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PubMed1978

Compound impulse response for the brain stem derived through combinations of cochlear and brain stem recordings.

To overcome some of the problems involved in the application of brain stem evoked responses (BSER) in otoneurological diagnosis an approach is developed which combines cochlear and brain stem recordings. The activity of the cochlea and brain stem generators, as seen from the far-field recording electrode, is considered to be the output from a single system. The impulse response of this system can be derived through deconvolution of the brain stem evoked responses, BSER, with the compound action potential, AP, followed by appropriate filtering. This method is used on the recordings from 15 subjects with various degrees of cochlear hearing loss. The results show that the compound impulse response, CIR, for the brain stem consists of five recognizable peaks. From the individual subjects this response pattern is largely independent of intensity. By plotting the amplitude and latency of the individual peaks for all 15 subjects a set of normative data is retrieved. The variation in the data is small, probably because interfeerence from the periphery is eliminated and the separation of activity from the different brain stem generators is improved.

Audiometry↗
PubMed1979

Antibodies against pluripotent stem cells: their use in studying stem cell function.

The biologic characteristics and specificity of rabbit anti-mouse brain (RAMB) serum for pluripotent hemopoietic stem cells (CFU-s) is reviewed. The application of RAMB serum to the functional analysis of stem cell differentiation and self renewal characteristics is discussed. Preliminary data are presented which suggest the existence of two stem cell subcompartments. The majority of stem cells express membrane determinants that are detected by RAMB serum. A minor (5%-10%) stem cell subpopulation lacks the stem cell antigen and exhibits a greater self-renewal capacity than those cells expressing the antigen.

Animals↗
PubMed1996

[Autologous stem cell transplantation. From bone marrow to selected blood stem cells: 100 consecutive procedures at a single center].

One hundred consecutive autologous stem cell transplants are reported: Non-Hodgkin's lymphoma 51 cases, Hodgkin's disease 27 cases, acute leukaemia 14 cases, multiple myeloma seven cases and chronic myeloid leukaemia one case. Most patients were in their second or later remission. The overall three-year survival for all patients was 60% and the three-year disease-free survival was 50% for lymphoma patients and 30% for acute leukaemia patients. The dominant source of stem cells was bone marrow during 1993, but from 1994 it has been peripheral blood, now totalling 33 cases. There were 12 toxic deaths, all among patients who were heavily treated before bone marrow harvest and transplantation. The patients transplanted with blood stem cells had significantly shorter duration of pancytopenia, and hospital stay, but their disease-free survival was not longer than that of a comparable group of bone marrow transplanted patients. Six patients were transplanted with purified CD34+ cells (selected by avidity column (Ceprate (R)), and had duration of thrombocytopenia and hospital stay similar to the patients transplanted with unmanipulated blood stem cells, but slightly longer duration of neutropenia. We conclude that high-dose therapy with autologous stem cell transplantation in not too heavily pretreated patients is a safe procedure irrespective of the source of stem cells.

Adolescent↗
PubMed2002

Absence of donor-derived keratinocyte stem cells in skin tissues cultured from patients after mobilized peripheral blood hematopoietic stem cell transplantation.

OBJECTIVE: Recent studies suggest that primitive bone marrow-derived cells contribute to regeneration of many tissues, including muscle, endothelium, myocardium, neural tissues, liver, and skin. Conversely, primitive cells resident in muscle and other tissues have been reported to reconstitute hematopoiesis. We investigated the contribution of cells with a primitive hematopoietic phenotype to human epidermal skin formation in recipients of allogeneic mobilized peripheral blood hematopoietic stem cell (HSC) transplantation. PATIENTS AND METHODS: Our study population included female patients who had received granulocyte colony-stimulating factor mobilized peripheral blood HSC transplants from male donors for a variety of benign and malignant hematologic disorders at least 6 months before study entry, with a history of skin graft-vs-host disease. Epidermal skin cells (keratinocytes) obtained from punch biopsies of the skin were cultured under conditions specific for growth and expansion of homogenous populations of keratinocytes from keratinocyte stem cells. After multiple passages, DNA was extracted from cultured cells and evaluated by two different polymerase chain reaction (PCR) method for detection of Y chromosome specific sequences. RESULTS: Neither sensitive PCR-based technique revealed the presence of male donor-derived keratinocyte stem cells in keratinocytes cultured from skin biopsies of female allogeneic transplantation recipients. CONCLUSIONS: We could not confirm the contribution of donor mobilized peripheral blood hematopoietic stem cells to keratinocyte stem cell populations after HSC transplantation. These results cannot explain the presence of donor-derived cells with keratinocyte phenotypic markers in tissue sections of HSC transplant recipients.

Adult↗
PubMed2005

Change in stem cell source for hematopoietic stem cell transplantation (HSCT) in Europe: a report of the EBMT activity survey 2003.

This EBMT activity survey presents the status of hematopoietic stem cell transplantation (HSCT) in Europe 2003 and focuses on changes in stem cell source over the last decade. There were 21 028 first HSCT, 7091 allogeneic (34%), 13 937 autologous (66%) and 4179 additional re- or multiple transplants reported from 597 centers in 42 European countries in the year 2003. Main indications were leukemias (6613 (31%; 78% allogeneic)); lymphomas (11 571 (55%; 93% autologous)); solid tumors (1792 (9%; 92% autologous)) and nonmalignant disorders (898 (5%; 93% allogeneic)). In 1991, the vast majority of autologous and all allogeneic HSCT were still bone marrow (BM) transplants. Stem cell source changed rapidly to peripheral blood (PB) for autologous HSCT between 1992 and 1996. In 2003, 97% of autologous HSCT were PB derived. The change to PB for allogeneic HSCT followed 3 years later and occurred at a lower rate. In 2003, 65% of all allogeneic HSCT were PB derived. The change in stem cell source was not homogeneous. It was associated with donor type, main diagnosis, disease stage and it differed between European countries. In 2003, bone marrow remains a significant source of stem cells in some European countries for autologous HSCT and for nonmalignant disorders in allogeneic HSCT.

Bone Marrow Transplantation↗
PubMed2004

Mesenchymal stem cells are present in peripheral blood and can engraft after allogeneic hematopoietic stem cell transplantation.

BACKGROUND AND OBJECTIVES: Whether human mesenchymal stem cells (MSC) can be transplanted is controversial and their presence in peripheral blood is not fully accepted. In the present study we have analyzed whether, within the allogeneic transplantation setting, MSC are of host or donor origin. DESIGN AND METHODS: Bone marrow MSC from 19 patients who had undergone allogeneic transplantation were expanded and identified using immunophenotypic markers. After that, chimerism studies were performed using reverse transcription polymerase chain reaction of short tandem repeat (STR) loci. Analyses were carried out at different time-points after transplantation, with a total of 44 samples studied. Bone marrow was used as the source of stem cells for transplantation in 4 cases and peripheral blood in 15 cases. The conditioning regimen was standard in 9 patients and non-myeloablative in 10 patients. RESULTS: Our results show that in the great majority of cases analyzed (17 out 19), MSC were of host origin. However, in 2 patients with multiple myeloma who had received a reduced intensity transplantation using peripheral blood stem cells, MSC were partially of donor origin (60.17% and 26.13% of total MSC). INTERPRETATION AND CONCLUSIONS: These findings indicate that after allogeneic transplantation MSC from the donor can engraft in bone marrow. Moreover, since the stem cells were obtained from peripheral blood, it can be concluded that MSC circulate among mobilized peripheral blood stem cells and can engraft in bone marrow after allogeneic transplantation.

Adipocytes↗
PubMed1993

Stem curvature and load angle influence the initial relative bone-implant motion of cementless femoral stems.

A 6 df measurement system was used to investigate the initial relative bone-implant motion of two types of cementless total hip replacement femoral components-a straight stem and a curved stem. Five pairs of fresh frozen femurs from human cadavers were tested with loads applied to the femoral head at angles characteristic of level walking, stair-climbing, and rising from a chair. The most important findings were that (a) the resultant proximal translations were twice as high with the straight stem as with the curved stem at load angles encountered in stair-climbing and rising from a chair, (b) both stem types had more motion at load angles encountered in stair-climbing and rising from a chair than in level walking, with the increases ranging from 3 to 14-fold, (c) there was as much as 66-fold more motion distally than proximally, and (d) the amount of interface motion varied by 5-fold between the medial and lateral surfaces of the distal part of the implant because of the combined effects of translation and rotation. The amount of initial bone-implant motion of the femoral component was found to be particularly sensitive to off-axis loading; this suggests that stair-climbing and rising from a chair should be avoided in the early postoperative period when a cementless porous-coated femoral stem has been used.

Adult↗
PubMed2005

Comparison between triple-tapered and double-tapered cemented femoral stems in total hip arthroplasty: a prospective study comparing the C-Stem versus the Exeter Universal early results after 5 years of clinical experience.

A prospective study was conducted comparing the early clinical and radiological results between the triple-tapered C-Stem (DePuy International, Leeds, UK) and the double-tapered Exeter Universal (Stryker Howmedica Osteonics, Mahwah, NJ) in cemented total hip arthroplasty. A total of 192 patients (200 hips) received the C-Stem and 189 patients (205 hips) received the Exeter Universal. Average follow-up was 29 and 31 months in the C-Stem and Exeter groups, respectively. From the short-term results, we found similar mean improvements in clinical scores and no difference was noted in the incidence of complications. Average subsidence was comparable (C-Stem, 0.77 mm +/- 0.56; Exeter, 0.82 +/- 0.63). Radiolucencies in the cement-stem and cement-bone interfaces were seen primarily in the proximal zones in both groups. No stems were considered at risk of aseptic loosening and the extent of proximal femoral resorption was comparable.

Aged↗
PubMed1995

The sequence of the stem and flanking sequences at the 3' end of histone mRNA are critical determinants for the binding of the stem-loop binding protein.

Complexes of different electrophoretic mobility containing the stem-loop binding protein, a 45 kDa protein, bound to the stem-loop at the 3' end of histone mRNA, are present in both nuclear and cytoplasmic extracts from mammalian cells. We have determined the effect of changes in the loop, in the stem and in the flanking sequences on the affinity of the SLBP for the 3' end of histone mRNA. The sequence of the stem is particularly critical for SLBP binding. Specific sequences both 5' and 3' of the stem-loop are also required for high-affinity binding. Expanding the four base loop by one or two uridines reduced but did not abolish SLBP binding. RNA footprinting experiments show that the flanking sequences on both sides of the stem-loop are critical for efficient binding, but that cleavages in the loop do not abolish binding. Thus all three regions of the RNA sequence contribute to SLBP binding, suggesting that the 26 nt at the 3' end of histone mRNA forms a defined tertiary structure recognized by the SLBP.

Animals↗
PubMed2005

Influence of stem geometry on the stability of polished tapered cemented femoral stems.

Polished, tapered stems are now widely used for cemented total hip replacement and many such designs have been introduced. However, a change in stem geometry may have a profound influence on stability. Stems with a wide, rectangular proximal section may be more stable than those which are narrower proximally. We examined the influence of proximal geometry on stability by comparing the two-year migration of the Exeter stem with a more recent design, the CPS-Plus, which has a wider shoulder and a more rectangular cross-section. The hypothesis was that these design features would increase rotational stability. Both stems subsided approximately 1 mm relative to the femur during the first two years after implantation. The Exeter stem was found to rotate into valgus (mean 0.2 degrees , sd 0.42 degrees ) and internally rotate (mean 1.28 degrees , sd 0.99 degrees ). The CPS-Plus showed no significant valgus rotation (mean 0.07 [correction] degrees, sd 0.29 [correction] degrees ) or internal rotation (mean -0.03 degrees , sd 0.75 degrees ). A wider, more rectangular cross-section improves rotational stability and may have a better long-term outcome.

Aged↗
PubMed2006

[Stem cell therapy. Biology of hematopoietic stem cells].

In recent years much progress has been made in the understanding of the biology of hematopoietic stem cells (HSC) and their involvement in normal blood cell development. Using immunophenotyping it is possible, to enrich HSC, however, so far we are not able to positively select HSC. For the identification, characterization and quantification of HSC it is necessary to use functional assay systems, such as xenotransplantation models. HSC from bone marrow, peripheral blood and in some cases also cord blood have been used for years in transplantation settings especially in patients with leukemia. A better understanding of the mechanisms underlying stem cell regulation as well as stem cell self renewal would have clinical implications e. g. for clinical transplantation strategies. A number of hematological diseases such as chronic myeloid leukemia originates from a malignant transformed HSC. A better understanding of the biology of normal as well as malignant HSC is therefore crucial not only for a better understanding of the disease, but also for the development of strategies aiming at the discrimination of normal and malignant stem cell candidates and the development of therapies targeting the leukemic stem cell.

Cell Transformation, Neoplastic↗
PubMed2006

Allogeneic stem cell transplantation with peripheral blood stem cells mobilized by pegylated G-CSF.

Mobilization of stem cells with pegylated granulocyte colony-stimulating factor (peg-G-CSF) modulates donor T- and natural killer T-cell (NKT-cell) functions, thus separating graft-versus-host from graft-versus-leukemia disease in animal models. We report a phase I/II study that analyzed the feasibility of mobilizing stem cells from normal donors with peg-G-CSF and the ability of these cells to restore hematopoiesis in allogeneic transplant recipients after myeloablative conditioning. Administration of 6 mg of peg-G-CSF resulted in suboptimal stem cell mobilization, with a peak peripheral blood CD34+ count of 29+/-5/microL. Apheresis 4 days after peg-G-CSF yielded 2.7+/-.4x10(6) CD34+ cells/kg recipient weight, and all donors required a second collection on day 5 to yield a total of 4.2+/-.5x10(6) CD34+ cells/kg recipient weight. After escalation of the dose to 12 mg, the peak CD34+ count was 99+/-11/microL and 12 of 13 donors collected sufficient stem cells for transplantation in a single apheresis (8.9+/-1.4x10(6) CD34+ cells/kg recipient weight). Late transient increases in serum hepatic transaminases were noted, but other side effects (predominantly bone pain) were otherwise similar to those seen in donors mobilized with standard G-CSF. Median neutrophil and platelet engraftments occurred on days 18 and 14, respectively, after transplantation and were identical to those seen with in recipients of grafts mobilized with standard G-CSF. With a median follow-up of 357 days, the incidence of grade II-IV acute graft-versus-host disease was 50% and there have been no relapses to date. Mobilization of stem cells with peg-G-CSF in normal donors is feasible and 12 mg results in mobilization characteristics similar to those of standard G-CSF.

Adult↗
PubMed2006

Peripheral blood stem cell mobilization: the CXCR2 ligand GRObeta rapidly mobilizes hematopoietic stem cells with enhanced engraftment properties.

Chemokines direct the movement of leukocytes, including hematopoietic stem and progenitor cells, and can mobilize hematopoietic cells from marrow to peripheral blood where they can be used for transplantation. In this review, we will discuss the stem cell mobilizing activities and mechanisms of action of GRObeta, a CXC chemokine ligand for the CXCR2 receptor. GRObeta rapidly mobilizes short- and long-term repopulating cells in mice and/or monkeys and synergistically enhances mobilization responses when combined with the widely used clinical mobilizer, granulocyte colony-stimulating factor (G-CSF). The hematopoietic graft mobilized by GRObeta contains significantly more CD34(neg), Sca-1+, c-kit+, lineage(neg) (SKL) cells than the graft mobilized by G-CSF. In mice, stem cells mobilized by GRObeta demonstrate a competitive advantage upon long-term repopulation analysis and restore neutrophil and platelet counts significantly faster than cells mobilized by G-CSF. Even greater advantage in repopulation and restoration of hematopoiesis are observed with stem cells mobilized by the combination of GRObeta and G-CSF. GRObeta-mobilized SKL cells demonstrate enhanced adherence to vascular cell adhesion molecule-1 and VCAM(pos) endothelial cells and home more efficiently to bone marrow in vivo. The marrow homing ability of GRObeta-mobilized cells is less dependent on the CXCR4/SDF-1 axis than cells mobilized by G-CSF. The mechanism of mobilization by GRObeta requires active matrix metalloproteinase-9 (MMP-9), which results from release of pro-MMP-9 from peripheral blood, and marrow neutrophils, which alters the stoichiometry between pro-MMP-9 and its inhibitor tissue inhibitor of metalloproteinase-1, resulting in MMP-9 activation. The efficacy and rapid action of GRObeta and lack of proinflammatory activity make it an attractive agent to supplement mobilization by G-CSF. In addition, GRObeta may also have clinical mobilizing efficacy on its own, reducing the overall time and costs associated with peripheral blood stem cell transplantation.

Animals↗
PubMed2006

Acute injury directs the migration, proliferation, and differentiation of solid organ stem cells: evidence from the effect of hypoxia-ischemia in the CNS on clonal "reporter" neural stem cells.

Clonal neural cells with stem-like features integrate appropriately into the developing and degenerating central and peripheral nervous system throughout the neuraxis. In response to hypoxic-ischemic (HI) injury, previously engrafted, integrated, and quiescent clonal neural stem cells (NSCs) transiently re-enter the cell cycle, migrate preferentially to the site of ischemia, and differentiate into neurons and oligodendrocytes, the neural cell types typically lost following HI brain injury. They also replenish the supply of immature uncommitted resident stem/progenitor cells. Although they yield astrocytes, scarring is inhibited. These responses appear to occur most robustly within a 3-7 day "window" following HI during which signals are elaborated that upregulate genetic programs within the NSC that mediate proliferation, migration, survival, and differentiation, most of which appear to be terminated once the "window closes" and the chronic phase ensues, sending the NSCs into a quiescent state. These insights derived from using the stem cell in a novel role--as a "reporter" cell--to both track and probe the activity of endogenous stem cells as well as to "interrogate" and "report" the genes differentially induced by the acutely vs. chronically injured milieu. NSCs may be capable of the replacement of cells, genes, and non-diffusible factors in both a widespread or more circumscribed manner (depending on the therapeutic demands of the clinical situation). They may be uniquely responsive to some types of neurodegenerative conditions. We submit that these various capabilities are simply the normal expression of the basic homeostasis-preserving biologic properties and attributes of a stem cell which, if used rationally and in concert with this biology, may be exploited for therapeutic ends.

Animals↗
PubMed2004

Stem cell factor is a chemoattractant and a survival factor for CNS stem cells.

Migration of neural cells to their final positions is crucial for the correct formation of the central nervous system. Several extrinsic factors are known to be involved in the regulation of neural migration. We asked if stem cell factor (SCF), well known as a chemoattractant and survival factor in the hematopoietic lineage, could elicit similar responses in neural stem cells. For that purpose, a microchemotaxis assay was used to study the effect of SCF on migration of neural stem cells from the embryonic rat cortex. Our results show that SCF-induced chemotaxis and that specific antibodies to SCF or tyrosine kinase inhibitors abolished the migratory response. The SCF-receptor, Kit, was expressed in neural stem cells and in their differentiated progeny. We also show that SCF is a survival factor, but not a mitogen or a differentiation factor for neural stem cells. These data suggest a role for SCF in cell migration and survival in the developing cortex.

Animals↗
PubMed2006

The continuum of stem cell transdifferentiation: possibility of hematopoietic stem cell plasticity with concurrent CD45 expression.

Recent years have seen a surge of scientific research examining adult stem cell plasticity. For example, the hematopoietic stem cell has been shown to give rise to skin, respiratory epithelium, intestinal epithelium, renal epithelium, liver parenchyma, pancreas, skeletal muscle, vascular endothelium, myocardium, and central nervous system (CNS) neurons. The potential for such stem cell plasticity seems to be enhanced by stressors such as injury and neoplasia. Interestingly, recent studies have demonstrated that hematopoietic stem cells may be able to adopt certain nonhematopoietic phenotypes, such as endothelial, neural, or skeletal muscle phenotypes, without entirely losing their initial hematopoietic identity. We propose that transdifferentiation can, in certain conditions, be a partial rather than a complete event, and we encourage further investigation into the phenomenon of a stem cell simultaneously expressing phenotypic features of two distinct cell fates.

Adult↗
PubMed2005

Tumorigenic heterogeneity in cancer stem cells evolved from long-term cultures of telomerase-immortalized human mesenchymal stem cells.

Long-term cultures of telomerase-transduced adult human mesenchymal stem cells (hMSC) may evolve spontaneous genetic changes leading to tumorigenicity in immunodeficient mice (e.g., hMSC-TERT20). We wished to clarify whether this unusual phenotype reflected a rare but dominant subpopulation or if the stem cell origin allowed most cells to behave as cancer stem cells. Cultures of the hMSC-TERT20 strain at population doubling 440 were highly clonogenic (94%). From 110 single-cell clones expanded by 20 population doublings, 6 underwent detailed comparison. Like the parental population, each clone had approximately 1.2 days doubling time with loss of contact inhibition. All retained 1,25-(OH)(2) vitamin D(3)-induced expression of osteoblastic markers: collagen type I, alkaline phosphatase, and osteocalcin. All shared INK4a/ARF gene locus deletion and epigenetic silencing of the DBCCR1 tumor suppressor gene. Despite in vitro commonality, only four of six clones shared the growth kinetics and 100% tumorigenicity of the parental population. In contrast, one clone consistently formed latent tumors and the other established tumors with only 30% penetrance. Changing the in vitro microenvironment to mimic in vivo growth aspects revealed concordant clonal heterogeneity. Latent tumor growth correlated with extracellular matrix entrapment of multicellular spheroids and high procollagen type III expression. Poor tumorigenicity correlated with in vitro serum dependence and high p27(Kip1) expression. Aggressive tumorigenicity correlated with good viability plus capillary morphogenesis on serum starvation and high cyclin D1 expression. Thus, hMSC-TERT20 clones represent cancer stem cells with hierarchical tumorigenicity, providing new models to explore the stem cell hypothesis for cancer.

Adult↗
PubMedDate not supplied

Effects of extracellular matrices on F9 teratocarcinoma stem cells: a crucial role of type IV collagen in the early stage of differentiation of F9 stem cells.

F9 teratocarcinoma stem cells treated with retinoic acid (RA) differentiate into visceral endoderm, and this process affects the expression of some extracellular matrix (ECM) proteins. As the direct influence of ECM molecules on the differentiation of F9 stem cells has not been studied, we investigated the effects of various ECM proteins on the early differentiation of these cells. Monolayers of F9 stem cells were cultured on dishes coated with various ECM, such as type I or IV collagen, fibronectin, or laminin. They aggregated and formed spheroid bodies in the absence of RA only on type IV collagen. The outer layer cells of the spheroid bodies exhibited numerous microvilli, junctional complexes and mature cell organelles. Alpha-fetoprotein was positive in the outer layer cells. A small amount of laminin was detected in the matrix of the spheroid bodies. These data suggest that type IV collagen promoted the early stage of the differentiation of F9 stem cells without RA. The other ECM molecules failed to induce them to form spheroid bodies. The reversibility of the structure of the spheroid bodies to a monolayer was also examined. When the spheroid bodies were reseeded only on fibronectin- or laminin-coated culture dishes, they broke down and the cells spread to the surface in the absence of RA. The differentiation of F9 stem cells induced by type IV collagen seemed to be reversible and to take place at an early stage of their morphogenesis. These findings suggest that type IV collagen plays an important role in early embryogenesis.

Animals↗