Potential Molecular Mechanisms Involved in 5-Aminolevulinic Acid–Based Photodynamic Therapy against Human Hypertrophic Scars:

Advances in photodynamic therapy of pathologic scar

Pathologic scars include keloids and hypertrophic scars due to abnormal wound healing. Both cause symptoms of itching and pain; they also affect one's appearance and may even constrain movement. Such scars place a heavy burden on the individual's physical and mental health; moreover, treatment with surgery alone is highly likely to leave more scarring. Therefore, there is an urgent need for a treatment that is both minimally invasive and convenient. Photodynamic therapy (PDT) is an emerging safe and noninvasive technology wherein photosensitizers and specific light sources are used to treat malignant tumors and skin diseases. Research on PDT from both the laboratory and clinic has been reported. These findings on the treatment of pathologic scars using photosensitizers, light sources, and other mechanisms are reviewed in the present article.

ALA-PDT promotes the death and contractile capacity of hypertrophic scar fibroblasts through inhibiting the TGF-β1/Smad2/3/4 signaling pathway

BACKGROUND

Hypertrophic scars, an abnormal wound-healing response to burn injuries, are characterized by massive fibroblast proliferation and excessive deposition of extracellular matrix and collagen. 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) is a promising therapy for hypertrophic scar, details of the mechanisms remain to be elucidated. In this study, we aimed to investigate the molecular mechanisms involved in ALA-PDT against hypertrophic scar fibroblasts.

METHODS

The morphologies of hypertrophic scar fibroblasts (HSFs) treated with ALA-PDT were observed under a light microscopy. The viability of HSFs was detected using the CCK-8 assay. HSFs-populated collagen gel contraction assays were conducted to examine the fibroblast contractility and the cytotoxicity of HSFs in 3D collagen tissues were observed using confocal microscopy. The effect of ALA-PDT on TGF-β1/Smad2/3/4 signaling pathway activation and effector gene expression were verified by immunoprecipitation, western blot and real-time quantitative PCR analysis.

RESULTS

We observed significant changes in cell morphology after ALA-PDT treatment of HSFs. As ALA concentration and light dose increased, the viability of HSFs significantly decreased. ALA-PDT can significantly alleviate the contractile capacity and promote the death of HSFs induced by TGF-β1 treatment in a three-dimensional collagen culture model. TGF-β1 treatment of HSFs can significantly induce phosphorylation of Smad2/3 (p-Smad2/3) in whole cells, as well as p-Smad2/3 and Smad4 proteins into the nucleus and increase the mRNA levels of collagen 1/3 and α-SMA. ALA-PDT hampers the TGF-β1-Smad2/3/4 signaling pathway activation by inducing K48-linked ubiquitination and degradation of Smad4.

CONCLUSIONS

Our results provide evidence that ALA-PDT can inhibit fibroblast contraction and promote cell death by inhibiting the activation of the TGF-β1 signaling pathway that mediates hypertrophic scar formation, which may be the basis for the efficacy of ALA-PDT in the treatment of hypertrophic scars.

NIR-triggered photodynamic therapy of traumatic heterotopic ossification with a type II collagen-targeted photosensitizer

Traumatic heterotopic ossification (HO) represents an intractable sequela following trauma with no currently effective prophylaxis or treatment. Photodynamic therapy (PDT) is a non-invasive treatment for various proliferative diseases. However, the specific effects of PDT on HO development remain unclear. In this study, the therapeutic potential of a near-infrared (NIR) probe-WL-808, composed of type II collagen-binding peptide (WYRGRL) and a PDT photosensitizer (IR-808), was evaluated for the innovative HO-targeted PDT approach. In vitro studies indicated that WL-808 could induce chondrocyte apoptosis and inhibit cell viability through ROS generation under NIR excitation. In vivo, the efficacy of WL-808-mediated PDT was tested on the tenotomy HO model mice. WL-808 specifically targeted the type II collagen cartilaginous template of HO, promoting cell apoptosis and enhancing extracellular matrix (ECM) degradation under 808 nm NIR excitation, which inhibited the final ectopic bone formation. Moreover, no obvious toxicity or side effects were detected after treatment with WL-808. Taken together, WL-808-mediated PDT significantly diminished ectopic cartilage and subsequent bone formation, providing a new perspective for HO prophylaxis and treatment.

The in vitro anti-cancer synergy of neurokinin-1 receptor antagonist, aprepitant, and 5-aminolevulinic acid in glioblastoma

Glioblastoma multiforme (GBM) is the most malignant type of cerebral neoplasm in adults with a poor prognosis. Currently, combination therapy with different anti-cancer agents is at the forefront of GBM research. Hence, this study aims to evaluate the potential anti-cancer synergy of a clinically approved neurokinin-1 receptor antagonist, aprepitant, and 5-aminolevulinic acid (5-ALA), a prodrug that elicits fluorescent porphyrins in gliomas on U-87 human GBM cells. We found that aprepitant and 5-ALA effectively inhibited GBM cell viability. The combinatorial treatment of these drugs exerted potent synergistic growth inhibitory effects on GBM cells. Moreover, aprepitant and 5-ALA induced apoptosis and altered the levels of apoptotic genes (up-regulation of Bax and P53 along with downregulation of Bcl-2). Furthermore, aprepitant and 5-ALA increased the accumulation of protoporphyrin IX, a highly pro-apoptotic and fluorescent photosensitizer. Aprepitant and 5-ALA significantly inhibited GBM cell migration and reduced matrix metalloproteinases (MMP-2 and MMP-9) activities. Importantly, all these effects were more prominent following aprepitant-5-ALA combination treatment than either drug alone. Collectively, the combination of aprepitant and 5-ALA leads to considerable synergistic anti-proliferative, pro-apoptotic, and anti-migratory effects on GBM cells and provides a firm basis for further evaluation of this combination as a novel therapeutic approach for GBM.

Desferrioxamine Enhances 5-Aminolaevulinic Acid- Induced Protoporphyrin IX Accumulation and Therapeutic Efficacy for Hypertrophic Scar

Hypertrophic scar is a common problem after skin burns or trauma which brings physical, psychological, and cosmetic problems to patients. Photodynamic therapy with 5-aminolevulinic acid (5-ALA) is a promising therapy for hypertrophic scar. However, clinical applications of 5-ALA are limited because of the low permeability of 5-ALA in the skin stratum corneum and the rapid binding of protoporphyrin IX (PpIX) with iron ions, which lead to insufficient PpIX production in target tissues. Herein, a mixture of 5-ALA and DFO (deferoxamine, a special iron chelator) was applied for the treatment of hypertrophic scar. 5-ALA/DFO could efficiently block the biotransformation of PpIX to heme, thus realizing a significant accumulation of photosensitizer. In addition, injection locally into the lesion was applied, which combined with enhanced photodynamic therapy to destroy hypertrophic scar fibroblasts. In vitro experiments showed that 5-ALA/DFO could increase more ROS generation by increasing the accumulation of PpIX, resulting in the apoptosis of hypertrophic scar fibroblasts. Furthermore, 5-ALA/DFO inhibited the proliferation and migration of hypertrophic scar fibroblasts. In vivo study showed that 5-ALA/DFO could effectively inhibit the formation of proliferative scar. Therefore, 5-ALA/DFO has the potential to enhance the photodynamic therapy of 5-ALA and provides a new treatment strategy for hypertrophic scar.

SPARC promotes fibroblast proliferation, migration, and collagen production in keloids by inactivation of p53

BACKGROUND

Keloid, an aggressive fibroproliferative disease of the skin, is usually caused by infectious skin diseases, burns, and trauma.

OBJECTIVE

This study aimed to assess the effect of SPARC on the keloid pathogenesis.

METHODS

In normal skin and keloid scar tissues, changes in SPARC expression were analysed by qRT-PCR, western blotting, and immunohistochemistry. Keloid fibroblasts were isolated from human keloid tissue. GSEA was performed to investigate the signalling pathways related to SPARC. Cell Counting Kit-8, 5-Ethynyl-2'-deoxyuridine, transwell assay, and scratching assays were used to assess fibroblast proliferation and migration. Changes in α-SMA, fibronectin, collagen I, and collagen III levels were examined in fibroblasts by western blotting.

RESULTS

SPARC expression was upregulated in keloid scar tissues. In fibroblasts, cell proliferation, migration, collagen production, and extracellular matrix (ECM) synthesis were promoted by SPARC overexpression, whereas SPARC knockdown resulted a converse result. GSEA showed that SPARC regulates the p53 pathway. In keloid scar tissues, there was a negative correlation between SPARC and p53 expression. p53 expression was decreased by SPARC overexpression, whereas SPARC knockdown increased p53 expression. Furthermore, the effects of SPARC on the fibroblast phenotype were reversed by p53 overexpression.

CONCLUSIONS

Fibroblast proliferation, migration, and ECM synthesis were promoted by SPARC overexpression, which was achieved by regulating the p53 pathway. Our findings provide new therapeutic targets for keloids.

Antitumor Effects of 5-Aminolevulinic Acid on Human Malignant Glioblastoma Cells

5-Aminolevulinic acid (5-ALA) is a naturally occurring non-proteinogenic amino acid, which contributes to the diagnosis and therapeutic approaches of various cancers, including glioblastoma (GBM). In the present study, we aimed to investigate whether 5-ALA exerted cytotoxic effects on GBM cells. We assessed cell viability, apoptosis rate, mRNA expressions of various apoptosis-related genes, generation of reactive oxygen species (ROS), and migration ability of the human U-87 malignant GBM cell line (U87MG) treated with 5-ALA at different doses. The half-maximal inhibitory concentration of 5-ALA on U87MG cells was 500 μg/mL after 7 days; 5-ALA was not toxic for human optic cells and NIH-3T3 cells at this concentration. The application of 5-ALA led to a significant increase in apoptotic cells, enhancement of Bax and p53 expressions, reduction in Bcl-2 expression, and an increase in ROS generation. Furthermore, the application of 5-ALA increased the accumulation of U87MG cells in the SUB-G1 population, decreased the expression of cyclin D1, and reduced the migration ability of U87MG cells. Our data indicate the potential cytotoxic effects of 5-ALA on U87MG cells. Further studies are required to determine the spectrum of the antitumor activity of 5-ALA on GBM.

HOXA5 counteracts the function of pathological scar-derived fibroblasts by partially activating p53 signaling

The inactivation of p53 can lead to the formation of pathological scars, including hypertrophic scars and keloids. HOXA5 has been reported to be a critical transcription factor in the p53 pathway in cancers. However, whether HOXA5 also plays a role in pathological scar progression through activating p53 signaling remains unknown. In this study, we first demonstrated that HOXA5 overexpression in hypertrophic scar-or keloids-derived fibroblasts decreased cell proliferation, migration and collagen synthesis, whereas increased cell apoptosis. Furthermore, the results of luciferase activity assays and ChIP PCR assays indicated that HOXA5 transactivated p53 by binding to the ATTA-rich core motif in the p53 promoter. HOXA5 also increased the levels of p21 and Mdm2, which are downstream targets of p53. Interestingly, silencing p53 in these pathological scar-derived fibroblasts partially attenuated HOXA5-mediated growth inhibition effect and HOXA5-induced apoptosis. In addition, 9-cis-retinoic acid augmented the expression of HOXA5 and promoted the effects of HOXA5 on pathological scar-derived fibroblasts, and these effects could be suppressed by HOXA5 knockdown. Thus, our study reveals a role of HOXA5 in mediating the cellular processes of pathological scar-derived fibroblasts by transcriptionally activating the p53 signaling pathway, and 9-cis-retinoic acid may be a potential therapy for pathological scars.

Strontium ions protect hearts against myocardial ischemia/reperfusion injury

Timely restoration of blood supply following myocardial infarction is critical to save the infarcted myocardium, while reperfusion would cause additional damage. Strontium ions have been shown to promote angiogenesis, but it is unknown whether they can save the damaged myocardium. We report that myocardial ischemia/reperfusion (I/R)-induced functional deterioration and scar formation were notably attenuated by injection of strontium ion-containing composite hydrogels into murine infarcted myocardium at 20 minutes of reperfusion following 60 minutes of ischemia. These beneficial effects were accompanied by reduced cardiomyocyte apoptosis and increased angiogenesis. The effects of strontium ions were further confirmed by the enhanced viability of cardiomyocytes and stimulated angiogenesis in vitro. These findings are the first to reveal the cardioprotective effects of strontium ions against I/R injury, which may provide a new therapeutic approach to ischemic heart disease at a lower cost, with higher stability, and with potentially greater safety.

Hematoporphyrin monomethyl ether-mediated photodynamic therapy inhibits the growth of keloid graft by promoting fibroblast apoptosis and reducing vessel formation

Photodynamic therapy (PDT) has been shown to significantly inhibit fibroblast activity. However, the effect of PDT mediated by the photosensitizer hematoporphyrin monomethyl ether (HMME) on keloids is not known well. The aim of our study was to examine the efficacy of HMME-PDT in cellular and animal models of keloids. Keloid fibroblasts (KFbs) were isolated from human keloid specimens and the proliferation, invasion, and migration of KFbs after HMME-PDT treatment was examined in vitro. Apoptosis in cells was measured by flow cytometry. Cysteinyl aspartate specific proteinase 3 (Caspase3) expression was determined by immunofluorescence staining and western blot. HMME-PDT inhibited KFbs proliferation, invasion, migration, increased apoptosis rate and enhanced caspase3 and cleaved caspase3 expression. The keloid graft transplantation was performed by using nude mice. The growth of the graft was monitored every third day. Interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) mRNA expression were detected by quantitative real time PCR. It was observed that HMME-PDT attenuated graft growth and reduced vessel density in the keloid grafts. However, HMME-PDT did not alter IL-6 and TNF-α mRNA expression in the keloid grafts. Moreover, HMME-PDT suppressed transforming growth-β1 (TGF-β1) and small phenotype and Drosophila Mothers Against Decapentaplegic 3 (Smad3) expression in both KFbs and keloid grafts. Collectively, the evidence suggests that HMME-PDT inhibits the growth of the keloid graft by promoting the apoptosis of fibroblasts and reducing vessel formation of the keloid graft.

Efficacy of 5-aminolevulinic acid-based photodynamic therapy against keloid compromised by downregulation of SIRT1-SIRT3-SOD2-mROS dependent autophagy pathway

Keloids exhibit cancer-like properties without spontaneous regression and usually recur post excision. Although photodynamic therapy (PDT) is a promising treatment, details of the mechanisms remain to be elucidated. In this study, we investigated mechanisms involved in 5-Aminolevulinic Acid (5-ALA)-based PDT against keloid. Found that 5-ALA-PDT induced superoxide anion-dependent autophagic cell death. Application of autophagy inhibitor 3-Methyladenine (3-MA) significantly prevented the effect that 5-ALA-PDT induced keloid-derived fibroblasts death, but Z-VAK-FMK (apoptotic inhibitor) did not. Interestingly, 5-ALA-PDT promoted the SIRT3 protein expression and the activity of mitochondrial superoxide dismutase 2 (SOD2), but SIRT1 protein expression level was decreased. SOD2 as a key enzyme can decrease mitochondrial ROS (mROS) level, Deacetylation of SOD2 by SIRT3 regulates SOD2 enzymatic activity has been identified. Then we explored SOD2 acetylation level with immunoprecipitation, found that 5-ALA-PDT significantly increased the acetylation levels of SOD2. In order to confirm deacetylation of SOD2 regulated by SIRT3, 3-TYP (SIRT3 inhibitor) was used. Found that inhibition of SIRT3 by 3-TYP significantly increased the level of SOD2 acetylation level compared with control group or 5-ALA-PDT group. To explore the connection of SIRT1 and SIRT3, cells were treated with EX527(SIRT1 inhibitor) or SRT1720 (SIRT1 activator), and EX527 increased SIRT3 protein level, however, SRT1720 displayed the opposite effect in the present or absence of 5-ALA-PDT. Moreover SIRT1-inhibited cells are more resistant to 5-ALA-PDT and showing decreased ROS accumulation. These results may demonstrate that 5-ALA-PDT induced SIRT1 protein level decreased, which promoted the effect of SIRT3 increased activity of SOD2 that can reduce mROS level, and then compromised 5-ALA-PDT induced autophagic cell death.

Biocompatible 5-Aminolevulinic Acid/Au Nanoparticle-Loaded Ethosomal Vesicles for In Vitro Transdermal Synergistic Photodynamic/Photothermal Therapy of Hypertrophic Scars

Biocompatible 5-aminolevulinic acid/Au nanoparticle-loaded ethosomal vesicle (A/A-ES) is prepared via ultrasonication for synergistic transdermal photodynamic/photothermal therapy (PDT/PTT) of hypertrophic scar (HS). Utilizing ultrasonication, Au nanoparticles (AuNPs) are synthesized and simultaneously loaded in ethosomal vesicles (ES) without any toxic agents, and 5-aminolevulinic acid (ALA) is also loaded in ES with 20% of the entrapment efficiency (EE). The prepared A/A-ES displays strong absorbance in 600-650 nm due to the plasmonic coupling effect between neighboring AuNPs in the same A/A-ES, which can simultaneously stimulate A/A-ES to produce heat and enhance quantum yields of reactive oxygen species (ROS) by using 632 nm laser. In vitro transdermal penetrability study demonstrates that A/A-ES acts as a highly efficient drug carrier to enhance both ALA and AuNPs penetration into HS tissue. Taking human hypertrophic scar fibroblasts (HSF) as therapeutic targets, synergistic PDT/PTT of HS indicates that A/A-ES could enhance quantum yields of ROS by photothermal effect and localized surface plasmon resonance (LSPR) of AuNPs, resulting in a high level of apoptosis or necrosis. In a word, the prepared A/A-ES shows a better synergistic PDT/PTT efficiency for HSF than the individual PDT and PTT, encouraging perspective for treatment of HS.

MicroRNA-22 may promote apoptosis and inhibit the proliferation of hypertrophic scar fibroblasts by regulating the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase/p21 pathway

Hypertrophic scarring (HS) is a common skin disorder that occurs during the wound healing process, and the pathogenesis of HS remains unclear. Increasing evidence indicated that specific microRNAs (miRs) may be involved in the onset and progression of HS. In the present study, the association between miR-22 and HS was investigated. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to examine the expression of miR-22 in 30 HS and matched normal skin tissues. In addition, human hypertrophic scar fibroblasts (HSFBs) were cultured and transfected with miR-22 mimics, and MTT and Annexin V apoptosis assays were performed to investigate the role of miR-22 in the proliferation and apoptosis of the human HSFBs. Next, RT-qPCR and western blot assays were performed to compare the expression levels of mitogen-activated protein kinase kinase (MEK), extracellular signal-regulated kinase (ERK) and p21 in untransfected and miR-22 mimic-transfected skin fibroblasts. The results identified that miR-22 was significantly downregulated in HS tissues as compared with the normal skin. Furthermore, transfection with miR-22 mimics in human HSFBs led to inhibited cell proliferation, increased apoptosis, as well as to decreased MEK expression and ERK1/2 phosphorylation, and increased expression of p21. In conclusion, the present study was the first to prove that aberrant expression of miR-22 may serve an important role in the pathogenesis of HS by regulating the MEK/ERK/p21 pathway, thus suggesting that miR-22 has the potential to become a therapeutic target for the treatment of HS.

Photodynamic Therapy: A Clinical Consensus Guide

BACKGROUND

The American Society of Dermatologic Surgery (ASDS) periodically develops consensus documents for its members concerning various aspects of dermatologic surgery. Advances in photodynamic therapy (PDT) have been many and PDT use has been established in a variety of skin conditions.

OBJECTIVE

The ASDS board of directors proposed a committee of experts in the field to develop consensus documents on different treatments. An expert panel reviewed the literature on PDT and discussed the findings. The consensus was reached with evidence-based recommendations on different clinical applications for PDT.

PATIENTS AND METHODS

This consensus document includes discussions regarding PDT, including different photosensitizers and various light source activators, historical perspective, mechanism of action, various therapeutic indications and expected outcomes, pre- and post-care, and management of adverse outcomes.

RESULTS

Photodynamic therapy is highly effective for pre-cancerous lesions, superficial nonmelanoma skin cancers, inflammatory acne vulgaris and other conditions. New protocols including laser mediated PDT significantly improve results for several indications.

CONCLUSION

The ASDS consensus document on PDT will be helpful for educating members on safe and effective PDT for a variety of indications.

5-Aminolevulinic acid loaded ethosomal vesicles with high entrapment efficiency for in vitro topical transdermal delivery and photodynamic therapy of hypertrophic scars

Photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) is an alternative therapy for hypertrophic scars (HS), which destroys human hypertrophic scar fibroblasts (HSF). However, the poor permeability of ALA both in HS tissue and HSF significantly restricts the PDT of HS. To overcome these barriers, ALA-loaded ethosomal vesicles (ALA-ES) were developed by a pH gradient active loading method and characterized by morphology, entrapment efficiency (EE) and stability. Results show that prepared ALA-ES are homogenous spherical lamellar vesicles, 53 ± 7 nm in size, 50.6 ± 2.3% in EE and have excellent stability. In vitro transdermal delivery studies through HS tissue were carried out by using Franz diffusion cells. Compared to the traditional ALA hydroalcoholic solution (ALA-HA), ALA-ES achieve higher drug retention in less administration time, and fluorescence microscopy showed that ALA-ES penetrate into the deeper dermis of HS in a shorter time, indicating that ALA-ES can enhance the penetration of ALA into HS. Additionally, ALA-ES was visualized in HS tissue for the first time by transmission electron microscopy (TEM). The irregular and collapsed ALA-ES suggest that they can squeeze through narrow spaces to the target area and release ALA into HS. Taking HSF as the target, the transcellular delivery of ALA-ES into HSF cells was investigated by intracellular protoporphyrin IX (PpIX) accumulation. The efficiency of PDT for HSF cells, including the formation of reactive oxygen species (ROS) and cell apoptosis, were also well investigated. Furthermore, the detailed changes of HSF were observed by TEM. The results strongly indicate that ALA-ES can facilitate ALA penetration into HSF cells, and can cause a higher level of cell apoptosis or necrosis than ALA-HA. ALA-ES with high EE is therefore a promising transdermal delivery system for topical ALA administration and has great potential in ALA-PDT of HS.