Nongenetic Optical Modulation of Pluripotent Stem Cells Derived Cardiomyocytes Function in the Red Spectral Range

Cardiac action potential generation mechanisms via an intramembrane photoswitch. A simulation study

Optical stimulation is emerging as a promising alternative to conventional methods for both research and therapeutic purposes due to its advantages, such as reduced energy consumption, minimal invasiveness, and exceptional spatial and temporal precision. Recently, we introduced Ziapin2, a novel light-sensitive azobenzene compound, as a tool to modulate cardiac cell excitability and contractility. The molecule proved to be effective in precisely regulating the excitation-contraction coupling process in both hiPS-derived cardiomyocytes and adult mouse ventricular myocytes (AMVMs). Experimental evidence suggests that stretch-activated channels (SACs) contribute to light-driven action potential (AP) generation, but the exact way this takes place remains unknown due to system complexity and lack of specific SAC blockers. Here, we aim to clarify the role of SACs and photostimulation mechanism by exploiting a computational model of murine AP that incorporates: 1) the variation in membrane capacitance resulting from the trans-cis isomerization of the molecule in response to light stimulation and 2) SACs activated by membrane tension due to the thickness variation induced by Ziapin2. Our numerical model accurately reproduces cell capacitance and membrane potential alterations induced by Ziapin2 photoisomerization. In addition, it elucidates the behavior observed experimentally in vitro in AMVMs, highlighting the pivotal role of calcium (Ca2+)-selective SACs in AP generation. The proposed model is thus a valid tool for cell behavior prediction in future experiments.

Nitrogen doped carbon dots for in vitro intracellular redox modulation via optical stimulation

Carbon dots (CDs) are promising candidates as oxygen photosensitizers, in cancer therapeutic applications due to their high quantum yield, superior chemical and photostability, low cytotoxicity and ease of chemical functionalization/tuning. Nitrogen doping can further improve oxygen photosensitization performance. Besides photodynamic therapy, however, the possibility to finely and remotely regulate the intracellular redox balance by using physical stimuli has been attracting more and more interest not only for nanotheranostic application, but also as a novel, fully biocompatible therapeutic tool. Here, we report on the synthesis of nitrogen-doped CDs by solvothermal methods starting from abundant, bioderived, low-cost precursors, and we characterize their interface with in vitro cultures of human embryonic kidney (HEK-293) cells, a widely accepted model of non-tumoral cells. While not affecting cell proliferation, synthesized CDs efficiently modulate, under visible light and physiological eustress conditions, intracellular calcium ion dynamics and reactive oxygen species concentration, resulting in a 4-fold increase. The reported results may broaden the application of CDs beyond photodynamic therapy, unveiling new opportunities in the field of redox medicine assisted by carbon-based nanomaterials and optical stimulation.

Phage-Templated Synthesis of Targeted Photoactive 1D-Thiophene Nanoparticles

Thiophene-based nanoparticles (TNPs) are promising therapeutic and imaging agents. Here, using an innovative phage-templated synthesis, a strategy able to bypass the current limitations of TNPs in nanomedicine applications is proposed. The phage capsid is decorated with oligothiophene derivatives, transforming the virus in a 1D-thiophene nanoparticle (1D-TNP). A precise control of the shape/size of the nanoparticles is obtained exploiting the well-defined morphology of a refactored filamentous M13 phage, engineered by phage display to selectively recognize the Epidermal Growth Factor Receptor (EGFR). The tropism of the phage is maintained also after the bioconjugation of the thiophene molecules on its capsid. Moreover, the 1D-TNP proved highly fluorescent and photoactive, generating reactive oxygen species through both type I and type II mechanisms. The phototheranostic properties of this platform are investigated on biosystems presenting increasing complexity levels, from in vitro cancer cells in 2D and 3D architectures, to the in vivo tissue-like model organism Hydra vulgaris. The phage-templated 1D-TNP showed photocytotoxicity at picomolar concentrations, and the ability to deeply penetrate 3D spheroids and Hydra tissues. Collectively the results indicate that phage-templated synthesis of organic nanoparticles represents a general strategy, exploitable in many diagnostic and therapeutic fields based on targeted imaging and light mediated cell ablation.

Enhancing the Maturation of Human Pluripotent Stem Cell-Derived Cardiomyocytes with an n-Type Organic Semiconductor Coating

Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) are a promising cell source for cardiac regenerative medicine and in vitro modeling. However, hPSC-CMs exhibit immature structural and functional properties compared with adult cardiomyocytes. Various electrical, mechanical, and biochemical cues have been applied to enhance hPSC-CM maturation but with limited success. In this work, we investigated the potential application of the semiconducting polymer poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2)) as a light-sensitive material to stimulate hPSC-CMs optically. Our results indicated that P(NDI2OD-T2)-mediated photostimulation caused cell damage at irradiances applied long-term above 36 μW/mm2 and did not regulate cardiac monolayer beating (after maturation) at higher intensities applied in a transient fashion. However, we discovered that the cells grown on P(NDI2OD-T2)-coated substrates showed significantly enhanced expression of cardiomyocyte maturation markers in the absence of a light exposure stimulus. A combination of techniques, such as atomic force microscopy, scanning electron microscopy, and quartz crystal microbalance with dissipation monitoring, which we applied to investigate the interface of the cell with the n-type coating, revealed that P(NDI2OD-T2) impacted the nanostructure, adsorption, and viscoelasticity of the Matrigel coating used as a cell adhesion promoter matrix. This modified cellular microenvironment promoted the expression of cardiomyocyte maturation markers related to contraction, calcium handling, metabolism, and conduction. Overall, our findings demonstrate that conjugated polymers such as P(NDI2OD-T2) can be used as passive coatings to direct stem cell fate through interfacial engineering of cell growth substrates.

Advances in Biointegrated Wearable and Implantable Optoelectronic Devices for Cardiac Healthcare

With the prevalence of cardiovascular disease, it is imperative that medical monitoring and treatment become more instantaneous and comfortable for patients. Recently, wearable and implantable optoelectronic devices can be seamlessly integrated into human body to enable physiological monitoring and treatment in an imperceptible and spatiotemporally unconstrained manner, opening countless possibilities for the intelligent healthcare paradigm. To achieve biointegrated cardiac healthcare, researchers have focused on novel strategies for the construction of flexible/stretchable optoelectronic devices and systems. Here, we overview the progress of biointegrated flexible and stretchable optoelectronics for wearable and implantable cardiac healthcare devices. Firstly, the device design is addressed, including the mechanical design, interface adhesion, and encapsulation strategies. Next, the practical applications of optoelectronic devices for cardiac physiological monitoring, cardiac optogenetics, and nongenetic stimulation are presented. Finally, an outlook on biointegrated flexible and stretchable optoelectronic devices and systems for intelligent cardiac healthcare is discussed.