Effects of Tumor Microenvironment on Hyperthermia, Photodynamic and Nanotherapy

Targeted photodynamic therapy — a promising strategy of tumor treatment

“…Moreover, the presence of hypoxia in tumor tissue may induce a variety of pro-angiogenic cytokines and decrease extracellular pH, influencing in this manner the cytotoxic effect of photosensitizers. 7 Thus, a new paradigm of PDT should be focused on the concepts of heterogeneity and dynamic state of tumor, whose morphology and physiology can intensively change during progression of disease and be strongly influenced by environment factors.…”

“…A human solid neoplasia should be regarded as an intricate yet poorly organized "organoid" whose function is maintained by a dynamic interplay between neoplastic and host cells. 7 Tumors develop their unique anatomical structure and build physiological barriers that reduce the penetration and transport of anti-cancer drugs, especially macromolecular agents. These barriers include poor blood flow in large tumors, tumor capillary wall permeability, elevated interstitial fluid pressure, stroma causing poor diffusion in the interstitium, modified fluidity of cancer cell membrane and heterogeneous antigen expression.…”

“…These barriers include poor blood flow in large tumors, tumor capillary wall permeability, elevated interstitial fluid pressure, stroma causing poor diffusion in the interstitium, modified fluidity of cancer cell membrane and heterogeneous antigen expression. 6, 7 The availability of oxygen is a critical feature for obtaining the desired photosensitization. Moreover, the presence of hypoxia in tumor tissue may induce a variety of pro-angiogenic cytokines and decrease extracellular pH, influencing in this manner the cytotoxic effect of photosensitizers.…”

“…Finally, cancer cells express and release unique enzymes such as matrix metalloproteinases, which are implicated in their movement and survival mechanism. [5][6][7] Dramatic increase in tumor drug accumulation -usually tenfold or greater -can be achieved when a drug is delivered by a nanoparticle. Interest in nanoparticles as drug carriers has been increased in recent years.…”