Transgenic expression of human CD47 markedly increases engraftment in a murine model of pig-to-human hematopoietic cell transplantation.

Mixed chimerism approaches for induction of tolerance of solid organ transplants have been applied successfully in animal models and in the clinic. However, in xenogeneic models (pig-to-primate), host macrophages participate in the rapid clearance of porcine hematopoietic progenitor cells, hindering the ability to achieve mixed chimerism. CD47 is a cell-surface molecule that interacts in a species-specific manner with SIRPα receptors on macrophages to inhibit phagocytosis and expression of human CD47 (hCD47) on porcine cells has been shown to inhibit phagocytosis by primate macrophages. We report here the generation of hCD47 transgenic GalT-KO miniature swine that express hCD47 in all blood cell lineages. The effect of hCD47 expression on xenogeneic hematopoietic engraftment was tested in an in vivo mouse model of human hematopoietic cell engraftment. High-level porcine chimerism was observed in the bone marrow of hCD47 progenitor cell recipients and smaller but readily measurable chimerism levels were observed in the peripheral blood of these recipients. In contrast, transplantation of WT progenitor cells resulted in little or no bone marrow engraftment and no detectable peripheral chimerism. These results demonstrate a substantial protective effect of hCD47 expression on engraftment and persistence of porcine cells in this model, presumably by modulation of macrophage phagocytosis.

Use of low-salt culture medium for in vitro maturation of porcine oocytes is associated with elevated oocyte glutathione levels and enhanced male pronuclear formation after in vitro fertilization.

The effects of sodium chloride (NaCl) in Whitten's medium on intracellular glutathione concentration and on cytoplasmic maturation, as determined by monospermic penetration and male pronuclear formation of porcine oocytes, were examined. Porcine cumulus-oocyte complexes were cultured for 20 h in BSA-free Whitten's medium containing different NaCl concentrations (44.50, 68.49, 92.40, 116.40, or 140.35 mM) and supplemented with 10% porcine follicular fluid and hormonal supplements; the complexes were then cultured without hormonal supplements for an additional 20-h period. The mean width of the perivitelline space of oocytes was increased with decreased concentration of NaCl in the culture medium. Intracellular glutathione concentration was elevated in oocytes cultured in medium with lower NaCl concentrations. After co-culture with spermatozoa for 6 h and culture in modified Whitten's medium for an additional 6 h, there were no differences in maturation and penetration rates among experimental groups. However, the rate of male pronuclear formation was higher in oocytes matured in media with the lower NaCl concentrations. In addition, the rates of monospermic penetration and male pronuclear formation were higher in oocytes matured in medium containing 44.50 mM NaCl (59.3 +/- 8.1 and 70.9 +/- 2.0%, respectively) than in medium containing 68.49 mM NaCl (39.4 +/- 5.5 and 57.1 +/- 4.5%, respectively). These data indicated that decreasing NaCl concentration in maturation medium for porcine oocytes below the customary level improved the quality of the matured oocytes as reflected in higher intracellular glutathione content, wider perivitelline space, higher monospermic penetration rate, and increased frequency of male pronuclear formation.

In vitro development of in vitro-matured porcine oocytes following chemical activation or in vitro fertilization.

Porcine cumulus-oocyte complexes were cultured in BSA-free Whitten's medium or modified Medium 199, each supplemented with porcine follicular fluid (PFF) and hormonal supplements (OMWM and OMM199, respectively) for 20 h; they then were cultured without hormonal supplements for an additional 20 (experiments 1 and 3) or 24 h (experiment 2). At the end of culture (experiment 1), the intracellular glutathione concentration was higher (p < 0.05) in oocytes matured in OMWM vs. OMM199. After activation by Ca2+ ionophore (experiment 2), the incidence of activation in the OMWM group was lower (p < 0.01) than in the OMM199 group. However, the incidence of pronuclear formation was higher (p < 0.01) in the OMWM group than in the OMM199 group at 8 h after activation. The percentage of embryos that developed to the morula stage was higher (p < 0.01) in the group matured in OMWM vs. OMM199 after 5 days of culture. After in vitro fertilization (experiment 3), the incidence of male pronuclear formation and the percentage of monospermic oocytes that formed one male and one female pronuclei were higher (p < 0.05) after maturation in OMWM vs. OMM199. The percentage of cleaved embryos that developed to the 8-cell and morula stages was higher (p < 0.05) in the OMWM group as compared to the OMM199 group. These results indicate that culture in modified Whitten's medium as compared with a standard medium (modified Medium 199) improves cytoplasmic maturation of porcine oocytes as evaluated by intracellular glutathione content, pronuclear formation, and development in vitro after artificial activation or fertilization in vitro.

Developmental ability of porcine oocytes matured and fertilized in vitro.

The developmental abilities of porcine oocytes matured and fertilized in vitro were examined in vivo and in vitro. Cumulus-oocyte complexes were cultured in mM199 supplemented with 10% porcine follicular fluid (PFF) and hormonal supplements (PMSG, hCG and estradiol-17beta) for 20 h and then without hormonal supplements for an additional 20 h. In Experiment 1, oocytes were then co-cultured for 6 h with spermatozoa which had been preincubated with 1% PFF (PFF-treated) or without (control). Oocytes were transferred to oviducts of gilts or cultured in modified Whitten's medium for 5 d. The percentages of oocytes with monospermic penetration (59%, 42 71 ) and with monospermic penetration and male and female pronuclei (32%, 23 71 ) were higher (P < 0.01) in the PFF-treated group than in controls (25%, 18 71 and 8%, 6 71 , respectively). After 5 d, the percentages of oocytes that developed to the morula or blastocyst stages in vitro and in vivo in the PFF-treated group (10%, 28 288 and 13%, 41 318 , respectively) were also higher (P < 0.05) than in controls (2%, 6 284 and 6%, 16 248 , respectively). Whereas some oocytes that were matured and fertilized in vitro developed to the blastocyst stage after 5 d in vivo culture (3%, 9 288 in PFF-treated group and 2%, 6 284 in control), no blastocysts were observed after 5 d when oocytes were cultured in vitro. When the progression of in vitro development of porcine oocytes that were matured and fertilized in vitro was examined in Experiment 2, morulae appeared after 72 h of culture, and 3% (3 100 ) of the oocytes developed to the blastocyst stage after 144 h (6 d) of culture. These results demonstrate that decreasing polyspermic penetration and increasing monospermic male pronuclear formation, as a result of PFF treatment of maturing spermatozoa, improved the developmental ability of porcine oocytes matured and fertilized in vitro. However, development in vitro was delayed by approximately 24 h compared with in vivo development, most of the embryos were blocked at the morula stage.

Effects of electrical stimulation before or after in vitro fertilization on sperm penetration and pronuclear formation of pig oocytes.

The effects of exposure of pig oocytes to an electrical pulse-on sperm penetration and pronuclear formation were determined before or after in vitro fertilization (IVF). After in vitro maturation (IVM) or after collection from oviducts of unmated gilts, pig oocytes either were not exposed or were exposed to an electrical pulse (a 10 sec pulse at 4.0 Vmm-1 AC followed by a 30 microseconds pulse at 120 V mm-1 DC), followed 30 min later by IVF. The incidence of male pronuclear formation of both IVM and in vivo-matured oocytes at 12 hr after insemination was decreased from 59% and 100%, respectively, to 2% and 36%, respectively, by the electrical pulse, but the penetration rates (88-100%) and polyspermic rates (79-100%) were not affected by exposure to an electrical pulse. Similarly, when pig IVM oocytes were exposed to an electrical pulse at 6 hr after insemination, electrical activation did not decrease penetration rates (93% vs. 90%), polyspermic rates (83% vs. 91%), or number of spermatozoa in penetrated oocytes (4.0 +/- 0.5 vs. 4.6 +/- 0.5) but did decrease the rate of male pronuclear formation from 58% to 18%. When oocytes were examined at 6 hr after insemination, 75% of them had been penetrated and resumed meiotic progression, but all sperm heads in penetrated oocytes were fully condensed or only partially decondensed. The percentage of penetrated eggs with multiple female pronuclei was increased when oocytes were exposed to an electrical pulse in all experimental series.(ABSTRACT TRUNCATED AT 250 WORDS)

Diacylglycerol-enhanced electrical activation of porcine oocytes matured in vitro.

This study was undertaken to examine the effect of second messengers added to the electroporation medium on electric pulse-induced artificial activation of meiotic Metaphase II porcine oocytes. Six separate experiments evaluated second messengers added to electroporation medium. When added to electroporation medium, neither phospholipase C (PLC: 0 to 2.5 Units/ml), D-myo-inositol triphosphate (IP(3): 0 to 10,000 muM), nor guanosine 5'-O-(3-thiotriphosphate; GTP-gamma-S: 0 to 100 muM) had any effect (P> 0.05) on activation rates. However, addition of 1,2-dioctanoyl-sn-glycerol (DiC(8)) increased activation rates in a dose-dependent response. At a level of 1,000 muM, DiC(8) resulted in a higher activation rate (P< 0,05) than 0.0, 0.1, 1 or 10 muM of DiC(8) with a pulse, and the 1,000 and 10,000 muM of DiC(8) no-pulse control groups. Effects of DiC(8) (1,000 muM) and IP(3) (100 muM) in combination or individually were investigated. At 1,000 muM, DiC(8) caused a higher rate of activation (P< 0.05) than 100 muM IP(3), but the result was not different from DiC(8) + IP(3). In another experiment, no difference (P> 0.05) was observed between DiC(8), GTP-gamma-S and IP(3), but DiC(8) + GTP-gamma-S + IP(3) + PLC yielded a higher (P< 0.05) activation rate than PLC or the rate of the controls. No significant development (blastocyst) was observed after 5 days of culture in any of the experiments. Protein profiles of activated oocytes, determined by 1D SDS-PAGE, were characteristic of pronuclear-stage embryos. These data indicate that the addition of DiC(8) to the electroporation medium synergistically enhances the rate of activation of electrically stimulated in vitro-matured porcine oocytes.

The effects of recombinant porcine somatotropin on reproductive function in gilts treated during the finishing phase.

The objective of this study was to determine the effects of recombinant porcine somatotropin (rpST) treatment during the finishing phase on subsequent reproductive function in crossbred gilts. Forty gilts weighing 50 kg and housed in a swine finishing facility were randomly assigned to control or rpST treatment. Four control and four rpST-treated gilts were allotted per pen. Twenty rpST-treated gilts received 6 mg of rpST.gilt-1.d-1 in 1 ml of buffered carrier and 20 control gilts received 1 ml of buffered carrier.gilt-1.d-1. Injections were administered daily at 1400 in the extensor muscle of the neck. All gilts received an 18% CP diet containing 1.2% lysine. Treatment was terminated when the average weight in each pen reached 110 kg. Gilts treated with rpST gained more weight (P less than .05) than control gilts (59.8 +/- 1.0 vs 53.5 +/- 1.0 kg). Age at puberty was not different (rpST, 182.2 +/- 3.3; control 181.4 +/- 3.1 d). Prior treatment with rpST did not significantly affect length of estrus (rpST, 1.9 +/- .1; control, 1.8 +/- .1 d) or estrous cycle length (rpST, 20.6 +/- .4; control, 20.4 +/- .4 d). Ovulation rates at second estrus were similar for rpST gilts (15.1 +/- .5) and control gilts (14.4 +/- .5). More embryos (P = .10) were recovered on d 9 to 12 of gestation from rpST-treated gilts than from control gilts (13.1 +/- .9 vs 10.7 +/- .9).(ABSTRACT TRUNCATED AT 250 WORDS)