312 ISOLATION, PROLIFERATION, AND CHARACTERIZATION OF MESENCHYMAL STEM CELLS FROM AMNIOTIC FLUID, AMNION, AND UMBILICAL CORD MATRIX IN THE DOG

Abstract

Mesenchymal stem cells (MSC) are defined as multipotent stem cells that can differentiate into various cell types in vivo and in vitro under controlled conditions. These cells express specific markers detectable by analysis at the mRNA or protein level. Important sources of MSC could be fetal adnexa, such as amniotic fluid (AF), amnion (AM), and umbilical cord matrix (UCM). Canine MSC should be of use for cell-based therapies and tissue engineering improving treatment of several diseases. Moreover, the dog has been considered an attractive animal model to study human diseases. In the present study, we successfully isolated and molecularly characterised AF-MSC, AM-MSC, and UCM-MSC from dogs. Chromosomal stability and telomerase activity were also investigated. Samples were recovered after elective ovariohysterectomy in 3 bitches 25 to 40 days of gestational age. After isolation, cells were maintained in culture (Bossolasco et al. 2006 Cell Res. 16, 329–336) for different passages to perform growth and doubling time (DT) studies. Expression analyses of embryonic (Oct-4, Nanog), mesenchymal (CD44, CD184, CD29), and haematopoietic (CD34, CD45) markers were carried out by RT-PCR. Karyotype analysis was performed by Q banding. Telomerase activity was analysed by TRAPeze Telomerase Detection Kit. In all 3 cell types, the morphology of proliferating cells appeared typically fibroblast-like. In the growth study, cells isolated from AF and AM were cultured until P3, and cells isolated from UCM were maintained until P7. The population DT in AF-MSC was significantly increased (Student’s t-test: P < 0.05) when comparing P1 v. P4. In AM-MSC, DT increased significantly in P1 v. P2 (P < 0.001), and in UCM-MSC, DT significantly increased in P1 v. P4 (P < 0.001). In AF-MSC, cell viability did not change with passages. In AM-MSC, cell viability significantly decreased (P < 0.001) between P1 and P4. In UCM-MSC, cell viability remained at approximately constant levels up to P6 and significantly decreased at P7 (P < 0.001). Amnion and UCM-MSC expressed Oct-4 and CD44, CD184, and CD29, whereas AF-MSC expressed only Oct-4 and CD44. Nanog, CD34, and CD45 were never found to be expressed in any cell line at any passage. In all cell lines, analysed metaphases at P4 showed normal chromosomal number and structure. Telomerase activity was observed in UCM-MSC, whereas tests on AF and AM-MSC are still on going. We first reported data on isolation, in vitro culture, and characterisation of MSC from AM and UCM in the dog. Cells expressed embryonic and MSC markers beginning at P1 and showed normal karyotype. These data indicated that canine MSC from fetal adnexa could be used to study stem cell biology and their application in therapeutic programs.