C.B-17 SCID mice develop epicardial calcinosis with unaltered cardiac function

Abstract

Inbred mouse strains are the most widely used mammalian model organism in biomedical research owing to ease of genetic manipulation and short lifespan; however, each inbred strain possesses a unique repertoire of deleterious homozygous alleles that can make a specific strain more susceptible to a particular disease. In the current study, we report dystrophic cardiac calcinosis (DCC) in C.B-17 SCID male mice at 10 weeks of age with no significant change in cardiac function. Acquisition of DCC was characterized by myocardial injury, fibrosis, calcification, and necrosis of the tissue. At 10 weeks of age, 38% of the C.B-17 SCID mice from two different commercial colonies exhibited significant calcinosis on the ventricular epicardium, predominantly on the right ventricle. The frequency of calcinosis was more than 50% for mice obtained from Taconic's Cambridge City colony and 25% for mice obtained from Taconic's German Town colony. Interestingly, the DCC phenotype did not affect cardiac function at 10 weeks of age. No differences in echocardiography or electrocardiography were observed between the calcinotic and non-calcinotic mice from either colony. Our findings suggest that C.B-17 SCID mice exhibit DCC as early as 10 weeks of age with no significant impact on cardiac function. This strain of mice should be cautiously considered for the study of cardiac physiology.

Keywords: SCID; calcinosis; cardiac; epicardial; heart; mouse model.

Figure 1:. Dystrophic cardiac calcinosis in C.B-17 SCID mice

Brightfield stereoimages of hearts obtained at 10 weeks of age from Cambridge City, IN (A) and German Town, NY (B). DCC is visible as white lesions on the surface of the ventricles. Masson’s Trichrome staining revealed dark blue staining within the surface lesions, indicative of abundant collagen deposition (C, D, E). Alizarin Red S staining showed dark orange areas within the lesions indicating the presence of calcium (F, G). Scale bars are 1 mm (A, B), 500 μm (C) 200 μm (D, E) and 50 μm (F, G).