Volume analysis of preadipocyte injection for vocal cord medialization

Preliminary results of tissue-engineered injection laryngoplasty material in a rabbit model

OBJECTIVES/HYPOTHESIS

Design and test a novel biomaterial for injection laryngoplasty aimed to increase the duration of effectiveness of micronized acellular dermis.

STUDY DESIGN

Animal model.

METHODS

Injection laryngoplasty was performed in three groups (n = 5) of New Zealand White rabbits. Acellular dermis was either used alone as a control (group 1), was combined with undifferentiated stem cells (group 2), or with predifferentiated chondrocytic cells (group 3). Groups 2 and 3 were supplemented with growth factors. Animals were sacrificed 4 and 12 weeks after laryngoplasty and histologic analysis was completed. The major outcome measure was volume of tissue remaining.

RESULTS

After 4 weeks, the mean volume of tissue remaining was 341 ± 89 mm³ , 295 ± 102 mm³ , and 133 ± 15 mm³ , for groups 1 to 3, respectively. At the 12-week time point, volumes were 62 ± 62 mm³ , 235 ± 35 mm³ , and 107 ± 99 mm³ . After 12 weeks, there was a significantly higher volume in group 2 compared to group 1 or 3 (P = .01, P = .04). Volumes between week 4 and week 12 were significantly lower in group 1 (P = .02), but not significantly different for groups 2 and 3 (P = .38, P = .74). Histologic evaluation revealed a robust lymphocytic infiltration in all cases as well as morphologic and immunophenotypic features suggestive of chondrogenic differentiation in a single animal.

CONCLUSIONS

Micronized acellular dermis combined with stem cells and growth factors showed significantly less resorption 12 weeks after injection laryngoplasty compared to micronized acellular dermis alone. Groups using novel tissue-engineered biomaterial showed a lower resorption rate over time compared with acellular dermis alone.

LEVEL OF EVIDENCE

NA. Laryngoscope, 128:160-167, 2018.

Soft tissue augmentation using in vitro differentiated adipocytes: a clinical pilot study

BACKGROUND

Although various commercially available filler materials are now commonly used, their variable degrees of resorption require repeated percutaneous injections. To overcome these drawbacks, a new injectable in vitro differentiated adipocyte filler has been developed, and animal studies have demonstrated that implantation of the filler successfully enhances in vivo adipose tissue formation. This study was undertaken to evaluate the clinical efficacy of this method, particularly in soft tissue augmentation.

MATERIALS AND METHODS

Autologous adipose-derived stromal cells were isolated, cultured, and differentiated to adipocytes in vitro. The differentiated adipocytes were suspended in Dulbecco's modified Eagle medium and injected into the lesion requiring soft tissue augmentation. Eight patients were treated with this tissue-engineered filler. Long-term follow-up for longer than 1 year was possible in all patients.

RESULTS

Two or 3 weeks after the injection, volume increment of subcutaneous tissue was observed around the injection area in the ensuing 1 to 5 weeks. Thereafter, additional volume augmentation was not found and the augmentation effect was well-maintained. All patients agreed on the clinical effectiveness of the procedure, and no complications occurred.

CONCLUSIONS

The results obtained indicate that this method is well tolerated and may be an effective means of achieving soft tissue augmentation. The authors have indicated no significant interest with commercial supporters.

Clinical applications of mesenchymal stem cells in laryngotracheal reconstruction

During the past several years, mesenchymal stem cells (MSCs) derived from adult tissue have rapidly moved from in vitro and animal studies into clinical trials as a therapeutic modality for a diverse group of clinical applications, including head and neck reconstruction. For many diseases, cell therapy could affect the underlying pathophysiologic processes through multiple pathways providing an advantage over current treatment modalities. There is an emerging body of evidence that MSCs have unique immunomodulatory properties in addition to the ability to differentiate into multiple tissue lineages which make them even more attractive for regenerative medicine. A variety of pre-clinical and clinical studies have shown that MSCs may have a useful role in tissue repair as well as engineering strategies in head and neck reconstructive surgery. Clinically, this has ranged from injection laryngoplasty to the implantation of a tracheal construct seeded with MSC-derived chondrocytes. Recent advances in stem cell immunobiology can offer insight to the multiple mechanisms through which MSCs could affect underlying pathophysiologic processes ranging from vocal fold scarring to composite tissue defects. Thorough evaluation of the current literature is necessary in understanding how MSCs could potentially revolutionize our approach to head and neck defects. The purpose of this review is to highlight the advances in MSC-based therapies in head and neck surgery, specifically laryngotracheal reconstruction. The clinical role of tissue-derived MSCs, though not well understood, holds promise for many therapeutic applications in regenerative medicine and reconstruction.

Comparative study of framework surgery and fat injection laryngoplasty

OBJECTIVE

To evaluate differences between the functional results of framework surgery and autologous fat injection laryngoplasty, for patients with unilateral vocal fold paralysis.

STUDY DESIGN

Sixty-two patients underwent framework surgery, while 64 received autologous fat injection laryngoplasty. Voice function before and after both procedures was assessed using aerodynamic and acoustic analysis, with differences evaluated using paired t-test in both groups.

RESULTS

In both groups, all parameters improved significantly after surgery, compared with before surgery. Post-operative improvement in all parameters was significantly greater after fat injection laryngoplasty, compared with framework surgery.

CONCLUSION

Autologous fat injection laryngoplasty was thus found to be a more effective and reliable therapy for improving voice function in patients with vocal fold paralysis, compared with framework surgery.

Long-Term Acoustic Comparison of Thyroplasty versus Autologous Fat Injection

Objectives:

Medialization by thyroplasty or intracordal autologous fat injection provides voice improvement in patients with unilateral vocal fold paralysis. Thyroplasty is considered a “permanent” medialization, whereas fat injection is considered “temporary” because of reabsorption. The objective of this study was to compare the evolution of acoustic parameters for these procedures over 1 year and to evaluate the results of fat injection at 2 years.

Methods:

From 1994 to 1998, 46 consecutive patients (17 women and 29 men) were treated exclusively by intracordal injection of autologous fat, and then from 1999 to 2002, 48 consecutive patients (19 women and 29 men) were treated with the Montgomery Thyroplasty Implant System or Gore-Tex thyroplasty. Each patient's voice was prospectively recorded before operation and at 1, 3, 12, and 24 months after operation. Six patients (13%) in the injection group underwent a second injection, and 1 patient (2%) in the thyroplasty group underwent revision surgery. Jitter, shimmer, and noise-to-harmonics ratio (NHR) were calculated for a 1,000-ms midvowel segment of the vowel / a/.

Results:

One month after operation, jitter, shimmer, and NHR were significantly improved in both groups (Wilcoxon's test, p < 0.05 in all cases). Jitter and shimmer did not change significantly between 1 and 3 months or between 1 and 12 months (p > 0.05). The NHR had improved at 12 months in both groups (injection, p = 0.0004; thyroplasty, p = 0.0178) and at 24 months in the injection group (p = 0.0076). No significant difference was noted between the two techniques before operation or at 1, 3, or 12 months after operation (Mann-Whitney test, p > 0.05). Jitter and shimmer had not changed significantly after 24 months in either group. At 24 months, there was no difference in acoustic parameters between the two treatment groups.

Conclusions:

The two techniques provided comparable objective acoustic voice improvement. At 2 years, autologous fat injection provides long-term acoustic voice improvement comparable to that of thyroplasty, but it has a higher rate of revision surgery.

[Vocal fold superficial layer of lamina propria histology after the position of mucosa pediculated flap: canine experimental study]

Many techniques were applied to treat patients with sulcus vocalis and scarred vocal folds. Their results were not good enough. In the Technique of Vocal Fold Pediculated Mucosa Flap, an anterior pediculated flap of vocal fold is positioned on the superficial layer of the lamina propria, below the free margin.

AIM

To describe histological postoperative findings on the superficial layer of lamina propria during the application of the technique Vocal Fold Pediculated Mucosa Flap. The following parameters were compared between tested and control groups: total, type I and type III collagen and number of cellular nucleus.

STUDY DESIGN

experimental.

MATERIAL AND METHOD

Fifteen dogs were used. One vocal fold was submitted to the intervention and the other was left as control. Each group of three dogs was sacrificed on 10, 30, 90, 180 and 360 days after the experimental surgery. Hematoxylin and eosin (H.E.) and Syrius Red were the staining techniques used.

RESULTS

Type I and total collagen suggested increased results in the tested group on postoperative days 90 and 180, nevertheless there was statistical significance only on postoperative day 180 (p<0.05). Type III collagen group area was less significant than the control group on postoperative day 180 (p<0.05). The number of cellular nucleus was increased on the 10th postoperative day, but decreased after the 30th day.

DISCUSSION

The findings about total and type I collagen and the amount of cellular nucleus on the superficial layer of lamina propria were similar to laryngeal postoperative studies in dogs. More complex studies would contribute with new data about the present subject.

Injection laryngoplasty for management of unilateral vocal fold paralysis

PURPOSE OF REVIEW

The purpose of this review is to provide an up-to-date review of injection laryngoplasty technique and currently available injectable materials in the management of unilateral vocal fold paralysis (UVP).

RECENT FINDINGS

Many new materials are currently available as substances for injection laryngoplasty. These materials have been developed along distinct of lines reasoning that address the inherent shortcomings of the previously available injectable substances, namely, poor tissue biocompatibility and poor persistence within the larynx. Accordingly, the past decade has seen heightened efforts toward developing implants with improved biocompatibility and longevity. The past year has witnessed publications reporting animal studies and, on occasion, human clinical trials involving the intralaryngeal injection of calcium hydroxyl-appetite, autologous fascia, particulate silicone and hyaluronic acid derivatives, and others, for managing glottic insufficiency.

SUMMARY

In recent years, the application of injection laryngoplasty to unilateral vocal fold paralysis (UVP) has regained popularity. The technique of injection laryngoplasty has several appealing qualities including relative technical ease, low cost, and wide availability in many clinical settings. A growing number of injectable substances have been developed and tested in the clinical setting of glottic insufficiency. When used to manage unilateral vocal fold paralysis, however, injection laryngoplasty has one irrefutable shortcoming: an inability to address posterior glottic insufficiency. Therefore, while injection laryngoplasty technique becomes increasingly popular for vocal fold augmentation in cases vocal fold paresis, atrophy, and scarring, its role in the treatment of UVP should be limited to cases with an appropriate glottal defect. These techniques should be considered as part of a complimentary armamentarium with framework surgery.