Differential Anti-Proliferation of Resveratrol on Human Hematopoietic Progenitor Cells and Leukemic Cells.

Resveratrol is present naturally in a variety of fruits and medicinal plants. It imparts protective benefits to plants against pathogenic attack and environmental stress. In human, it was noted to be able to protect against cardiovascular disease and inhibit platelet aggregation. Its anti-oxidant activities were also suggestive in human cancer chemoprevention and chemotherapy. In this in-vitro study we investigated the anti-proliferative effect of resveratrol on human normal hematopoietic progenitor cells and leukemic cells. Resveratrol of 1 mM to 0.1 μM at 10-fold dilutions were applied to hematopoietic progenitor cultures. Duplicates of 5 x 10⁴ mononuclear cells (n=7) and 5 x 10³ CD34⁺ cells (n=3) derived from 10 umbilical cord blood (UCB) samples were cultured for two weeks in methylcellulose enriched with 100 ng/mL granulocyte-macrophage colony-stimulating factor, 20 ng/mL stem cell factor, 2 IU/mL erythropoietin and various concentration of resveratrol. There was no growth of colony-forming unit (CFU) in cultures supplemented with high-dose resveratrol (10 UCB: 100% in 1 mM, 90% in 100 μM and 10% in 10 μM), exhibiting an inhibitory effect on the proliferation of hematopoietic stem and progenitor cells in a dose-dependent manner. The numbers of CFU-GEMM, CFU-GM and BFU derived from cultures with 10 μM, 1 μM and 0.1 μM resveratrol demonstrated no significant difference as compared to that of control cultures without resveratrol. Ten μM resveratrol were added to 12 human leukemic cell lines (AML: KG-1a, Kasumi-1, HL60, NB4, Meg-01, CHRF 288-11; CML: K562; B-lineage ALL: 697, RS-411, REH; T-lineage ALL: Molt-3, CCRF-CEM) at 5 x 10⁵/mL and cultured for four days in triplicate. Cell counts, trypan blue dye exclusion tests and flow cytometry were conducted daily on cultures to evaluate growth, viability and cell cycle phase distribution, respectively. There was a significant and progressive decrease in the numbers of viable cells in resveratrol-supplemented cultures (median [range]: 26.1% [14.3% – 50.3%] at 24 hours, 43.1% [18.2% – 54.6%] at 48 hours, 45.6% [9.3% – 67.6%] at 72 hours and 32.5% [15.7% – 55.3%] at 96 hours). Cell cycle analysis revealed a remarkably elevated proportion of apoptotic cells at pre-G₁ phase in resveratrol-supplemented cultures on day one (with vs. without: 15.9% [2.0% – 41.2%] vs. 7.8% [2.4% – 17.6%]; p=0.011). Besides, a growth arrest of CHRF 288-11 (51.6% vs. 39.8%; p=0.032) and Molt-3 (70.2% vs. 54.2%; p=0.002) was noted in G₁ phase, whereas an accumulation of KG-1a (25.8% vs. 19.6%; p=0.019) and CCRF-CEM (26.2% vs. 23.2%; p=0.026) in S phase was observed. Data of this study suggest that 10 μM resveratrol may exert an anti-proliferative effect against human leukemic cells but pose no apparent suppression to normal hematopoiesis.