Double-PEGylated Cyclopeptidic Photosensitizer Prodrug Improves Drug Uptake from In Vitro to Hen’s Egg Chorioallantoic Membrane Model

Cyclopeptidic photosensitizer prodrugs (cPPPs) are compounds designed to specifically target overexpressed hydrolases such as serine proteases, resulting in their specific activation in close proximity to tumor cells. In this study, we explored a series of conjugates that can be selectively activated by the urokinase plasminogen activator (uPA). They differ from each other by their pheophorbide a (Pha) loading, their number of PEG chains and the eventual presence of black hole quenchers (BHQ3). The involvement of a peptidic linker between the drugs and the cyclopeptidic carrier allows specific cleavage by uPA. Restoration of the photophysical activity was observed in vitro on A549 lung and MCF7 breast cancer cells that exhibited an increase in red fluorescence emission up to 5.1-fold and 7.8-fold, respectively for uPA-cPPQ2+2/5. While these cPPP conjugates do not show dark toxicity, they revealed their phototoxic potential in both cell lines at 5 µM of Phaeq and a blue light fluence of 12.7 J/cm2 that resulted in complete cell death with almost all conjugates. This suggests, in addition to the promising use for cancer diagnosis, a use as a PDT agent. Intravenous injection of tetrasubstituted conjugates in fertilized hen eggs bearing a lung cancer nodule (A549) showed that a double PEGylation was favorable for the selective accumulation of the unquenched Pha moieties in the tumor nodules. Indeed, the diPEGylated uPA-cPPP4/52 induced a 5.2-fold increase in fluorescence, while the monoPEGylated uPA-cPPP4/5 or uPA-cPPQ2+2/5 led to a 0.4-fold increase only.

Effect of serial photodynamic therapy with curcumin on Leishmania braziliensis and Leishmania amazonensis promastigotes

Photodynamic Therapy (PDT) consists of using a light source and a photosensitive drug at an appropriate wavelength and molecular oxygen to trigger cell death through the production of reactive oxygen species. Because it is a localised therapy, PDT is shown to be ideal for skin diseases. American cutaneous Leishmaniasis (ACL) is a highly prevalent protozoan disease worldwide that presents different clinical evolutions and may result in ulcerations and disfiguring lesions on the skin and cartilage. This study was aimed at evaluating the effect in vitro of PDT applied serially using curcumin as a photosensitiser. For this, a concentration of 125 µg.mL-1 of curcumin was used on Leishmania braziliensis and Leishmania amazonensis strains, with a light fluence of 10 J.cm-2 and irradiance of 110 mW.cm-2. The tests done were viability analysis by trypan blue exclusion test, analysis of photosensitizer (PS) internalization by confocal microscopy and morphological alterations by May-Grunwald/Giemsa staining. We observed that there was internalisation of the PS before the first and second application of PDT, with L. braziliensis and L. amazonensis strains mortality of 92% and 82% respectively, after the second application, and induction of alterations in the structural conformation, such as cell size and non-evidence of nucleus and flagellum, demonstrating that PDT was effective. We conclude that serial PDT was effective in inducing the mortality of promastigotes forms of L. braziliensis and L. amazonensis in vitro, thus highlighting its potential for the treatment of leishmaniasis.

Differing biophysical properties underpin the unique signaling potentials within the plant phytochrome photoreceptor families

Many aspects of photoperception by plants and microorganisms are initiated by the phytochrome (Phy) family of photoreceptors that detect light through interconversion between red light- (Pr) and far-red light-absorbing (Pfr) states. Plants synthesize a small family of Phy isoforms (PhyA to PhyE) that collectively regulate photomorphogenesis and temperature perception through redundant and unique actions. While the selective roles of these isoforms have been partially attributed to their differing abundances, expression patterns, affinities for downstream partners, and turnover rates, we show here from analysis of recombinant Arabidopsis chromoproteins that the Phy isoforms also display distinct biophysical properties. Included are a hypsochromic shift in the Pr absorption for PhyC and varying rates of Pfr to Pr thermal reversion, part of which can be attributed to the core photosensory module in each. Most strikingly, PhyB combines strong temperature dependence of thermal reversion with an order-of-magnitude faster rate to likely serve as the main physiological thermosensor, whereby thermal reversion competes with photoconversion. In addition, comparisons of Pfr occupancies for PhyA and PhyB under a range of red- and white-light fluence rates imply that low-light environments are effectively sensed by PhyA, while high-light environments, such as full sun, are effectively sensed by PhyB. Parallel analyses of the Phy isoforms from potato and maize showed that the unique features within the Arabidopsis family are conserved, thus indicating that the distinct biophysical properties among plant Phy isoforms emerged early in Phy evolution, likely to enable full interrogation of their light and temperature environments.

Long-range optofluidic control with plasmon heating

Using light to manipulate fluids has been a long-sought-after goal for lab-on-a-chip applications to address the size mismatch between bulky external fluid controllers and microfluidic devices. Yet, this goal has remained elusive due to the complexity of thermally driven fluid dynamic phenomena, and the lack of approaches that allow comprehensive multiscale and multiparameter studies. Here, we report an innovative optofluidic platform that fulfills this need by combining digital holographic microscopy with state-of-the-art thermoplasmonics, allowing us to identify the different contributions from thermophoresis, thermo-osmosis, convection, and radiation pressure. In our experiments, we demonstrate that a local thermal perturbation at the microscale can lead to mm-scale changes in both the particle and fluid dynamics, thus achieving long-range transport. Furthermore, thanks to a comprehensive parameter study involving sample geometry, temperature increase, light fluence, and size of the heat source, we showcase an integrated and reconfigurable all-optical control strategy for microfluidic devices, thereby opening new frontiers in fluid actuation technology.

Photodynamic Therapy Using Cerenkov and Radioluminescence Light

In this short review the potential use of Cerenkov radiation and radioluminescence as internal sources for Photodynamic therapy (PDT) is discussed. PDT has been developed over the course of more than 100 years and is based on the induced photo conversion of a drug called photosensitizer (PS) that triggers the production of cytotoxic reactive oxygen species (ROS) leading to the killing of the cells. In order to overcome the problem of light penetration in the tissues, different solutions were proposed in the past. The use of radioisotopes like: 18F, 64Cu, 90Y, 177Lu as internal light sources increase the light fluence at the PS compared to an external source, resulting in a larger cytotoxic effect.

Learned spectral decoloring enables photoacoustic oximetry

The ability of photoacoustic imaging to measure functional tissue properties, such as blood oxygenation sO$$_2$$ 2 , enables a wide variety of possible applications. sO$$_2$$ 2 can be computed from the ratio of oxyhemoglobin HbO$$_2$$ 2 and deoxyhemoglobin Hb, which can be distuinguished by multispectral photoacoustic imaging due to their distinct wavelength-dependent absorption. However, current methods for estimating sO$$_2$$ 2 yield inaccurate results in realistic settings, due to the unknown and wavelength-dependent influence of the light fluence on the signal. In this work, we propose learned spectral decoloring to enable blood oxygenation measurements to be inferred from multispectral photoacoustic imaging. The method computes sO$$_2$$ 2 pixel-wise, directly from initial pressure spectra $$S_{\text {p}_0}(\lambda , \mathbf {x})$$ S p 0 ( λ , x ) , which represent initial pressure values at a fixed spatial location $$\mathbf {x}$$ x over all recorded wavelengths $$\lambda$$ λ . The method is compared to linear unmixing approaches, as well as pO$$_2$$ 2 and blood gas analysis reference measurements. Experimental results suggest that the proposed method is able to obtain sO$$_2$$ 2 estimates from multispectral photoacoustic measurements in silico, in vitro, and in vivo.

Treatment results from a phase I study of WST11 phototherapy (VTP) for upper tract urothelial carcinoma.

460 Background: Localized treatment of upper tract urothelial carcinoma (UTUC) is technically challenging which limits the ability to provide organ-sparing therapies to preserve renal function and representing a serious unmet need. Vascular-targeted photodynamic therapy (VTP) using intravascular photosensitizing agent padeliporfin (WTS11) has demonstrated preclinical safety and effective tumoricidal activity. Endoluminal application of this therapy offers a promising alternative to radical surgery for patients with upper tract cancers seeking to avoid extirpative surgery. Herein we present early results from a phase I dose-finding study of padeliporfin VTP for UTUC. Methods: Fourteen patients with recurrent UTUC were treated with up to 2 sessions of endoscopic padeliporfin VTP treatment. Eligibility included residual or recurrent urothelial carcinoma of the ureter or renal pelvis failing prior endoscopic treatment in patients who were unable or unwilling to undergo surgical management by resection of the involved ureter or kidney. WST-11 was administered at 4mg/kg and infused over 10 minutes. An intermedic diode laser was used to illuminate tumors with light at a wavelength 753 nm through a flexible ureteroscope. A light dose escalation model was employed with increasing light fluence from 100mW/cm up to a maximally tolerated dose of 200mW/cm. The primary endpoint was the determination of maximally tolerated laser light fluence rate, with the secondary objective to evaluate treatment efficacy defined by absence of visible tumor and negative urine cytology following treatment. Results: Among 14 treated patients, complete response and tumor recurrence rates at 30 days after treatment were 64% and 29%, respectively. A second VTP treatment was performed in 6 (43%) patients. The efficacy rates were comparable among patients who received the intermediate and highest light fluence and between the first and second treatment. At the last follow-up (mean: 11.5 months), 13 patients (93%) had maintained their affected kidney and renal function was not significantly affected. Graded adverse events related to treatment were rigorously evaluated prospectively as the primary endpoint of the trial to be reported separately in detail. Treatment related toxicities were limited, and no ureteral strictures were identified with the procedure. No evidence of increased toxicity was identified among patients who received a second VTP treatment. Conclusions: WST11-VTP shows promising evidence of therapeutic treatment effect in low- and high-grade upper tract urothelial tumors with limited treatment related toxicity. These early results provide support for further investigation to evaluate the curative potential for this therapy in a planned multicenter trial. Clinical trial information: NCT03617003.

Improvement of light penetration in biological tissue using an ultrasound-induced heating tunnel

The major obstacles of optical imaging and photothermal therapy in biomedical applications is the strong scattering of light within biological tissues resulting in light defocusing and limited penetration. In this study, we propose high intensity focused ultrasound (HIFU)-induced heating tunnel to reduce the photon scattering. To verify our idea, Monte Carlo simulation and intralipid-phantom experiments were conducted. The results show that the thermal effect created by HIFU could improve the light fluence at the targeted region by 3% in both simulation and phantom experiments. Owing to the fluence increase, similar results can also be found in the photoacoustic experiments. In conclusion, our proposed method shows a noninvasive way to increase the light delivery efficiency in turbid medium. It is expected that our finding has a potential for improving the focal light delivery in photoacoustic imaging and photothermal therapy.