Use of Conditioned Extracellular Matrix as a Tissue-engineered Tumor Matrisome for Prostate Cancer and Melanoma Immunotherapy

Background/Aim: Decellularized extracellular matrix (ECM) acts as a depot for biochemical factors when conditioned by the growth of cells that are subsequently removed, and in the case of tumors, this ECM depot is known as the matrisome. This study was undertaken to determine whether a tissue-engineered matrisome could be used as an antigenic depot to stimulate protective immunity against tumor regrowth and metastasis following surgical reduction of the tumor. Materials and Methods: Using two transplanted tumor cell models, the PAIII rat model of prostate cancer and the B16F1 mouse model of melanoma, mice were administered either media (control), a suspension of inactivated tumor cells, extracellular matrix (SIS), or a matrisome engineered through growth and removal of tumor cells on SIS that was then implanted either directly onto the resected tumor bed or at an anatomical site distant to the tumor bed. Tumor weights were determined at 21 days (rats) and at 17 days (mice), and the number of metastatic foci on the lungs were enumerated at 21 days in rats. Results: Data showed that for both PAIII and B16F1 tumors, mean PAIII and B16F1 tumor weights were significantly reduced for vaccinated animals compared to controls. Furthermore, significantly fewer metastatic foci from PAIII tumors were present on the lungs in vaccinated rats compared to controls. Conclusion: Antigens within the tissue-engineered matrisome stimulated an inhibitory response to tumor growth; this strategy should be explored further as a means of cancer immunotherapy.