Fig. 1

hTERT-MSC migrate to damaged MIN6-cells and protect them from STZ toxicity. After treatment of MIN6-cells with 0.5, 1.0, or 2.0 mM STZ for 24 h, hTERT-MSC were added to attain direct contact (DC) for 24 h. For studying indirect paracrine effects (IDC), MIN6-cells were subjected to a transwell 96-well plate overnight and incubated for 24 h with STZ. On the next day, hTERT-MSC were added for 24 h to inserts of the wells separating them from MIN6-cells by a membrane with a pore size of 0.4 μm to allow for diffusion of soluble factors only. The influence of hTERT-MSC on the viability of MIN6-cells in DC (a) and IDC (b) at three concentrations of STZ (0.5, 1.0, and 2.0 mM) with MTT assay is demonstrated. The MIN6-cells’ viability expressed is depicted in the percentage of untreated controls in the presence (STZ) and absence (control) of STZ with their respective controls. Approximately 60% viability was noticed in DC which reduced to 35% in IDC at 2.0 mM. c hTERT-MSC migration was evaluated on the membrane of the Boyden chamber with FDA staining in IDC. Unspecific background migration of hTERT-MSC was neutralized by considering 20% FBS in both the chamber (Boyden chamber and well). d RT-PCR was employed to identify the expression of murine SDF-1 in MIN6-cells and human CXCR4 in hTERT-MSC. IDC, indirect culture; DC, direct culture; hTERT-MSC, human telomerase reverse transcriptase mesenchymal stem cells; CXCR-4, C-X-C chemokine receptor type 4; SDF1, stromal cell-derived factor 1. Data represent the mean ± SEM, n = 4. Value considered significant at p ≤ 0.05, **p ≤ 0.01, and ***p ≤ 0.001