The benefits of antimicrobial photodynamic therapy with RLP068 in the management of diabetic foot ulcers

One-pot synthesis and covalent conjugation of methylene blue in mesoporous silica nanoparticles - A platform for enhanced photodynamic therapy

Photodynamic therapy (PDT) is an emerging clinical modality for diverse disease conditions, including cancer. This technique involves, the generation of cytotoxic reactive oxygen species by a photosensitizer in the presence of light and oxygen. Methylene blue (MB) is a cationic dye with an ability to act as photosensitizing and bioimaging agent. The direct utilization of MB as photosensitizer for biological applications has often been impeded by its poor photostability and unwanted tissue interactions. Nanocarriers such as mesoporous silica nanoparticles (MSNs) provide an effective means of overcoming these limitations. However, the mere physical adsorption of the dye within the MSN can result in leakage, compromising the effectiveness of PDT. Therefore, in this work, we report the conjugation of MB into MSNs using novel MB-silane derivatives, namely MBS1 and MBS2, to create dye-doped and amine-functionalized MSNs (MBS1-AMSN and MBS2-AMSN). The PDT efficacy and bioimaging capability of these nanoparticles were compared with those of MSNs in which MB was non-covalently encapsulated (MB@AMSN). The synthesized nanoparticles, ultra-small in size (≤ 35 ± 4 nm) with monodispersity, exhibited enhanced fluorescence quantum yields. MBS1-AMSN demonstrated 70-fold increase, while MBS2-AMSN showed 33-fold improvement in fluorescence quantum yields compared to MB@AMSN at the same concentration. Covalent conjugation resulted in a 2-fold enhancement in the singlet oxygen quantum yield of the dye in MBS1-AMSN and 1.2-fold improvement in MBS2-AMSN, compared to non-covalent encapsulation. Assessment on RAW 264.7 macrophages revealed superior fluorescence in cell imaging for MBS1-AMSN, establishing it as a more efficient PDT agent compared to MBS2-AMSN and MB@AMSN. These findings suggest that MBS1-AMSN holds significant potential as a theranostic nanoplatform for image-guided PDT.

A meta-analysis and systematic review of photodynamic therapy for diabetic foot ulcers

BACKGROUND

Diabetic foot ulcer (DFU) is a chronic and challenging condition, addressed through various treatments including photodynamic therapy (PDT) and standard of care (SOC), yet lacking consensus on the optimal approach. This study presents a comprehensive meta-analysis of randomized controlled trials to evaluate the efficacy and safety of PDT versus SOC in managing DFU.

METHODS

An extensive literature search was conducted across PubMed, Embase, and the Cochrane Library databases to identify RCTs that compared the effectiveness of PDT with SOC in treating DFU. The primary metrics evaluated included changes in ulcer area, wound healing indices, and pain levels experienced by the patients.

RESULTS

This meta-analysis incorporated data from 6 RCTs, encompassing 458 patients with 467 DFUs. The analysis indicated that while PDT led to a faster reduction in ulcer size compared to SOC, the difference was not statistically significant [mean difference (MD): 2.73cm², 95 % Confidence Interval (CI) -2.98 to 8.44; p > 0.05]. However, a notable improvement was observed in the wound healing rate in the PDT group [MD: 29.26 %, 95 % CI 7.24 to 51.28; p = 0.01]. Based on the Visual Analog Scale (VAS), pain assessment revealed no significant difference between the two treatment groups [MD: 2.35, 95 % CI -2.36 to 7.06; p = 0.33].

CONCLUSION

The study suggests that PDT might offer an enhanced healing rate for DFUs compared to SOC alone, potentially leading to improved patient outcomes. Importantly, our findings highlight the superiority of photodynamic therapy in accelerating ulcer healing without an associated increase in complications.

PROSPERO

2023 CRD42023493930.

Adjuvant effect of antimicrobial photodynamic therapy (aPDT) in the treatment of diabetic foot ulcers: A case series

This study aimed to evaluate the clinical evolution of patients with diabetic foot ulcer treated with antimicrobial photodynamic therapy (aPDT) using the Bates-Jensen (BJ) scale. A total of 21 patients were monitored, with an average age of 58 years. Patients underwent the standard treatment protocol of the institution, supplemented with aPDT utilizing 0.01% methylene blue (MB) and laser irradiation (660 nm, 100 mW, 6 J per point). Following aPDT, the lesions were protected with hydrofiber dressings containing silver. The Bates-Jensen Scale was employed at pre-treatment and post-aPDT sessions to assess lesion progression. The results demonstrated a significant difference between pre- and post-treatment values in the overall BJ score. The use of MB in aPDT proved to be an effective, safe, well-tolerated treatment with high patient adherence and the potential for implementation in the care of diabetic foot conditions.

Photodynamic Therapy With RLP068 and 630-nm Red LED Light in Foot Ulcers in Patients With Diabetes: A Case Series

The management and healing of lower extremity ulcers have always been a complex health problem because the clinical course is typically chronic, the results are often poor, and the socioeconomic impact is considerable. The healing process of foot ulcers of people with diabetes is further hindered by the concomitant presence of obstructive arterial disease, neuropathy, and foot malformation. It is frequently associated with multiresistant infections and often results in micro/macro amputations. Photodynamic therapy employs a photosensitizer activated by light of a specific wavelength able to generate reactive oxygen species, which initiate further oxidative responses locally with components of the bacteria. The experience of the treatment center for the lower extremity ulcers in 17 persons with diabetes in Acerra (Italy) with photoactivated RLP068, reported here, corroborates the results of the clinical trials and of the previous case reports. In all cases, examined photodynamic therapy with photosensitizer RLP068 and red light at 630 nm was found to reduce lesion area and inflammation and to ensure the decrease of bacterial load, hence reducing treatment times and antibiotics use, improving patient outcomes, and reducing the incidence of amputations. The simultaneous combination of photodynamic therapy with other ancillary physical-based treatments such as therapeutic magnetic resonance or Bio-Electro-Magnetic-Energy-Regulation was observed to be safe, time-saving, and able to lead to faster healing.

Photodynamic therapy for infected foot ulcers in people with diabetes mellitus: a systematic review

BACKGROUND

Ulceration of the feet in patients with diabetes is a frequent complication that increases morbidity, mortality, hospitalization, treatment costs, and non-traumatic amputations.

OBJECTIVE

To present a systematic review of the treatment of patients with diabetes mellitus and infected foot ulcers using photodynamic therapy.

DESIGN AND SETTING

A systematic review was performed in the postgraduate program in nursing at the Universidade da Integração Internacional da Lusofonia Afro-Brasileira, Ceará, Brazil.

METHODS

PubMed, CINAHL, Web of Science, EMBASE, Cochrane Library, Scopus, and LILACS databases were screened. The methodological quality, risk of bias, and quality of evidence of each study were assessed. Review Manager was used for the meta-analysis.

RESULTS

Four studies were included. They highlighted significantly better outcomes in patient groups treated with photodynamic therapy than those in the control groups that were treated with topical collagenase and chloramphenicol (P = 0.036), absorbent (P < 0.001), or dry covers (P = 0.002). Significant improvements were noted in terms of the microbial load in the ulcers and tissue repair, with a reported reduction in the need for amputation by up to 35 times. Photodynamic therapy resulted in significantly better outcomes between the experimental and control groups (P = 0.04).

CONCLUSION

Photodynamic therapy is significantly more effective in treating infected foot ulcers than standard therapies.

SYSTEMATIC REVIEW REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO) - CRD42020214187, https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=214187.

Photodynamic therapy for treating infected skin wounds: A systematic review and meta-analysis from randomized clinical trials

BACKGROUND

Infected skin wounds represent a public health problem that effects 20 million people worldwide. Photodynamic therapy (PDT) is a treatment option with excellent results against several infections.

OBJECTIVE

This study aimed to perform a systematic review and meta-analysis on PDT efficacy for treating infected wounds based on randomized clinical trials (RCTs).

METHODS

PubMed, Scopus, Web of Science, SciELO, and the Cochrane library were searched. The Delphi List criteria and the Revised Cochrane risk-of-bias (Rob 2) were used for evaluating the quality of clinical trials. Meta-analyses were performed with the random-effect model. The odds ratio was the effect measure for binary outcomes, while the standard mean difference was used for continuous outcomes. The trim-and-fill method was used to detect small-study effects. The quality of evidence was verified for each outcome.

RESULTS

Only four out of 573 articles were selected for the qualitative and quantitative analyses. The most frequent cause of infected wounds was impaired venous circulation (75%). All studies used red LED light. PDT reduced healing time and improved the healing process and wound oxygenation. Patients treated with PDT showed 15% to 17% (p = 0.0003/ I²=0%) lower microbial cell viability in the wound and a significantly smaller wound size (0.72 cm²/p = 0.0187/I²=0%) than patients treated with placebo or red-light exposure. There was a high level of evidence for each meta-analysis outcome.

CONCLUSION

PDT can be an excellent alternative treatment for infected skin wounds, though larger trials are needed.

Photodynamic disinfection and its role in controlling infectious diseases

Photodynamic therapy is witnessing a revival of its origins as a response to the rise of multi-drug resistant infections and the shortage of new classes of antibiotics. Photodynamic disinfection (PDDI) of microorganisms is making progresses in preclinical models and in clinical cases, and the perception of its role in the clinical armamentarium for the management of infectious diseases is changing. We review the positioning of PDDI from the perspective of its ability to respond to clinical needs. Emphasis is placed on the pipeline of photosensitizers that proved effective to inactivate biofilms, showed efficacy in animal models of infectious diseases or reached clinical trials. Novel opportunities resulting from the COVID-19 pandemic are briefly discussed. The molecular features of promising photosensitizers are emphasized and contrasted with those of photosensitizers used in the treatment of solid tumors. The development of photosensitizers has been accompanied by the fabrication of a variety of affordable and customizable light sources. We critically discuss the combination between photosensitizer and light source properties that may leverage PDDI and expand its applications to wider markets. The success of PDDI in the management of infectious diseases will ultimately depend on the efficacy of photosensitizers, affordability of the light sources, simplicity of the procedures, and availability of fast and efficient treatments.

Amplify antimicrobial photo dynamic therapy efficacy with poly-beta-amino esters (PBAEs)

Light-activated antimicrobial agents (photosensitisers) are promising alternatives to antibiotics for the treatment of skin infections and wounds through antimicrobial photo dynamic therapy (aPDT); utilisation of this technique is still restricted by general low efficacy requiring long exposure time (in the order of tens of minutes) that make the treatment very resource intensive. We report for the first time the possibility of harvesting the cell penetrating properties of poly-beta-amino esters (PBAEs) in combination with toluidine blue O (TBO) to shorten aPDT exposure time. Candidates capable of inactivation rates 30 times quicker than pure TBO were discovered and further improvements through PBAE backbone optimisation could be foreseen. Efficacy of the complexes was PBAE-dependent on a combination of TBO uptake and a newly discovered and unexpected role of PBAEs on reactive species production. Chemometric approach of partial least square regression was employed to assess the critical PBAE properties involved in this newly observed phenomenon in order to elicit a possible mechanism. The superior antimicrobial performance of this new approach benefits from the use of well established, low-cost and safe dye (TBO) coupled with inexpensive, widely tested and biodegradable polymers also known to be safe. Moreover, no adverse cytotoxic effects of the PBAEs adjuvated TBO delivery have been observed on a skin cells in vitro model demonstrating the safety profile of this new technology.

New Perspective to Improve Care of Patients with Infected Diabetic Foot Ulcer: Early Economic Impact of the Use of Photodynamic Therapy with RLP068 (Based) System

Objective

To perform an early economic evaluation of a system based on photodynamic advanced adjuvant therapy with photosensitizer RLP068/CI to facilitate the healing process of foot/leg skin lesions/ulcers with an excellent safety profile.

Design

An early short-term (10 weeks) cost-effectiveness and a budget impact analysis (over 5 years) comparing photodynamic therapy with photosensitizer RLP068/CI based (PDT-RLP068) system added to Standard of Care (SoC) vs SoC alone.

Setting

The Italian National Healthcare System perspective considering both the outpatient and the day-hospital regimen.

Participants

Hypothetical patients with diabetic foot infection (DFI) grades I/IIB.

Interventions

The PDT-RLP068 system as an add-on to Standard of Care (SoC) vs SoC alone as the first-line treatment for the management of DFIs.

Main Outcomes

Days within which the clinical target was achieved and direct health costs for patients' management.

Results

Additional costs generated by the use of the PDT-RLP068 system progressively decreased as time to reach the target induced by the novel system decreased. In the outpatient regimen, when time to reach clinical target decreased in the range 7-28 days, ICERs varied from about 1€ to 70€ for each additional day gained with clinical target achieved. The system was dominant when halving time to reach the target in the outpatient regimen and even for modest reduction of time in day-hospital regimen. In terms of budget impact, when considering day-hospital regimen, if the PDT-RLP068 based system allowed a shortened duration to reach the clinical target of between 7-28 days, BI was 8,100,000€ to 700,000€, with saving less than 2,000,000€ with 50% reduction of time. Considering the inpatient setting, the use of the PDT-RLP068 system would result in saving even with the modest impact on the time needed to activate the healing process.

Conclusion

The early economic evaluation performed suggested that, if the claimed effectiveness of the technology demonstrated in case reports and in preliminary clinical studies can be confirmed in larger population studies, and allowing for shortening of the time needed to activate the healing process, the PDT-RLP068 system could offer the chance to improve care for DFI patients without compromising the sustainability of the system.

Photodynamic Topical Antimicrobial Therapy for Infected Diabetic Foot Ulcers in Patients With Diabetes: A Case Series

Diabetic foot ulcers (DFUs) are common, complex, costly complications, associated with frequent recurrences and increased morbidity and mortality. DFUs can be prevented and their healing can be mostly influenced by appropriately and aggressively managing any infection, but the role of antiseptic therapies in reducing healing time lacks sufficient evidence. Several therapeutic interventions have been developed based on the principles of photomedicine to overcome the issue of poor drug circulation in infected areas, with the aim of killing microbial agents while leaving the surrounding host cells unharmed. Such techniques use absorption of photons by specific chromophores. Among these, RLP068 is a tetracationic Zn(II) phthalocyanine derivative activated by exposure to red light, used as a topical treatment for superficial bacterial and fungal infections. The photoactivation of RLP068 results in the production of singlet oxygen and other reactive oxygen species, able to affect a range of cellular targets, including cell membrane and/or wall, cytoplasm, and cellular components, resulting in a rapid, broad range, bactericidal and fungicidal effect. The phase IIa study showed that photoactivated RPL068 is capable of inducing a dose-dependent reduction in total and pathogen microbial load in infected diabetic foot ulcers. In this article, a case series of 22 DFU treated with photoactivated RLP068 at 5 different centers in Italy is presented. Considering microbial agents reduction, ulcer healing facilitation, healing rate (9 DFUs out of 22), and amputation rate (only 1 case over 22), the decrease in the cost of DFU seems to be a point in favor of RLP068 and its cost-effectiveness.

Efficacy and safety of photodynamic therapy with RLP068 for diabetic foot ulcers: a review of the literature and clinical experience

This article is the second part of a literature review concerning diabetic foot ulcers (DFUs) and the use of antimicrobial photodynamic therapy (PDT). PDT involves the topical application of a photosensitiser into the tissue, followed by illumination that induces the formation of reactive oxygen species (ROS). PDT provides bacterial inactivation and promotes wound healing, and it can be used to manage the infection and microbial colonisation of DFUs. It has pivotal advantages in comparison with chemotherapeutics, such as no potential to induce resistance, and a wide spectrum of activity. Tetracationic Zn(II) phthalocyanine derivatives have been developed for PDT. Among these, we would like to focus on RLP068, whose antimicrobial activity has been widely demonstrated in preclinical studies and in a clinical trial. This article reports previously published evidence and presents four unpublished clinical cases of DFUs treated in the real-life setting with PDT.