Biomedical subjects

Shlomit Reich-Zeliger

Publications and source records attributed to Shlomit Reich-Zeliger.

10 recordsLinked to original sources

PubMed2006

Isolation and characterization of nontubular sca-1+lin- multipotent stem/progenitor cells from adult mouse kidney.

Tissue engineering and cell therapy approaches aim to take advantage of the repopulating ability and plasticity of multipotent stem cells to regenerate lost or diseased tissue. Recently, stage-specific embryonic kidney progenitor tissue was used to regenerate nephrons. Through fluorescence-activated cell sorting, microarray analysis, in vitro differentiation assays, mixed lymphocyte reaction, and a model of ischemic kidney injury, this study sought to identify and characterize multipotent organ stem/progenitor cells in the adult kidney. Herein is reported the existence of nontubular cells that express stem cell antigen-1 (Sca-1). This population of small cells includes a CD45-negative fraction that lacks hematopoietic stem cell and lineage markers and resides in the renal interstitial space. In addition, these cells are enriched for beta1-integrin, are cytokeratin negative, and show minimal expression of surface markers that typically are found on bone marrow-derived mesenchymal stem cells. Global gene profiling reveals enrichment for many genes downstream of developmental signaling molecules and self-renewal pathways, such as TGF-beta/bone morphogenic protein, Wnt, or fibroblast growth factor, as well as for those that are involved in specification of mesodermal lineages (myocyte enhancer factor 2A, YY1-associated factor 2, and filamin-beta). In vitro, they are plastic adherent and slowly proliferating and result in inhibition of alloreactive CD8(+) T cells, indicative of an immune-privileged behavior. Furthermore, clonal-derived lines can be differentiated into myogenic, osteogenic, adipogenic, and neural lineages. Finally, when injected directly into the renal parenchyma, shortly after ischemic/reperfusion injury, renal Sca-1(+)Lin(-) cells, derived from ROSA26 reporter mice, adopt a tubular phenotype and potentially could contribute to kidney repair. These data define a unique phenotype for adult kidney-derived cells, which have potential as stem cells and may contribute to the regeneration of injured kidneys.

Animals↗

PubMed2005

Hematopoietic stem cell transplantation across major genetic barriers: tolerance induction by megadose CD34 cells and other veto cells.

Studies in mice and humans demonstrate that transplantation of hematopoietic progenitors in numbers larger than commonly used overcomes major genetic barriers. In vitro studies suggest that veto cells, within the population of hematopoietic progenitors, facilitate this favorable outcome. Tolerance induction can be further enhanced by other veto cells. Perhaps the most potent veto cell is the CD8(+) CTL. However, this cell is also associated with marked GVHD, which can be separated from the veto activity by generating anti-third party CTLs under IL-2 deprivation.

Animals↗

PubMed2004

Tolerance induction by veto CTLs in the TCR transgenic 2C mouse model. I. Relative reactivity of different veto cells.

Several bone marrow cells and lymphocyte subpopulations, known as veto cells, were shown to induce transplantation tolerance across major histocompatibility Ags. Due to the low frequency of the effector T cells against which the veto cells inhibitory activity is aimed, the fate of the effector cells was traditionally followed indirectly by functional limiting dilution assays, which are cumbersome and depend on numerous parameters. In the present study the fate of the effector T cells was monitored directly by FACS, using TCR transgenic mouse CD8(+) T cells in which the transgene is directed against H-2(d) (the 2C model). This assay is validated by demonstrating the potency, selectivity, radiation sensitivity, and contact dependency of anti-third-party CTLs previously demonstrated by the limiting dilution assay. In contrast to veto CTLs, nonactivated CD8(+) T cells lack veto activity. Comparison by FACS in the 2C model revealed a hierarchy of veto cells, in the order of veto CTLs activated NK cells, activated CD4(+) T cells, and activated B cells. The latter cells as well as nonactivated CD4(+) or NK cells were shown to be completely devoid of veto activity.

Animals↗

PubMed2004

Tolerance induction by veto CTLs in the TCR transgenic 2C mouse model. II. Deletion of effector cells by Fas-Fas ligand apoptosis.

The direct assay of veto CTLs in the 2C mouse model enables monitoring, by FACS, the fate of the TCR transgenic effector CD8(+) T cells, the transgene of which can be stained with clonotypic Ab 1B2. After the addition of veto cells, CD8(+)1B2(+) effector cells increasingly express annexin V, and maximal apoptosis is attained 72 h after initiation of MLR. This veto activity can be partially blocked by anti-CD8 Abs directed against the allele expressed by the veto CTLs, but not by the effector cells. When effector CD8(+) T cells were from 2C mice, which lack Fas expression ((2CX lpr)F(2)), deletion of effector cells was not exhibited by veto cells. The protein levels of the apoptosis inhibitors FLIP and Bcl2 in purified CD8(+)1B2(+) effector cells at different time points after MLR showed an initial up-regulation of these inhibitors, with marked reduction of FLIP, but not of Bcl2, by 48 h after initiation of culture. Taken together, these results are in accordance with a Fas-FasL-based mechanism in which prolonged binding between the effector cell and the veto cell might be required to allow FLIP to be down-regulated. Such prolonged interaction might be afforded through the interaction of CD8 molecules on the veto cell with the alpha3 domain of H2 class 1 on the effector cell.

Animals↗

PubMed2004

Expression of FasL by tumor cells does not abrogate anti-tumor CTL function.

The effects of Fas-ligand (FasL) expression by tumor cells on their tumorigenicity and immunogenicity have been reported as opposite, contradictory results. In some systems the killing of Fas positive cytotoxic T-cells (CTL) by FasL expressing tumors resulted in increased tumorigenicity while in other systems tumors expressing FasL were eliminated by neutrophil mediated inflammation. In the present study, we investigated how FasL expression influences the low immunogenic Lewis lung carcinoma clone D122 and its highly immunogenic MHC I (H-2Kb) and B7-1 (CD80) transfectant 39.5-B7, by transfecting the human FasL (FasL) gene into these cells. Despite the fact that FasL-expressing cells kill effectively appropriate target cells (L1210-fas) compared to parental cells (D122) and low expressors (DFasL-33), these tumor cells were completely rejected in syngeneic mice (C57BL/6), but not in Fas mutant B6-MRL mice, suggesting that functional Fas receptor expression in the host was required to induce an anti-tumor mechanism. In addition, although FasL-expressing immunogenic tumor cells (39.5-B7-FasL 7) kill effectively target cells in vitro, both the transfectant and the mock transfectant (39.5-B7-pBabe) were rejected in syngenic mice. The sensitivity of FasL expressing tumor cells to lysis by CTLs was similar to that of FasL non-expressors. Therefore, these results indicate that FasL expression on immunogenic tumor cells does not affect their immunogenicity in vivo, as well as CTL functions in vitro.

Animals↗

PubMed2003

Anti-third-party veto CTLs overcome rejection of hematopoietic allografts: synergism with rapamycin and BM cell dose.

Several bone marrow cells and lymphocyte subpopulations, known as "veto cells," were shown to induce transplantation tolerance across major histocompatibility antigens. Some of the most potent veto cells are of T-cell origin, and in particular a very strong veto activity was documented for cytotoxic T-lymphocyte (CTL) lines or clones. However, these cells also possess marked graft-versus-host (GVH) reactivity. In the present study we evaluated a new approach to deplete CTLs of antihost clones by stimulating the donor T cells against third-party stimulators in the absence of exogenous interleukin 2 (IL-2). We demonstrate that such CTLs are depleted of GVH reactivity while maintaining marked veto activity in vitro. Furthermore, marked synergism was exhibited between the veto CTLs and rapamycin when tested in a murine model, which measures T-cell-mediated bone marrow allograft rejection, or in sublethally irradiated allogeneic hosts. Our results suggest that engraftment of early progenitors could be enhanced by using host-nonreactive anti-third-party CTLs, in conjunction with nonmyeloablative rapamycin-based conditioning protocols, thereby significantly reducing the toxicity of allogeneic transplantation.

Animals↗

PubMed2003

Hematopoietic stem cell transplantation across major genetic barriers: tolerance induction by megadose CD34 cells and other veto cells.

Studies in mice and humans demonstrate that transplantation of hematopoietic progenitors in numbers larger than commonly used ("megadose" transplants) overcomes major genetic barriers. In vitro studies suggest that veto cells, within the population of hematopoietic progenitors, facilitate this favorable outcome. Thus, when purified CD34(+) cells were added to bulk mixed-lymphocyte reactions (MLRs) they suppressed CTLs against the donor's stimulators, but not against stimulators from a third party. This tolerizing activity depends on cell contact and can be blocked by the caspase inhibitor BD-FMK, suggesting that the effector host T cells are deleted by apoptosis upon interaction with the CD34(+) cells. Early myeloid CD33(+) cells generated by short-term ex vivo expansion of CD34(+) cells also exhibit veto activity, and these cells can be grown in large numbers. Tolerance induction can be further enhanced by other veto cells. Perhaps the most potent veto cell is the CD8+ CTL. However, this cell is also associated with marked GVHD (graft-versus-host disease. GVHD can be separated from the veto activity by generating anti-third party CTLs under IL2 deprivation. Under such selective pressure only the stimulated clones which make IL2 can survive, while anti-host clones die. In vivo studies show that such anti-third party veto CTLs can be used safely for tolerance induction without GVHD.

Animals↗

PubMed2002

Human and porcine early kidney precursors as a new source for transplantation.

Kidney transplantation has been one of the major medical advances of the past 30 years. However, tissue availability remains a major obstacle. This can potentially be overcome by the use of undifferentiated or partially developed kidney precursor cells derived from early embryos and fetal tissue. Here, transplantation in mice reveals the earliest gestational time point at which kidney precursor cells, of both human and pig origin, differentiate into functional nephrons and not into other, non-renal professional cell types. Moreover, successful organogenesis is achieved when using the early kidney precursors, but not later-gestation kidneys. The formed, miniature kidneys are functional as evidenced by the dilute urine they produce. In addition, decreased immunogenicity of the transplants of early human and pig kidney precursors compared with adult kidney transplants is demonstrated in vivo. Our data pinpoint a window of human and pig kidney organogenesis that may be optimal for transplantation in humans.

Adult↗

PubMed2002

T cells from newborn humans are fully capable of developing into cytotoxic T lymphocyte effector cells in adoptive hosts.

BACKGROUND: The finding of reduced incidence of graft-versus-host disease (GVHD) associated with cord blood transplantation, compared to unrelated allogeneic bone marrow, could be related to the lower number of T cells infused in the cord blood (CB) inoculum or it might represent an intrinsic property of CB T cells. We investigated the in vivo function of human cord blood mononuclear cells (CBMC) after their adoptive transfer into lethally irradiated BALB/c radioprotected with severe combined immunodeficiency (SCID) mouse bone marrow. METHODS: The ability of human CBMC to engraft and produce antigen-specific alloreactive cytotoxic T lymphocytes (CTLs) and antibodies was determined by FACS, 51Chromium-release assay, and ELISA. RESULTS: Recipients of human CBMC showed engraftment of high levels of both CD14+ and CD3+ cells. Human cells recovered from the peritoneal cavity of chimeric mice, 1 week after immunization with irradiated allogeneic cells, showed adult-level human CTL response against the immunizing cells, without further stimulation in vitro. In contrast, immunization with the tetanus (TT) antigen did not lead to the generation of anti-TT immunoglobulins (Ig) in the cord blood chimera. Furthermore, whereas the addition of purified adult T cells to the cord blood inoculum resulted in the enhancement of human Ig production of both IgG and IgM subclasses, it could not induce antigen-specific antibodies after immunization. CONCLUSION: This report demonstrates in mice for the first time the generation of classical human alloreactive CTLs, derived from cord blood cells. The alloreactivity exhibited by the cord blood mononuclear cells is not different from that displayed by cells originating from adult blood. Any reduction in the observed GVHD associated with cord blood transplants might therefore represent a quantitative difference in the total number of T cells infused.

Adoptive Transfer↗

PubMedDate not supplied

Crossing the HLA barriers.

Studies in mice and humans demonstrate that transplantation of hematopoietic progenitors in numbers larger than commonly used ("megadose" transplants) overcomes major genetic barriers. In vitro studies suggest that veto cells, within the population of hematopoietic progenitors, facilitate this favorable outcome. Thus, when purified CD34+ cells were added to bulk mixed-lymphocyte reactions (MLRs), they suppressed CTLs against donor's stimulators but not against stimulators from a third party. This tolerizing activity depends on cell contact and can be blocked by the caspase inhibitor BD-FMK, suggesting that the effector host T cells are deleted by apoptosis upon interaction with the CD34+ cells. Early myeloid CD33+ cells generated by short-term ex vivo expansion of CD34+ cells also exhibit veto activity, and these cells can be grown in large numbers. Tolerance induction can be further enhanced by other veto cells. Perhaps the most potent veto cell is the CD8+ CTL. However, this cell is also associated with marked graft-versus-host disease (GVHD). GVHD can be separated from the veto activity by generating anti-third party CTLs under IL2 deprivation. Under such selective pressure, only the stimulated clones which make IL2 can survive, while anti-host clones die. In vivo studies show that such anti-third party veto CTLs can be used safely for tolerance induction without GVHD.

Animals↗