible fate mapping demonstrates that BMI1 is expressed in vivo by multipotent OE progenitors,validating our culture model. These findings provide mechanistic insights into the renewal and potency of olfactory stem cells. View Publication

Mutations at the steel locus (Sl) of the mouse affect the same cellular targets as mutations at the white spotting locus (W),which is allelic with the c-kit proto-oncogene. We show that KL,a hematopoietic growth factor obtained from conditioned medium of BALB/c 3T3 fibroblasts that stimulates the proliferation of mast cells and early erythroid progenitors,specifically binds to the c-kit receptor. The predicted amino acid sequence of isolated KL-specific cDNA clones suggests that KL is synthesized as an integral transmembrane protein. Linkage analysis maps the KL gene to the Sl locus on mouse chromosome 10,and KL sequences are deleted in the genome of the Sl mouse. These results indicate that the Sl locus encodes the ligand of the c-kit receptor,KL. View Publication

Activating mutations of c-KIT lead to ligand-independent growth. Internal tandem duplications (ITDs) of exon 11,which encodes the juxtamembrane domain (JMD),are constitutively activating mutations found in 7% of gastrointestinal stromal tumors (GISTs) but have not been described in childhood acute myeloid leukemia (AML). DNA and cDNA from 60 children with AML were screened by polymerase chain reaction (PCR) for mutations of the JMD. A complex ITD (kit cITD) involving exon 11 and exon 12 was identified with a relative frequency of 7% (4/60). The human kit cITDs were inserted into the murine c-Kit backbone and expressed in Ba/F3 cells. KIT cITD induced factorindependent growth and apoptosis resistance,and exhibited constitutive autophosphorylation. KIT cITD constitutively activated the PI3K/AKT pathway and phosphorylated STAT1,STAT3,STAT5,and SHP-2. Imatinib (IM) or rapamycin (Rap) led to complete inhibition of growth,with IC50 values at nanomolar levels. IM and Rap synergistically inhibited growth and surmounted KIT cITD-induced apoptosis resistance. IM but not LY294002 inhibited phosphorylation of STAT3 and STAT5,suggesting aberrant cross talk between PI3K- and STAT-activating pathways. The findings presented may have immediate therapeutic impact for a subgroup of childhood AML-expressing c-KIT mutations. View Publication