Morphologic, Proliferative, and Cytogenetic Changes during In Vitro Propagation of Cat Adipose Tissue-Derived Mesenchymal Stromal/Stem Cells.

Stem cell therapy in cat patients needs a high quantity of mesenchymal stromal/stem cells (MSCs) requiring in vitro propagation under culture conditions which may potentially impact cellular characteristics and genetic stability. This study aimed to assess the in vitro characteristics and cytogenetic stability of cat adipose tissue-derived MSCs (cAT-MSCs). For this purpose, morphological features, clonogenic potential, and proliferative capacity of cAT-MSCs were assessed at passages 2 (P 2 ), P 4 , and P 6 . Multipotency and immunophenotype were evaluated. Cytogenetic analyses were conducted up to P 6 . The cAT-MSCs exhibited a spindle-shaped morphology in early passages. The doubling time increased from 2.5 days at P 2 to 9.4 at P 4 and 10.5 at P 6 , accompanied by the observation of nuclear abnormalities such as cluster formation, karyorrhexis, karyolysis, and a decline in the mitotic index at P 4 . Cells demonstrated multipotency capacity and were CD45-, CD90+, and CD44+. Metaphase analysis at P 2 and P 4 revealed some indications of structural instability such as gaps, breaks, deletions, duplications, and early chromatid segregation, but these alterations did not show an increase across passages. In conclusion, cAT-MSCs decreased their proliferative capacity after P 4 , accompanied by morphological alterations and signs of structural instability.