Hematopoiesis toxicity induced by CdTe quantum dots determined in an invertebrate model organism

Quantum dots (QDs) have gained significant attention due to their superior optical properties and wide usage in biological and biomedical studies. In recent years, there has been intense concern regarding the in vivo toxicity of QDs. This study was undertaken to examine the toxicity of CdTe QDs on hematopoiesis in an invertebrate model organism, Bombyx mori. Vascular injection of sub-lethal doses of QDs in B. mori larvae caused time- and dose-dependent damage in the hematopoietic organ and hematocytes. QDs with the maximum emission wavelength of 530 nm (QDs530) were quickly observed in cystocytes and plasmacytes, and gradually bleached their green fluorescence, followed by a decrease in peripheral hematocytes. Additionally, the proportion of abnormal hematocytes increased. In marked contrast, QDs with the maximum emission wavelength of 720 nm (QDs720) were quickly surrounded by hematocytes and subsequently enriched in cystocytes like the human's leukocytes, but with weaker cytotoxicity. QDs exposure promoted the mitotic nucleus in prohemocytes and hematocytes similar to peripheral blood stem cells in humans, but aggravated apoptosis. A decrease in hematopoiesis was accompanied by shrinkage and death of hematopoietic organs via an increase in reactive oxygen species. QDs with smaller size resulted in more severe hematopoiesis toxicity.