Photosensitizer Effects of Artificial Red Cells on Dye Laser Irradiation in an Animal Model Assuming Port-Wine Stain Treatment:

Simulating PDT of port-wine stains in the in vivo chicken wattle model using Hemoporfin and radiation at 532 nm: Comparison of a LED and a laser source

Port-wine stain (PWS) birthmarks are congenital capillary malformations occurring in 0.3 %∼0.5 % of newborns. Hemoporfin-mediated vascular-acting photodynamic therapy (Hemoporfin PDT) is an emerging option for treating PWS. This in vivo study aimed to compare laser and light-emitting diodes (LED) as light source for Hemoporfin PDT. Chicken wattles were used as the animal model. Color and histopathological changes were evaluated after combining Hemoporfin with KTP laser or LED light source of 532 nm at the same doses. Both PDT approaches could induce significant vascular injury and color bleaching. Although the use of the laser resulted in a greater vascular clearance, the LED showed more uniform distribution both in the beam profiles and tissue reaction and exhibited better safety. This in vivo study suggests that the LED is a favorable choice for larger PWS lesion.

Cutaneous Hypervascularization Treatment Using Photo-Mediated Ultrasound Therapy

Photo-mediated ultrasound therapy (PUT) is a cavitation-based, highly selective antivascular technique. In this study, the effectiveness and safety of PUT on cutaneous vascular malformation was examined through in vivo experiments in a clinically relevant chicken wattle model, whose microanatomy is similar to that of port-wine stain and other hypervascular dermal diseases in humans. Assessed by optical coherence tomography angiography, the blood vessel density in the chicken wattle decreased by 73.23% after one session of PUT treatment in which 0.707 J/cm2 fluence laser pulses were applied concurrently with ultrasound bursts (n = 7, P < .01). The effectiveness of removing blood vessels in the skin at depth up to 1 mm was further assessed by H&E-stained histology at multiple time points, which included days 1, 3, 7, 14, and 21 after treatment. Additional immunohistochemical analyses with CD31, caspase-3, and Masson's trichrome stains were performed on day 3 after treatment. The results show that the PUT-induced therapeutic effect was confined and specific to blood vessels only, whereas unwanted collateral damage in other skin tissues such as collagen was avoided. The findings from this study demonstrate that PUT can efficiently and safely remove hypervascular dermal capillaries using laser fluence at a level that is orders of magnitude smaller than that used in conventional laser treatment of vascular lesions, thus offering a safer alternative technique for clinical management of cutaneous vascular malformations.

Carbon monoxide combined with artificial blood cells acts as an antioxidant for tissues thermally-damaged by dye laser irradiation

Artificial red blood cells [i.e., hemoglobin vesicles (HbVs)] can be used as photosensitizers in pulsed-dye laser (PDL) treatment for port wine stains in animal models. Small HbVs are distributed in the vicinity of the endothelial cells of the blood vessels. In our previous in vivo experiments, both HbVs and red blood cells absorbed photons of the laser and generated heat, contributing to removal of very small blood vessels and large deeper subcutaneous blood vessels with PDL irradiation. Herein, we tested carbon monoxide-bound HbVs (CO-HbVs) that would produce heat energy while releasing CO in vessels after dye laser irradiation in a rabbit auricle model. We conducted this experiment to confirm secondary progression of thermal injury being reduced with the antioxidative property of CO. We histopathologically evaluated the damages to the large vessels and surrounding dermal tissue following PDL irradiation alone or subsequent to the intravenous injection of the qualified HbVs. The soft tissue damages were graded on a five-point scale and compared statistically. Intravenous CO-HbVs significantly reduced damage to the surrounding tissue after subsequent PDL irradiation; however, the degree of damage to the larger vessel wall resulted in a variety of changes, including a slight increase in our histopathological grades. This beneficial effect in dye laser treatment for port wine stains may be the result of the antioxidative property of CO against free radicals in the zone of stasis that may still be theoretically viable in burns. This effect of CO protecting tissues from thermal damage is consistent with previous reports of CO as a reducing agent. If the reducing agent can be delivered directly to the affected area immediately after the burn injury, even in a small amount, the complex inflammatory cascade may be reduced and unnecessary inflammation after laser treatment that lowers the patient's quality of life can be avoided.

Research of storable and ready-to-use artificial red blood cells (hemoglobin vesicles) for emergency medicine and other clinical applications

Hemoglobin (Hb) is the most abundant protein in blood, with concentration of about 12-15 g/dl. The highly concentrated Hb solution (35 g/dl) is compartmentalized in red blood cells (RBCs). Once Hb is released from RBCs by hemolysis during blood circulation, it induces renal and cardiovascular toxicities. To date, hemoglobin-based oxygen carriers of various types have been developed as blood substitutes to mitigate the Hb toxicities. One method is Hb encapsulation in phospholipid vesicles (liposomes). Although the Hb toxicity can be shielded, it is equally important to ensure the biocompatibility of the liposomal membrane. We have developed Hb-vesicles (HbV). A new encapsulation method using a rotation-revolution mixer which enabled efficient production of HbV with a high yield has considerably facilitated R&D of HbV. Along with our academic consortium, we have studied the preclinical safety and efficacy of HbV extensively as a transfusion alternative, and finally conducted a phase I clinical trial. Moreover, carbonyl-HbV and met-HbV are developed respectively for an anti-inflammatory and anti-oxidative agent and an antidote for poisons. This review paper specifically presents past trials of liposome encapsulated Hb, biocompatible lipid bilayer membranes, and efficient HbV preparation methods, in addition to potential clinical applications of HbV based on results of our in vivo studies.

GNAQ mutations drive port wine birthmark-associated Sturge-Weber syndrome: A review of pathobiology, therapies, and current models

Port-wine birthmarks (PWBs) are caused by somatic, mosaic mutations in the G protein guanine nucleotide binding protein alpha subunit q (GNAQ) and are characterized by the formation of dilated, dysfunctional blood vessels in the dermis, eyes, and/or brain. Cutaneous PWBs can be treated by current dermatologic therapy, like laser intervention, to lighten the lesions and diminish nodules that occur in the lesion. Involvement of the eyes and/or brain can result in serious complications and this variation is termed Sturge-Weber syndrome (SWS). Some of the biggest hurdles preventing development of new therapeutics are unanswered questions regarding disease biology and lack of models for drug screening. In this review, we discuss the current understanding of GNAQ signaling, the standard of care for patients, overlap with other GNAQ-associated or phenotypically similar diseases, as well as deficiencies in current in vivo and in vitro vascular malformation models.

Histological Characteristics of Port-Wine Stains with Complete Regression After Photodynamic Therapy Treatment: A 7-Year Follow-Up

Background: Vascular-targeted photodynamic therapy (PDT) is an effective alternative treatment choice for port-wine stains (PWSs). The histological characteristics of PWSs after PDT treatment have not yet been reported. Objective: To investigate the morphological features of PWSs treated by PDT and define the histopathological characteristics of PWS that achieve clinical cure. Methods: Thirteen patients with facial PWSs, who presented with complete regressive PWS lesions after a mean of 4.38 (standard deviation = 4.907) sessions of PDT. Post-treatment biopsy samples were obtained from each patient. The number of blood vessels, vascular diameter, and depth were measured and compared in all samples of PDT-regressive sites, PDT-resistant sites, and normal skin. Results: Within the 7-year follow-up after PDT, there was no recurrence in the regression area of PDT. In the PDT-regressive sites, within 800 μm of the dermal-epidermal junction, the dilated vessels were occluded and remained fissure-like after PDT. Conclusions: When the vascular lesions within 800 μm of the dermal-epidermal junction were closed after PDT, a stable clinical cure (no recurrence) was achieved.

Preparation of Artificial Red Blood Cells (Hemoglobin Vesicles) Using the Rotation-Revolution Mixer for High Encapsulation Efficiency

Hemoglobin vesicles (Hb-V) are artificial red blood cells encapsulating highly concentrated hemoglobin (Hb) in liposomes comprising phospholipids, cholesterol, negatively charged lipids, and polyethylene glycol (PEG)-conjugated phospholipids. Safety and efficacy of Hb-V as a transfusion alternative have been extensively studied. For this study, we prepared Hb-V using the kneading method with a rotation-revolution mixer as an alternative to the conventional extrusion method. We optimized the kneading operation parameters to obtain Hb-V with a high yield. Results show that the Hb encapsulation efficiency was increased dramatically up to 74.2%, which is higher than that of the extrusion method (20%) because the kneading method enabled mixing of a highly concentrated carbonylhemoglobin (HbCO) solution (40 g/dL) and a considerably large amount of powdered lipids in only 10 min. The high viscosity of the Hb-lipid mixture paste (ca. 10³-10⁵ cP) favorably induces frictional heat by kneading and increases the paste temperature (ca. 60 °C), which facilitates lipid dispersion and liposome formation. During the kneading operation using a thermostable HbCO solution, Hb denaturation was prevented. Hb-V prepared using this method showed no marked changes in particle sizes, Hb denaturation, or Hb leakage from liposomes during two years of long-term storage-stability tests. Collectively, these results demonstrate that the kneading method using a rotation-revolution mixer shows good potential as a new method to produce Hb-V.

Artificial red blood cells increase large vessel wall damage and decrease surrounding dermal tissue damage in a rabbit auricle model after subsequent flashlamp-pumped pulsed-dye laser treatment

Artificial red blood cells (i.e. hemoglobin [Hb] vesicles [Hb-Vs]) function effectively as photosensitizers in flashlamp-pumped pulsed-dye laser (PDL) treatment for port-wine stains in animal models. Hb-Vs deliver more Hb to the vicinity of the endothelial cells. Both Hb-Vs and red blood cells absorb the laser energy and generate heat, supporting the removal of very small blood vessels and deeper subcutaneous blood vessels with PDL irradiation in in vivo experiments. Here, we analyzed the photosensitizing effect of Hb-Vs in PDL irradiation on large blood vessels and surrounding soft tissues. We histopathologically analyzed markers of damage to the large vessels and surrounding dermal tissue in a rabbit auricle model following PDL irradiation alone or subsequent to the addition of intravenous Hb-V injection. Markers were graded on a five-point scale and statistically compared. The changes in laser light absorption and reflection in a human skin model caused by the administration of Hb-Vs were evaluated using Monte Carlo light-scattering programs. Histological markers of damage to blood vessels were significantly greater in Hb-V-injected arteries and veins measuring 1-3 mm in diameter as compared with the controls. However, Hb-V injection significantly reduced PDL-induced necrosis and hemorrhage in the surrounding tissues. During computer simulation, photon absorption increased within the vessel layer and decreased around the layer. Intravenous Hb-Vs increase the extent of damage in larger vessel walls but significantly reduce damage to the surrounding skin after subsequent PDL irradiation. These beneficial effects are the result of improving vessel selectivity by Hb-Vs in vessels. Hb-V administration prior to PDL irradiation therapy could mechanically improve the outcomes and safety profiles of port-wine stain treatment protocols.

Double Pass 595 nm Pulsed Dye Laser Does Not Enhance the Efficacy of Port Wine Stains Compared with Single Pass: A Randomized Comparison with Histological Examination

OBJECTIVE

To compare the efficacy and safety of double-pass pulsed dye laser (DWL) and single-pass PDL (SWL) in treating virgin port wine stain (PWS).

BACKGROUND

The increase in the extent of vascular damage attributed to the use of double-pass techniques for PWS remains inconclusive. A prospective, side-by-side comparison with a histological study for virgin PWS is still lacking.

MATERIALS AND METHODS

Twenty-one patients (11 flat PWS, 10 hypertrophic PWS) with untreated PWS underwent 3 treatments at 2-month intervals. Each PWS was divided into three treatment sites: SWL, DWL, and untreated control. Chromametric and visual evaluation of the efficacy and evaluation of side effects were conducted 3 months after final treatment. Biopsies were taken at the treated sites immediately posttreatment.

RESULTS

Chromametric and visual evaluation suggested that DWL sites showed no significant improvement compared with SWL (p > 0.05) in treating PWS. The mean depth of photothermal damage to the vessels was limited to a maximum of 0.36-0.41 mm in both SWL and DWL sides. Permanent side effects were not observed in any patients.

CONCLUSIONS

Double-pass PDL does not enhance PWS clearance. To improve the clearance of PWS lesions, either the depth of laser penetration should be increased or greater photothermal damage to vessels should be generated.

Gold nanospheres enhanced photothermal therapy in a rat model

BACKGROUND AND OBJECTIVE

Efficient photothermal conversion of gold nanoparticles with strong light absorption suggests their wide use as selective photothermal agents in biomedical fields. The aim of this study is to investigate the use of gold nanospheres (GNPs) as exogenous visible light absorbers to improve laser treatment of port-wine stains.

MATERIALS AND METHODS

Thiol-terminated methoxypolyethylene glycol modified GNPs (PEG-GNPs) with peak extinction matching the visible light wavelength of the laser being used were synthesized. An in vitro capillary experiment was prepared to investigate the thermal response of blood vessels with and without injection of 4.54 mg PEG-GNPs in mice prior to irradiation by a frequency-doubled Nd:YAG laser at a wavelength of 532 nm.

RESULTS

The in vitro results demonstrated that the photocoagulation size in blood vessels after exposed to laser light increased with the increment of concentration of PEG-GNPs in blood within a certain range. However, the unwanted thermal response (i.e., cavitation) occurred when the concentration of PEG-GNPs in blood was larger than 2.5 mg/ml. The in vivo results suggested that more obvious blood thermal response can be induced by laser light after injection of PEG-GNPs. After injection of 4.54 mg PEG-GNPs, laser radiant exposure required for thread-like constriction of blood vessels decreased from 12.5 to 9.8 J/cm2 with the pulse duration of 10 ms, from 15 to 11.85 J/cm2 with the pulse duration of 30 ms, respectively.

CONCLUSION

This in vitro and in vivo experimental results show that PEG-GNPs combined with laser light could be a promising modality to reduce the radiant exposure required for obvious blood thermal response, thereby providing a potential strategy for improving the laser treatment of cutaneous vascular lesions. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc.

Artificial Red Blood Cells as Potential Photosensitizers in Dye Laser Treatment Against Port-Wine Stains

We suggest a novel method that uses artificial blood cells (hemoglobin vesicles, Hb-Vs) as photosensitizers in dye laser treatment (at 595-nm wavelength) for port-wine stains (i.e., capillary malformations presenting as red birthmarks) based on the results of animal experiments. As compared with human red blood cells, Hb-Vs have the same absorbance of 595 nm wavelength light and produce the same level of heat following dye laser irradiation. Small sized Hb-Vs (250 nm) distribute in the plasma phase in blood and tend to flow in the marginal zone of microvessels. Intravenous injections of Hb-Vs caused the dilatation of microvessels, and dye laser treatment with Hb-Vs destroyed the vessel wall effectively. Following the intravenous injection of Hb-Vs, the microvessels contained more Hb that absorbed laser photons and produced heat. This extra Hb tended to flow near the endothelial cells, which were the target of the laser treatment. These attributes of Hb-Vs will potentially contribute to enhancing the efficacy of dye laser treatment for port-wine stains. Hemoglobin is a type of porphyrin. Thus, our proposed treatment may have aspects of photodynamic therapy using porphyrin that leads to a cytotoxicity effect by active oxygen.

Overview of Potential Clinical Applications of Hemoglobin Vesicles (HbV) as Artificial Red Cells, Evidenced by Preclinical Studies of the Academic Research Consortium

Hemoglobin (Hb) is the most abundant protein in whole blood. This fact implies that the oxygen binding and releasing function of Hb is the most vital for sustaining life. All Hb is compartmentalized in red blood cells (RBCs) with corpuscular Hb concentration of about 35 g/dL, covered with a thin biomembrane. In spite of its abundance, Hb sometimes shows toxicity once it is leaked from RBCs. The shielding effect of the RBC membrane is physiologically important. Based on this structural importance, we have studied artificial red cells (Hb vesicles, HbV) as artificial oxygen carriers, which encapsulate a purified and concentrated Hb solution in phospholipid vesicles, mimicking the cellular structure of RBCs. Our academic research consortium has clarified the safety and efficacy of this HbV, aiming at clinical applications. Because of some superior characteristics to those of RBCs, HbV has the potential for use not only as a transfusion alternative but also for oxygen and carbon monoxide therapeutics, perfusate for transplant organs, and photosensitizer. In this review paper, such potential applications are summarized.