Tissue Engineering and Photodynamic Therapy: A New Frontier of Science for Clinical Application -An Up-To-Date Review

Abstract

Tissue engineering (TE) connects principles of life sciences and engineering to develop biomaterials as alternatives to biological systems and substitutes that can improve and restore tissue function. The principle of TE is the incorporation of cells through a 3D matrix support (scaffold) or using scaffold-free organoid cultures to reproduce the 3D structure. In addition, 3D models developed can be used for different purposes, from studies mimicking healthy tissues and organs as well as to simulate and study different pathologies. Photodynamic therapy (PDT) is a non-invasive therapeutic modality when compared to conventional therapies. Therefore, PDT has great acceptance among patients and proves to be quite efficient due to its selectivity, versatility and therapeutic simplicity. The PDT mechanism consists of the use of three components: a molecule with higher molar extinction coefficient at UV-visible spectra denominated photosensitizer (PS), a monochromatic light source (LASER or LED) and molecular oxygen present in the microenvironment. The association of these components leads to a series of photoreactions and production of ultra-reactive singlet oxygen and reactive oxygen species (ROS). These species in contact with the pathogenic cell, leads to its target death based on necrotic and apoptosis ways. The initial objective of PDT is the production of high concentrations of ROS in order to provoke cellular damage by necrosis or apoptosis. However, recent studies have shown that by decreasing the energy density and consequently reducing the production of ROS, it enabled a specific cell response to photostimulation, tissues and/or organs. Thus, in the present review we highlight the main 3D models involved in TE and PS most used in PDT, as well as the applications, future perspectives and limitations that accompany the techniques aimed at clinical use.

UV C Light from a Light-Emitting Diode at 275 Nanometers Shortens Wound Healing Time in Bacterium- and Fungus-Infected Skin in Mice

“…It has great potential to be used in vivo . In addition, the reactive oxygen species (ROS) generated during UVC irradiation can also induce critical damage for microorganisms ( 54 – 56 ). However, it is difficult to control UVC-LED intensity to such a narrow beam in a realistic system.…”

“…On the other hand, the thermal effect caused by long-time and high-dose irradiation is also one of the factors to be considered. In addition, there are also reports about the ROS generated by UVC irradiation, which can induce the critical damage ( 54 ). Furthermore, the generated ROS can induce multiple failure in cell components such as protein denaturation, DNA oxidation, and lipid oxidation ( 64 , 65 ).The long-term influence of ROS generated by UVC irradiation should also be considered.…”

Three‐in‐One Oncolytic Adenovirus System Initiates a Synergetic Photodynamic Immunotherapy in Immune‐Suppressive Cholangiocarcinoma

“…KR was chosen to be the photosensitizer in the system because of its 1000-fold phototoxicity than other green fluorescent proteins and genetically editable characteristics, [18,19] while CAT was employed to alleviate hypoxic condition and help to reshape the immune-suppressive TME by enzymatic hydrolyzing the excessive H 2 O 2 in CHOL. [20] Considering the inherent immunogenicity and large gene capacity, onco-Adv was applied to carry KR and CAT gene fragments in order to realize their sustainable generation and initiate the in situ antitumor photo-immunity. [21][22][23] However, the innate immune attacks and neutralization by widespread pre-existing anti-adv antibodies in the population can reduce the blood concentration and limit administration methods.…”