Photothermal treatment of port-wine stains using erythrocyte-derived particles doped with indocyanine green: a theoretical study

Efficacy and safety of hemoporfin photodynamic therapy in treating port-wine stains in Chinese children: a systematic review and meta-analysis

Objective

The purpose of this study is to explore the efficacy and safety of hematoporphyrin monomethyl ether mediated photodynamic therapy (HMME-PDT) in treating children with port-wine stains (PWS).

Method

Literature related to the topic was searched in PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Wanfang, and China Science Technology Journal Database online databases. The quality of the literature was evaluated using the Effective Public Health Practice Project. The I2 statistic was used to evaluate the consistency of the results.

Results

A total of 19 papers were included. Meta-analysis showed that more than half of the children (56.3%) achieved efficacy I (improvement ≥ 60%). 17% of children achieved efficacy II (improvement ≥ 75%). Regardless of whether the outcome variable was efficacy I or efficacy II, the therapeutic efficacy in children with PWS aged 0-3 years was superior to those aged 3-6 and 6-18 years, and children who underwent a treatment course of ≥3 sessions showed better outcomes compared to those who have only 1 or 2 sessions. After treatment with HMME-PDT, better efficacy was seen in the PWS of the face and neck and pink/red PWS. Additionally, almost all children with PWS treated with HMME-PDT developed edema (99.9%), more than half presented purpura (67.6%), some developed crust (30.8%) and hyperpigmentation (15.0%), and a few occurred scar (2.4%) and hypopigmentation (1.4%).

Conclusion

After HMME-PDT treatment, more than half of the pediatric patients showed an improvement of ≥60%, and no serious adverse reaction events occurred. This study demonstrated that HMME-PDT possessed promising therapeutic efficacy in children with PWS, suggesting that HMME-PDT could be considered a recommended treatment strategy for pediatric PWS. However, future development of standardized assessment guidelines and comparative studies are needed to validate the aforementioned conclusions.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/#loginpage, PROSPERO (CRD42024592367).

Ultralow radiant exposure of a short-pulsed laser to disrupt melanosomes with localized thermal damage through a turbid medium

Short-pulsed lasers can treat dermal pigmented lesions through selective photothermolysis. The irradiated light experiences multiple scattering by the skin and is absorbed by abnormal melanosomes as well as by normal blood vessels above the target. Because the fluence is extremely high, the absorbed light can cause thermal damage to the adjacent tissue components, leading to complications. To minimize radiant exposure and reduce the risk of burns, a model of the melanosome-disruption threshold fluence (MDTF) has been developed that accounts for the light-propagation efficiency in the skin. However, the light-propagation efficiency is attenuated because of multiple scattering, which limits the extent to which the radiant exposure required for treatment can be reduced. Here, this study demonstrates the principle of melanosome disruption with localized thermal damage through a turbid medium by ultralow radiant exposure of a short-pulsed laser. The MDTF model was combined with a wavefront-shaping technique to design an irradiation condition that can increase the light-propagation efficiency to the target. Under this irradiation condition, melanosomes were disrupted at a radiant exposure 25 times lower than the minimal value used in conventional laser treatments. Furthermore, almost no thermal damage to the skin was confirmed through a numerical simulation. These experimental and numerical results show the potential for noninvasive melanosome disruption and may lead to the improvement of the safety of short-pulsed laser treatment.

Proteomes of Micro- and Nanosized Carriers Engineered from Red Blood Cells

Red blood cell (RBC)-derived systems offer a potential platform for delivery of biomedical cargos. Although the importance of specific proteins associated with the biodistribution and pharmacokinetics of these particles has been recognized, it remains to be explored whether some of the key transmembrane and cytoskeletal proteins responsible for immune-modulatory effects and mechanical integrity of the particles are retained. Herein, using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and quantitative tandem mass tag mass spectrometry in conjunction with bioinformatics analysis, we have examined the proteomes of micro- and nanosized erythrocyte ghosts doped with indocyanine green and compared them with those of RBCs. We identified a total of 884 proteins in each set of RBCs, micro-, and nanosized particles, of which 8 and 45 proteins were expressed at significantly different relative abundances when comparing micro-sized particles vs RBCs and nanosized particles vs RBCs, respectively. We found greater differences in relative abundances of some mechano-modulatory proteins, such as band 3 and protein 4.2, and immunomodulatory proteins like CD44, CD47, and CD55 in nanosized particles as compared to RBCs. Our findings highlight that the methods utilized in fabricating RBC-based systems can induce substantial effects on their proteomes. Mass spectrometry data are available at ProteomeXchange with the identifier PXD038780.

Pathogenesis of Port-Wine Stains: Directions for Future Therapies

Port-wine stains (PWSs) are congenital vascular malformations that involve the skin and mucosa. To date, the mechanisms underlying the pathogenesis and progression of PWSs are yet to be clearly elucidated. The potential reasons for dilated vessels are as follows: (1) somatic GNAQ (R183Q) mutations that form enlarged capillary malformation-like vessels through angiopoietin-2, (2) decreased perivascular nerve elements, (3) the coexistence of Eph receptor B1 and ephrin B2, and (4) the deficiency of αSMA expression in pericytes. In addition, ERK, c-JNK, P70S6K, AKT, PI3K, and PKC are assumed to be involved in PWS development. Although pulsed-dye laser (PDL) remains the gold standard for treating PWSs, the recurrence rate is high. Topical drugs, including imiquimod, axitinib, and rapamycin, combined with PDL treatments, are expected to alter the recurrence rate and reduce the number of PDL sessions for PWSs. For the deep vascular plexus, photosensitizers or photothermal transduction agents encapsulated by nanocarriers conjugated to surface markers (CD133/CD166/VEGFR-2) possess a promising therapeutic potential in photodynamic therapy or photothermal therapy for PWSs. The pathogenesis, progression, and treatment of PWSs should be extensively investigated.

Advances on erythrocyte-mimicking nanovehicles to overcome barriers in biological microenvironments

Although nanocarriers offer many advantages as drug delivery systems, their poor stability in circulation, premature drug release and nonspecific uptake in non-target organs have prompted biomimetic approaches using natural cell membranes to camouflage nanovehicles. Among them, erythrocytes, representing the most abundant blood circulating cells, have been extensively investigated for biomimetic coating on artificial nanocarriers due to their upgraded biocompatibility, biodegradability, non-immunogenicity and long-term blood circulation. Due to the cell surface mimetic properties combined with customized core material, erythrocyte-mimicking nanovehicles (EM-NVs) have a wide variety of applications, including drug delivery, imaging, phototherapy, immunomodulation, sensing and detection, that foresee a huge potential for therapeutic and diagnostic applications in several diseases. In this review, we summarize the recent advances in the biomedical applications of EM-NVs in cancer, infection, heart-, autoimmune- and CNS-related disorders and discuss the major challenges and opportunities in this research area.

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.

Incident Fluence Analysis for 755-nm Picosecond Laser Treatment of Pigmented Skin Lesions Based on Threshold Fluences for Melanosome Disruption

Background and Objectives

In this study, the threshold fluences for disrupting the melanosomes for pigmented skin lesion treatment were determined using a 755‐nm picosecond laser for clinical use. Based on the melanosome disruption thresholds, incident fluences corresponding to the target lesion depths were evaluated in silico for different laser spot sizes.

Study Design/Materials and Methods

Melanosome samples were isolated from porcine eyes as alternative samples for human cutaneous melanosomes. The isolated melanosomes were exposed to 755‐nm picosecond laser pulses to measure the mean particle sizes by dynamic light scattering and confirm their disruption by scanning electron microscopy. The threshold fluences were statistically determined from the relationships between the irradiated fluences and the mean particle sizes. Incident fluences of picosecond laser pulses for the disruption of melanosomes located at different depths in skin tissue were calculated through a light transport simulation using the obtained thresholds.

Results

The threshold fluences of 550‐ and 750‐picosecond laser pulses were determined to be 2.19 and 2.49 J/cm², respectively. The numerical simulation indicated that appropriate incident fluences of picosecond laser pulses differ depending on the depth distribution of the melanosomes in the skin tissue, and large spot sizes are desirable for disrupting the melanosomes more deeply located within the skin tissue.

Conclusion

The threshold fluences of picosecond laser pulses for melanosome disruption were determined. The incident fluence analysis based on the thresholds for melanosome disruption provides valuable information for the selection of irradiation endpoints for picosecond laser treatment of pigmented skin lesions. Lasers Surg. Med. © 2021 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC

Acute Immune Response of Micro- and Nanosized Erythrocyte-Derived Optical Particles in Healthy Mice

Erythrocyte-derived particles activated by near-infrared (NIR) light present a platform for various phototheranostic applications. We have engineered such a platform with indocyanine green as the NIR-activated agent. A particular feature of these particles is that their diameters can be tuned from micro- to nanoscale, providing a potential capability for broad clinical utility ranging from vascular to cancer-related applications. An important issue related to clinical translation of these particles is their immunogenic effects. Herein, we have evaluated the early-induced innate immune response of these particles in healthy Swiss Webster mice following tail vein injection by measurements of specific cytokines in blood serum, the liver, and the spleen following euthanasia. In particular, we have investigated the effects of particle size and relative dose, time-dependent cytokine response for up to 6 h postinjection, functionalization of the nanosized particles with folate or Herceptin, and dual injections of the particles 1 week apart. Mean concentrations of interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α, and monocyte chemoattractant protein (MCP)-1 in response to injection of microsized particles at the investigated relative doses were significantly lower than the corresponding mean concentrations induced by lipopolysaccharide (positive control) at 2 h. All investigated doses of the nanosized particles induced significantly higher concentrations of MCP-1 in the liver and the spleen as compared to phosphate buffer saline (PBS) (negative control) at 2 h. In response to micro- and nanosized particles at the highest investigated dose, there were significantly higher levels of TNF-α in blood serum at 2 and 6 h postinjection as compared to the levels associated with PBS treatment at these times. Whereas the mean concentration of TNF-α in the liver significantly increased between 2 and 6 h postinjection in response to the injection of the microsized particles, it was significantly reduced during this time interval in response to the injection of the nanosized particles. In general, functionalization of the nanosized particles was associated with a reduction of IL-6 and MCP-1 in blood serum, the liver, and the spleen, and TNF-α in blood serum. With the exception of IL-10 in the spleen in response to nanosized particles, the second injection of micro- or nanosized particles did not lead to significantly higher concentrations of other cytokines at the investigated dose as compared to a single injection.

RBC-Derived Optical Nanoparticles Remain Stable After a Freeze-Thaw Cycle

Nanosized carriers engineered from red blood cells (RBCs) provide a means for delivering various cargos, including drugs, biologics, and imaging agents. We have engineered nanosized particles from RBCs, doped with the near-infrared (NIR) fluorochrome, indocyanine green (ICG). An important issue related to clinical translation of RBC-derived nanocarriers, including these NIR nanoparticles, is their stability postfabrication. Freezing may provide a method for long-term storage of these and other RBC-derived nanoparticles. Herein, we have investigated the physical and optical stability of these particles in response to a single freeze-thaw cycle. Nanoparticles were frozen to -20 °C, stored frozen for up to 8 weeks, and then thawed at room temperature. Our results show that the hydrodynamic diameter, zeta potential, optical density, and NIR fluorescence emission of these nanoparticles are retained following the freeze-thaw cycle. The ability of these nanoparticles in NIR fluorescence imaging of ovarian cancer cells, as well as their biodistribution in reticuloendothelial organs of healthy Swiss Webster mice after the freeze-thaw cycle is similar to that for freshly prepared nanoparticles. These results indicate that a single cycle of freezing the RBC-derived nanoparticles to -20 °C followed by thawing at room temperature is an effective method to retain the physical and optical characteristics of the nanoparticles, and their interactions with biological systems without the need for use of cryoprotectants.

Intravital Vascular Phototheranostics and Real-Time Circulation Dynamics of Micro- and Nanosized Erythrocyte-Derived Carriers

Erythrocyte-based carriers can serve as theranostic platforms for delivery of imaging and therapeutic payloads. Engineering these carriers at micro- or nanoscales makes them potentially useful for broad clinical applications ranging from vascular diseases to tumor theranostics. Longevity of these carriers in circulation is important in delivering a sufficient amount of their payloads to the target. We have investigated the circulation dynamics of micro (∼4.95 μm diameter) and nano (∼91 nm diameter) erythrocyte-derived carriers in real time using near-infrared fluorescence imaging, and evaluated the effectiveness of such carrier systems in mediating photothermolysis of cutaneous vasculature in mice. Fluorescence emission half-lives of micro- and nanosized carriers in response to a single intravenous injection were ∼49 and ∼15 min, respectively. A single injection of microsized carriers resulted in a 3-fold increase in signal-to-noise ratio that remained nearly persistent over 1 h of imaging time. Our results also suggest that a second injection of the carriers 7 days later can induce a transient inflammatory response, as manifested by the apparent leakage of the carriers into the perivascular tissue. The administration of the carriers into the mice vasculature reduced the threshold laser fluence to induce photothermolysis of blood vessels from >65 to 20 J/cm2. We discuss the importance of membrane physicochemical and mechanical characteristics in engineering erythrocyte-derived carriers and considerations for their clinical translation.

Functionalized erythrocyte-derived optical nanoparticles to target ephrin-B2 ligands

Over- or under-expression of erythropoietin-production human hepatocellular receptors (Eph) and their ligands are associated with various diseases. Therefore, these molecular biomarkers can potentially be used as binding targets for the delivery of therapeutic and/or imaging agents to cells characterized by such irregular expressions. We have engineered nanoparticles derived from erythrocytes and doped with the near-infrared (NIR) FDA-approved dye, indocyanine green. We refer to these nanoparticles as NIR erythrocyte-derived transducers (NETs). We functionalized the NETs with the ligand-binding domain of a particular Eph receptor, EphB1, to target the genetically modified human dermal microvascular endothelial cells (hDMVECs) with coexpression of EphB1 receptor and its ligand ephrin-B2. This cell model mimics the pathological phenotypes of lesional endothelial cells (ECs) in port wine stains (PWSs). Our quantitative fluorescence imaging results demonstrate that such functionalized NETs bind to the ephrin-B2 ligands on these hDMVECs in a dose-dependent manner that varies sigmoidally with the number density of the particles. These nanoparticles may potentially serve as agents to target PWS lesional ECs and other diseases characterized with over-expression of Eph receptors or their associated ligands to mediate phototherapy.

Biodistribution and toxicological evaluation of micron- and nano-sized erythrocyte-derived optical particles in healthy Swiss Webster mice

Particle-based systems provide a capability for the delivery of imaging and/or therapeutic payloads. We have engineered constructs derived from erythrocytes, and doped with the FDA-approved near infrared dye, indocyanine green (ICG). We refer to these optical particles as NIR erythrocyte-mimicking transducers (NETs). A particular feature of NETs is that their diameters can be tuned from micron- to nano-scale. Herein, we investigated the effects of micron- (≈2.6 μm diameter), and nano- (≈145 nm diameter) sized NETs on their biodistribution, and evaluated their acute toxicity in healthy Swiss Webster mice. Following tail vein injection of free ICG and NETs, animals were euthanized at various time points up to 48 hours. Fluorescence analysis of blood showed that nearly 11% of the injected amount of nano-sized NETs (nNETs) remained in blood at 48 hours post-injection as compared to ≈5% for micron-sized NETs (μNETs). Similarly, at this time point, higher levels of nNETs were present in various organs including the lungs, liver, and spleen. Histological analyses of various organs, extracted at 24 hours post-injection of NETs, did not show pathological alterations. Serum biochemistry profiles, in general, did not show elevated levels of the various analyzed biomarkers associated with liver and kidney functions. Values of various hematological profiles remained within the normal ranges following the administration of μNETs and nNETs. Results of this study suggest that erythrocyte-derived particles can potentially provide a non-toxic platform for delivery of ICG.