Combining the strengths of cytotoxic T cells and nanomedicines for cancer immunotherapy

Cancer remains one of the most devastating diseases worldwide, with every year 14 million new cases and 8 million cancer-related deaths. Nowadays, conventional cancer therapies consist of surgery, radiotherapy, and chemotherapy. These methods, however, hold a potential risk for relapse, metastasis, and systemic toxicity. To reduce the risk of systemic toxicities, researchers have developed strategies to encapsulate chemotherapeutics in nanocarriers, aiming to improve the specific delivery of therapeutics to the tumor. Despite the success of anti-cancer nanomedicines in (pre)clinical trials, the number of commercially available therapeutics remains remarkably low. One of the main causes is their low targeting capacity and limited infiltration into the tumor after systemic injection. Therefore, this project aimed to investigate the cell-mediated delivery of nanomedicines to the tumor. For this purpose, cytotoxic T cells (CTLs) were selected as transport vehicles based on their spontaneous migration to the tumor and their potential to specifically kill tumor cells. We were the first to show the reversible coupling of lipid-based nanoparticles (NPs) to the surface of CTLs for tumor-targeted delivery of membrane-impermeable macromolecules such as small interfering RNA (siRNA). Further, preliminary in vitro and in vivo data illustrated promising results for the combination of CTLs with NPs that were loaded with immune adjuvants. Unfortunately, it has been shown in the literature that a variety of immunosuppressive mediators, especially in the tumor microenvironment, hinders the T cell anti-tumor responses. To tackle this important challenge, we developed a technique based on vapor-nanobubble photoporation for the efficient delivery of siRNA molecules to CTLs, inducing silencing of target genes. Consequently, the knockdown of important immunosuppressive pathways can give T cells more power to eradicate tumor

Hitchhiking nanoparticles: reversible coupling of lipid-based nanoparticles to cytotoxic T lymphocytes

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Comparing photoporation and nucleofection for delivery of small interfering RNA to cytotoxic T cells

The success of cancer immunotherapy through the adoptive transfer of cytotoxic T lymphocytes (CTLs) is highly dependent on the potency of the elicited anti-tumor responses generated by the transferred cells, which can be hindered by a variety of upregulated immunosuppressive pathways. Downregulation of these pathways in the T cells via RNA interference (RNAi) could significantly boost their capacity to infiltrate tumors, proliferate, persist, and eradicate tumor cells, thus leading to a durable anti-tumor response. Unfortunately, it is well known that primary T cells are hard-to-transfect and conventional non-viral transfection agents are generally ineffective. Viral transduction and electroporation are more efficient but their use is restricted by high cost, safety issues, and cytotoxicity. Photoporation has recently gained interest as a more gentle alternative physical approach to deliver membrane-impermeable macromolecules into cells. By attaching gold nanoparticles (AuNPs) to the cell surface followed by pulsed laser illumination, transient membrane pores can be generated that allow the diffusion of macromolecules directly into the cell cytosol. Here, we evaluated this technique for the non-toxic and effective delivery of small interfering RNA (siRNA) and subsequent silencing of target genes in activated CTLs. We compared photoporation with nucleofection, the current standard physical technique for T cell transfection, and demonstrated a significantly reduced cytotoxicity and higher average dose per cell for the photoporation technique