Figure 3. Cell viability and colony formation detection. (A) After NRK co-cultured with exosomes and Cp, the percentage of cell viability was measured by MTT assay; *, p < 0.05, **, p < 0.01, ***, p < 0.001. (B) and (C) The changes of colony number were measured by colony formation assay. *, p < 0.05 vs. Control; #, p < 0.05 vs. Exo1h+Cp; &, p < 0.05 vs. Exo6h+Cp; $, p < 0.05 vs. Exo12h+Cp.