Facial vein injection of human cells in severe combined immunodeficiency (SCID) neonatal mice

Intravenous injection is a standard procedure for delivering human stem cells and therapeutic agents. Currently, genetically modified severe combined immunodeficiency (SCID) mice are used for engraftment studies using human cells. SCID neonates have better integration and survivability of human cells compared to adult SCID mice, as their immune system will not be developed in the first few days after birth. However, intravenous injections in neonates are difficult. This protocol describes a reliable and reproducible method for injecting cells into the facial vein of P3/P4 (3 or 4 days post-birth) SCID neonates to study their engraftment. The injection was safe and well tolerated by the pups. Post-injection analysis revealed the distribution of tagged cells in different organs. Results suggest that this new method can serve as a pre-analysis for transplantation studies using human stem cells before in vivo animal model testing.