Effects of AZA treatment on stromal support of healthy and MDS HSPCs. (A) Primary healthy or MDS CD34⁺ cells were cultured in serum-free medium in suspension or on EL08-1D2 stromal cells. After 4 days, CD34⁺ cells were harvested and viability was assessed by Annexin V/PI flow cytometry. (B) Primary healthy or MDS CD34⁺ cells were cultured on untreated EL08-1D2 stroma or on stroma treated with 10 µM AZA for 48 hours. After 4 days, CD34⁺ cells were harvested and viability was assessed by Annexin V/PI flow cytometry. Shown is the percentage of viable (Annexin V−/PI−) CD34⁺ cells for each culture condition; each circle represents 1 individual sample (healthy samples, n = 10; MDS samples, n = 10). n.s., not significant.