15 research outputs found
Hyperbaric oxygen improves engraftment of ex-vivo expanded and gene transduced human CD34+ cells in a murine model of umbilical cord blood transplantation
Delayed engraftment and graft failure represent major obstacles to successful umbilical cord blood (UCB) transplantation. Herein, we evaluated the use of hyperbaric oxygen (HBO) therapy as an intervention to improve human UCB stem/progenitor cell engraftment in an immune deficient mouse model. Six-to eight-week old NSG mice were sublethally irradiated 24 hours prior to CD34+ UCB cell transplant. Irradiated mice were separated into a non-HBO group (where mice remained under normoxic conditions) and the HBO group (where mice received two hours of HBO therapy; 100% oxygen at 2.5 atmospheres absolute). Four hours after completing HBO therapy, both groups intravenously received CD34+ UCB cells that were transduced with a lentivirus carrying luciferase gene and expanded for in vivo imaging. Mice were imaged and then sacrificed at one of 10 times up to 4.5 months post-transplant. HBO treated mice demonstrated significantly improved bone marrow, peripheral blood , and spleen (p=0.0293) retention and subsequent engraftment. In addition, HBO significantly improved peripheral, spleen and bone marrow engraftment of human myeloid and B-cell subsets. In vivo imaging demonstrated that HBO mice had significantly higher ventral and dorsal bioluminescence values. These studies suggest that HBO treatment of NSG mice prior to UCB CD34+ cell infusion significantly improves engraftment
PPARĪ±-Independent Arterial Smooth Muscle Relaxant Effects of PPARĪ± Agonists
We sought to determine direct vascular effects of peroxisome proliferator-activated receptor alpha (PPARĪ±) agonists using isolated mouse aortas and middle cerebral arteries (MCAs). The PPARĪ± agonists GW7647, WY14643, and gemfibrozil acutely relaxed aortas held under isometric tension and dilated pressurized MCAs with the following order of potency: GW7647ā«WY14643>gemfibrozil. Responses were endothelium-independent, and the use of PPARĪ± deficient mice demonstrated that responses were also PPARĪ±-independent. Pretreating arteries with high extracellular K+ attenuated PPARĪ± agonist-mediated relaxations in the aorta, but not in the MCA. In the aorta, the ATP sensitive potassium (KATP) channel blocker glibenclamide also impaired relaxations whereas the other K+ channel inhibitors, 4-aminopyridine and Iberiotoxin, had no effect. In aortas, GW7647 and WY14643 elevated cGMP levels by stimulating soluble guanylyl cyclase (sGC), and inhibition of sGC with ODQ blunted relaxations to PPARĪ± agonists. In the MCA, dilations were inhibited by the protein kinase C (PKC) activator, phorbol 12,13-dibutyrate, and also by ODQ. Our results demonstrated acute, nonreceptor-mediated relaxant effects of PPARĪ± agonists on smooth muscle of mouse arteries. Responses to PPARĪ± agonists in the aorta involved KATP channels and sGC, whereas in the MCA the PKC and sGC pathways also appeared to contribute to the response
2,2,2-Trichloroethanol Activates a Nonclassical Potassium Channel in Cerebrovascular Smooth Muscle and Dilates the Middle Cerebral ArterySā
Trichloroacetaldehyde monohydrate [chloral hydrate (CH)] is a sedative/hypnotic that
increases cerebral blood flow (CBF), and its active metabolite 2,2,2-trichloroethanol
(TCE) is an agonist for the nonclassical two-pore domain K+
(K2P) channels TREK-1 and TRAAK. We sought to determine whether TCE
dilates cerebral arteries in vitro by activating nonclassical K+ channels.
TCE dilated pressurized and perfused rat middle cerebral arteries (MCAs) in a manner
consistent with activation of nonclassical K+ channels. Dilation to TCE
was inhibited by elevated external K+ but not by an inhibitory cocktail
(IC) of classical K+ channel blockers. Patch-clamp electrophysiology
revealed that, in the presence of the IC, TCE increased whole-cell currents and
hyperpolarized the membrane potential of isolated MCA smooth muscle cells. Heating
increased TCE-sensitive currents, indicating that the activated channel was
thermosensitive. Immunofluorescence in sections of the rat MCA demonstrated that,
like TREK-1, TRAAK is expressed in the smooth muscle of cerebral arteries. Isoflurane
did not, however, dilate the MCA, suggesting that TREK-1 was not functional. These
data indicate that TCE activated a nonclassical K+ channel with the
characteristics of TRAAK in rat MCA smooth-muscle cells. Stimulation of K+
channels such as TRAAK in cerebral arteries may therefore explain in part how CH/TCE
increases CBF
Efficacious Cyclic <i>N</i>āAcyl <i>O</i>āAmino Phenol Duocarmycin Prodrugs
Two novel cyclic <i>N</i>-acyl <i>O</i>-amino
phenol prodrugs are reported as new members of a unique class of reductively
cleaved prodrugs of the duocarmycin family of natural products. These
prodrugs were explored with the expectation that they may be cleaved
selectively within hypoxic tumor environments that have intrinsically
higher concentrations of reducing nucleophiles and were designed to
liberate the free drug without the release of an extraneous group.
In vivo evaluation of the prodrug <b>6</b> showed that it exhibits
extraordinary efficacy (<i>T</i>/<i>C</i> >
1500,
L1210; 6/10 one year survivors), substantially exceeding that of the
free drug, that its therapeutic window of activity is much larger,
permitting a dosing ā„40-fold higher than the free drug, and
yet that it displays a potency in vivo that approaches the free drug
(within 3-fold). Clearly, the prodrug <b>6</b> benefits from
either its controlled slow release of the free drug or its preferential
intracellular reductive cleavage
A Novel, Unusually Efficacious Duocarmycin Carbamate Prodrug That Releases No Residual Byproduct
A unique heterocyclic carbamate prodrug of <i>seco</i>-CBI-indole<sub>2</sub> that releases no residual byproduct is reported
as a new member of a class of hydrolyzable prodrugs of the duocarmycin
and CC-1065 family of natural products. The prodrug was designed to
be activated by hydrolysis of a carbamate releasing the free drug
without the cleavage release of a traceable extraneous group. Unlike
prior carbamate prodrugs examined that are rapidly cleaved in vivo,
the cyclic carbamate was found to be exceptionally stable to hydrolysis
under both chemical and biological conditions providing a slow, sustained
release of the exceptionally potent free drug. An in vivo evaluation
of the prodrug found that its efficacy exceeded that of the parent
drug, that its therapeutic window of efficacy versus toxicity is much
larger than the parent drug, and that its slow free drug release permitted
the safe and efficacious use of doses 150-fold higher than the parent
compound