Myxoma Virus-Loaded Mesenchymal Stem Cells in Experimental Oncolytic Therapy of Murine Pulmonary Melanoma

Abstract

Oncolytic viruses can target neoplasms, triggering oncolytic and immune effects. Their delivery to melanoma lesions remains challenging. Bone-marrow-derived mesenchymal stem cells (MSCs) were shown to be permissive for oncolytic myxoma virus (MYXV), allowing its transfer to melanoma cells, leading to their killing. Involvement of progeny virus was demonstrated in the transfer from MSCs to co-cultured melanoma cells. The inhibitory effect of virus on melanoma foci formation in murine lungs was revealed using melanoma cells previously co-cultured with MYXV-infected MSCs. Virus accumulation and persistence in lungs of lesion-bearing mice were shown following intravenous administration of MSC-shielded MYXV construct encoding luciferase. Therapy of experimentally induced lung melanoma in mice with interleukin (IL)-15-carrying MYXV construct delivered by MSCs led to marked regression of lesions and could increase survival. Elevated natural killer (NK) cell percentages in blood indicated robust innate responses against unshielded virus only. Lung infiltration by NK cells was followed by inflow of CD8+ T lymphocytes into melanoma lesions. Elevated expression of genes involved in adaptive immune response following oncolytic treatment was confirmed using RT-qPCR. No adverse pathological effects related to MSC-mediated oncolytic therapy with MYXV were observed. MSCs allow for safe and efficient ferrying of therapeutic MYXV to pulmonary melanoma foci triggering immune effects.

Systemic delivery of TNF-armed myxoma virus plus immune checkpoint inhibitor eliminates lung metastatic mouse osteosarcoma

“…PBMCs were isolated from whole blood using SepMate-50 from STEMCELL Technologies and Histopaque-1077 density gradient via centrifugation at 1,200 × g for 10 min. vMyx-135KO (used as the standard unarmed oncolytic MYXV), vMyx-11LKO (GFP-expressing knockouts of the viral M135 and M11L genes, respectively), vMyx-GFP (GFP-expressing wild-type MYXV with the GFP transgene inserted at an intergenic locus between M135 and M136 genes), vMyx-Fluc-tdTom (MYXV expressing firefly luciferase on the poxvirus synthetic early/late promoter, and tdTomato on the poxvirus late promoter P11), 57 , 58 and vMyx-hTNF (GFP-expressing knockin of the human TNF gene inserted into the M131 gene) constructs were used in this study. 59 , 60 The construction of vMyx-hTNF was previously described in Wang et al.…”

Myxoma Virus Expressing LIGHT (TNFSF14) Pre-Loaded into Adipose-Derived Mesenchymal Stem Cells Is Effective Treatment for Murine Pancreatic Adenocarcinoma

“…ADSCs, in contrast, support viral infection without rapid cell death, making this viral cell carrier useful for in vivo experiments where cell viability and taxis need only be maintained for a brief period in order to ferry the virus into cancerous sites, likely hours or less. The ability of cultured ADSCs to support MYXV replication is similar to that observed with bone marrow-derived mesenchymal stem cells [ 23 ]. This is a key feature of ADSCs, allowing the successful transfer of the virus into adjacent tumor cells via cell–cell contact.…”

“…Thus, the model is a sensitive indicator of the efficiency of delivery of an OV to tumor cells at the pancreatic site of PDAC. Essentially similar outcomes seen with co-implantation of cancer cells and therapeutic constructs provide evidence of viral construct transfer from infected MSCs to cancer cells under in vivo conditions [ 23 ].…”

“…In studies involving mice and repetitive treatment in which the access route is challenging, IP delivery remains an alternative to IV when the latter strategy is clearly ineffective, as it generally is for PDAC. Targeting the pancreas with an OV using mesenchymal stem cells as carriers is not nearly as effective via IV delivery, for the same reason that targeting lung neoplasias in this manner is ineffective—the “first pass” effect [ 23 ]. Although IP administration of pharmacological agents is minimally used in the clinic (mostly for the treatment of peritoneal cancers), in experimental animals it is a justifiable route for proof-of-concept studies where the goal is to evaluate the effect(s) of target engagement rather than the properties of a drug formulation and/or its pharmacokinetics for clinical translation [ 34 ].…”

“…In addition, ADSCs show natural chemotactic tropism for cancer tissues. However, in cases where IV delivery of cell-protected OV would not be effective (due to the “first pass” effect in the lungs) [ 23 ], the transfer of oncovirus cargo to a defined and identifiable tumor site can be accomplished through locoregional injection. In this study, we investigated whether carrier cells could also be beneficial for the delivery of OVs to PDAC via the intraperitoneal (IP) route.…”