Intra-Articular Injections of Polyphenols Protect Articular Cartilage from Inflammation-Induced Degradation: Suggesting a Potential Role in Cartilage Therapeutics.

Arthritic diseases, such as osteoarthritis and rheumatoid arthritis, inflict an enormous health care burden on society. Osteoarthritis, a degenerative joint disease with high prevalence among older people, and rheumatoid arthritis, an autoimmune inflammatory disease, both lead to irreversible structural and functional damage to articular cartilage. The aim of this study was to investigate the effect of polyphenols such as catechin, quercetin, epigallocatechin gallate, and tannic acid, on crosslinking type II collagen and the roles of these agents in managing in vivo articular cartilage degradation. The thermal, enzymatic, and physical stability of bovine articular cartilage explants following polyphenolic treatment were assessed for efficiency. Epigallocatechin gallate and tannic acid-treated explants showed >12 °C increase over native cartilage in thermal stability, thereby confirming cartilage crosslinking. Polyphenol-treated cartilage also showed a significant reduction in the percentage of collagen degradation and the release of glycosaminoglycans against collagenase digestion, indicating the increase physical integrity and resistance of polyphenol crosslinked cartilage to enzymatic digestion. To examine the in vivo cartilage protective effects, polyphenols were injected intra-articularly before (prophylactic) and after (therapeutic) the induction of collagen-induced arthritis in rats. The hind paw volume and histomorphological scoring was done for cartilage damage. The intra-articular injection of epigallocatechin gallate and tannic acid did not significantly influence the time of onset or the intensity of joint inflammation. However, histomorphological scoring of the articular cartilage showed a significant reduction in cartilage degradation in prophylactic- and therapeutic-groups, indicating that intra-articular injections of polyphenols bind to articular cartilage and making it resistant to degradation despite ongoing inflammation. These studies establish the value of intra-articular injections of polyphenol in stabilization of cartilage collagen against degradation and indicate the unique beneficial role of injectable polyphenols in protecting the cartilage in arthritic conditions.

2,2,2-Trifluoroethanol disrupts the triple helical structure and self-association of type I collagen.

Collagen, a fibrous structural protein, is a major component of skin, tendon, bone, and other connective tissues. Collagen is one of the dominant biomaterials used for tissue engineering and drug delivery applications. 2,2,2-Trifluoroethanol (TFE) has been used as a co-solvent in the preparation of collagen based biomaterials, which are used for tissue engineering applications. However, the basic knowledge about the structural behavior of collagen in TFE is necessary for an adequate application of collagen as a carrier system. In this work, the effect of TFE on the structure and self-association of collagen has been studied in detail using different spectroscopic methods such as circular dichroism (CD), Fourier transform infrared (FTIR), and UV-Vis absorption. The results obtained from CD and FTIR suggest that collagen transform its structure from triple helix to predominantly unordered conformation with increasing concentration of TFE. Thermal melting studies reveal that the stability of collagen triple helix decreases even at low concentration of TFE. Turbidity measurements indicate that TFE, at higher concentrations, inhibits the collagen fibril formation which arises due to the self-association of collagen molecules. TFE has conventionally been known to promote the ordered structures in proteins and peptides. Destabilization of collagen triple helix by TFE is first of its kind information on the effect of TFE to disrupt the native conformation of proteins.

Preparation and properties of tannic acid cross-linked collagen scaffold and its application in wound healing.

A biodurable porous scaffold of collagen with good biocompatibility and enhanced wound healing potential is prepared through casting technique using tannic acid (TA) as crosslinker. The morphological analysis of the tannic acid cross-linked collagen scaffold (TCCs) distinctively shows scaly interlinks with large pores. The enzymatic stability of the scaffold is characterized in vitro to detail the role of TA in stabilization of collagen matrix against collagenolytic degradation. TCCs shows more stability (>54%) against collagenase than that of the collagen scaffolds (Cs). The attenuated total reflectance Fourier transform infrared analysis of the TCCs confirms the noncovalent interaction between collagen and TA. The biocompatibility of the scaffold (TCCs) in vitro has been established using 3T3 fibroblasts. Therapeutic and wound healing potential of the TCCs has been studied in vivo using excision wound model in rats. The results clearly indicates that the TCCs has greater and significant effect in wound closure and increased the wound healing rate compared with native Cs. This biocompatible and biodurable scaffold may find broad applications in the tissue engineering and drug delivery applications.

Collagen adsorption on quercetin loaded polycaprolactone microspheres: approach for "stealth" implant.

We recently experimented with collagen coating on the surface of quercetin loaded polycaprolactone microspheres by simple adsorption technique to mimic extra cellular matrix and reduce immune or inflammatory responses at the site of implants. The collagen immobilization on polymeric scaffold surfaces through various surface modification techniques was the current scenario to improve bio-integration of the polymers with the in vivo system. Nevertheless, it requires other chemicals or processing methods to modify the surface of polymers to immobilize the collagen covalently. Here protein adsorption principle is used for the coating of collagen onto the surface of solid microspheres and characterized. Optical, ATR-FTIR, SEM analysis confirm collagen coating. The reduction in burst release of the quercetin from the PCL microspheres further confirms its presence and role in the controlled release. The results indicate that the adsorption technique can be the simple strategy to coat collagen on the surface of polyester implants to develop stealth implant in shorter time with low cost technology.

Formulation and evaluation of quercetin polycaprolactone microspheres for the treatment of rheumatoid arthritis.

Quercetin had been shown to be effective in the management of arthritis. However, bioavailability of quercetin is a concern for such treatment. This work aims at the development of intra-articular drug delivery system by controlled release of quercetin (loaded in microspheres) for the management of rheumatoid arthritis. Polycaprolactone has been used for the preparation of microspheres (with quercetin) using the solvent evaporation method. The physio-chemical characterisation of polycaprolactone-loaded quercetin microspheres was carried out to obtain information about particle size distribution, drug loading efficiency, morphology, thermal properties, polymorphism and release trends in phosphate-buffered saline at pH 7.4 and 37°C. Quercetin-loaded polycaprolactone microspheres were found to be biocompatible as evidenced from in vitro and in vivo studies using a rabbit synovial cells and Wistar rats, respectively. Quercetin release from microspheres of selected formulations showed biphasic nature due to initial burst effect followed by a controlled release. These results suggest that optimised quercetin-loaded polycaprolactone microspheres may be the viable strategy for controlled release of quercetin in the joint cavity for more than 30 days by intra-articular injection to treat rheumatoid arthritis.