Structuring a BALB/c mice colony in the Unidad Experimental de Inmunoterapia of Fundación Jacinto Convit - Venezuela

Animal models are a fundamental part of preclinical scientific research in the development of new therapies, including drugs and gene therapies. For such purposes, it is crucial to have an animal model appropriate for the study being conducted.

At the bioterio of the Unidad Experimental de Inmunoterapia (UEI) of the Fundación Jacinto Convit (FJC), a colony of BALB/c mice was established to maintain a pure strain for experimental breast cancer research projects using the 4T1 autologous tumor cell line. This colony was initiated from two pairs of BALB/c mice provided by the Universidad Simón Bolívar, ensuring strict housing conditions in microisolators, appropriate feeding, environmental enrichment, and detailed control of the micro and macroenvironment required for the species. Animal care was overseen by a specialized biologist.

The expansion of this BALB/c mouse strain was assessed following a scheduled inbreeding scheme for every third litter. Homozygosity was determined through skin grafting among individuals of the same strain and comparative analysis of microsatellites. Data from 135 litters were analyzed, with a maximum of six litters per breeding box, originating from monogamous pairs where no unexpected deaths occurred. An average of 6.25 ± 2.38 pups per litter and an interbirth interval of 27 ± 7.5 days were observed.

The results of this study demonstrated that the breeding, care, and maintenance protocol for the BALB/c mouse colony at the bioterio of the UEI of the FJC is effective in ensuring the expansion and genetic purity of this strain, henceforth referred to as BALB/c//USB//FJC.