Xenoreactivity and engraftment of human mesenchymal stem cells transplanted into infarcted rat myocardium.

OBJECTIVE: It is thought that adult human mesenchymal stem cells do not induce immunoreactivity even to xenografts. We wanted to study whether adult human mesenchymal stem cells survive and engraft in experimentally induced ischemic rat myocardium. METHODS: Bone marrow-derived adult human mesenchymal stem cells (2.5 x 10(6)) were injected into the myocardium of 4 Sprague-Dawley rats. One week after injection, peripheral blood rat lymphocytes were added to adult human mesenchymal stem cells in a mixed lymphocyte reaction. Furthermore, an infarction was created by left anterior descending artery ligation of 8 Sprague-Dawley rats, 4 of which were immunosuppressed with tacrolimus (0.1 mg/kg/d) and 4 RNU athymic rats. One week after left anterior descending artery ligation, 2.5 to 3.5 x 10(6) adult human mesenchymal stem cells were injected around the infarcted area. The adult human mesenchymal stem cells were identified with fluorescence in situ hybridization technique and myocardial antigens by immunohistochemistry. The immune response was studied by hematoxylin and eosin staining and by antibodies directed toward macrophages. RESULTS: Significant rat lymphocyte proliferation was observed when adult human mesenchymal stem cells were added to peripheral blood from Sprague-Dawley rats previously exposed to adult human mesenchymal stem cells. No reactivity was seen in lymphocytes from untreated Sprague-Dawley rats and athymic rats. Adult human mesenchymal stem cells could only be identified in the myocardium of athymic rats. Further, in normal Sprague-Dawley rats, there was a significant myocardial infiltration of round cells, mostly macrophages, in the area of injection of adult human mesenchymal stem cells. In RNU rats, this reaction was less intense. CONCLUSION: Adult human mesenchymal stem cells did not induce xenoreactivity in vitro in previously unexposed immunocompetent Sprague-Dawley rats. However, although mesenchymal stem cells are transplantable across allogeneic barriers, transplant rejection can occur in a xenogenic model. When transplanted into an immunoincompetent host, adult human mesenchymal stem cells showed persistent engraftment.

Prostaglandin E2 increases calcium conductance and stimulates release of substance P in avian sensory neurons.

Prostaglandins are known to lower activation threshold to thermal, mechanical, and chemical stimulation in small-diameter sensory neurons. Although the mechanism of prostaglandin action is unknown, agents known to elevate intracellular calcium produce a sensitization that is similar to that produced by prostaglandins. Consistent with the idea of prostaglandin-induced elevations in calcium, prostaglandins might also stimulate the release of neurotransmitter from sensory neurons. We therefore examined whether prostaglandin E2 (PGE2) could enhance the release of the putative sensory transmitter substance P (SP) from isolated neurons of the avian dorsal root ganglion grown in culture. Utilizing the whole-cell patch-clamp recording technique, we also examined whether PGE2 could alter calcium currents in these cells. Exposure of sensory neurons to PGE2 produced a dose-dependent increase in the release of SP. One micromolar PGE2 increased release approximately twofold above basal release, whereas 5 and 10 microM PGE2 increased release by about fourfold. The release evoked by these higher concentrations of PGE2 was similar in magnitude to the release induced by 50 mM KCl. Neither arachidonic acid (10 microM), prostaglandin F2 alpha (10 microM), nor the lipoxygenase product leukotriene B4 (1 microM) significantly altered SP release. The addition of 1 microM PGE2 increased the peak calcium currents by 1.8-fold and 1.4-fold for neurons held at potentials of -60 and -90 mV, respectively. The action of PGE2 was rapid with facilitation occurring within 2 min. As with release studies, arachidonic acid, prostaglandin F2 alpha, and leukotriene B4 had no significant effect on the amplitude of the calcium current. These results suggest that PGE2 can stimulate the release of SP through the activation or facilitation of an inward calcium current. The capacity of PGE2 to facilitate the calcium current in these sensory neurons may be one mechanism to account for the ability of prostaglandins to sensitize sensory neurons to physical or chemical stimuli.

Analysis of rat EEG using autoregressive power spectra.

The main objective of this paper is to make the auto regressive (AR) power spectrum estimation method accessible to electrophysiologists and present some typical applications. The AR method is explained, choices of various parameters are explored and examples from the analysis of rat hippocampal EEG are given. We also provide the pseudocode for the computation of the AR coefficients and the AR spectrum. We compare the results from the AR method to the FFT-based power spectrum method and demonstrate the superiority of the AR method. We also show the differences in the spectra of the EEG of alcohol-preferring (P) and non-preferring (NP) rats in the baseline condition when no alcohol is infused. We found a statistically significant difference in peak theta frequency which was at 6.96 Hz for the P rats and at 7.74 Hz for the NP rats. There were also other observable differences in the shape of the spectra of the EEG of the P and NP rats.

Role for cyclic AMP in the postreceptor control of cytokine-stimulated stromal cell growth factor production.

We examined the role of augmented formation of intracellular cyclic AMP (cAMP) in the mediation of stromal cell growth factor production that occurs constitutively or upon cytokine stimulation. Clonal murine marrow adherent cell lines were stimulated under serum-free conditions by interleukin-1 (IL-1) or lipopolysaccharide (LPS) and one (+/+ -1.LDA11) was found to produce low quantities of granulocyte macrophage colony-stimulating factor (GM-CSF). GM-CSF identity was confirmed by the ability of supernatants from stromal cells to promote proliferation of the factor-dependent cell line FDC-P1, neutralization of this activity by antiserum to GM-CSF, and by Northern blot analysis. However, optimal concentrations of IL-1 and tumor necrosis factor-alpha (TNF-alpha), in combination, led to synergistic (greater than 5-fold higher quantity) GM-CSF production compared with either stimulus alone in the +/+ -1. LDA11 cell line, capable of GM-CSF production after only single stimulation with IL-1 or LPS. In addition, synergistic stimulation by IL-1 and TNF-alpha led to equivalent high amounts of GM-CSF in another cell line incapable of GM-CSF production after induction with only IL-1 or LPS. Any of several means to raise intracellular cAMP levels, including addition of 8-bromo-cyclic AMP (8Br cAMP) (0.25-1mM), pertussis toxin (20-100 ng/ml), or addition of prostaglandin E1 (PGE1) (1 microM), failed to stimulate GM-CSF production alone and strongly inhibited GM-CSF production in stromal cells stimulated by IL-1, LPS, or the synergistic combination of IL-1 and TNF-alpha. In addition, PGE1 and pertussis intoxication were agonists of adenylate cyclase in membranes of marrow adherent cells, whereas IL-1 and LPS were not. The role for regulators of intracellular cAMP was specific because any of the cAMP agonists alone, or in the presence of cytokine stimulators of stromal cells, strongly enhanced IL-6 production, an event known to be cAMP-responsive. Thus, acute formation of intracellular cAMP is a negative regulator of stromal cell GM-CSF production mediated by cytokines, but positively regulates IL-6 production and may be an important determinant of cytokine-directed marrow microenvironmental function. These findings on the requirement for augmentation versus inhibition of cytokine-mediated production of hemopoietic growth factors might be applied to an analysis of marrow stromal cell heterogeneity.

Effector function for RAS oncogene in interleukin-3-dependent myeloid cells involves diminished efficacy of prostaglandin E1-mediated inhibition of proliferation.

Leukemic cell growth in the marrow microenvironment may be modulated by stromal cell products, including stimulatory growth factors and the inhibitory regulator prostaglandin E. The production of both of these stromal cell products induced by cytokine mediators appears to be closely linked. Cyclic AMP (cAMP) is an intracellular second messenger that inhibits myeloid cell proliferation and is produced in myeloid leukemia cells on stimulation of adenylate cyclase enzyme by prostaglandin E1 (PGE1). Cells expressing the product of an RAS oncogene have been observed to display diminished hormone-stimulated adenylate cyclase of membranes. If this observation were applicable to myeloid cells, a potentially important mode for leukemia cells expressing p21 RAS to escape inhibitory regulation within the hematopoietic microenvironment would be identified. We studied an interleukin-3 (IL-3)-dependent myeloid cell line, NFS/N1.H7, and a derivative line transfected with H-RAS codon 12 (T24) oncogene, H7 Neo Ras.F3, for inhibition of proliferation by PGE1, 1 microM, alone or in combination with pertussis toxin, which inactivates Gi, an inhibitory regulatory guanosine triphosphate (GTP)-binding protein of adenylate cyclase. NFS/N1.H7 cells were inhibited in interleukin-3-dependent proliferation (dose range, IL-3 10 to 100 U/mL) by PGE1 79 +/- 11%, by pertussis toxin 51 +/- 9%, and by the combination 92 +/- 2%, whereas H7 Neo RAS.F3 was inhibited 51 +/- 7%, 6 +/- 2%, or 58 +/- 9% by PGE1, pertussis toxin, and the combination, respectively. These differences in capacity for inhibition by adenylate cyclase agonists between RAS-transfectant cells (lower inhibition) versus parent cells (greater inhibition) were all highly significant (P less than .0005). Intracellular cAMP formed on PGE1 stimulation of pertussis-intoxicated cells was 150% lower in RAS-transfectant cells than in parent cells. The adenylate cyclase activity of membranes from pertussis-intoxicated RAS-transfected cells was 1.5 to two times lower than that of pertussis-intoxicated parent-cell membranes on Mg2+-dependent activation by hormone and/or guanine nucleotide. However, very similar adenylate cyclase activity was observed in oncogenic p21 RAS-containing membranes compared with parental membranes under conditions of direct activation by 4 mM Mn2+ and forskolin, where inhibitory or stimulatory G-protein influences are minimal. These studies showed diminished adenylate cyclase activity in mutant RAS-bearing myeloid-cell membranes compared with parent-cell membranes independent of the pertussis toxin-sensitive G protein, Gi.(ABSTRACT TRUNCATED AT 400 WORDS)

Restoration of adenylate cyclase responsiveness in murine myeloid leukemia permits inhibition of proliferation by hormone. Butyrate augments catalytic activity of adenylate cyclase.

Mechanisms of leukemic cell clonal dominance may include aberrations of transmembrane signaling. In particular, neoplastic transformation has been associated with reduced capacity for hormone-stimulated adenylate cyclase activity. In the present study, prostaglandin E, a hormonal activator of adenylate cyclase that has antiproliferative activity in myeloid cells, and cholera toxin, an adenylate cyclase agonist that functions at a postreceptor site by activating the adenylate cyclase stimulatory GTP-binding protein (Gs), were studied for antiproliferative activity in two murine myeloid cell lines. FDC-P1, an interleukin 3 (IL 3)-dependent myeloid cell line and a tumorigenic IL 3-independent subline, FI, were resistant to these antiproliferative agents. The in vitro ability of the "differentiation" agent, sodium butyrate, to reverse their resistance to adenylate cyclase agonists was studied. The antiproliferative action of butyrate involved augmentation of transmembrane adenylate cyclase activity. Increased adenylate cyclase catalyst activity was the primary alteration of this transmembrane signaling group leading to the functional inhibitory effects on leukemia cells, although alterations in regulatory G-proteins appear to play a secondary role.