Silk fibroin hydrogel containing Sesbania sesban L. extract for rheumatoid arthritis treatment

Abstract

Purpose: Rheumatoid arthritis, a chronic and progressive inflammation condition in the joints, has significantly reduced the patient quality of life and life expectancy. Crucially, there is no complete therapy for this disease, and the current treatments possess numerous side effects. Thus, novel therapeutic approach is necessary. To that end, this study developed novel silk fibroin in-situ hydrogel containing Sesbania sesban L. extract, a plant with high anti-inflammatory actions that are beneficial for rheumatoid arthritis treatments.

Methods: The hydrogels were manufactured using simple method of spontaneous gelation at different temperature. The gel properties of morphology, gelation time, viscosity, gel strength, stability, drug loading capacity, drug release rate, and in-vitro anti-inflammatory activity were investigated with appropriate methods.

Results: The optimal formulation had highly porous structure, with a gelation time of 0.5 h at room temperature and bodily temperature of 37 °C, a viscosity of 2530 ± 50 cP, a gel strength of 1880.14 ± 35.10 g, and a physical stability of >6 months. Moreover, the hydrogel contained the Sesbania sesban L. leaf extract with a total phenolic content of 92.8 ± 8.30 mg GAE/g, and sustained the release rate for >20 dạys, followed the Higuchi model. Regarding the in-vitro activities, all formulations were nontoxic to the RAW 264.7 cell line and demonstrated comparable anti-inflammatory activity to the free extract, in terms of the NO reduction levels.

Conclusion: Conclusively, the systems possessed potential properties to be further investigated to become a prospective rheumatoid arthritis treatment.

Keywords: Hydrogel; Sesbania sesban; Silk fibroin; anti-inflammation; rheumatoid arthritis.

Figure 1.

Total phenolic content (mg gallic acid equivalent (GAE)/g) of the Sesbania sesban L. leaves and flowers extracts at various conditions of the extraction time of 60 or 120 min, at a temperature of 30 °C, 50 °C, or 60 °C (n = 3). *, **: significant differences (p<.05) between the flower and leaf extracts, and between the temperature of 30 °C and 50 °C, respectively.

Figure 2.

Fibroin hydrogel appearance at a fibroin concentration of (A) 1%, (B) 2%, and (C) 5%.

Figure 3.

The cross-sectional scanning electron microscopy image of the Sesbania sesban L. extract loaded fibroin hydrogel.

Figure 4.

The in-vitro cumulative release profile, in terms of the total phenolic content, of the Sesbania sesban L. extract loaded fibroin hydrogel in the simulated inflammatory condition at pH 6.5 (n = 3).

Figure 5.

Cytotoxicity MTS assay on the RAW 264.7 cell line of the Sesbania sesban L. extract (SSE), the blank (unloaded) fibroin hydrogel, and the SSE loaded fibroin hydrogel at the concentrations of 75, 150, 300, and 500 µg/mL, equivalent to the total phenolic content (n = 3).

Figure 6.

Anti-inflammatory activities, in terms of the NO concentration reduction, on the LPS-induced RAW 264.7 cell line of the Sesbania sesban L. extract (SSE), the blank (unloaded) fibroin hydrogel, and the SSE loaded fibroin hydrogel at the concentrations of 75, 150, 300, and 500 µg/mL, equivalent to the total phenolic content (n = 3). The negative (−) and positive (+) were the non-LPS-induced RAW 264.7 cells and the LPS-induced RAW 264.7 cells without treatments, respectively. *: significant differences (p<.05) between the SSE/SSE loaded hydrogel and the blank hydrogel; (Ve.): vehicle control.