Abstract Brachycephalic breeds of dogs, most of which show signs of the brachycephalic syndrome may have greater parasympathetic stimulation than other breeds, leading to higher values of heart rate variability and vagal tone index. The aim of this study was to establish a computerized electrocardiographic study and an assessment of the vagus sympathetic balance through heart rate variability and vagal tone index of five brachycephalic breeds compared to mesocephalic dogs. Sixty dogs were used, divided into groups made up of Boxers, English Bulldogs, French Bulldogs, Pugs, Shih-Tzu and no defined breed mesocephalic dogs. Statistical analysis was carried out using the Shapiro-Wilk test, Kruskal-Wallis and Dunn’s test or ANOVA and Bonferroni (p<0.05). In the evaluation of vagal sympathetic balance among all the dogs, there was a negative correlation between heart rate and HRV 10RR (r = - 0.7678; p < 0.0001), HRV 20RR (r = - 0.8548, p < 0.0001) and VVTI (r = - 0.2770; p = 0.0321). It can therefore be concluded that the dog’s breed and morphology did not alter its electrocardiographic parameters or heart rate variability. The vagal tone index, which in other studies differed in brachycephalic dogs, showed no difference when compared separately in brachycephalic breeds. used Boxers Bulldogs Pugs ShihTzu Shih Tzu ShapiroWilk Shapiro Wilk KruskalWallis Kruskal Wallis Dunns Dunn s p<0.05. p005 p<0.05 . 0 05 (p<0.05) RR r 0.7678 07678 7678 0.0001, 00001 0.0001 , 0001 08548 8548 0.8548 0.2770 02770 2770 0.0321. 00321 0.0321 0321 0.0321) dog p00 p<0.0 (p<0.05 0.767 0767 767 0000 0.000 000 0854 854 0.854 0.277 0277 277 0032 0.032 032 p0 p<0. (p<0.0 0.76 076 76 0.00 00 085 85 0.85 0.27 027 27 003 0.03 03 p<0 (p<0. 0.7 07 7 0.0 08 8 0.8 0.2 02 2 p< (p<0 0. (p< (p

Abstract Mesenchymal stem cells present clinical potential to recover and regenerate injured tissues in diverse pathologies. The in vitro expansion and characterization of these cells contribute to elucidation of the mechanisms of senescence and strategies involving cell therapies. This study aimed to compare specific characteristics between initial and advanced passages of mesenchymal stem cells derived from adipose tissue and bone marrow. Both cell types were characterized according to immunophenotype, osteogenic differentiation, genomic instability, migration assay, doubling population time and colony forming ability. Our results demonstrated that both cell types were able to maintain an immunophenotypic profile typical of mesenchymal stem cells during increasing passages. Adipose stem cells at initial passage presented greater migration capacity compared to advanced passage cells, and advanced passage cells proliferated faster than initial passage cells. Bone marrow stem cells at early passages presented higher osteogenic potential than advanced. At advanced passages they presented higher colony forming capacity and genetic damage than those at initial passage. These results suggest that mesenchymal stem cells maintained in culture presented characteristics of senescence that should be monitored prior the use in regenerative medicine and cells derived from bone marrow at initial passage have better potential for therapeutic use in bone tissue engineering.