218 DONOR-MATCHED FUNCTIONAL AND MOLECULAR CHARACTERIZATION OF CANINE MESENCHYMAL STEM CELLS DERIVED FROM DIFFERENT ORIGINS

Abstract

Canine mesenchymal stem cells (cMSC) have been successfully isolated from several adult tissue sources. However, differences in the biological properties of MSC have been shown to be associated with donor variability. Further, the stem cell capacity of cMSC of various tissues isolated from a single donor is currently unclear. Therefore, this study investigated the functional and molecular characteristics of cMSC derived from bone marrow (cBM-MSC), adipose tissue (cA-MSC) and dermal skin (cDS-MSC) of a single donor. Three kinds of cMSC were isolated by following previously published protocols. AP activity was assessed with a chromogen kit (Abcam Inc., Cambridge, MA, USA). Expression of CD markers (CD45, 90 and 105) and stem cell transcription factors (Oct3/4, Nanog and Sox2) was analysed by immunocytochemical staining. All cells were induced into osteogenesis and adipogenesis by following protocols described earlier and confirmed by cytochemical staining and the detection of lineage specific genes by RT-PCR. Chromosomal stability was assessed by a method described earlier (Ock and Rho 2008 J. Vet. Med. Sci. 70, 1165–1172) and cell cycle status was determined by a flow cytometry. Telomere length was analysed by Telo TAGGG Telomere Length Assay kit (Roche, Mannheim, Germany) and telomerase activity was evaluated by semiquantitative nested RT-PCR. Statistical analysis was performed by ANOVA using SPSS 12.0 and significance was tested when P < 0.05. Expressions of AP activity and the transcription factors, such as Oct3/4, Nanog and Sox2 were absent in all cMSC. All 3 types of cMSC positively expressed the surface markers CD90 and 105 but not CD45. Exposure of all cell lines to osteogenic and adipogenic induction medium resulted in the calcium deposition evidenced by Alizarin red S staining and the accumulation of fat globules indicated by Oil red O staining, respectively. Differentiation was further confirmed by the detection of marker genes, such as Runx2 and Pparγ. However, the degree of osteogenic or adipogenic differentiation among the 3 kinds of cMSC was different and particularly, cA-MSC had enhanced cytochemical staining associated with expression of specific genes, Runx2 and Pparγ. Ploidy analysis showed that the diploid rate was high with over 90% in all cMSC and indicated no noticeable chromosomal abnormalities. Further, less than 52% of cells were found at G1 phase in all cMSC, with lowest percentage observed in cDS-MSC (33.3%). Regardless of varied tissue sources, cMSC from a single donor showed no differences in telomere lengths (∼18–19 kbp), but the telomerase activity was different with significantly higher levels found in cBM-MSC. In conclusion, the above results suggest that tissue specific cMSC derived from a single donor possess differences in stem cell capacity and support the consideration of tissue source before judging the suitability of cells for therapeutic applications. This work was supported by grant from Basic Science Research Program through NRF funded by the Ministry of Education, Science and Technology (2009-0064229).