OBJECTIVE: This laboratory has demonstrated that lipid-coated microbubbles
(LCMs) effectively aggregate and deliver chemotherapeutic drugs into rat br
ain tumor cells and antigliosis agents into maturing rat brain injury sites
. In this study, we report the affinity of tail vein-injected LCMs to the i
njured rat spinal cord by a compressive lesion to the upper thoracic region
METHODS: The accumulation of LCMs in the injured spinal cord was analyzed b
y labeling it with a lipid-soluble fluorescent dye, 3,3'-dioctadecyloxacarb
ocyanine perchlorate. Indices of glial fibrillary acidic protein were measu
red concomitantly with 3,3'-dioctadecyloxacarbocyanine perchlorate-labeled
LCMs using confocal microscopy.
RESULTS: There was no aggregation of LCMs accumulated 1 and 6 hours after i
njury; however, when given 2, 4, and 7 days after injury, LCMs showed a cle
ar affinity for the injured region. LCM aggregation shifted from the centra
l necrotic area of the injury on postinjury Day 2 and postinjury Day 4 to t
he white matter among glial fibrillary acidic protein-positive astrocytes b
y postinjury Day 7.
CONCLUSION: Affinity of LCMs for spinal cord injury sites may be mediated i
n the early stages after injury by proliferating macrophages in the necroti
c center, and then in later stages by glial fibrillary acidic protein-posit
ive astrocytes in adjacent white matter. These findings suggest a potential
for using LCMs as a delivery vehicle to concentrate lipid-soluble agents i
n spinal cord injury sites.