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

In Vitro Evaluation of Antibacterial Properties of NIR-Light Responsive Alginate Hydrogels Embedding Polydopamine Nanoparticles

Bacterial infections are one of the most serious health problems worldwide and represent a significant threat to humans. In this article, we designed an injectable alginate-based hydrogel embedding polydopamine nanoparticles (nPDA) and applied it as a (nano)phototherapeutic agent and nanocarrier for photodynamic (PDT) and photothermal (PTT) therapies with the perspective of treating bacterial infections and overcoming microbial resistance. For this purpose, nPDA were functionalized with Chlorin e6 as a photosensitizer and embedded in an alginate hydrogel to apply the PDT treatment. The photothermal properties of nPDA were exploited for the "on demand" local release of antibiotics such as Ciprofloxacin (for Gram-negative bacteria) and Rifampicin (for Gram-positive bacteria) to address respectively Escherichia coli and Staphylococcuss aureus as these antimicrobial-resistant pathogens are commonly found in bacterial infections. In vitro experiments have shown that PDT and PTT treatments were both highly efficient for the treatment of S. aureus, leading to the complete eradication of this bacterium. On the contrary, PDT was less effective for treating E. coli, while PTT revealed an excellent antibacterial activity toward this pathogen.

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.

Cell Therapy of Vascular and Neuropathic Complications of Diabetes: Can We Avoid Limb Amputation?

Globally, a leg is amputated approximately every 30 seconds, with an estimated 85 percent of these amputations being attributed to complications arising from diabetic foot ulcers (DFU), as stated by the American Diabetes Association. Peripheral arterial disease (PAD) is a risk factor resulting in DFU and can, either independently or in conjunction with diabetes, lead to recurring, slow-healing ulcers and amputations. According to guidelines amputation is the recommended treatment for patients with no-option critical ischemia of the limb (CTLI). In this article we propose cell therapy as an alternative strategy for those patients. We also suggest the optimal time-frame for an effective therapy, such as implanting autologous mononuclear cells (MNCs), autologous and allogeneic mesenchymal stromal cells (MSC) as these treatments induce neuropathy relief, regeneration of the blood vessels and tissues, with accelerated ulcer healing, with no serious side effects, proving that advanced therapy medicinal product (ATMPs) application is safe and effective and, hence, can significantly prevent limb amputation.

The photosensitizer-based therapies enhance the repairing of skin wounds

Wound repair remains a clinical challenge and bacterial infection is a common complication that may significantly delay healing. Therefore, proper and effective wound management is essential. The photosensitizer-based therapies mainly stimulate the photosensitizer to generate reactive oxygen species through appropriate excitation source irradiation, thereby killing pathogenic microorganisms. Moreover, they initiate local immune responses by inducing the recruitment of immune cells as well as the production of proinflammatory cytokines. In addition, these therapies can stimulate the proliferation, migration and differentiation of skin resident cells, and improve the deposition of extracellular matrix; subsequently, they promote the re-epithelialization, angiogenesis, and tissue remodeling. Studies in multiple animal models and human skin wounds have proved that the superior sterilization property and biological effects of photosensitizer-based therapies during different stages of wound repair. In this review, we summarize the recent advances in photosensitizer-based therapies for enhancing tissue regeneration, and suggest more effective therapeutics for patients with skin wounds.

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.

Biofilms in Diabetic Foot Ulcers: Impact, Risk Factors and Control Strategies

Diabetic foot ulcers (DFUs) are a serious complication from diabetes mellitus, with a huge economic, social and psychological impact on the patients' life. One of the main reasons why DFUs are so difficult to heal is related to the presence of biofilms. Biofilms promote wound inflammation and a remarkable lack of response to host defences/treatment options, which can lead to disease progression and chronicity. In fact, appropriate treatment for the elimination of these microbial communities can prevent the disease evolution and, in some cases, even avoid more serious outcomes, such as amputation or death. However, the detection of biofilm-associated DFUs is difficult due to the lack of methods for diagnostics in clinical settings. In this review, the current knowledge on the involvement of biofilms in DFUs is discussed, as well as how the surrounding environment influences biofilm formation and regulation, along with its clinical implications. A special focus is also given to biofilm-associated DFU diagnosis and therapeutic strategies. An overview on promising alternative therapeutics is provided and an algorithm considering biofilm detection and treatment is proposed.

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.