 In summary, we have developed a novel approach to non-invasively monitor the progress of tissue engineered structures in a living organism using upconversion nanoparticles, UCNPs, as photoluminescent nanomarkers and scaffolds. Our results suggest that the UCNP's photoluminescent signal monotonously decreases in all the examined scaffolds, indicating their gradual biodegradation followed by the release of photoluminescent nanoparticles into the surrounding tissues. This suggests that UCNPs can be used as a promising tool for non-invasive visualization and monitoring of tissue engineered structures in a living organism. This article was authored by Ekaterina M. Triphanova, Gula like Bobahiva, Maria A. Coristina and others.