Enhanced Antitumor Efficacy of Oncolytic Adenovirus–loaded Menstrual Blood–derived Mesenchymal Stem Cells in Combination with Peripheral Blood Mononuclear Cells

Abstract

Several studies have evaluated the efficacy of using human oncolytic adenovirus (OAdv)-loaded mesenchymal stem cells (MSC) for cancer treatment. For example, we have described the antitumor efficacy of CELYVIR, autologous bone marrow-mesenchymal stem cells infected with the OAdv ICOVIR-5, for treatment of patients with neuroblastoma. Results from this clinical trial point out the role of the immune system in the clinical outcome. In this context, a better understanding of the immunophenotypic changes of human MSCs upon adenoviral infection and how these changes affect human autologous or allogeneic peripheral blood mononuclear cells (PBMC) could guide strategies to improve the antitumor efficacy of infected MSCs. In this work, we show how infection by an OAdv induces toll-like receptor 9 overexpression and activation of the NFB pathway in menstrual blood-derived MSCs, leading to a specific cytokine secretion profile. Moreover, a proinflammatory environment, mainly mediated by monocyte activation that leads to the activation of both T cells and natural killer cells (NK cell), is generated when OAdv-loaded MSCs are cocultured with allogeneic PBMCs. This combination of allogeneic PBMCs and OAdv-loaded MSCs enhances antitumor efficacy both in vitro and in vivo, an effect partially mediated by monocytes and NK cells. Altogether our results demonstrate not only the importance of the immune system for the OAdv-loaded MSCs antitumor efficacy, but in particular the benefits of using allogeneic MSCs for this therapy.

Enhanced antitumor efficacy of an oncolytic adenovirus armed with an EGFR-targeted BiTE using menstrual blood-derived mesenchymal stem cells as carriers

“…Isolation and characterization of MenSCs has been previously described. 5 Experiments employing human PBMCs were approved by the ethics committees of the University Hospital of Bellvitge and the Blood and Tissue Bank (BST) from Catalonia. PBMCs of healthy donors were isolated from blood by ficoll (Rafer, Spain) density gradient centrifugation in Leucosep tubes (Greiner Bio-one, Kremsmünster, Austria) following the manufacturer's recommendations.…”

“…The oncolytic adenovirus ICOVIR15 have been previously described. 5 ICOVIR15-cBiTE was engineered to express cBiTE gene under the control of the viral major late promoter by homologous recombination in bacteria, similarly to previous described for ICOVIR15K-BiTE. 6 Production of supernatants A549 or MenSCs (2.5x10 6 ) were infected with ICOVIR15 or ICOVIR15-cBiTE (MOI=5 or 50 respectively) and supernatants were harvested 72 hours after infection.…”

“…4 We have recently reported the advantages of using menstrual blood-derived mesenchymal stem cells (MenSCs) as cell carriers for ICOVIR15, an OAdv developed in our laboratory. 5 We demonstrated not only an efficient OAdv tumor delivery, but also a significant, although modest, antitumor efficacy of OAdv-loaded MenSCs in combination with human peripheral blood mononuclear cells (hPBMCs). This increased antitumor effect was mainly mediated by monocyte activation leading to both T cell and natural killer cell activation.…”

“…This increased antitumor effect was mainly mediated by monocyte activation leading to both T cell and natural killer cell activation. 5 In a different line of research aimed at redirecting T cells towards tumor cells, we have recently engineered an armed OAdv (ICOVIR15K-cBiTE) expressing an epidermal growth factor receptor (EGFR)-targeting bispecific T-cell engager (cBiTE). 6 BiTEs are well-established immunotherapeutic molecules that combine the minimal binding domains (scFv) of two different monoclonal antibodies fused by a short flexible linker.…”

Oncolytic viruses: overcoming translational challenges

“…A few studies have shown that SCs possess immuno suppressive properties (94)(95)(96), suggesting that they would not be ideal carriers for OV-mediated immune stimulation. However, recent studies have clarified that OV infection in SCs induces TLR 9 over expression and activation of the NF-κB pathway, leading to a specific cytokine secretion profile by SCs and generating a proinflammatory environment (97).…”