Influence of Di(2-ethylhexyl)phthalate on migration rate and differentiation of human hematopoietic stem and progenitor cells (CD34+)

Introduction: Phthalates are a group of synthetic plasticizers that are ubiquitous environmental pollutants with toxic and endocrine disrupting characteristics. DEHP is the most commonly used plasticizer in the world and is still applied to stem cell transfusion bags used for storage of hematopoietic stem and progenitor cells (CD34+ HSPC), which are transferred during stem cell transplantation. Here we examined the effect of DEHP on vitality of CD34+ HSPC as well as stem cell specific properties like migration and differentiation capacity - both important for successful stem cell transplantations.

Material and methods: CD34+ HSPC were incubated for 24 h and 72 h with DEHP concentrations ranging from 1 μg/ml to 250 μg/ml. DEHP was diluted in DMSO. Migration rate was analyzed along an SDF-1α gradient using Transwell migration inserts. Differentiation of CD34+ HSPC was investigated after two weeks in methylcellulose with colony stimulating factors. Apoptosis rate was measured via Annexin V and 7-AAD staining.

Results: 24 h of incubation with 10 μg/ml DEHP led to a significant (p < 0.01) decrease in migration rate of CD34+ HSPC (70.70% ± 7.53% ) with a minimum migration rate of 48.33% ± 6.72% in relation to control after incubation with 100 μg/ml DEHP for 72 h. Incubation with the highest tested DEHP concentrations (50 and 100 μg/ml) significantly (p < 0.05) altered colony formation rate and cell type distribution. Apoptosis rate of CD34+ HSPC significantly (p < 0.05) increased after incubation with concentrations of 10 μg/ml DEHP for 24 h (1.46 ± 0.19) with a maximum apoptosis rate of 2.71 ± 0.66 after 24 h incubation with the highest DEHP concentration (250 μg/ml) in relation to control.

Conclusions: As shown, DEHP takes impact on migration rate, apoptosis rate, and differentiation of CD34+ HSPC. As these are functions with an important role in stem cell transplantations, the usage of DEHP-free stem cell transfusion bags should be considered.