3D bioprinted CRC model brings to light the replication necessity of an oncolytic vaccinia virus encoding FCU1 gene to exert an efficient anti-tumoral activity.

The oncolytic virus represents a promising therapeutic strategy involving the targeted replication of viruses to eliminate cancer cells, while preserving healthy ones. Despite ongoing clinical trials, this approach encounters significant challenges. This study delves into the interaction between an oncolytic virus and extracellular matrix mimics (ECM mimics). A three-dimensional colorectal cancer model, enriched with ECM mimics through bioprinting, was subjected to infection by an oncolytic virus derived from the vaccinia virus (oVV). The investigation revealed prolonged expression and sustained oVV production. However, the absence of a significant antitumor effect suggested that the virus's progression toward non-infected tumoral clusters was hindered by the ECM mimics. Effective elimination of tumoral cells was achieved by introducing an oVV expressing FCU1 (an enzyme converting the prodrug 5-FC into the chemotherapeutic compound 5-FU) alongside 5-FC. Notably, this efficacy was absent when using a non-replicative vaccinia virus expressing FCU1. Our findings underscore then the crucial role of oVV proliferation in a complex ECM mimics. Its proliferation facilitates payload expression and generates a bystander effect to eradicate tumors. Additionally, this study emphasizes the utility of 3D bioprinting for assessing ECM mimics impact on oVV and demonstrates how enhancing oVV capabilities allows overcoming these barriers. This showcases the potential of 3D bioprinting technology in designing purpose-fit models for such investigations.

World's First Long-Term Colorectal Cancer Model by 3D Bioprinting as a Mechanism for Screening Oncolytic Viruses.

Long-term modelization of cancer as it changes in the human body is a difficult goal, particularly when designing and testing new therapeutic strategies. This becomes even more difficult with metastasis modeling to show chemotherapeutic molecule delivery directly to tumoral cells. Advanced therapeutics, including oncolytic viruses, antibody-based and cell-based therapies are increasing. The question is, are screening tests also evolving? Next-generation therapeutics need equally advanced screening tests, which whilst difficult to achieve, are the goal of our work here, creating models of micro- and macrotumors using 3D bioprinting. We developed advanced colorectal cancer tumor processing techniques to provide options for cellular expansion, microtumor printing, and long-term models, which allow for the evaluation of the kinetics of penetration testing, therapeutic success, targeted therapies, and personalized medicine. We describe how we tested tumors from a primary colorectal patient and, applying 3D bioprinting, matured long-term models for oncolytic metastatic screening. Three-dimensional microtumors were kept alive for the longest time ever recorded in vitro, allowing longitudinal studies, screening of oncolytic viruses and realistic modelization of colorectal cancer. These 3D bioprinted models were maintained for around 6 months and were able to demonstrate the effective delivery of a product to the tumoral environment and represent a step forward in therapeutic screening.