Murine neonatal intravascular injections: modeling newborn disease.

The ability to perform murine neonatal intravascular injections likely will prove useful in studying many newborn-specific disease states that are modeled in mice. Unfortunately, effective intravascular injection in the neonatal mouse has been limited by developmental immaturity and small size. To establish a mouse model of neonatal intravascular injection, C57Bl/6 pups between birth and 6 d of age were injected with a buffered solution containing cells or vehicle alone. For both external jugular and superficial temporal vein injections, a 2-member team was used to position the pup, insert the needle, and perfuse the injectate. For superficial temporal vein injections, the vascular anatomy was visualized by using transillumination. After injection into the jugular or superficial temporal vein, the survival rate to adulthood was 100% (n = 30 pups per group), with no long-term complications. Occasional extravasation of injectate was well tolerated, allowing for serial injections (n = 40 pups). Intravascular access was confirmed by using fluorescent dye perfusion studies and cellular engraftment analysis. The 2 techniques are safe and reproducible methods of obtaining intravascular access via the external jugular and superficial temporal veins in newborn mice. These methods provide a mechanism for delivering a wide variety of substances, ranging from aqueous solutions to suspensions.