**Acknowledgements**

narrow balance beams than untreated mice [26]. These data clearly demonstrate that MLD model mice can be effectively treated through systemic administration of AAV9/ASA vector to neonates. Thus, neonatal gene therapy is one approach with the potential to overcome the limitation imposed by the BBB on treating genetic disorders of the CNS. Other advantages of systemic gene transfer to neonates with genetic disease over treatment of adults are as follows: (1) because the immune system is immature, recipients are immunologically tolerant of the vector; (2) it may prevent early onset of genetic diseases; (3) neonates can be effectively treated with a smaller amount of vectors than adults; and (4) nearly all organs are efficiently trans‐ duced. Systemic neonatal gene therapy thus appears to be a promising method for treating

**Figure 7.** Correction of sulfatide storage by neonatal systemic injection of AAV9/ASA vectors. After injection of AAV9/ASA into the jugular vein of newborn MLD mice, ASA expression in the brain (A) and spinal cord (C) was ana‐ lyzed by immunohistochemistry using an anti-ASA antibody at 15 months after injection. Correction of sulfatide stor‐

age in the brain (B) and spinal cord (D) was analyzed by alcian blue staining.

systemic genetic diseases with neurological symptoms.

114 Gene Therapy - Principles and Challenges

We thank Dr. James Wilson (University of Pennsylvania), Dr. R. Jude Samulski (University of North Carolina), Dr. Robert M. Kotin (National Institutes of Health), Dr. David W. Russell (University of Washington), Dr. Arun Srivastava (University of Florida College of Medicine), and Dr. A. Dusty Miller (Fred Hunchins Cancer Research Center) for kindly providing AAV packaging or vector plasmids. We also thank Dr. Toshiyuki Kurai, Dr. Naotaka Iwamoto, Dr. Yoshiyuki Yamazaki, Dr. Yukihiko Hirai, and Dr. Yuki Oue for the joint research and helpful discussions. This work was supported in part by grants from the Ministry of Health and Welfare of Japan and the Ministry of Education, Science and Culture of Japan.
