Co-delivery of temozolomide and quercetin with folic acid-conjugated exosomes in glioblastoma treatment.

Aim: The study aims to improve glioblastoma multiforme (GBM) treatment by combining temozolomide (TMZ) and quercetin (Qct), using folic acid (FA)-conjugated exosomes to overcome TMZ resistance and enhance blood–brain barrier (BBB) penetration. Methods: Exosomes were isolated and after characterizing and modifying their surfaces with FA, drug loading of TMZ and Qct into exosomes was done. In vitro assays, including cell viability tests, RT-PCR, Western-blotting and flow-cytometry, were performed using U87MG and U251MG GBM cell lines. In vivo analysis included administering exosome-drug formulations to glioblastoma-bearing Wistar rats, monitored through optical imaging and PET scans, followed by post-mortem immunohistochemistry and histological examination. Results: The results showed successful exosome isolation and FA conjugation, with drug release studies indicating accelerated release of TMZ and Qct in acidic conditions, enhancing cytotoxicity. Immunofluorescence indicated greater exosome uptake in GBM cells due to FA conjugation. Cell viability assays demonstrated increased toxicity of the combination therapy, correlating with elevated apoptosis. In vivo studies revealed significant tumor size reduction, alongside increased apoptosis and reduced angiogenesis, particularly in the TMZ-Qct-Exo-FA group. Conclusion: FA-conjugated exosomes loaded with TMZ and Qct represent a promising strategy to enhance GBM treatment efficacy by improving drug delivery, apoptosis induction and inhibiting the PI3K/Akt/mTOR pathway. Graphical Abstract Schematic illustration of exosome isolation and conjugation followed by loading with temozolomide (TMZ) and Quercetin (Qct) for glioblastoma therapy. (A) Process of isolating exosomes and conjugating them with folic acid loaded with TMZ and Qct (B) Function of exosomes conjugated with folic acid in a rat model of glioblastoma (C) Mechanism of how exosomes bearing TMZ and Qct work inside the glioblastoma cell line. Article highlights The study emphasizes the successful use of exosome encapsulation to enhance the delivery of temozolomide (TMZ) and quercetin (Qct) across the blood–brain barrier (BBB), improving drug stability for glioblastoma multiforme (GBM) therapy. Encapsulating TMZ and Qct within exosomes (TMZ-Qct-Exo) showed significantly greater potential in reducing GBM cell viability compared with their unencapsulated counterparts, suggesting an effective approach against TMZ resistance. The introduction of folic acid-conjugated exosomes (TMZ-Qct-Exo-FA) enhanced the targeting of GBM cells, leading to better cellular uptake and improved therapeutic outcomes marked by greater apoptosis and increased caspase-3 levels. The combined treatment effectively inhibited the PI3K/Akt/mTOR signaling pathway, vital for tumor growth and survival, thereby boosting the anti-tumor effects of the TMZ-Qct-Exo-FA treatment. In vivo studies demonstrated that the TMZ-Qct-Exo-FA formulation resulted in superior tumor targeting, significantly reduced tumor size and higher levels of apoptotic markers compared with alternative treatment methods. The findings highlight that exosome-mediated drug delivery could serve as a promising strategy to circumvent resistance mechanisms commonly associated with TMZ in GBM treatment. The research indicates that combining exosome technology with conventional chemotherapy could pave the way for new therapeutic modalities in the treatment of aggressive brain tumors like GBM. The use of folic acid as a targeting moiety suggests an innovative approach to enhance specificity in drug delivery systems directed at tumor cells. These results underscore the need for further clinical studies to explore the full potential of exosome-mediated delivery systems in enhancing the effectiveness of existing cancer therapies. [ABSTRACT FROM AUTHOR]