Maturational Changes in Laminin, Fibronectin, Collagen IV, and Perlecan in Germinal Matrix, Cortex, and White Matter and Effect of Betamethasone Hongmin Xu, 1 Furong Hu, 1 Yoshikazu Sado, 2 Yoshifumi Ninomiya, 2 Dorin-Bogdan Borza, 3 Zoltan Ungvari, 4 Edmund F. LaGamma, 1 Anna Csiszar, 4 Maiken Nedergaard, 5 and Praveen Ballabh 1,6 * 1 Department of Pediatrics, New York Medical College-Westchester Medical Center, Valhalla, New York 2 Shigei Medical Research Institute, Okayama, Japan 3 Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 4 Department of Physiology, New York Medical College-Westchester Medical Center, Valhalla, New York 5 Department of Neurosurgery, Center of Aging and Developmental Biology, University of Rochester, Rochester, New York 6 Department of Anatomy and Cell Biology, New York Medical College-Westchester Medical Center, Valhalla, New York Germinal matrix is selectively vulnerable to hemorrhage in premature infants, and use of prenatal betametha- sone is associated with a lower occurrence of germinal matrix hemorrhage. Because the major components of extracellular matrix of the cerebral vasculature—laminin, fibronectin, collagen IV, and perlecan—provide struc- tural stability to blood vessels, we examined whether the expression of these molecules was decreased in the germinal matrix and affected by betamethasone. In both human fetuses and premature infants, fibronectin was significantly lower in the germinal matrix than in the cortical mantle or white matter anlagen. Conversely, laminin a1 gene expression was greater in the human germinal matrix compared with the cortical mantle or white matter. Expression of a1- and a2(IV) collagen chains increased with advancing gestational age. Low- dose prenatal betamethasone treatment enhanced fi- bronectin level by 1.5–2-fold whereas a high dose reduced fibronectin expression by 2-fold in rabbit pups. Because fibronectin provides structural stability to the blood vessels, its reduced expression in the germinal matrix may contribute to the fragility of germinal matrix vasculature and the propensity to hemorrhage in prema- ture neonates. V V C 2008 Wiley-Liss, Inc. Key words: laminin; fibronectin; collagen IV; perlecan; GM; cerebral cortex; white matter; germinal matrix hemorrhage; intraventricular hemorrhage About 1.45% of all live births are premature infants weighing less than 1,500 g, and the incidence of germi- nal matrix hemorrhage-intraventricular hemorrhage (GMH-IVH) in these very-low-birth-weight infants is about 20% (12,240 infants/year; Investigators of the Ver- mont-Oxford Trial Network Database Project, 1993; Heuchan et al., 2002). These infants are predisposed to cerebral palsy, hydrocephalus, and neurodevelopmental delay (Volpe, 1997; Ballabh et al., 2004). Germinal ma- trix (GM) vasculature, like blood vessels in other brain regions, forms a blood–brain barrier, and its components, including endothelial tight junctions, basal lamina, astro- cyte endfeet, and capillary pericytes, potentially contrib- ute to the stabilization of blood vessels. Thus, weakness of any of the constituents might cause fragility of GM vasculature and its propensity to hemorrhage. The ex- pression levels of primary tight junction molecules, in- cluding claudin-5, occludin, and junction adhesion mol- ecule-1, are comparable among GM, cortical mantle, and white matter anlagen (Ballabh et al., 2005). Notably, the perivascular coverage by glial fibrillary acidic protein (GFAP)-positive astrocyte endfeet is less in the GM vas- culature than in the cortex or white matter, suggesting their role in the pathogenesis of IVH (El-Khoury et al., 2006). A molecular evaluation of basal lamina, another element of the blood–brain barrier that ensheathes the Contract grant sponsor: NIH/NINDS; Contract grant number: NS050586 (to P.B.). *Correspondence to: Praveen Ballabh, MD, Regional Neonatal Center, 2nd floor, Maria Fareri Children’s Hospital, Westchester Medical Center, Valhalla, NY 10595. E-mail: pballabh@msn.com Received 6 July 2007; Revised 20 September 2007; Accepted 3 November 2007 Published online 23 January 2008 in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/jnr.21618 Journal of Neuroscience Research 86:1482–1500 (2008) ' 2008 Wiley-Liss, Inc.