Successful maintenance of key physiological parameters in preterm lambs treated with ex vivo uterine environment therapy for a period of 1 week


      Extremely preterm infants born at the border of viability (22-24 weeks’ gestation) have high rates of death and lasting disability. Ex vivo uterine environment therapy is an experimental neonatal intensive care strategy that provides gas exchange using parallel membranous oxygenators connected to the umbilical vessels, sparing the extremely preterm cardiopulmonary system from ventilation-derived injury.


      In this study, we aimed to refine our ex vivo uterine environment therapy platform to eliminate fetal infection and inflammation, while simultaneously extending the duration of hemodynamically stable ex vivo uterine environment therapy to 1 week.

      Study Design

      Merino-cross ewes with timed, singleton pregnancies were surgically delivered at 112-115 days of gestation (term is ∼150 days) and adapted to ex vivo uterine environment therapy (treatment group; n = 6). Physiological variables were continuously monitored; humerus and femur length, ductus arteriosus directional flow, and patency were estimated with ultrasound; serial blood samples were collected for hematology and microbiology studies; weight was recorded at the end of the experiment. Control group animals (n = 7) were euthanized at 122 days of gestation and analyzed accordingly. Bacteremia was defined by positive blood culture. Infection and fetal inflammation was assessed with white blood cell counts (including differential leukocyte counts), plasma and lung proinflammatory cytokine measurements, and lung histopathology.


      Five of 6 fetuses in the treatment group completed the 1-week study period with key physiological parameters, blood counts remaining within normal ranges, and no bacteremia detected. There were no significant differences (P > .05) in arterial blood oxygen content or lactate levels between ex vivo uterine environment therapy and control groups at delivery. There was no significant difference (P > .05) in birthweight between control and ex vivo uterine environment groups. In the ex vivo uterine environment group, we observed growth of fetal humerus (P < .05) and femur (P < .001) over the course of the 7-day experimental period. There was no difference in airway or airspace morphology or consolidation between control and ex vivo uterine environment animals, and there was no increase in the number of lung cells staining positive for T-cell marker CD3+.


      Five preterm lambs were maintained in a physiologically stable condition for 1 week with significant growth and without clinically significant bacteremia or systemic inflammation. Although substantial further refinement is required, a life support platform based around ex vivo uterine environment therapy may provide an avenue to improve outcomes for extremely preterm infants.

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        • March of Dimes; Partnership for Maternal, Newborn, and Child Health; Save the Children, WHO
        Born too soon: the global action report on preterm birth.
        World Health Organization, Geneva2012
        • Blencowe H.
        • Cousens S.
        • Oestergaard M.Z.
        • et al.
        National, regional, and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications.
        Lancet. 2012; 379: 2162-2172
        • Zeitlin J.
        • Manktelow B.N.
        • Piedvache A.
        • et al.
        Use of evidence based practices to improve survival without severe morbidity for very preterm infants: results from the EPICE population based cohort.
        BMJ. 2016; 354: i2976
        • Glass H.C.
        • Costarino A.T.
        • Stayer S.A.
        • Brett C.M.
        • Cladis F.
        • Davis P.J.
        Outcomes for extremely premature infants.
        Anesth Analg. 2015; 120: 1337-1351
        • Stoll B.J.
        • Hansen N.I.
        • Bell E.F.
        • et al.
        Trends in care practices, morbidity, and mortality of extremely preterm neonates, 1993-2012.
        JAMA. 2015; 314: 1039-1051
        • Burri P.H.
        Fetal and postnatal development of the lung.
        Annu Rev Physiol. 1984; 46: 617-628
        • Smith L.J.
        • McKay K.O.
        • van Asperen P.P.
        • Selvadurai H.
        • Fitzgerald D.A.
        Normal development of the lung and premature birth.
        Paediatr Respir Rev. 2010; 11: 135-142
        • Baraldi E.
        • Filippone M.
        Chronic lung disease after premature birth.
        N Engl J Med. 2007; 357: 1946-1955
        • Speer C.P.
        Chorioamnionitis, postnatal factors and proinflammatory response in the pathogenetic sequence of bronchopulmonary dysplasia.
        Neonatology. 2009; 95: 353-361
        • Carraro S.
        • Filippone M.
        • Da Dalt L.
        • et al.
        Bronchopulmonary dysplasia: the earliest and perhaps the longest lasting obstructive lung disease in humans.
        Early Hum Dev. 2013; 89: S3-S5
        • Saigal S.
        • Doyle L.W.
        An overview of mortality and sequelae of preterm birth from infancy to adulthood.
        Lancet. 2008; 371: 261-269
        • O'Reilly M.
        • Sozo F.
        • Harding R.
        Impact of preterm birth and bronchopulmonary dysplasia on the developing lung: long-term consequences for respiratory health.
        Clin Exp Pharmacol Physiol. 2013; 40: 765-773
        • Stoll B.J.
        • Hansen N.I.
        • Bell E.F.
        • et al.
        Neonatal outcomes of extremely preterm infants from the NICHD Neonatal Research Network.
        Pediatrics. 2010; 126: 443-456
        • Loftin C.D.
        • Trivedi D.B.
        • Tiano H.F.
        • et al.
        Failure of ductus arteriosus closure and remodeling in neonatal mice deficient in cyclooxygenase-1 and cyclooxygenase-2.
        Proc Natl Acad Sci U S A. 2001; 98: 1059-1064
        • Campbell M.
        Natural history of persistent ductus arteriosus.
        Br Heart J. 1968; 30: 4-13
        • Brooks J.M.
        • Travadi J.N.
        • Patole S.K.
        • Doherty D.A.
        • Simmer K.
        Is surgical ligation of patent ductus arteriosus necessary? The Western Australian experience of conservative management.
        Arch Dis Child Fetal Neonatal Ed. 2005; 90: F235-F239
        • Van Israel N.
        • Dukes-McEwan J.
        • French A.T.
        Long-term follow-up of dogs with patent ductus arteriosus.
        J Small Anim Pract. 2003; 44: 480-490
        • Shah S.S.
        • Ohlsson A.
        Ibuprofen for the prevention of patent ductus arteriosus in preterm and/or low birth weight infants.
        Cochrane Database Syst Rev. 2006; 1: Cd004213
        • Noori S.
        • Seri I.
        Hemodynamic antecedents of peri/intraventricular hemorrhage in very preterm neonates.
        Semin Fetal Neonatal Med. 2015; 20: 232-237
        • Miura Y.
        • Saito M.
        • Usuda H.
        • et al.
        Ex-vivo uterine environment (EVE) therapy induced limited fetal inflammation in a premature lamb model.
        PLoS One. 2015; 10: e0140701
        • Miura Y.
        • Matsuda T.
        • Usuda H.
        • et al.
        A parallelized pumpless artificial placenta system significantly prolonged survival time in a preterm lamb model.
        Artif Organs. 2016; 40: E61-E68
        • Miura Y.
        • Usuda H.
        • Watanabe S.
        • et al.
        Healthy survival and pulmonary maturation in premature lambs treated with combined ex vivo uterine environment (EVE) and corticosteroid therapy.
        Reprod Sci. 2016; 23: 192A
        • Gomez R.
        • Romero R.
        • Ghezzi F.
        • Yoon B.H.
        • Mazor M.
        • Berry S.M.
        The fetal inflammatory response syndrome.
        Am J Obstet Gynecol. 1998; 179: 194-202
        • Mittendorf R.
        • Covert R.
        • Montag A.G.
        • et al.
        Special relationships between fetal inflammatory response syndrome and bronchopulmonary dysplasia in neonates.
        J Perinat Med. 2005; 33: 428-434
        • Miura Y.
        • Usuda H.
        • Watanabe S.
        • et al.
        Stable control of physiological parameters, but not infection, in preterm lambs maintained on ex-vivo uterine environment therapy.
        Artif Organs. 2017 Sep 11; ([Epub ahead of print])
        • Miura Y.
        • Matsuda T.
        • Funakubo A.
        • et al.
        Novel modification of an artificial placenta: pumpless arteriovenous extracorporeal life support in a premature lamb model.
        Pediatr Res. 2012; 72: 490-494
        • Comline R.S.
        • Silver M.
        Daily changes in fetal and maternal blood of conscious pregnant ewes, with catheters in umbilical and uterine vessels.
        J Physiol. 1970; 209: 567-586
        • Rasmusen B.A.
        Blood groups in sheep.
        Ann N Y Acad Sci. 1962; 97: 306-319
        • Carvalho J.S.
        • Allan L.D.
        • Chaoui R.
        • et al.
        • International Society of Ultrasound in Obstetrics and Gynecology
        ISUOG practice guidelines (updated): sonographic screening examination of the fetal heart.
        Ultrasound Obstet Gynecol. 2013; 41: 348-359
        • Kemp M.W.
        • Kannan P.
        • Saito M.
        • et al.
        Selective exposure of the fetal lung and skin/amnion (but not gastro-intestinal tract) to LPS elicits acute systemic inflammation in fetal sheep.
        PLoS One. 2013; 8: e63355
        • Banker B.Q.
        • Larroche J.C.
        Periventricular leukomalacia of infancy. A form of neonatal anoxic encephalopathy.
        Arch Neurol. 1962; 7: 386-410
        • Kemp M.W.
        • Miura Y.
        • Payne M.S.
        • et al.
        Repeated maternal intramuscular or intraamniotic erythromycin incompletely resolves intrauterine Ureaplasma parvum infection in a sheep model of pregnancy.
        Am J Obstet Gynecol. 2014; 211: 134.e1-134.e9
        • Kemp M.W.
        • Molloy T.J.
        • Usuda H.
        • et al.
        Outside-in? Acute fetal systemic inflammation in very preterm chronically catheterized sheep fetuses is not driven by cells in the fetal blood.
        Am J Obstet Gynecol. 2016; 214: 281.e1-281.e10
        • Miura Y.
        • Payne M.S.
        • Keelan J.A.
        • et al.
        Maternal intravenous treatment with either azithromycin or solithromycin clears Ureaplasma parvum from the amniotic fluid in an ovine model of intrauterine infection.
        Antimicrob Agents Chemother. 2014; 58: 5413-5420
        • Bustin S.A.
        • Benes V.
        • Garson J.A.
        • et al.
        The MIQE guidelines: minimum information for publication of quantitative real-time PCR experiments.
        Clin Chem. 2009; 55: 611-622
        • Faber J.J.
        • Green T.J.
        Fetal placental blood flow in the lamb.
        J Physiol. 1972; 223: 375-393
        • Assad R.S.
        • Lee F.Y.
        • Hanley F.L.
        Placental compliance during fetal extracorporeal circulation.
        J Appl Physiol (1985). 2001; 90: 1882-1886
        • Parisi V.M.
        • Walsh S.W.
        Fetal vascular responses to prostacyclin.
        Am J Obstet Gynecol. 1989; 160: 871-878
        • Hall R.W.
        • Shbarou R.M.
        Drugs of choice for sedation and analgesia in the NICU.
        Clin Perinatol. 2009; 36: 15-26
        • Anand K.J.
        • Hall R.W.
        Pharmacological therapy for analgesia and sedation in the newborn.
        Arch Dis Child Fetal Neonatal Ed. 2006; 91: F448-F453
        • Schain R.J.
        • Watanabe K.
        Effect of chronic phenobarbital administration upon brain growth of the infant rat.
        Exp Neurol. 1975; 47: 509-515
        • Rozé J.
        • Denizot S.
        • Carbajal R.
        • et al.
        Prolonged sedation and/or analgesia and 5-year neurodevelopment outcome in very preterm infants: results from the EPIPAGE cohort.
        Arch Pediatr Adolesc Med. 2008; 162: 728-733
        • Dantas G.
        • Laste G.
        • Rozisky J.R.
        • Torres I.L.
        • Ferreira M.B.C.
        Thiopental alters long term nociceptive response of young rats.
        J Basic Appl Pharm Sci. 2015; 36
        • Unno N.
        • Kuwabara Y.
        • Okai T.
        • et al.
        Development of an artificial placenta: survival of isolated goat fetuses for three weeks with umbilical arteriovenous extracorporeal membrane oxygenation.
        Artif Organs. 1993; 17: 996-1003
        • Kemp M.W.
        Preterm birth, intrauterine infection, and fetal inflammation.
        Front Immunol. 2014; 5: 574
        • Larroche J.C.
        • Aubry M.C.
        • Narcy F.
        Intrauterine brain damage in nonimmune hydrops fetalis.
        Biol Neonate. 1992; 61: 273-280
        • Hadlock F.P.
        • Harrist R.B.
        • Sharman R.S.
        • Deter R.L.
        • Park S.K.
        Estimation of fetal weight with the use of head, body, and femur measurements–a prospective study.
        Am J Obstet Gynecol. 1985; 151: 333-337
        • Falkner F.
        Ultrasonography and fetal growth: key perinatal factors.
        J Perinatol. 1995; 15: 114-118
        • Tahmasebpour A.R.
        • Pirjani R.
        • Rahimi-Foroushani A.
        • Ghaffari S.R.
        • Rahimi-Sharbaf F.
        • Masrour F.F.
        Normal ranges for fetal femur and humerus diaphysis length during the second trimester in an Iranian population.
        J Ultrasound Med. 2012; 31: 991-995
        • Brett C.
        • Dekle M.
        • Leonard C.H.
        • et al.
        Developmental follow-up of hyperventilated neonates: preliminary observations.
        Pediatrics. 1981; 68: 588-591
        • Fujimoto S.
        • Togari H.
        • Yamaguchi N.
        • Mizutani F.
        • Suzuki S.
        • Sobajima H.
        Hypocarbia and cystic periventricular leukomalacia in premature infants.
        Arch Dis Child. 1994; 71: F107-F110
        • Ambalavanan N.
        • Carlo W.A.
        Hypocapnia and hypercapnia in respiratory management of newborn infants.
        Clin Perinatol. 2001; 28: 517-531
        • Collins M.P.
        • Lorenz J.M.
        • Jetton J.R.
        • Paneth N.
        Hypocapnia and other ventilation-related risk factors for cerebral palsy in low birth weight infants.
        Pediatr Res. 2001; 50: 712-719
        • Beale E.
        • Nelson R.
        • Bucciarelli R.
        • Donnelly W.
        • Eitzman D.
        Intrahepatic cholestasis associated with parenteral nutrition in premature infants.
        Pediatrics. 1979; 64: 342-347
        • Benjamin D.R.
        Hepatobiliary dysfunction in infants and children associated with long-term total parenteral nutrition. A clinico-pathologic study.
        Am J Clin Pathol. 1981; 76: 276-283
        • Farrell M.
        • Balistreri W.
        Parenteral nutrition and hepatobiliary dysfunction.
        Clin Perinatol. 1986; 13: 197-212
        • Marin J.J.
        • Macias R.I.
        • Briz O.
        • et al.
        Molecular bases of the fetal liver-placenta-maternal liver excretory pathway for cholephilic compounds.
        Liver Int. 2008; 28: 435-454
        • Macias R.I.R.
        • Marin J.J.G.
        • Serrano M.A.
        Excretion of biliary compounds during intrauterine life.
        World J Gastroenterol. 2009; 15: 817-828