Isolation and characterisation of peripheral blood-derived feline mesenchymal stem cells.

The aim of this study was to isolate mesenchymal stem cells (MSCs) from feline peripheral blood (fPB-MSCs) and to characterise the cells' in vitro properties. The mononuclear cell fractions were isolated from venous blood of cats by density gradient centrifugation and cultured on plastic dishes under various culture conditions to isolate MSCs. When these cells were cultured with 5% autologous plasma (AP) and 10% foetal bovine serum (FBS), adherent spindle shaped fibroblast-like cells (fPB-MSCs) were obtained from 15/22 (68%) cats. These cells were isolated only from medium containing both AP and FBS. The morphology of these MSCs was similar to those isolated from other species and from other feline tissues. fPB-MSCs expanded steadily up to 5-6 passages, but had increased population doubling time during passaging and almost all cells stopped proliferation at passages 7-9. These cells expressed CD44 and CD90, and were mostly negative for major histocompatibility class II and CD4. The cells could be induced to differentiate into adipogenic, osteogenic and chondrogenic cell lineages. These findings indicate that fPB-MSCs can be generated but appear to require specific culture conditions.