There can be few areas of medicine that are as emotionally and ethically fraught as the treatment of babies born with life threatening or debilitating illness. Doctors must constantly weigh up potential benefits to the baby of any procedure against risk that the procedure may harm either the baby or mother. Nevertheless, it’s an area of medicine that has seen significant progress in recent years, and as we have discussed before many of the medical advances have stemmed from animal research.
Earlier this week the New York Times reported on a large clinical trial at three medical centres that specialise in fetal surgery, which demonstrated that infants with Spina Bifida were more likely to walk and experience fewer neurological problems if operated on before being born rather than afterward. Spina Bifida is a birth defect caused by the incomplete closure of the embryonic neural tube, the precursor to the brain and spinal cord, which should take place during the first month of pregnancy, and it is associated with major lifelong disability.
Before surgery, babies in the prenatal group had more severe spinal lesions than the postnatal group, but more in the prenatal group had better results, said a co-author, Dr. Scott Adzick, chief of pediatric surgery at Children’s Hospital of Philadelphia.
Those who received prenatal surgery were half as likely to have a shunt, and eight times as likely to have a normally positioned brainstem. There was “much better motor function of the legs,” Dr. Adzick said, and at 30 months old, nearly twice as many walked without crutches or orthotics.
Although they were born at 34 weeks of pregnancy on average, compared with 37 weeks for the postnatal group, there was no difference in cognitive development, said Dr. Catherine Spong, chief of pregnancy and perinatology at the child health institute.
Dr. Adzick said prenatal surgery may “stop exposure of the developing spinal cord and perhaps avert further neurological damage” or stop the leak of spinal fluid that causes brainstem problems. ”
Professor Adzik is one of the pioneers of fetal surgery for Spina Bifida, having performed the first such operation in 1997, and you won’t be too surprised to learn that animal research informed his decision to attempt this procedure.
Before attempting this surgery Professor Adzik needed to know whether the disability seen in Spina Bifida was due to the neural cord defect, or to a secondary effect due to the exposure of the spinal cord to the interuterine fluid. In the first case surgery would not help to prevent disability, in the second case it might help and experimental surgery on human fetuses would be ethically justifiable.
To determine which case applied Professor Adzik and colleagues performed a series of studies in sheep (1). They found that surgically exposing the normal spinal cord of midgestational sheep fetuses to amniotic fluid leads to a human-like Spina Bifida with paraplegia at birth, indicating that the exposed neural tissue is progressively destroyed during pregnancy, and that much of the disability seen in Spina Bifida is due a secondary effect of exposure to the interuterine environment rather than the primary neural cord defect. When they repaired the spinal cord in utero, the disability in animals at birth was greatly reduced. This result gave Professor Adzik and his colleagues at the Children’s Hospital of Philadelphia the confidence to undertake the first operation to correct Spina Bifida in utero, an operation that led to the far larger clinical trial reported this week.
By way of contrast an article in the Seattle Times reports on how the very misleadingly named “Physicians Committee for Responsible Medicine” (PCRM) is trying to stop a medical training program for very early pre-term infants from using live ferrets in its training program. What is very refreshing about this story is how Dr. Dennis Maycock, the leader of the University of Washington program, patiently explaining why simulators are not appropriate for some of the very specialist training they undertake, and the very good care they take of ferrets used in this training. Of course we are very familiar with the anti-scientific agenda of PCRM, and applaud Dr. Maycock for exposing their hollow propaganda.
So all in all it’s been a week that has highlighted the difference between those who seek to save lives through the responsible and ethical use of animals in research and training, and those who would favor animal rights ideology over the lives and health of the youngest members of our society.
Addendum: While we are on the subject of animal rights groups who like to give the impression that they are not animal rights groups, check out this great new post on HSUS by scienceblogger Erv.
1) Meuli M, Meuli-Simmen C, Hutchins GM, Yingling CD, Hoffman KM, Harrison MR, Adzick NS. “In utero surgery rescues neurological function at birth in sheep with spina bifida.” Nat Med. 1995 Apr;1(4):342-7. PubMed:7585064