Exploring the anti-inflammatory potential of topical hyaluronic acid for vocal fold injury in a rat model

PURPOSE

Vocal fold injuries are associated with fibrosis and dysphonia, which is a major obstacle to surgical treatment. The aim of this study is to evaluate the effect of topical hyaluronic acid with or without diclofenac on the inflammatory phase of vocal fold wound healing.

METHODS

Forty-one male Sprague-Dawley rats were randomly assigned to four groups: an uninjured control group, an injured control group without any treatment, and two intervention groups in which hyaluronic acid with or without diclofenac was applied to the injured vocal fold. Gene expression of inflammatory markers and ECM-related molecules were examined.

RESULTS

Vocal fold injury resulted in a significant upregulation of inflammatory parameters [Ptgs2, Il1b and Il10] and Has1. Tgfb1, Has3 and Eln gene expression were significantly downregulated by the topical application of hyaluronic acid. The combination of hyaluronic acid and diclofenac did not result in any significant changes.

CONCLUSIONS

Vocal fold wound healing was significantly improved by a single post-operative topical application of hyaluronic acid. The addition of diclofenac may provide no additional benefit.

SOCS3 Silencing Promotes Activation of Vocal Fold Fibroblasts via JAK2/STAT3 Signaling Pathway

Suppressor of cytokine signaling 3 (SOCS3) is a negative regulatory protein that has been identified as a key inhibitory regulator of JAK/STAT signaling pathway. However, the mutual regulatory relationship between SOCS3 and JAK2/STAT3 signaling pathway after vocal fold injury remains unclear. In this study, we used small interfering RNA (siRNA) to investigate the mechanism of SOCS3 regulating of fibroblasts through JAK2/STAT3 signaling pathway after vocal fold injury. Our data shows that SOCS3 silencing promotes the transformation of normal vocal fold fibroblasts (VFFs) into an fibrotic phenotype and activates the JAK2/STAT3 signaling pathway. JAK2 silencing significantly inhibits the increase in type I collagen and α-smooth muscle actin (α-SMA) secretion in VFFs induced by TGF-β but has no significant effect on normal VFFs. The silencing of SOCS3 and JAK2 reverses the fibrotic phenotype of VFFs induced by SOCS3 silencing. Therefore, we suggest that SOCS3 can affect the activation of vocal fold fibroblasts by regulating the JAK2/STAT3 signaling pathway after vocal fold injury. It provides a new insight for promoting the repair of vocal fold injury and preventing the formation of fibrosis.

Antifibrotic effects of Quercetin on TGF-β1-induced vocal fold fibroblasts

OBJECTIVE

To investigate the effects of Quercetin on vocal fold fibroblasts induced by TGF-β1 and vocal fold injury.

METHODS

The effects of Quercetin on collagen type I (COL-I), collagen type III (COL-III), and fibronectin (FN) expressions in transforming growth factor-β1 (TGF-β1)-induced human vocal fold fibroblasts were examined by the quantitative reverse transcription-polymerase chain reaction and the enzyme-linked immunosorbent assay. The Cell Counting Kit-8 was used to assess the influence of Quercetin on cell proliferation. A rat vocal fold injury model was developed. These rats were divided into a control group, a model group, and a Quercetin group. Pathorphological observations from Hematoxylin-eosin staining, the density of fibroblasts, and hypertrophic index were compared among the three groups.

RESULTS

Compared with cells untreated with TGF-β1, the mRNA and protein expression levels of COL-I, COL-II, and FN and proliferation ability in TGF-β1-induced human vocal fold fibroblasts were increased (all P<0.05). Compared with human vocal fold fibroblasts induced by TGF-β1, the mRNA and protein expression levels of COL-I, COL-II, and FN and proliferation ability in TGF-β1-induced human vocal fold fibroblasts following Quercetin stimulation were decreased (all P<0.05). There were no statistical differences between human vocal fold fibroblasts treated with or without Quercetin regarding cell proliferation and COL-I, COL-II, and FN expressions. Compared with the model group, Quercetin suppressed the fibrosis of the vocal fold following injury and the protein levels of COL-I, COL-II, and FN in tissue samples (all P<0.001). The density of fibroblasts and hypertrophic index in the vocal fold scar from the Quercetin group were lower than those in the model group (all P<0.05).

CONCLUSIONS

Quercetin inhibited TGF-β1-induced fibrotic changes and proliferation in human vocal fold fibroblasts and had an antifibrotic effect in vocal fold after injuries.

HGF and bFGF Secreted by Adipose-Derived Mesenchymal Stem Cells Revert the Fibroblast Phenotype Caused by Vocal Fold Injury in a Rat Model

OBJECTIVE

To investigate how adipose-derived mesenchymal stem cells (ADSCs), secreted hepatocyte growth factor (HGF), and basic fibroblast growth factor (bFGF) affect the fibroblast phenotype after vocal fold injury.

METHODS

We cultured primary normal (uninjured) and injured vocal fold fibroblasts (VFFs). A transwell co-culture system of ADSCs and injured VFFs was constructed in vitro, then the effects of HGF or bFGF were inhibited. The proliferation, extracellular matrix (ECM) secretion and transformation of VFFs were observed.

RESULTS

Compared with uninjured VFFs, the secretion of collagen by injured VFFs increased significantly, hyaluronan synthase 1 (HAS1) secretion decreased, and VFF transformation increased significantly. After co-culture with ADSCs, the proliferation of VFFs was accelerated and the transformation was inhibited. Co-culture inhibited the expression of type I and III collagen and promoted the expression of HAS1. When HGF or bFGF secretion was inhibited, the proliferation of injured VFFs was inhibited. The inhibitory effect on collagen was reduced by both groups, but this was more obvious with the anti-HGF group. The anti-bFGF group had a more prominent effect on HAS1 secretion after injury than the anti-HGF group but the difference was not statistically significant. The inhibition of the transformation of injured VFFs was reduced while α-smooth muscle actin was upregulated, which was more obvious with the anti-HGF group.

CONCLUSIONS

ADSCs and secreted HGF and bFGF can revert the fibroblast phenotype caused by vocal fold injury. The effects of HGF are more significant than bFGF on collagen secretion and the transformation of VFFs into myofibroblasts. However, bFGF is more effective than HGF in upregulating HAS1.

Prolactin may serve as a regulator to promote vocal fold wound healing

Reduced prolactin (PRL) has been shown to delay wound healing with a limited understanding of the underlying mechanisms. Here, we aim to explore the role of PRL in the repair of vocal fold (VF) injury. A microarray was used to detect the expressed levels of PRL in rat VF tissue at 1, 4, and 8 weeks after VF injury compared with normal uninjured rats. Then, a systematic bioinformatics analysis has been conducted to explore the literature-based biology network and signaling pathways involved in the repair of VF injury. The expression of PRL was significantly decreased in all VF injury groups (week 1, 4, and 8) compared with the control group (F stats = 280.34; P=4.88e-14), with no significant difference among the three VF injury groups (F stats = 1.97; P=0.18). Wounding has been shown to interfere with both PRL-promoting and inhibiting pathways that were involved in wound healing, including 11 PRL inhibitors and 6 PRL promoters. Our results reveal decreased PRL expression levels in VF injury, which is not in favor of the wound healing. The pathways identified may help in understanding the role of PRL as a treatment target for VF wound healing.

Regenerative potential of basic fibroblast growth factor contained in biodegradable gelatin hydrogel microspheres applied following vocal fold injury: Early effect on tissue repair in a rabbit model

Introduction

Postoperative dysphonia is mostly caused by vocal fold scarring, and careful management of vocal fold surgery has been reported to reduce the risk of scar formation. However, depending on the vocal fold injury, treatment of postoperative dysphonia can be challenging.

Objective

The goal of the current study was to develop a novel prophylactic regenerative approach for the treatment of injured vocal folds after surgery, using biodegradable gelatin hydrogel microspheres as a drug delivery system for basic fibroblast growth factor.

Methods

Videoendoscopic laryngeal surgery was performed to create vocal fold injury in 14 rabbits. Immediately following this procedure, biodegradable gelatin hydrogel microspheres with basic fibroblast growth factor were injected in the vocal fold. Two weeks after injection, larynges were excised for evaluation of vocal fold histology and mucosal movement.

Results

The presence of poor vibratory function was confirmed in the injured vocal folds. Histology and digital image analysis demonstrated that the injured vocal folds injected with gelatin hydrogel microspheres with basic fibroblast growth factor showed less scar formation, compared to the injured vocal folds injected with gelatin hydrogel microspheres only, or those without any injection.

Conclusion

A prophylactic injection of basic fibroblast growth factor -containing biodegradable gelatin hydrogel microspheres demonstrates a regenerative potential for injured vocal folds in a rabbit model.

Characterization of extracellular matrix proteins during wound healing in the lamina propria of vocal fold in a canine model: a long-term and consecutive study

The characterization of vocal fold wound healing can be reflected by the changes of extracellular matrix (ECM) proteins in the lamina propria. Although the expression of ECM proteins after vocal fold injury has been widely studied, such observations have lacked time continuity and integrity of marker proteins. In this study, we observed the morphology of injured vocal folds in a canine model. We used immunofluorescence staining to evaluate the expression and distribution of ECM proteins, such as collagen, elastin, hyaluronic acid, decorin and fibronectin, from 15 days to 6 months after injury. The results showed that large amounts of ECM proteins were secreted 15-40 days after injury. Collagen and fibronectin secretion increased significantly, and were disorderly deposited. The secretion of decorin and elastin increased slightly, while hyaluronic acid decreased. The 15-40 day post-injury period may be the critical intervention stage in wound healing of vocal folds. From 3 to 6 months after injury, the secretion of ECM proteins declined. However, collagen and fibronectin secretion were still significantly higher than normal with irregular arrangement, while the secretion of elastin, hyaluronic acid and decorin decreased significantly at 6 months. This led to vocal fold inelasticity and stiffness, which required effective long-term interventions to treat scar formation.