Evaluation of human monocytes as carrier cells for the systemic delivery of oncolytic viruses based on Herpes Simplex Type 1 virus in advanced glioblastoma organoids-on chip model

Glioblastoma (GBM) is a type of primary brain tumour and is one of the most frequent, aggressive and lethal types of brain cancer worldwide. The standard treatment is a combinational therapy consisting of surgical resection, followed by radiation therapy and chemotherapeutic temozolomide (TMZ). Ultimately, immunotherapies failed due to challenging characteristics of GBM, such as having high tumour heterogeneity, high invasiveness and recurrences of cancer in distant areas, unresectable nature, immunosuppression of the tumour microenvironment (TME), and limited trafficking across the blood-brain barrier (BBB). To avoid these therapeutic challenges, the potential use of oncolytic viruses (OVs) has emerged to address the challenges and present a new therapeutical approach. Oncolytic viruses are naturally occurring or genetically engineered viruses to preferentially target the tumour microenvironment, selectively replicate in the tumour mass and induce tumour cell lysis and immunogenic cell death. OVs have high selectivity towards the malignant cells with defective antiviral responses, allowing the viral replication to occur in the tumour mass. One of the challenges that must be addressed is the route of administration of the OVs, taking into account drug accumulation, delivery to the target site, invasiveness of the administration, and the presence of the BBB, that strictly regulates trafficking between the blood circulation and the central nervous system (CNS). A type of OV, oncolytic herpes simplex type 1 virus (oHSV1), induces tumour cell lysis, immune activation and gene delivery, however, it has high seroprevalence in the population, meaning they are rapidly sequestered by the immune system. To overcome this, monocytes have been selected as carrier cells, thanks to their favourable characteristics, such as high tropism for tumour tissues and ability to cross the BBB to reach the CNS. In this study, we demonstrated the monocytes and their ability to be carrier cells to deliver oHSV1 to patient-derived multicellular tumoroids, and their ability to cross the BBB and reach the GBM tumoroids, in physiologically relevant advanced in vitro models. Monocytes have been loaded with oHSV1-mCherry, and targeted tumoroids to analyse carrier abilities and viral infection monitoring. Furthermore, monocytes loaded with oHSV1-mCherry are perfused to the BBB-on-chip model to evaluate efficiency of monocytes to cross the BBB in the presence of GBM tumoroids. It has been demonstrated that monocytes efficiently work as carrier cells to deliver the oHSV1-mCherry, cross the BBB and promote viral infection.