Effects of preoperative hypoxia on white matter injury associated with cardiopulmonary bypass in a rodent hypoxic and brain slice model.
BACKGROUND
White matter (WM) injury is common after cardiopulmonary bypass or deep hypothermic circulatory arrest in neonates who have cerebral immaturity secondary to in utero hypoxia. The mechanism remains unknown. We investigated effects of preoperative hypoxia on deep hypothermic circulatory arrest-induced WM injury using a combined experimental paradigm in rodents.


METHODS
Mice were exposed to hypoxia (prehypoxia). Oxygen-glucose deprivation was performed under three temperatures to simulate brain conditions of deep hypothermic circulatory arrest including ischemia-reperfusion/reoxygenation under hypothermia.


RESULTS
WM injury in prenormoxia was identified after 35 °C-oxygen-glucose deprivation. In prehypoxia, injury was displayed in all groups. Among oligodendrocyte stages, the preoligodendrocyte was the most susceptible, while the oligodendrocyte progenitor was resistant to insult. When effects of prehypoxia were assessed, injury of mature oligodendrocytes and oligodendrocyte progenitors in prehypoxia significantly increased as compared with prenormoxia, indicating that mature oligodendrocytes and progenitors that had developed under hypoxia had greater vulnerability. Conversely, damage of oligodendrocyte progenitors in prehypoxia were not identified after 15 °C-oxygen-glucose deprivation, suggesting that susceptible oligodendrocytes exposed to hypoxia are protected by deep hypothermia.


CONCLUSIONS
Developmental alterations due to hypoxia result in an increased WM susceptibility to injury. Promoting WM regeneration by oligodendrocyte progenitors after earlier surgery using deep hypothermia is the most promising approach for successful WM development in congenital heart disease patients.
1] Department of Cardiac Surgery, Children's National Medical Center, Washington, DC [2] Center for Neuroscience Research, Children's National Medical Center, Washington, DC.
Kota
K
Agematsu
1] Department of Cardiac Surgery, Children's National Medical Center, Washington, DC [2] Center for Neuroscience Research, Children's National Medical Center, Washington, DC.
Ludmila
L
Korotcova
Center for Neuroscience Research, Children's National Medical Center, Washington, DC.
Joseph
J
Scafidi
Center for Neuroscience Research, Children's National Medical Center, Washington, DC.
Vittorio
V
Gallo
1] Department of Cardiac Surgery, Children's National Medical Center, Washington, DC [2] Center for Neuroscience Research, Children's National Medical Center, Washington, DC.
Richard A
RA
Jonas
1] Department of Cardiac Surgery, Children's National Medical Center, Washington, DC [2] Center for Neuroscience Research, Children's National Medical Center, Washington, DC.
Nobuyuki
N
Ishibashi
D000818:Animals; D001921:Brain / Q000473:pathology; D001930:Brain Injuries / Q000503:physiopathology*; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D019070:Cell Lineage; D004195:Disease Models, Animal; D005947:Glucose / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000737:chemistry; D007035:Hypothermia; D000860:Hypoxia; D051379:Mice; D009836:Oligodendroglia / Q000166:cytology; D010100:Oxygen / Q000737:chemistry; D010477:Perfusion; D015427:Reperfusion Injury; D066127:White Matter / Q000473:pathology*
D049452:Green Fluorescent Proteins; D005947:Glucose; D010100:Oxygen