2003). As expected, the ability to characterise spiny mouse MSCs on the basis of cell surface markers used routinely for mouse, was not possible in the current study. maintained as previously described (Dickinson and Walker 2007). Briefly, spiny mice are housed in a conventional animal UR 1102 facility and are routinely checked for pathogens. At the time of the described experiment, the colony of spiny mice was deemed to be virus and pathogen free (Serology and molecular diagnostics report October 2009, Institute of Medical and Veterinary Science, South Adelaide, Australia). Tissue collection The procedure for Akt3 isolating putative MSCs from the spiny mouse (with the femurs and tibias. Bone isolation Under sterile conditions, the femur was separated from the tibia and iliac crest for each leg and the foot removed from the tibia and discarded. The iliac crests, femurs and tibias were then scraped free of all visible flesh using a scalpel. The bone marrow was flushed with Dulbeccos Modified Eagle Medium (DMEM; high glucose, sodium pyruvate, no l-Glutamine; Gibco, USA) supplemented with 10% Fetal Calf Serum (FCS) and 1% (v:v) PenicillinCStreptomycin. A single cell suspension was filtered through a 40?m cell strainer, a live cell number determined and the cells discarded. Once flushed of bone marrow, the iliac crests, femurs and tibias were crushed using a mortar and pestle in 5?mL of 3?mg/mL Collagenase type I (Invitrogen, USA) which was prepared UR 1102 in PBS with 2% FCS. The crushed bone solution was incubated with agitation at 37?C for 45?min, filtered through a 40?m cell strainer and a live cell number determined. Flow cytometric analysis Cells isolated from the compact bone were analysed by flow cytometry for their expression of the murine MSC markers Sca-1, CD44, CD31 and CD45 (Table?1; all markers were purchased from BD Biosciences Pharmingen). Three samples were prepared for each marker of interest and included, (a) an unstained sample, (b) an isotype control, and (c) a cell preparation stained for the marker of interest. Cells isolated from the compact bone were counted, aliquoted at 1??106?cells/tube, with PBS and 2% FCS, centrifuged and the supernatant aspirated. Each cell aliquot was stained with either the antibody for the marker of interest or the corresponding UR 1102 isotype control, at a 1:400 dilution, and incubated at room temperature in the dark for 30?min. Following incubation, the cells were washed, centrifuged, the washing solution was aspirated and the cells were resuspended in PBS with 2% FCS for analysis on an FC500 Flow Cytometer Analyser. The position of gates used to identify positively stained cells was set on the basis of the signal observed with the corresponding isotype control for the antibodies. UR 1102 Table?1 MSC antibodies phycoerythrin, fluorescein isothiocyanate Tissue culture and colony forming unit assay Isolated cells from the compact bone fraction (n?=?3) were cultured at 37?C in a humidified incubator with 5% (v:v) CO2 and 95% (v:v) air infusion. Passage 0 cultures were plated in 25?cm2 flasks and cultured in DMEM supplemented with 10% FCS and 1% (v:v) PenicillinCStreptomycin. After 48?h in culture, non-adherent UR 1102 cells were removed by aspirating and replacing the culture medium, which was changed every 4?days thereafter. At approximately 85% confluency, the cells were harvested and passaged into 75?cm2 flasks. At the next passage, the cells were replated into 175?cm2 flasks. At each passage, the numbers of colony forming units were counted. For a cluster of cells to be considered as a colony and to be included in the colony forming unit count, it contained a minimum of 50 cells, as defined by Friedenstein et al. (1974). These assays were used to determine the incidence of putative MSCs in the isolated compact bone fraction. General growth characteristics and multi-lineage differentiation potential A defining property of MSCs is their ability to undergo adipogenic, osteogenic and chondrogenic differentiation (Horwitz et al. 2005; Alison and Islam 2009). As a part of characterizing the putative spiny mouse MSCs, it was therefore necessary to assess their tri-lineage differentiation potential. Adipogenesis and osteogenesis Passage 5 cells were plated at a density of 50,000?cells/chamber in each chamber of a four well chamber slide (BectonCDickinson, USA). The cells were incubated for 24?h in DMEM containing 10% FCS and 1% (v:v) PenicillinCStreptomycin to enable adherence to the growth surface prior to the.