Single, high-dose local injection of bFGF improves thyroarytenoid muscle atrophy after paralysis

Effects of intracordal trafermin injection on mutational voice disorder

INTRODUCTION

Mutational voice disorder is the inability of the voice to adjust to the changes in the larynx during puberty, resulting in the speaking fundamental frequency failing to decrease. Standard treatments for mutational voice disorder are voice therapy and thyroplasty. However, voice therapy takes time to show its effects, and thyroplasty is highly invasive. Herein, we present a case of mutational voice disorder successfully treated with intracordal trafermin injection.

CASE SUMMARY

A 31-year-old male patient was diagnosed with mutational voice disorder and offered standard treatment, but he requested a less invasive treatment with early effects. We performed intracordal trafermin injection with his consent. Two months after the procedure, the speaking fundamental frequency decreased from 155.5 Hz to 93.0 Hz, and the voice handicap index decreased from 14 to 2.

DISCUSSION

This case suggests that intracordal trafermin injection is an effective treatment option for mutational voice disorder. Furthermore, compared with the standard treatment methods, it is less invasive and provides effects shortly with only one injection.

Molecular mechanisms of uterine incision healing and scar formation

Wound healing is a tandem process involving inflammation, proliferation, and remodeling, through which damage is repaired and ultimately scar tissue is formed. This process mainly relies on the complex and extensive interaction of growth factors and cytokines, which coordinate the synthesis of various cell types. The loss of normal regulation in any part of this process can lead to excessive scarring or unhealed wounds. Recent studies have shown that it is possible to improve wound healing and even achieve scar-free wound healing through proper regulation of cytokines and molecules in this process. In recent years, many studies have focused on accelerating wound healing and reducing scar size by regulating the molecular mechanisms related to wound healing and scar formation. We summarized the role of these factors in wound healing and scar formation, to provide a new idea for clinical scar-free healing treatment of uterine incisions.

Effects of early local administration of high-dose bFGF on a recurrent laryngeal nerve injury model

BACKGROUND

Research on regenerative medicine using basic fibroblast growth factor (bFGF) has recently advanced in the field of laryngology. We previously reported that local administration of bFGF 1 month after recurrent laryngeal nerve (RLN) paralysis compensated for atrophy of the thyroarytenoid muscle. The objective of this study was to elucidate the effects of early bFGF administration on the thyroarytenoid muscle after RLN transection and to investigate the underlying mechanisms.

METHODS

A rat model of RLN paralysis was established in this study. One day after RLN transection, low- (200 ng) or high-dose (2000 ng) bFGF or saline (control) was administered to the thyroarytenoid muscle. The larynges were excised for histological and immunohistochemical examinations at 1, 7, 14, 28, and 56 days after administration.

RESULTS

The cross-sectional thyroarytenoid muscle area was significantly larger in the high-dose group than in the saline and low-dose groups on days 28 and 56. Immunohistochemistry indicated that bFGF significantly increased the number of satellite cells in the thyroarytenoid muscle up to day 14 and that of neuromuscular junctions on days 28 and 56.

CONCLUSIONS

A single, early local administration of high-dose bFGF prevented atrophic changes in the thyroarytenoid muscles by activating satellite cell proliferation and reforming neuromuscular junctions. As increased neuromuscular junctions are expected to maintain myofiber volume, bFGF administration may prevent thyroarytenoid muscle atrophy in the mid to long term.

One Year Outcomes and Longitudinal Changes in Voice Improvement With Single High Dose Intracordal Trafermin Injections for Age-Related Vocal Fold Atrophy

OBJECTIVE

Although intracordal trafermin injection has been performed in the treatment of age-related vocal fold atrophy, the effects of single high dose trafermin injections are unknown. In this study, we examined the 1 year outcomes and longitudinal changes in voice improvement with single high dose intracordal trafermin injections.

STUDY DESIGN

Retrospective study with approval by our Ethics Committee.

METHODS

The medical records of 34 patients who underwent single high dose (50ug per side) intracordal trafermin injections under local anesthesia for vocal fold atrophy were retrospectively reviewed at 1 month pre-injection and 1 month, 6 months and 1 year post injection.

RESULTS

Maximum phonation time (MPT), pitch range (PR), Japanese version of voice handicap index (VHI), grade of GRBAS evaluation, and jitter% improved significantly at 1-year post-injection compared to 1-month pre-injection. MPT and PR improved as early as 1-month post-injection and continued to improve most at 1-year post-injection. VHI showed negative progression from 6-months to 1-year post-injection, during which time the speaking fundamental frequency (SFF) changed to the high pitch in men.

CONCLUSIONS

Single high dose intracordal trafermin injections can be expected to improve voice in the early post-injection period and to maintain its effect for 1 year. SFF may play a role in worsening VHI in men.

LEVEL OF EVIDENCE

level 4.

Augmentation and vocal fold biomechanics in a recurrent laryngeal nerve injury model

Objectives/hypothesis

Composite vocal fold (VF) biomechanical data are lacking for augmentation after recurrent laryngeal nerve (RLN) injury. We hypothesize resulting atrophy decreases VF stiffness and augmentation restores native VF biomechanics.

Methods

Sixteen Yorkshire Crossbreed swine underwent left RLN transection and were observed or underwent carboxymethylcellulose (CMC) or calcium hydroxyapatite (CaHa) augmentation at 2 weeks. Biomechanical measurements (structural stiffness, displacement, and maximum load) were measured at 4 or 12 weeks. Thyroarytenoid (TA) muscle cross‐sectional area was quantified and compared with two‐way ANOVA with Tukey's post hoc test.

Results

After 4 weeks, right greater than left structural stiffness (mean ± SE) was observed (49.6 ± 0.003 vs. 28.4 ± 0.002 mN/mm), left greater than right displacement at 6.3 mN (0.54 ± 0.01 vs. 0.46 ± 0.01 mm, p < .01) was identified, and right greater than left maximum load (72.3 ± 0.005 vs. 40.8 ± 0.003 mN) was recorded. TA muscle atrophy in the injured group without augmentations was significant compared to the noninjured side, and muscle atrophy was seen at overall muscle area and individual muscle bundles. CMC augmentation appears to maintain TA muscle structure in the first 4 weeks with atrophy present at 12 weeks.

Conclusions

VF biomechanical properties match TA muscle atrophy in this model, and both CMC and CaHa injection demonstrated improved biomechanical properties and slower TA atrophy compared to the uninjured side. Taken together, these data provide a quantifiable biomechanical basis for early injection laryngoplasty to improve dysphonia and potentially improve healing in reversible unilateral vocal fold atrophy.

Level of evidence

N/A

Novel Thermosensitive Hydrogel Promotes Spinal Cord Repair by Regulating Mitochondrial Function

The repair of spinal cord injury (SCI) is still a tough clinical challenge and needs innovative therapies. Mitochondrial function is significantly compromised after SCI and has emerged as an important factor causing neuronal apoptosis and hindering functional recovery. In this study, umbilical cord mesenchymal stem cells (UCMSC), which are promising seed cells for nerve regeneration, and basic fibroblast growth factor (bFGF) that have been demonstrated to have a variety of effects on neural regeneration were jointly immobilized in extracellular matrix (ECM) and heparin-poloxamer (HP) to create a polymer bioactive system that brings more hope and possibility for the treatment of SCI. Our results in vitro and in vivo showed that the UCMSC-bFGF-ECM-HP thermosensitive hydrogel has good therapeutic effects, mainly in reducing apoptosis and improving the mitochondrial function. It showed promising utility for the functional recovery of impaired mitochondrial function by promoting mitochondrial fusion, reducing pathological mitochondrial fragmentation, increasing mitochondrial energy supply, and improving the metabolism of MDA, LDH, and ROS. In addition, we uncovered a distinct molecular mechanism underlying the protective effects associated with activating p21-activated kinase 1 (PAK1) and mitochondrial sirtuin 4 (SIRT4) by the UCMSC-bFGF-ECM-HP hydrogel. The expansion of new insights into the molecular relationships between PAK1 and SIRT4, which links the mitochondrial function in SCI, can lay the foundation for future applications and help to provide promising interventions of stem-cell-based biological scaffold therapies and potential therapeutic targets for the clinical formulation of SCI treatment strategies.

Long‐term results and safety of fibroblast growth factor injection for unilateral vocal fold paralysis

Objectives

Treatments for unilateral vocal fold paralysis (UVFP) include conservative voice rehabilitation, vocal fold injection, and laryngeal framework surgery. We proposed basic fibroblast growth factor (bFGF) injection as a potential novel treatment for UVFP and have reported the short‐term results. In this study, we present the long‐term results and safety of vocal fold bFGF injection as a treatment for UVFP.

Methods

This retrospective study included 42 patients (25 males and 17 females) with UVFP who were administered a local injection of bFGF. The injection regimen involved injecting FGF (0.5 μg/ml in 0.5 ml per side) into the bilateral vocal folds using a 23‐gauge injection needle. Phonological outcomes were evaluated 6 months and 12 months after the injection.

Results

Overall, 26 patients received a single injection of bFGF, six patients received an additional injection, and 10 patients received the additional framework surgery. Maximum phonation time, mean flow rate, pitch range, jitter and shimmer percentages, the total GRBAS (grade, roughness, breathiness, asthenia, strain) score, and voice handicap index scores improved significantly in the long term. In patients who received the additional injection or framework surgery, the effects of bFGF injection were temporary, but did not interfere with the performance of the framework surgery.

Conclusion

In total, 42 patients who underwent vocal fold bFGF injections were reviewed. The bFGF injections were effective and safe in the long‐term results for UVFP in the selected cases. Some patients with severe symptoms benefited from the additional framework surgery but not the additional bFGF injection.

Effect of Fascia Implantation and Controlled Release of Basic Fibroblast Growth Factor for Muscle Atrophy in Rat Laryngeal Paralysis

OBJECTIVE

To improve lateral thyroarytenoid (TA) muscle atrophy after laryngeal paralysis, reconstruction of the vascular network of the atrophied muscle is necessary. We therefore evaluated whether the controlled release of basic fibroblast growth factor (bFGF) with autologous fascia implantation could affect vascular reconstruction in the lateral TA muscle.

STUDY DESIGN

Animal experiment.

SETTING

Laboratory.

METHODS

Unilateral laryngeal paralysis was induced in 20 rats. The rats were implanted with autologous fascia and a gelatin hydrogel sheet with or without 1 µg of bFGF (fascia and bFGF + fascia groups; n = 5 each) and with only a gelatin hydrogel sheet with bFGF (bFGF group: n = 5). Another group remained untreated (n = 5) at 4 months after paralysis. At 3 months since transplantation, intra- and intergroup comparisons of the muscle volumes and total area of blood vessels in the lateral TA muscle were performed.

RESULTS

When compared with the untreated group, the bFGF + fascia group showed a significant increase in muscle volume (P =.0008) and vascular area (P =.0002) in the lateral TA muscle, whereas the other 2 treated groups demonstrated an insufficient effect.

CONCLUSION

bFGF + fascia implantation showed histologic improvement in severe laryngeal paralysis. We demonstrated that the decrease in lateral TA muscle mass after paralysis might be countered by the reconstruction of the vascular network. Our findings indicate that hypovascular and denervated areas of the laryngeal muscle can be regenerated by the implantation of growth factors and scaffolds with surgical stress.

LEVEL OF EVIDENCE

5.

Effect of Fibroblast Growth Factor 2 on Extraocular Muscle Structure and Function

Purpose

Mutations in the fibroblast growth factor (FGF) receptor can result in strabismus, but little is known about how FGFs affect extraocular muscle structure and function. These were assessed after short-term and long-term exposure to exogenously applied FGF2 to determine the effect of enhanced signaling.

Methods

One superior rectus muscle of adult rabbits received either a series of three injections of 500 ng, 1 µg, or 5 µg FGF2 and examined after 1 week, or received sustained treatment with FGF2 and examined after 1, 2, or 3 months. Muscles were assessed for alterations in force generation, myofiber size, and satellite cell number after each treatment.

Results

One week after the 5 µg FGF2 injections, treated muscles showed significantly increased force generation compared with naïve controls, which correlated with increased myofiber cross-sectional areas and Pax7-positive satellite cells. In contrast, 3 months of sustained FGF2 treatment resulted in decreased force generation, which correlated with decreased myofiber size and decreased satellite cells compared with naïve control and the untreated contralateral side.

Conclusions

FGF2 had distinctly different effects when short-term and long-term treatments were compared. The decreased size and ability to generate force correlated with decreased myofiber areas seen in individuals with Apert syndrome, where there is sustained activation of FGF signaling. Knowing more about signaling pathways critical for extraocular muscle function, development, and disease will pave the way for improved treatment options for strabismus patients with FGF abnormalities in craniofacial disease, which also may be applicable to other strabismus patients.

The Regenerative Potential of bFGF in Dental Pulp Repair and Regeneration

Regenerative endodontic therapy intends to induce the host’s natural wound-healing process, which can restore the vitality, immunity, and sensitivity of the inflammatory or necrotic pulp tissue destroyed by infection or trauma. Myriads of growth factors are critical in the processes of pulp repair and regeneration. Among the key regulatory factors are the fibroblast growth factors, which have turned out to be the master regulators of both organogenesis and tissue homeostasis. Fibroblast growth factors, a family composed of 22 polypeptides, have been used in tissue repair and regeneration settings, in conditions as diverse as burns, ulcers, bone-related diseases, and spinal cord injuries. Meanwhile, in dentistry, the basic fibroblast growth factor is the most frequently investigated. Thereby, the aim of this review is 2-fold: 1) foremost, to explore the underlying mechanisms of the bFGF in dental pulp repair and regeneration and 2) in addition, to shed light on the potential therapeutic strategies of the bFGF in dental pulp–related clinical applications.

Title: Gene transfer by pyro-drive jet injector is a novel therapeutic approach for muscle diseases

The angiogenic gene therapy is an attractive approach for the treatment of ischemic muscle diseases, including peripheral arterial disease and ischemic heart diseases. Although a variety of gene transfer methods have been developed, the efficiency of gene transfer is still limited. We have been developing the needleless high-energy bioinjector device, Pyro-drive Jet Injector (PJI), based on pyrotechnics using a combination of ignition powder and gunpowder, however, the utility of PJI in gene transfer into muscle tissues remains unclear. pcDNA3.1 plasmid containing Flag was injected to the thigh muscles of C57BL/6J mice using PJI or needle, as a control. Histological analysis demonstrated that the protein expression of Flag was observed in a wider range in PJI group than in needle group. To assess the validity of PJI for gene therapy, pcDNA3.1-human fibroblast growth factor 2 (FGF2), which has angiogenic activity and tissue protective properties, was injected into the ischemic thigh muscles with PJI or needle. ELISA assay revealed that the protein expression of FGF2 was increased in the thigh muscle tissues by PJI-mediated gene delivery. Significantly, histological analyses revealed that muscle fiber cross-sectional area and the number of endothelial marker CD31 (+) cells was increased in ischemic hind-limb tissues of the PJI-FGF2 group but not in those of needle-FGF2 group. To expand the applicability of the PJI-mediated gene transfer, pcDNA3.1-venus plasmid was injected into murine hearts with PJI or needle. PJI method was successful in gene transfer into murine hearts, especially into cardiomyocytes, with high efficiency when compared to needle method. Collectively, the non-needle, non-liposomal and non-viral gene transfer by PJI could be a novel therapeutic approach for muscle diseases.

Effect of a Single Injection of Basic Fibroblast Growth Factor into the Vocal Folds: A 36-Month Clinical Study

OBJECTIVE

A single injection of basic fibroblast growth factor (bFGF) into the vocal folds of patients with glottal insufficiency has been shown to be effective for a few years. However, the long-term therapeutic effect of a single injection of bFGF into the vocal folds has yet to be demonstrated. In this study, the therapeutic effect of a single injection of bFGF into the vocal folds was investigated over several years by monitoring patients for 36 months following this treatment.

METHODS

Nineteen patients with glottal insufficiency received injections of bFGF diluted to 20 μg/mL in the superficial layer of the lamina propria of the bilateral vocal folds. The following parameters were evaluated at preinjection baseline and 6, 12, 18, 24, and 36 months later, and statistical comparisons were performed. The parameters evaluated were: the Grade, Rough, Breathy, Asthenic, and Strained (GRBAS) scale score; maximum phonation time; acoustic analysis; and glottal wave analysis (GWA) and kymograph edge analysis (KEA) using high-speed digital imaging (HSDI). The amplitude perturbation quotient (APQ) and period perturbation quotient (PPQ) were measured by acoustic analysis. The mean minimum glottal area during vocalization and mean minimum distance between the vocal folds were measured by GWA. The amplitudes of the bilateral vocal folds were measured by KEA.

RESULTS

Postinjection, the GRBAS scale score decreased from 6 months after injection, and maximum phonation time was prolonged. The mean minimum glottal area during vocalization and the mean minimum distance between the vocal folds calculated by GWA of HSDI decreased significantly after 6 months. These effects persisted until 36 months postinjection. APQ and PPQ derived from acoustic analysis tended to decrease, but not significantly. There was no clear change in the amplitudes of the bilateral vocal folds calculated by KEA of HSDI before and after injection.

CONCLUSIONS

These results suggest that the effects of a single injection of bFGF into the vocal folds persist for 36 months.

Therapeutic Efficacy of Basic Fibroblast Growth Factor in Patients With Vocal Fold Atrophy

OBJECTIVES/HYPOTHESIS

In recent years, basic fibroblast growth factor (bFGF) injection has been used in the treatment of aging-related vocal fold atrophy. This injection not only improves closure by increasing the mass of the vocal fold but also improves its viscoelasticity. However, it has been reported that fibroblasts targeted by bFGF treatment decrease in number with age. The purpose of this study was to examine the effects of local injection of bFGF on age-related vocal atrophy as well as the influence of age on phonological outcomes.

STUDY DESIGN

Retrospective chart review.

METHODS

Fifty-three patients with age-related vocal fold atrophy underwent single injections of bFGF in their vocal folds. Phonological outcomes were evaluated 3 and 6 months after injection by acoustic and aerodynamic measurements.

RESULTS

Voice Handicap Index (VHI), maximum phonation time (MPT), jitter, shimmer, and pitch range improved after injection, and the effects continued for 6 months. In those over 70 years of age, VHI and MPT showed improvement at 3 and 6 months after injection. In addition, the degree of improvement in VHI and MPT did not differ significantly between those older than 70 years and those younger than 70 years.

CONCLUSIONS

Regenerative treatments dependent on bFGF single injection was safe and effective for both early and late elderly patients suffering of vocal fold atrophy.

LEVEL OF EVIDENCE

2c Laryngoscope, 2020.