Autologous fat injection therapy including a high concentration of adipose-derived regenerative cells in a vocal fold paralysis model: animal pilot study

3D-exoscopic microlaryngoscopy in phonosurgery for glottic insufficiency

PURPOSE

We hypothesized that using a 3D-exoscope (3Dex) in microlaryngoscopic phonosurgery is non-inferior to using a standard operating microscope (OM). To compare the above, we utilized a 3Dex and an OM for microlaryngoscopic vocal fold augmentation with autologous fat in patients with glottic insufficiency and compared the procedure itself and the long-term impact of vocal fold augmentation on subjective and objective voice parameters in both groups.

METHODS

36 patients with glottic insufficiency received microlaryngoscopic laryngeal augmentation with autologous fat. A 3Dex was utilized in 24 cases for visualization and compared to twelve cases in which an OM was used. Voice parameters were evaluated over a period of twelve months.

RESULTS

Comparison of operation time and voice parameters between the 3Dex and OM groups did not reveal significant differences. Significant improvement of mean voice quality in all parameters excluding roughness was observed at 3 and 6 months followed then by a slight decrease of voice quality parameters between the 6 and 12 months interval in both groups.

CONCLUSION

Our findings indicate no difference concerning operation time and outcome between the use of a 3Dex and an OM in phonosurgery. Our results highlight a significant voice improvement after vocal fold augmentation with autologous fat in glottic insufficiency mediated dysphonia. The smaller viewing system, better ergonomics for the primary surgeon and the assistant and a direct view for the entire surgical team make a 3Dex an interesting alternative for visualization in microlaryngoscopic phonosurgery.

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

Eliciting and Characterizing Porcine Vocalizations: When Pigs Fly

BACKGROUND/OBJECTIVES

While voice-related therapeutic interventions are often researched preclinically in the porcine model, there are no well-established methods to induce porcine glottic phonation. Described approaches, such as training animals to phonate for positive reinforcement are time-consuming and plagued by inherent variability in the type of phonation produced and contamination of background noise. Thus, a reliable method of assessing glottic phonation in the porcine model is needed.

METHODS

In this study, we have created a novel pulley-based apparatus with harness for "pig-lifting" with surrounding acoustic insulation and high-directional microphone with digital recorder for recording phonation. Praat and Matlab were used to analyze all porcine vocalizations for fundamental frequency (F0), intensity, duration of phonation and cepstral peak prominence (CPP). Glottic phonation was detected using F0 (≥2000 hz), duration (≥3 seconds) and researcher perceptual judgment. Partial-glottic phonations were also analyzed. Reliability between researcher judgment and acoustic measures for glottic phonation detection was high.

RESULTS

Acoustic analysis demonstrated that glottic and partial-glottic phonation was consistently elicited, with no formal training of the minipigs required. Glottic vocalizations increased with multiple lifts. Glottic phonation continued to be elicited after multiple days but became less frequent. Glottic and partial-glottic phonations had similar CPP values over the 6 experimental days.

CONCLUSION

Our cost-effective, reliable method of inducing and recording glottic phonation in the porcine model may provide a cost effective, preclinical tool in voice research.

Clinical study of injectable collagen scaffold with autologous fat cells for repair of severe vocal fold injury

Cell retention and survival after transplantation remains a major problem for long-term efficiency in therapy of severe vocal fold injury with autologous cells. In this study, injectable collagen scaffold was used to deliver autologous fat cells (AFCs) for repairing of severe vocal fold injury. We found injectable collagen scaffold could enhance the retention and survival of green fluorescent protein (GFP) labeled fat cells in the transplantation sites in rats. Based on these data, a randomized controlled clinical trial was conducted to evaluate the safety and efficiency of transplantation of collagen scaffold with AFCs for severe vocal fold injury. Ten patients with vocal fold paralysis were randomly assigned to control (AFCs only) and intervention (AFCs + collagen) groups. AFCs with or without collagen scaffold were injected into vocal folds of patients under general anesthesia, respectively. The safety and efficacy were regularly assessed during 24 months post-surgery. No obvious complications occurred in all patients during the follow-up. The collagen scaffold maintained the stability of implants after injection and reconstructed the vocal fold structure. The improvement of voice quality of patients was observed through voice quality evaluation with the voice handicap index (VHI) questionnaire, as well as acoustic analysis of maximum phonation time, jitter, and shimmer. The VHI score of patients in AFCs + collagen group improved significantly than those in AFCs group at 6, 12 and 24 months post-surgery. It demonstrates the injectable collagen scaffold is safe and efficient for delivering AFCs for vocal fold injury.

Achievements and Challenges in Transplantation of Mesenchymal Stem Cells in Otorhinolaryngology

Otorhinolaryngology enrolls head and neck surgery in various tissues such as ear, nose, and throat (ENT) that govern different activities such as hearing, breathing, smelling, production of vocal sounds, the balance, deglutition, facial animation, air filtration and humidification, and articulation during speech, while absence of these functions can lead to high morbidity and even mortality. Conventional therapies for head and neck damaged tissues include grafts, transplants, and artificial materials, but grafts have limited availability and cause morbidity in the donor site. To improve these limitations, regenerative medicine, as a novel and rapidly growing field, has opened a new therapeutic window in otorhinolaryngology by using cell transplantation to target the healing and replacement of injured tissues. There is a high risk of rejection and tumor formation for transplantation of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs); mesenchymal stem cells (MSCs) lack these drawbacks. They have easy expansion and antiapoptotic properties with a wide range of healing and aesthetic functions that make them a novel candidate in otorhinolaryngology for craniofacial defects and diseases and hold immense promise for bone tissue healing; even the tissue sources and types of MSCs, the method of cell introduction and their preparation quality can influence the final outcome in the injured tissue. In this review, we demonstrated the anti-inflammatory and immunomodulatory properties of MSCs, from different sources, to be safely used for cell-based therapies in otorhinolaryngology, while their achievements and challenges have been described too.

Therapeutic effect of adipose-derived regenerative cells on bladder function in rats with underactive bladder

We examined the effect of adipose-derived regenerative cells (ADRC) on bladder functions in a rat model of detrusor underactivity (DU) induced by bladder over-distention. Adult female Sprague Dawley rats were divided into 3 groups: sham group (control); over-distention group; and over-distention with ADRC treatment group. Bladder was over-distended with saline (2.7mL) on day 1, 8, 15 and 22 of the study. ADRCs, which were harvested from male F344 rats, expanded via culture, were injected into the bladder wall at day 15. Cystometry and in vitro organ bath functional studies were performed on day 28. Moreover, histological assessment of the bladder was performed. In cystometry, significant prolongation of the inter-contraction interval (ICI) and decrease of voiding efficiency (VE) were observed in the over-distention group, compared to that in the control group. Significant improvement in ICI and VE was seen in the ADRC treatment group in comparison with the over-distention group. The over-distention group showed significantly weaker bladder contractile responses to carbachol and electrical field stimulation than the control group, while bladder contractile responses were significantly stronger in the ADRC treatment group than that in the over-distention group. The over-distention group showed substantial fibrosis of the bladder compared to the control group, whereas bladder fibrosis was alleviated in the ADRC treatment group. In conclusion, the injection of ADRC into bladder wall improved bladder dysfunction and histological changes induced by bladder over-distention. ADRCs-based regenerative therapy could be novel treatment for DU.

Endoscopic soft palate augmentation using injectable materials in dogs to ameliorate velopharyngeal insufficiency

Background

Velopharyngeal structure augmentation methods are used as alternatives to pharyngeal flap operations. Recently, we investigated the sites of velopharyngeal structure augmentation in dogs and reported that the most effective injection location is the soft palate. However, there have been no reports regarding the optimal materials for implantation or injection. In this study, we aimed to investigate the injectable materials used in soft palate augmentation in dogs to ameliorate velopharyngeal insufficiency (VPI).

Methods

Endoscopic soft palate augmentation (ESPA) was performed in dogs using purified sodium hyaluronate, atelocollagen, or autogenic fat tissue. ESPA is an original technique developed by our group, and this is the first report of its performance. Moreover, we assessed the amount of nasal air leakage during inspiration at rest and during expiration under the rebreathing system at 1, 2, 3, 4, 5, and 6 months after injection of these materials.

Results

The amount of nasal air leakage during expiration under the rebreathing system was significantly decreased in all dogs injected with the ESPA materials, but neither apnea nor hypopnea was observed.

Conclusions

We investigated the optimal materials for use in ESPA, such as purified sodium hyaluronate, atelocollagen, or autogenic fat tissue. We found that all of them reduced nasal air leakage and only autogenic fat tissue showed significant histologic differences in dogs at 6 months. This technique may also be useful for the treatment of patients with VPI.

Safety and feasibility of fat injection therapy with adipose-derived stem cells in a rabbit hypoglossal nerve paralysis model: A pilot study

OBJECTIVE

The aim of this study is to establish a unilateral tongue atrophy model by cutting the hypoglossal nerve and to evaluate the safety and feasibility of a fat injection of adipose-derived stem cells (ADSCs) to restore swallowing function.

METHODS

A total of 12 rabbits were randomized to three groups; the ADSCs+fat group (n=4), the fat group (n=4) and the control group (n=4). All rabbits were treated with denervation of the left hypoglossal nerve and their conditions including body weight and food intake were checked during follow-up periods (8 weeks). At 4 weeks after the transection of the nerve, rabbits received the injection therapy into the denervated side of the tongue with 1.0mL fat tissue premixed with 0.5mL ADSCs in the ADSCs+fat group, 1.0mL fat tissue premixed with 0.5mL PBS in the fat group and 1.5mL PBS in the control group. Rabbits were euthanized 8 weeks post-treatment and resected tongues were collected, formalin-fixed and paraffin embedded. To evaluate the change of the intrinsic muscles of the tongue, muscle fibers around the treatment area was analyzed by evaluating 5 consecutive hematoxylin-eosin slides per rabbit.

RESULTS

Food intake did not decrease upon nerve denervation, and none of the rabbits displayed adverse effect such as aspiration, surgical wound dehiscence or infection. No significant body weight changes were found between the three groups at 4 and 8 weeks after nerve transection (p>0.05). In the control group, the denervated side of tongue had significantly smaller muscle fiber areas and diameters compared to the non-denervated side (p<0.05). The ADSCs+fat group demonstrated a larger area of inferior longitudinal muscle fibers compared to the control and the fat groups (582±312µm² vs. 405±220µm² and 413±226µm²; p<0.05). A significant thicker lesser diameter of inferior longitudinal muscle fibers was found in the ADSCs+fat group compared to the control and the fat groups (24±8µm vs. 20±6µm and 20±7µm; p<0.05).

CONCLUSION

The rabbit tongue atrophy model was found suitable for the assessment of muscle change after nerve transection. Fat injection therapy with ADSCs demonstrated great potential to prevent the muscle atrophy after denervation and to promote the muscle regeneration around the injection area.

Surgical Options for Pediatric Bilateral Vocal Cord Palsy: State of the Art

Management of pediatric bilateral vocal cord palsy (BVCP) is a controversial and challenging topic. It may represent a severe obstructive condition usually associated with respiratory distress, and, in such condition, tracheostomy has been considered the gold standard for a long time. Many surgical options have been described and used to increase the glottic space in BVCP (1), with ongoing research of less invasive techniques. The challenge and current trend in our department and in many major pediatric centers is to avoid tracheotomy through an early treatment. Many techniques introduced in the last decade reduced the number of tracheotomies and increased the decannulation rate. Furthermore, we observed a recent increase in attention to preserve the quality of the voice with new techniques, such as endoscopic arytenoid abduction lateropexy which is in our opinion an important innovation to improve glottic space with satisfactory voice results. We present a review of the literature about the evolution of the treatment options for pediatric BVCP during the years.

[Postoperative complications after major lung resection]

INTRODUCTION

The advent of the minimally invasive techniques has allowed an expansion of the indications for thoracic surgery, particularly in older patients and those with more comorbidities. However, the rate of postoperative complications has remained stable.

STATE OF THE ART

Postoperative complications are defined as any variation from the normal course. They occur in 30% but majority of them are minor. The 30-day mortality rate for lung resection varies range between 2 % and 3% in the literature. Complications can be classified as: (1) early (occurring in the first 24hours) including both "generic" surgical complications (especially postoperative bleeding) and complications more specific to lung surgery (Acute respiratory syndrome, atelectasis); (2) in-hospital complications and those occurring during the first 3 months; these are dominated by infectious events in particular pneumonia but also bronchial (bronchopleural fistula), pleural (pneumothorax, hydrothorax) or cardiac complications; (3) late complications are dominated by chronic pain, affecting 60% of patients having a thoracotomy at three months. Lobectomy is the most common lung resection. Pneumonectomy is a distinct procedure requiring a specific peri- and postoperative management. Right pneumonectomy is associated with a higher risk with a treatment related-mortality ranging between 7 and 10%.

CONCLUSION

Major lung resection has benefited from minimally invasive approaches and fast track to surgery. However, it is important to note the occurrence of new and specific complications related to those news surgical access.

Comparative Anatomy of Pig Arytenoid Cartilage and Human Arytenoid Cartilage

OBJECTIVE

This study aims to investigate the feasibility of pig arytenoid cartilage as an animal model for simulating arytenoidectomy under microlaryngoscope by comparing the similarities and differences between pig arytenoid cartilage and human arytenoid cartilage.

STUDY DESIGN

This is a methodological study on the excised pig arytenoid cartilage and human arytenoid cartilage.

METHODS

Five excised human adult cadaver larynges and five adult excised porcine larynges were dissected and all the soft tissue and mucous membrane attached to the arytenoid and cricoarytenoid joint were removed. The anatomical structure and morphology of the arytenoid cartilage were observed and measured with a vernier caliper. Measurements included cricoarytenoid articular facet major and minor diameter, cricoarytenoid articular facet center distance, cricoarytenoid facet major and minor diameter, length of vocal process and muscular process, and distance between tip of vocal process, muscular process, and junction/apex of arytenoid cartilage. Data were then compared across these major anatomic markers using student t test.

RESULTS

The gross anatomy of the pig arytenoid cartilage was similar to the human. However, the size of the pig larynx arytenoid cartilage was obviously larger in total, and there was statistical significance for almost all measurements (P < 0.05), except the mean value of cricoarytenoid articular facet center distance, the cricoarytenoid facet minor diameter, and the length of vocal process of pig and human, without statistically significant difference (P > 0.05). Moreover, the biggest differences between the pig arytenoid cartilage and the human arytenoid cartilage were that the pig arytenoid cartilage apex had the angle winding structure toward the back, and that the posterior part of the bilateral arytenoid cartilages was partially connected. Whereas after the angle winding was removed from the junction, pig arytenoid cartilage and human arytenoid cartilage were shaped both like a triangular pyramid.

CONCLUSION

The data of this metric comparative study indicate that pig arytenoid, after resecting the angle winding structure and incising the interarytenoid cartilage, is similar to the human's. Therefore, pig larynx is an appropriate experimental model for endoscopic arytenoidectomy. In addition, regarding the pig laryngeal angle winding structure, we still require further basic and clinical research to clarify its physiological function and significance.

Computed tomographic assessment of autologous fat injection augmentation for vocal fold paralysis

Objective

To perform a quantitative computed tomography (CT) assessment of short‐ and long‐term outcomes of autologous fat injection augmentation in patients with unilateral vocal fold paralysis.

Study Design

Retrospective case series.

Methods

Twelve patients who had undergone autologous fat injection augmentation for unilateral vocal fold paralysis in our hospital between 2011 and 2015 were enrolled in this study. The autologous fat for injection was acquired from periumbilical subcutaneous tissue and was injected orally using a special‐purpose laryngeal injection needle. To evaluate the injected fat at the follow‐up assessments, CT was performed at several times after surgery in clinical practice. All thin‐section CT images were transferred to a workstation, and the volume of the injected fat was calculated.

Results

Patients comprised 6 men and 6 women with a mean age at the time of surgery of 62.9 years (range, 46–82 years). The actual injected fat volume was 1.1–2.5 ml (mean, 1.6 ml). In seven patients assessed by CT two days after surgery, the average residual rate of the injected fat was 63.9%. The mean residual rates of the injected fat were 30.0% at 3 months, 33.7% at 6 months, 29.2% at 12 months, and 32.0% at 24 months.

Conclusions

Although the injected fat volume decreased within the first three months and the residual rate of the injected fat was 30.0% at three months after injection, the residual fat volume remained at the same level for 24 months after injection.

Level of Evidence

4

Structural Fat Grafting to Improve Outcomes of Vocal Folds’ Fat Augmentation: Long-term Results

Objective

Evaluating the long-term outcomes of vocal fold structural fat grafting.

Study Design

Case series with chart review.

Setting

University hospital.

Subjects and Methods

Seventy-nine dysphonic patients (16-82 years; 55 with unilateral laryngeal paralysis and 24 with vocal fold scarring) underwent vocal fold fat injection. Fat was harvested by low-pressure liposuction and then processed by centrifugation. Refined fat aliquots were placed in the vocal fold and paraglottic space in multiple tunnels to enhance graft neovascularization. All patients were followed for 12 months, 15 for 3 years, and 5 for 10 years with videolaryngostroboscopy, maximal phonation time (MPT) measurement, Voice Handicap Index (VHI) questionnaire, and GRBAS (grade, roughness, breathiness, asthenia, strain) perceptual evaluation. Laryngeal computed tomography (CT) and/or magnetic resonance imaging (MRI) studies were performed in 16 patients 3 to 28 months postoperatively; MRI was repeated in 5 cases 12 to 18 months after the first radiological study.

Results

The voice quality of all patients improved after surgery, and long-term stability was confirmed by MPT, GRBAS, and VHI ( P ranging between .004 and <.001). The results achieved 1 year postoperatively remained stable at 3 and 10 years. Videolaryn-gostroboscopy showed improved glottic closure in all patients despite a limited amount of fat resorption. CT and MRI demonstrated survival of the fat grafts in all of the 16 examined cases. Serial MRI scans showed no change in graft size over time.

Conclusions

The reported clinical and radiological data demonstrate that fat is an effective filler for permanent vocal fold augmentation if the refined micro-aliquots are placed in multiple tunnels.

Current Treatment Options for Bilateral Vocal Fold Paralysis: A State-of-the-Art Review

Vocal fold paralysis (VFP) refers to neurological causes of reduced or absent movement of one or both vocal folds. Bilateral VFP (BVFP) is characterized by inspiratory dyspnea due to narrowing of the airway at the glottic level with both vocal folds assuming a paramedian position. The primary objective of intervention for BVFP is to relieve patients’ dyspnea. Common clinical options for management include tracheostomy, arytenoidectomy and cordotomy. Other options that have been used with varying success include reinnervation techniques and botulinum toxin (Botox) injections into the vocal fold adductors. More recently, research has focused on neuromodulation, laryngeal pacing, gene therapy, and stem cell therapy. These newer approaches have the potential advantage of avoiding damage to the voicing mechanism of the larynx with an added goal of restoring some physiologic movement of the affected vocal folds. However, clinical data are scarce for these new treatment options (i.e., reinnervation and pacing), so more investigative work is needed. These areas of research are expected to provide dramatic improvements in the treatment of BVFP.