Development of a neonatal and metastatic murine neuroblastoma model

A neonatal murine neuroblastoma (NB) model has been developed in addition to a murine NB model for metastatic involvement. The S20Y NB cell line used was cloned from the A/Jax murine C1300 NB and was a gift from Dr. M. Nirenberg. Dose-response studies on adult male and female mice given s.c. injections showed no meaningful sex-re-lated differences in either the appearance or the growth rate of the tumors. No significant difference in tumor appearance or growth rate was observed between 10-day-old pups and adults. However, 24- to 48-hr-old pups (neo-nates) inoculated with the same number of cells as the adults demonstrated a marked delay in tumor appearance. Neonates challenged with 5 x 10^s cells showed a 75% reduction in tumor appearance when compared with their adult counterparts. An inoculum of 2 × 10⁵ S20Y cells resulted in 100% of the adult mice developing tumors within 26 days, while none of the 24- to 48-hr-old pups had developed tumors more than 90 days postinjection. Comparison of the s.c. and intradermal routes of injection of NB cells was made using 6- to 8-week-old male mice. Tumors developed at approximately the same rate. The intradermal tumors were removed at various stages of growth. Over 90% of the mice which underwent surgery and a similar percentage of the mice with intradermal tumors which did not have surgery subsequently developed metastases to the lymph nodes, liver, lungs, adrenals, heart, kidney, spleen, and abdominal area, sites commonly found to harbor metastatic lesions in cases of human NB. Metastases at these sites were not observed with s.c. inoculations.