Synovial ablation in a rabbit rheumatoid arthritis model using photodynamic therapy

Poor Translatability of Biomedical Research Using Animals - A Narrative Review

The failure rate for the translation of drugs from animal testing to human treatments remains at over 92%, where it has been for the past few decades. The majority of these failures are due to unexpected toxicity - that is, safety issues revealed in human trials that were not apparent in animal tests - or lack of efficacy. However, the use of more innovative tools, such as organs-on-chips, in the preclinical pipeline for drug testing, has revealed that these tools are more able to predict unexpected safety events prior to clinical trials and so can be used for this, as well as for efficacy testing. Here, we review several disease areas, and consider how the use of animal models has failed to offer effective new treatments. We also make some suggestions as to how the more human-relevant new approach methodologies might be applied to address this.

Treatment of rheumatoid arthritis by phototherapy: advances and perspectives

Rheumatoid arthritis (RA) is an inflammatory disease that is prevalent worldwide and seriously threatens human health. Though traditional drug therapy can alleviate RA symptoms and slow progression, high dosage and frequent administration would cause unfavorable side effects. Phototherapy including photodynamic therapy (PDT) and photothermal therapy (PTT) has demonstrated distinctive potential in RA treatment. Under light irradiation, phototherapy can convert light into heat, or generate ROS, to promote necrosis or apoptosis of RA inflammatory cells, thus reducing the concentration of related inflammatory factors and relieving the symptoms of RA. In this review, we will summarize the development in the application of phototherapy in the treatment of rheumatoid arthritis.

Correlation of synovial caspase-3 concentration and the photodynamic effectiveness in osteoarthritis treatment

BACKGROUND

The present study focuses on investigation of Intra-articular PDT mechanisms for OA treatment. Also, a search for determination of the most effective dose of chlorin e6 (Ce6) for anti-inflammatory PDT of OA was carried out.

METHODS

The study was carried out on laboratory animals (11 Chinchilla rabbits, 1 year, 2.5 kg) with a gonarthritis model of post-traumatic OA. According to the instructions for using Photoditazin (Ce6 based PS) for PDT of human oncological and non-oncological diseases, the recommended dose is 0.7-1.2 mg/kg. For studies on rabbits, taking into account the conversion coefficient (3.2), the PS doses of 2.4, 3.2 and 6.4 mg/kg were selected. Fluorescence spectra were measured intra-articular before and after PDT using spectrometer with fiber-optic probe. The intrajoint PDT was carried out using a laser (662 ± 10 nm) and a fiber-optic catheter with a cylindrical diffuser inside a sapphire needle for a uniform distribution of the laser radiation. The immunohistochemical study was carried out by staining the samples with caspase-3.

RESULTS

Histological and immunohistochemical analysis showed that the best PS dose for intravenous administration for PDT of rabbit gonarthritis is 3.2 mg/kg. The PS concentration directly in the synovial tissue was 0.5 mg/kg, and this was enough to achieve the most positive results to reduce the caspase-3 level.

CONCLUSION

The caspase-3 level correlates well with other signs of inflammation in the synovial membrane (edema, etc.). Therefore, to assess the PDT effectiveness in the treatment of gonarthritis accompanied by synovitis, it is sufficient to analyze only for caspase-3. The efficacy of PDT with Ce6 showed that 3.2 mg/kg PS dose (1 mg/kg for a human) is the most effective.

Joint blood flow is more sensitive to inflammatory arthritis than oxyhemoglobin, deoxyhemoglobin, and oxygen saturation

Joint hypoxia plays a central role in the progression and perpetuation of rheumatoid arthritis (RA). Thus, optical techniques that can measure surrogate markers of hypoxia such as blood flow, oxyhemoglobin, deoxyhemoglobin, and oxygen saturation are being developed to monitor RA. The purpose of the current study was to compare the sensitivity of these physiological parameters to arthritis. Experiments were conducted in a rabbit model of RA and the results revealed that joint blood flow was the most sensitive to arthritis and could detect a statistically significant difference (p<0.05, power = 0.8) between inflamed and healthy joints with a sample size of only four subjects. Considering that this a quantitative technique, the high sensitivity to arthritis suggests that joint perfusion has the potential to become a potent tool for monitoring disease progression and treatment response in RA.

Gonarthritis photodynamic therapy with chlorin e6 derivatives

BACKGROUND

The new methods of osteoarthritis treatment are in constant demand due to the complexity of the early diagnosis and therapy. Specific features of Сhlorin e6 derivative (Ce6) accumulation in knee joint tissues and the efficiency of photodynamic therapy (PDT) of gonarthritis were studied.

METHODS

The experimental research was conducted on the model of posttraumatic gonarthritis on rabbits. The analysis of dynamics of change of Ce6 concentration in tissues of a knee joint was carried out by the method of fluorescent diagnostics. The intra-joint PDT was carried out using 662nm laser with energy density of 120-150J/cm(2) and a sapphire diffuser. An analysis of slices was conducted to confirm the anti-inflammatory effect through apoptosis.

RESULTS

The method of fluorescent spectroscopy revealed that the highest amount of Ce6 was accumulated in the synovial membrane of a damaged knee joint 2.5h after its intravenous introduction. On 14th day after gonarthritis modeling but before PDT the synovial membrane showed signs of synovitis. On 21st day after PDT the synovial membrane possessed noticeable villous structure, and no cells of inflammatory nature were observed.

CONCLUSION

Fluorescent diagnostics in knee joint tissues can be used in clinical practice of gonarthritis before, during and after PDT for monitoring the Ce6 accumulation and for treatment control. Optimal radiation energy density was determined to be 150J/cm(2). In the studied time intervals (5-25min) no dependency of PDT effect on irradiation time at the same energy density was observed. The analysis of results of clinical and morphological research shows that PDT is a low-invasive method of gonarthritis treatment with a high degree of efficiency and selectivity.

Photodynamic therapy induces an immune response against a bacterial pathogen

Photodynamic therapy (PDT) employs the triple combination of photosensitizers, visible light and ambient oxygen. When PDT is used for cancer, it has been observed that both arms of the host immune system (innate and adaptive) are activated. When PDT is used for infectious disease, however, it has been assumed that the direct antimicrobial PDT effect dominates. Murine arthritis caused by methicillin-resistant Staphylococcus aureus in the knee failed to respond to PDT with intravenously injected Photofrin(®). PDT with intra-articular Photofrin produced a biphasic dose response that killed bacteria without destroying host neutrophils. Methylene blue was the optimum photosensitizer to kill bacteria while preserving neutrophils. We used bioluminescence imaging to noninvasively monitor murine bacterial arthritis and found that PDT with intra-articular methylene blue was not only effective, but when used before infection, could protect the mice against a subsequent bacterial challenge. The data emphasize the importance of considering the host immune response in PDT for infectious disease.

Photodynamic therapy using intra-articular Photofrin for murine MRSA arthritis: biphasic light dose response for neutrophil-mediated antibacterial effect

BACKGROUND AND OBJECTIVE

Bacterial arthritis does not respond well to antibiotics and moreover multidrug resistance is spreading. We previously tested photodynamic therapy (PDT) mediated by systemic Photofrin® in a mouse model of methicillin-resistant Staphylococcus aureus (MRSA) arthritis, but found that neutrophils were killed by PDT and therefore the infection was potentiated.

STUDY DESIGN/MATERIALS AND METHODS

The present study used an intra-articular injection of Photofrin® and optimized the light dosimetry in order to maximize bacterial killing and minimize killing of host neutrophils. MRSA (5 × 10(7)  CFU) was injected into the mouse knee followed 3 days later by 1 µg of Photofrin® and 635-nm diode laser illumination with a range of fluences within 5 minutes. Synovial fluid was sampled 6 hours or 1-3, 5, and 7 days after PDT to determine MRSA colony-forming units (CFU), neutrophil numbers, and levels of cytokines.

RESULTS

A biphasic light dose response was observed with the greatest reduction of MRSA CFU seen with a fluence of 20 J cm(-2), whereas lower antibacterial efficacy was observed with fluences that were either lower or higher. Consistent with these results, a significantly higher concentration of macrophage inflammatory protein-2, a CXC chemokine, and greater accumulation of neutrophils were seen in the infected knee joint after PDT with a fluence of 20 J cm(-2) compared to fluences of 5 or 70 J cm(-2).

CONCLUSION

PDT for murine MRSA arthritis requires appropriate light dosimetry to simultaneously maximize bacterial killing and neutrophil accumulation into the infected site, while too little light does not kill sufficient bacteria and too much light kills neutrophils and damages host tissue as well as bacteria and allows bacteria to grow unimpeded by host defense.

Bactericidal effect of photodynamic therapy using Na-pheophorbide a: evaluation of adequate light source

OBJECTIVE

To evaluate the efficacy of photodynamic therapy (PDT) against methicillin resistant-Staphylococcus aureus (MRSA) by selecting different light sources for irradiation and combining them with the photosensitizer Na-Pheophorbide a (Na-Phde a).

BACKGROUND

The treatment of drug-resistant bacterial infection is a serious issue. Recently, as a new clinical approach against septic arthritis, an experimental in vivo and in vitro model for the inactivation of MRSA by PDT using the photosensitizer Na-Phde a has been developed.

MATERIALS AND METHODS

Na-Phde a solution (280 micromol/L) was mixed with MRSA strain bacterial inoculum. After 60 minutes, light was irradiated for 30 minutes using the following light sources: GaA1p semiconductor laser (300 mW, 670 nm), halogen lamp (75 W), xenon lamp (300 W) and fluorescent lamp (27 W). Bacterial growth was evaluated after 24 hours incubation in a blood agar culture.

RESULTS

The semiconductor laser and halogen lamp groups showed perfect bactericidal effects after PDT. The xenon lamp and fluorescent lamp groups showed partial bactericidal effects.

CONCLUSIONS

The results of this experiment showed that PDT using the combination of Na-Phde a with a semiconductor laser or halogen lamp showed a better bactericidal performance than with xenon or fluorescent lamps. These findings indicated that PDT using Na-Phde a could be a useful treatment for septic arthritis and soft tissue infection.

Influence of intra-articular neutrophils on the effects of photodynamic therapy for murine MRSA arthritis

Although there have been some reports about the cytotoxic effects of photodynamic therapy (PDT) on multidrug-resistant bacteria, there have been few reports in which favorable results of PDT on a local infection site are described. This study aimed to verify the hypothesis that the low efficacy of PDT on a local infection site is due to the cytotoxic effect of PDT on leukocytes. PDT using Photofrin exerted significant cytotoxicity for cultured methicillin-resistant Staphylococcus aureus (MRSA). Nevertheless, this therapeutic modality was not effective for a murine MRSA arthritis model. Approximately 30% of intra-articular leukocytes, mainly neutrophils, died immediately after PDT, and a further decrease in the number of intra-articular leukocytes and atrophy of the synovial tissue were seen 24 h after PDT. Isolated peripheral neutrophils showed significant affinity for Photofrin and showed significant morphological damage, resulting in cell death, when they were subject to PDT using Photofrin. These results indicate that intra-articular neutrophils have an influence on the effects of PDT for MRSA arthritis.

Thrombin-sensitive photodynamic agents: a novel strategy for selective synovectomy in rheumatoid arthritis

Protease-sensitive macromolecular prodrugs have attracted interest for bio-responsive drug delivery to sites with up-regulated proteolytic activities such as inflammatory or cancerous lesions. Here we report the development of a novel polymeric photosensitizer prodrug (T-PS) to target thrombin, a protease up-regulated in synovial tissues of rheumatoid arthritis (RA) patients, for minimally invasive photodynamic synovectomy. In T-PS, multiple photosensitizer units are tethered to a polymeric backbone via short, thrombin-cleavable peptide linkers. Photoactivity of the prodrug is efficiently impaired due to energy transfer between neighbouring photosensitizer units. T-PS activation by exogenous and endogenous thrombin induced an increase in fluorescence emission by a factor of 16 after in vitro digestion and a selective fluorescence enhancement in arthritic lesions in vivo, in a collagen-induced arthritis mouse model. In vitro studies on primary human synoviocytes showed a phototoxic effect only after enzymatic digestion of the prodrug and light irradiation, thus demonstrating the functionality of T-PS induced PDT. The developed photosensitizer prodrugs combine the passive targeting capacity of macromolecular drug delivery systems with site-selective photosensitizer release and activation. They illuminate lesions with pathologically enhanced proteolytic activity and induce cell death, subsequent to irradiation.

Differential response of porcine osteoblasts and chondrocytes in cell or tissue culture after 5-aminolevulinic acid-based photodynamic therapy

OBJECTIVE

Outcome in osteochondral allografting is limited by the immunological incompatibility of the grafted tissue. Based on a resistance of chondrocytes to photodynamic therapy in cell culture it is proposed that 5-aminolevulinic acid-based photodynamic therapy (5-ALA-PDT) might be used to inactivate bone while maintaining viability of chondrocytes and thus immunomodulate bone selectively.

METHODS

Chondrocytes and osteoblasts from porcine humeral heads were either isolated (cell culture) or treated in situ (tissue culture). To quantify cytotoxic effects of 5-ALA-PDT (0-20 J/cm(2), 100 mW/cm(2)) an (3-(4,5-dimethylthiazol-2-yl)-2,5-di-phenyltetrazolium bromide) (MTT)-assay was used in cell culture and in situ hybridization in tissue culture to assess metabolic active cells (functional osteoblasts: col alpha(1)(I) mRNA, functional chondrocytes: col alpha(1)(II) mRNA).

RESULTS

In cell culture, survival after 5-ALA-PDT was significantly higher for chondrocytes (5 J/cm(2): 87+/-12% compared to untreated cells) than for osteoblasts (5J/cm(2): 12+/-11%). In tissue culture, the percentage of functional chondrocytes in cartilage showed a decrease after 5-ALA-PDT (direct fixation: 92+/-2%, 20 J/cm(2): 35+/-15%; P<0.0001). A significant decrease in the percentage of bone surfaces covered by functional osteoblasts was observed in freshly harvested (31+/-3%) compared to untreated tissues maintained in culture (11+/-4%, P<0.0001), with no further decrease after 5-ALA-PDT.

CONCLUSION

Chondrocytes were more resistant to 5-ALA-PDT than osteoblasts in cell culture, while in tissue culture a loss of functional chondrocytes was observed after 5-ALA-PDT. Since osteoblasts - but not chondrocytes - were sensitive to the tissue culture conditions, devitalized bone with functional cartilage might already be achieved by applying specific tissue culture conditions even without 5-ALA-PDT.

The minimum influences for murine normal joint tissue by novel bactericidal treatment and photodynamic therapy using na-pheophorbide a for septic arthritis

OBJECTIVE

In this study, we examined the effect of photodynamic therapy (PDT) using Na-pheophorbide a (Na-Phde a) on normal joint tissue.

BACKGROUND DATA

The treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection is a serious issue. Recently, an experimental in vivo and in vitro model for the inactivation of MRSA by PDT using a photosensitizer, Na-Phde a, has been developed.

MATERIALS AND METHODS

The knee joints of mice were injected with 560 or 280 micromol/L of Na-Phde a. Thirty minutes after injection, percutaneous laser irradiation was applied for 5 min using a semiconductor laser (power: 125 mW; wavelength: 664 nm; total energy: 12 J/cm2). The joint perimeter and body weight of the treated mice were monitored, and histological evaluation was also done.

RESULTS

Joint swelling was observed up to 3 wk after PDT (p < 0.05). On histology 1 wk post-PDT, the treated knees were found to have inflammatory changes, primarily in synovial tissue. Eight weeks after PDT, the synovitis was no longer present. No significant effects were observed on cartilage, bone marrow, or menisci.

CONCLUSIONS

The results of this experiment showed that PDT with Na-Phde a induced arthritis for a short time after treatment. However, this arthritis was reversible, and the PDT did not appear to induce osteoarthritic changes in normal joint tissue. These findings indicate that PDT using Na-Phde a caused minimal but reversible changes in joint tissue, suggesting that it would be a safe and useful treatment for bacterial septic arthritis.

Photodynamic therapy using talaporfin sodium for synovial membrane from rheumatoid arthritis patients and collagen-induced arthritis rats

We investigated the efficacy of photodynamic therapy (PDT) using talaporfin sodium as a new method of synovectomy for rheumatoid arthritis (RA). We first used RA synovial membrane (RASM) for in vitro and in vivo study. The RASM was obtained from patients with RA during total knee replacement. In the in vitro study, RA fibroblast-like synoviocytes (RASCs) obtained from the RASM were examined by fluorescent microscopy to measure the intracellular localization of talaporfin sodium. The cells were then subjected to PDT, and their viability was examined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphophenyl)-2H-tetrazolium inner salt assay. In the in vivo assay, RASM was obtained as described above, grafted onto severe combined immunodeficiency (SCID) mice and subjected to PDT. The damaged area of RASM was evaluated histologically at 1 day after PDT. Next, we performed a separate experiment using rats with collagen-induced arthritis (CIA). After intra-articular injection of talaporfin sodium, the concentration of talaporfin sodium accumulated in the CIA synovial membrane (CIASM) was compared with that in cartilage, periarticular muscle, and skin. We then performed PDT with intra-articular injection of talaporfin sodium and intra-articular irradiation. The damaged area of the CIASM was measured at 1 day after the PDT, and the articular histological and radiological changes of the ankle were observed at 56 days after the PDT. In RASM, talaporfin sodium accumulated in lysosomes in vitro, and the phototoxicity to RASCs in vitro and to RASM grafted onto SCID mice in vivo depended on the concentration of talaporfin sodium and the laser energy. In CIA rats, there was a greater accumulation of talaporfin sodium in the CIASM than in normal tissue. The CIASM was selectively damaged at 1 day after the PDT, and the bone and cartilage destruction were ameliorated at 56 days after the PDT. In conclusion, PDT using talaporfin sodium might be a new method for synovectomy in patients with RA.

Transdermal photodynamic therapy—a treatment option for rheumatic destruction of small joints?

BACKGROUND AND OBJECTIVE

Synovectomy of small joints is a therapeutic approach in patients suffering from rheumatoid arthritis (RA). We examined the feasibility of transdermal photodynamic therapy (tPDT) in a fibroblast-induced model of joint destruction using the novel photosensitizer (PS) tetrahydroporphyrin-tetratosylat that shows strong absorption at the near infra-red spectral region.

MATERIALS AND METHODS

The functionality of the PDT system was assessed in vitro. Following arthritis induction and PS application, tPDT was applied in vivo. Therapy results were evaluated by measuring joint swelling, serum amyloid A (SAA) and histologically.

RESULTS

We were able to present a fully functional PDT in vitro. The in vivo therapy modalities were well tolerated by mice. We could demonstrate photodynamic ablation of subcutaneously located tissue (skeletal muscle) without skin damage.

CONCLUSION

This study provides the basis for transdermal accessibility of tissue through a photodynamic process which may serve as a minimally invasive synovectomy strategy.

Novel transdermal photodynamic therapy using ATX-S10·Na(II) induces apoptosis of synovial fibroblasts and ameliorates collagen antibody-induced arthritis in mice

We aimed to test the effect of transdermal photodynamic therapy (PDT) on synovial proliferation in vitro and in vivo, using a novel photosensitizer, ATX-S10.Na(II). Synovial fibroblasts were obtained from patients with RA (RASF). Cell viability with or without PDT was determined by MTT assay. Cell morphology was examined by light and transmission electron microscopy. DNA fragmentation was labeled by TUNEL stain. Collagen antibody-induced arthritis (CAIA) was induced in DBA/1 mice, and the effects of transdermal PDT were evaluated by clinical and histological examination. PDT showed drug concentration-dependent and laser dose-dependent cytotoxicity on RASF. TUNEL stain and TEM study revealed the induction of apoptotic cell death of RASF. Transdermal PDT significantly reduced clinical arthritis and synovial inflammation in this model of arthritis. These results suggest that transdermal PDT using ATX-S10.Na(II) might be a novel less invasive treatment strategy for small joint arthritis and tenosynovitis.

Spectroscopic study of ALA-induced endogenous porphyrins in arthritic knee tissues: targeting rheumatoid arthritis PDT

The inflamed synovium of rheumatoid arthritis exhibits many features typical for neoplastic tissue implying that the photodynamic therapy might be an efficient modality for chronic poliarthritis. The accumulation of endogenously produced porphyrins after administration of exogenous 5-aminolevulinic acid (ALA) in a rabbit model of rheumatoid arthritis was evaluated by fluorescence spectroscopy. Independent of the way, intravenously or intra-articularly, in which ALA was administered to the experimental animals, the highest fluorescence intensity of endogenously produced porphyrins was detected in the tissues of the inflamed joints. Besides, the application of ALA had a systemic sensitising effect on the whole organism of rabbits. The highest amount of endogenously produced porphyrins in the inflamed joints measured from the surface of the skin above the synovium tissues was detected 1-3 h after the administration of ALA. Fluorescence measurements performed on the tissue specimens ex vivo showed the predominant accumulation of porphyrins in the synovium of the inflamed joints. The fluorescence of porphyrins was also observed in the cartilage tissues taken from knee joints. However, the fluorescence spectra features indicated that the composition of porphyrins detected in the cartilage tissues was different than that in the synovial tissues. The selective accumulation of porphyrins in the inflamed synovial tissues stands up for the application of photodynamic therapy in the treatment of rheumatoid arthritis and implies the possibility to use optical non-invasive methods based on fluorescence detection of endogenously produced porphyrins for diagnostics of inflamed tissues.