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Innate immune barrier to the engraftment of prenatally transplanted embryonic stem cell derived hematopoietic progenitors
Vol. 203, No. 3S, September 2006
receptor pathways. Taken with our previous observation that that NE enhances bone marrow-derived macrophage phagocytic function, these results point to NE as a tissue-bed specific mediator of innate immunity and a potential immunomodulatory target.
Inhaled nitrite treats experimental pulmonary arterial hypertension Kevin Mollen MD, Augustine Choi MD, Michael Mathier MD, Emeka Ifedigbo, Mark Gladwin MD, Brian Zuckerbraun MD University of Pittsburgh Medical Center, Pittsburgh, PA INTRODUCTION: Pulmonary arterial hypertension (PAH) is a disease of pulmonary arteries characterized by proliferation and remodeling, resulting in an increase in vascular resistance and heart failure. The vasoregulatory and protective role of nitric oxide in PAH has been characterized. The purpose of these studies was to test the hypothesis that inhaled nitrite protects against/reverses PAH. METHODS: C57BL/6 mice were exposed to 10% oxygen for 4 weeks. Animals were randomized to treatment with or without nebulized sodium nitrite (30mg/5ml;1x or 3x/week) on weeks 1-4 (preventive) or weeks 3-4 (therapeutic). On day 29, prior to sacrifice echocardiograms were performed and mean right ventricular pressures were determined. PAH was also assayed by RV:body mass, RV:LV⫹Septal mass, and histology. Pulmonary artery smooth muscle cells (PASMC) were utilized for in vitro experiments. RESULTS: Hypoxia significantly increased RV:LV⫹S mass, RV pressure, and dP/dT compared to normoxic controls (P⬍0.01). Nebulized nitrite treatment (1x/week; weeks1-4) prevented the development of PAH, and therapeutic nebulized nitrite (3X/week; weeks 3-4) reversed established PAH (P⬍0.05). For example, RV: LV⫹S ratios were 0.34⫹/⫺.02 in controls, 0.49⫹/⫺.07 in hypoxic animals, 0.32⫹/⫺.07 in the preventive group, and 0.32⫹/⫺.07 in the therapeutic group. Furthermore, sodium nitrite (5-25uM) significantly decreased PASMC proliferation. CONCLUSIONS: Inhaled nitrite improves hypoxic-induced PAH. Inhaled nitrite may represent a future clinical adjunct in the treatment of PAH.
Pediatric Surgery
S53
Innate immune barrier to the engraftment of prenatally transplanted embryonic stem cell derived hematopoietic progenitors Aimen F Shaaban MD, Lasya Gaur BS, Deepika Rajesh PhD University of Wisconsin School of Medicine and Public Health, Madison, WI INTRODUCTION: The transplantation of embryonic stem cellderived hematopoietic progenitors cells (ESHPC’s) holds great promise for the treatment of numerous diseases. However, this approach is stymied by failure of ESHPC’s to conclusively engraft in allogeneic or xenogeneic hosts. To investigate whether failed engraftment results from incompatibilities with the adult host microenvironment, we studied the homing, proliferation and engraftment of ESHPC’s in the allogeneic fetal murine microenvironment. METHODS: ESHPC’s were harvested from CJ7 murine embryoid bodies (EB’s) at various developmental stages and evaluated for hematopoietic progenitor (CFU) and pluripotent cell content prior to in utero transplantation. RESULTS: Short term assays revealed selective homing and survival of CD45⫹ cell subsets from unenriched day 6 ESHPC’s. CD45⫹ enrichment of ESHPC’s led to retention of hematopoietic CFU’s with loss of pluripotent cells. However, prenatal transplantation of CD45⫹ ESHPC’s led to significant fetal mortality. Elimination of Mac-1⫹ monocyte progenitors but not DX5⫹ NK cells from enriched CD45⫹ ESHPC’s led to dramatically improved recipient survival suggesting fetal loss resulted from a macrophage-mediated graft vs. host response. However, the transplantation of CD45⫹Mac-1- ESHPC’s resulted in only microchimerism. Similarly, when co-cultured in vitro with lymphocyte-depleted but macrophage replete allogeneic fetal liver stroma, poor survival of ESHPC’s was seen despite excellent survival in media alone. CONCLUSIONS: These findings suggest the existence of an innate immune barrier to the engraftment of prenatally transplanted allogeneic ESHPC’s. Future studies are needed to better characterize the response of fetal macrophages to allogeneic ESHPC’s.
receptor pathways. Taken with our previous observation that that NE enhances bone marrow-derived macrophage phagocytic function, these results point to NE as a tissue-bed specific mediator of innate immunity and a potential immunomodulatory target.
Inhaled nitrite treats experimental pulmonary arterial hypertension Kevin Mollen MD, Augustine Choi MD, Michael Mathier MD, Emeka Ifedigbo, Mark Gladwin MD, Brian Zuckerbraun MD University of Pittsburgh Medical Center, Pittsburgh, PA INTRODUCTION: Pulmonary arterial hypertension (PAH) is a disease of pulmonary arteries characterized by proliferation and remodeling, resulting in an increase in vascular resistance and heart failure. The vasoregulatory and protective role of nitric oxide in PAH has been characterized. The purpose of these studies was to test the hypothesis that inhaled nitrite protects against/reverses PAH. METHODS: C57BL/6 mice were exposed to 10% oxygen for 4 weeks. Animals were randomized to treatment with or without nebulized sodium nitrite (30mg/5ml;1x or 3x/week) on weeks 1-4 (preventive) or weeks 3-4 (therapeutic). On day 29, prior to sacrifice echocardiograms were performed and mean right ventricular pressures were determined. PAH was also assayed by RV:body mass, RV:LV⫹Septal mass, and histology. Pulmonary artery smooth muscle cells (PASMC) were utilized for in vitro experiments. RESULTS: Hypoxia significantly increased RV:LV⫹S mass, RV pressure, and dP/dT compared to normoxic controls (P⬍0.01). Nebulized nitrite treatment (1x/week; weeks1-4) prevented the development of PAH, and therapeutic nebulized nitrite (3X/week; weeks 3-4) reversed established PAH (P⬍0.05). For example, RV: LV⫹S ratios were 0.34⫹/⫺.02 in controls, 0.49⫹/⫺.07 in hypoxic animals, 0.32⫹/⫺.07 in the preventive group, and 0.32⫹/⫺.07 in the therapeutic group. Furthermore, sodium nitrite (5-25uM) significantly decreased PASMC proliferation. CONCLUSIONS: Inhaled nitrite improves hypoxic-induced PAH. Inhaled nitrite may represent a future clinical adjunct in the treatment of PAH.
Pediatric Surgery
S53
Innate immune barrier to the engraftment of prenatally transplanted embryonic stem cell derived hematopoietic progenitors Aimen F Shaaban MD, Lasya Gaur BS, Deepika Rajesh PhD University of Wisconsin School of Medicine and Public Health, Madison, WI INTRODUCTION: The transplantation of embryonic stem cellderived hematopoietic progenitors cells (ESHPC’s) holds great promise for the treatment of numerous diseases. However, this approach is stymied by failure of ESHPC’s to conclusively engraft in allogeneic or xenogeneic hosts. To investigate whether failed engraftment results from incompatibilities with the adult host microenvironment, we studied the homing, proliferation and engraftment of ESHPC’s in the allogeneic fetal murine microenvironment. METHODS: ESHPC’s were harvested from CJ7 murine embryoid bodies (EB’s) at various developmental stages and evaluated for hematopoietic progenitor (CFU) and pluripotent cell content prior to in utero transplantation. RESULTS: Short term assays revealed selective homing and survival of CD45⫹ cell subsets from unenriched day 6 ESHPC’s. CD45⫹ enrichment of ESHPC’s led to retention of hematopoietic CFU’s with loss of pluripotent cells. However, prenatal transplantation of CD45⫹ ESHPC’s led to significant fetal mortality. Elimination of Mac-1⫹ monocyte progenitors but not DX5⫹ NK cells from enriched CD45⫹ ESHPC’s led to dramatically improved recipient survival suggesting fetal loss resulted from a macrophage-mediated graft vs. host response. However, the transplantation of CD45⫹Mac-1- ESHPC’s resulted in only microchimerism. Similarly, when co-cultured in vitro with lymphocyte-depleted but macrophage replete allogeneic fetal liver stroma, poor survival of ESHPC’s was seen despite excellent survival in media alone. CONCLUSIONS: These findings suggest the existence of an innate immune barrier to the engraftment of prenatally transplanted allogeneic ESHPC’s. Future studies are needed to better characterize the response of fetal macrophages to allogeneic ESHPC’s.