Clinical and pathologic features of cloned transgenic calves and fetuses (13 case studies).
The neonatal abnormalities, treatments and outcomes in a group of 13 cloned transgenic calves and fetuses that progressed into the third trimester of pregnancy are described. From these 13 fetuses, 8 calves were born live, 4 stillborn fetuses were recovered from 3 cows that died 7 d to 2 mo before term, and 1 aborted fetus was recovered at 8 mo gestation. All fetuses and calves were derived from the same male fetal Holstein fibroblast cell line transfected with a beta-galactosidase marker gene. Six calves were delivered by Cesarian section and two by vaginal delivery between 278 and 288 d of gestation. Birth weights ranged from 44 to 58.6 kg. Five of the 8 live born calves were judged to be normal within 4 h of birth based on clinical signs and blood gas measurements. One of these 5 calves died at 6 wk of age from a suspected dilated cardiomyopathy. Three of the 8 calves were diagnosed with neonatal respiratory distress immediately following birth, one of which died (at 4 d of age) as a result of pulmonary surfactant deficiency coupled with pulmonary hypertension and elevated systemic venous pressures. Similar findings of chronic pulmonary hypertension were also observed in 2 of 5 fetuses. Placental edema was present in both calves that later died and in the 2 fetuses with cardiopulmonary abnormalities. Hydrallantois occurred with or without placental edema in 6 cows, and only 1 calf from this group survived. The 6 cows without hydrallantois or placental edema produced 5 live calves and 1 aborted fetus. The cardiopulmonary abnormalities observed in the calves and fetuses occurred in utero in conjunction with placental abnormalities, and it is likely that the cloning technique and/or in vitro embryo culture conditions contributed to these abnormalities, although the mechanism remains to be determined.
Hill
J R
JR
College of Veterinary Medicine, Texas A&M University, College Station 77843-4475, USA.
Roussel
A J
AJ
Cibelli
J B
JB
Edwards
J F
JF
Hooper
N L
NL
Miller
M W
MW
Thompson
J A
JA
Looney
C R
CR
Westhusin
M E
ME
Robl
J M
JM
Stice
S L
SL
D000818:Animals; D030801:Animals, Genetically Modified; D000831:Animals, Newborn / Q000502:physiology*; D002245:Carbon Dioxide / Q000097:blood; D002318:Cardiovascular Diseases / Q000662:veterinary; D002417:Cattle / Q000196:embryology*; D002418:Cattle Diseases; D019976:Cloning, Organism; D005260:Female; D005313:Fetal Death / Q000662:veterinary; D008297:Male; D010100:Oxygen / Q000097:blood; D010922:Placenta Diseases / Q000662:veterinary; D011247:Pregnancy; D011256:Pregnancy Outcome
D002245:Carbon Dioxide; D010100:Oxygen