Targeting human brain cancer stem cells by curcumin-loaded nanoparticles grafted with anti-aldehyde dehydrogenase and sialic acid: Colocalization of ALDH and CD44.

The use of chemotherapy against brain tumors faces various limitations to achieving its therapeutic effect, due to both the inability of anticancer agents to cross the blood-brain barrier (BBB) and the formation of brain cancer stem cells (BCSCs). Without adequate exposure, these chemotherapeutic drugs cannot have an antiproliferative effect on the tumors. Here, we developed curcumin (CCM)-loaded chitosan-poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) modified with sialic acid (SA) to permeate the BBB and with anti-aldehyde dehydrogenase (anti-ALDH) to target BCSCs. An increased chitosan concentration plays a pivotal role in maintaining a steady release of CCM from NPs. The viability of BBB cells and transendothelial electrical resistance were maintained after treatment with NPs for 4 h. Immunochemical staining of human brain microvascular endothelial cells confirmed that modification of SA on the surface of NPs greatly helped in permeation of the BBB through the use of N-acetylglucosamine. In addition, immunofluorescence images evidenced the assistance of anti-ALDH in inhibiting U87MG cells and BCSCs through targeting ALDH. ALDH was colocalized with CD44 in U87MG cells and BCSCs. The cell viability assay of U87MG cells and BCSCs supported the high level of inhibition after treatment with anti-ALDH-modified NPs. The drug delivery system in this study was designed in such a way to deliver CCM into the brain and subsequently inhibit the proliferation of glioblastoma cells and BCSCs.