The Effects of Amniotic Membrane Transplantation on Vocal Fold Regeneration

OBJECTIVES/HYPOTHESIS

Vocal fold (VF) scar and sulcus cause severe vocal problems, but optimal methods have not been established. Total replacement of the mucosa is required particularly for cases in which the whole lamina propria is occupied by severe fibrosis and vibratory function is totally lost. The amniotic membrane (AM) has been proven to have regenerative potential, as it contains stem cells and growth factors. The current study investigated the biocompatibility and effects of AM for regeneration of the VF mucosa.

STUDY DESIGN

In vitro and in vivo studies.

METHODS

Vocal fold fibroblasts (VFFs) from 13 Sprague-Dawley rats were seeded on AM and subjected to histology and immunohistochemistry, and gene expressions in the VFFs on AM were examined in in vitro study. Twelve New Zealand White rabbits were used in in vivo study. VFs were stripped down and were reconstructed with AM. The regenerative effects were examined 3 months later by histological examination.

RESULTS

In vitro study indicated VFFs survived on AM and stained positively for Ki67, vimentin, and fibronectin. Gene expressions of Has1, Has2, and Hgf were significantly increased in the VFFs on AM compared with the other groups. The in vivo study indicated AM-transplanted VFs showed a significantly higher density of hyaluronic acid and lower density of collagen compared with sham VFs.

CONCLUSIONS

The current preliminary study suggests biocompatibility and possible regenerative effects of AM for VFs.

LEVEL OF EVIDENCE

NA Laryngoscope, 2021.

Pathophysiology of Fibrosis in the Vocal Fold: Current Research, Future Treatment Strategies, and Obstacles to Restoring Vocal Fold Pliability

Communication by voice depends on symmetrical vibrations within the vocal folds (VFs) and is indispensable for various occupations. VF scarring is one of the main reasons for permanent dysphonia and results from injury to the unique layered structure of the VFs. The increased collagen and decreased hyaluronic acid within VF scars lead to a loss of pliability of the VFs and significantly decreases their capacity to vibrate. As there is currently no definitive treatment for VF scarring, regenerative medicine and tissue engineering have become increasingly important research areas within otolaryngology. Several recent reviews have described the problem of VF scarring and various possible solutions, including tissue engineered cells and tissues, biomaterial implants, stem cells, growth factors, anti-inflammatory cytokines antifibrotic agents. Despite considerable research progress, these technical advances have not been established as routine clinical procedures. This review focuses on emerging techniques for restoring VF pliability using various approaches. We discuss our studies on interactions among adipose-derived stem/stromal cells, antifibrotic agents, and VF fibroblasts using an in vitro model. We also identify some obstacles to advances in research.

Comparison of ASCs and BMSCs combined with atelocollagen for vocal fold scar regeneration

OBJECTIVES/HYPOTHESIS

Vocal fold scar remains a therapeutic challenge. Mesenchymal stromal cells (MSCs) are promising tools for regenerative medicine. Nevertheless, few in vivo studies have directly compared various sources of MSCs. The aim of this study was to investigate the therapeutic potential of adipose-derived stromal cells (ASCs) in comparison with bone marrow-derived stromal cells (BMSCs) for vocal fold regeneration.

STUDY DESIGN

Prospective animal experiments with controls.

METHODS

Two months after stripping of the lamina propria, 18 beagles were divided into four implantation groups: atelocollagen alone (collagen group), atelocollagen with BMSCs (BMSC-collagen), atelocollagen with ASCs (ASC-collagen), or a sham-treated group. One or 6 months after implantation, vibratory and histological examinations were performed.

RESULTS

Mucosal vibration was significantly improved in both of the MSC-implanted groups compared with the sham-treated group, whereas only the ASC-collagen group showed a significantly smaller glottal gap than the collagen group. Moreover, in the ASC-collagen group, a significant reduction of collagen density was observed compared to the sham-treated group, and there was a trend for better restoration of hyaluronic acid (HA). Implanted MSCs were detected 1 month postimplantation; however, none survived 6 months postimplantation.

CONCLUSIONS

Although implantation of an atelocollagen sponge and ASCs into vocal fold scars induced vibratory recovery comparable to that of BMSCs, ASCs might have more potential in terms of restoration of HA and suppression of excessive collagen deposition.

LEVEL OF EVIDENCE

NA Laryngoscope, 126:1143-1150, 2016.

Regenerative medicine of the larynx. Where are we today? A review

Tissue engineering is a multidimensional process combining cells, scaffold matrices, and chemical signals to produce a structure similar to a target tissue. These techniques have opened a completely new field in diagnosis and therapy in numerous fields, including that of laryngology. Laryngeal tissue engineering has emerged in the last decade, although clinical applications are rare. The reasons therefore are numerous including ethical reasons, as well as the extremely complex anatomical structure of the vocal fold. The search for new treatment options has also enlarged our knowledge about the microphysiology and micropathophysiology of the vocal fold. To date, only specific growth factors are in clinical use for treatment of vocal fold atrophy. Big advances have been made in creating state-of-the-art scaffolds with various techniques including biomaterials as well as fully synthetic polymers. These scaffolds are supposed to provide an optimal environment for residual or implanted cells. Several in vitro settings showed practicability of these scaffolds, also in studying effects of growth factors. Cell therapy is a powerful tool in regenerative medicine but bears the uncertainty of possible malignant transformation. The aim of this review was to give a comprehensive overview about current knowledge in the field of laryngeal tissue engineering and regenerative medicine, including restoration of both vocal folds and laryngeal cartilage, and furthermore to elucidate further trends in this fascinating field.

Autologous bone marrow derived mononuclear cells combined with β-tricalcium phosphate and absorbable atelocollagen for a treatment of aneurysmal bone cyst of the humerus in child

Aneurysmal bone cyst is a benign, locally destructive lesion of bone. Based on progressive cortical thinning pathological fractures are common, and are often the presenting feature. Despite the long experience of orthopaedists, radiologists and pathologists with aneurysmal bone cyst there is limited knowledge regarding the cause of the lesion and optimal treatment. Common methods of treatment vary considerably in the literature, particularly in children. A large variety of bone substitutes have been used to fill the cystic lesions. To date there has been no graft material which can be regarded as completely satisfactory. Our experience with freshly isolated autologous bone marrow derived mononuclear cells combined with β-tricalcium phosphate and absorbable atelocollagen for bone formation is presented. The concept of this treatment is based on stimulation of natural events continuously present in living bone appear to be a reasonable and beneficial alternative to promote healing of bone cysts and offering both osteoinduction and osteoconductive features.

Micronized acellular dermal matrix as an efficient expansion substrate and delivery vehicle of adipose-derived stem cells for vocal fold regeneration

OBJECTIVES/HYPOTHESIS

Cell therapy has been shown to prevent vocal fold scarring and atrophy. However, problems that include the expansion of large numbers of cells in vitro and the poor survival of transplanted cells in vivo must be solved. The aim of this study was to use micronized acellular dermal matrix (MADM) as an expansion substrate of rabbit allogeneic adipose-derived stem cells (ADSCs) and to apply the combination of the matrix and cells, ADSC-MADM, to vocal fold regeneration.

STUDY DESIGN

Animal experiment.

METHODS

The proliferation of ADSCs that were cultured on the MADM was evaluated using 3-(4,5-dimethylthizazol-2-yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfonyl)-2H-tetrazolium, and a rabbit acute vocal fold injury model was established by laser injury. Eighteen New Zealand white rabbits were randomly divided into three groups, which were injected with ADSC-MADM, ADSCs, and MADM, respectively. Morphological analysis was performed by laryngoscope, and histological analyses were indicated by hematoxylin and eosin staining, van Gieson staining, and immunofluorescence. Additionally, the in vivo survival of the ADSCs was determined by CM-Dil cell labeling.

RESULTS

When compared with a two-dimensional culture, the MADM significantly promoted proliferation of ADSCs. Morphological and histological analyses indicated that, when compared to only using of MAMD or the nontreatment sample, the use of ADSC-MADM or only using ADSCs successfully prevent scarring and atrophy. Moreover, ADSC-MADM exhibited a better therapeutic effect than when only using ADSCs, which was probably due to the MADM significantly enhancing the survival of transplanted ADSCs.

CONCLUSIONS

MADM could be used as an efficient expansion substrate and delivery vehicle for ADSCs in vocal fold regeneration.

Implantation of an atelocollagen sponge with autologous bone marrow-derived mesenchymal stromal cells for treatment of vocal fold scarring in a canine model

OBJECTIVES

Vocal fold scarring remains a therapeutic challenge. A new regenerative approach is needed to restore disorganized extracellular matrix. Tissue regeneration requires appropriate cells and a scaffold. Bone marrow-derived mesenchymal stromal cells (BMSCs) are multipotent and secrete many kinds of growth factors to regenerate tissues. Atelocollagen sponges have many large pores that permit cell entry. The present study was performed to evaluate whether implantation of an atelocollagen sponge plus BMSCs is effective for the treatment of vocal fold scarring.

METHODS

Twelve beagles underwent implantation of an atelocollagen sponge or of an atelocollagen sponge with autologous BMSCs (1.0 x 10(6) cells) in the subepithelial pockets of scarred vocal folds. Six months after the operation, vibratory examinations and histologic examinations were performed.

RESULTS

Mucosal vibrations improved significantly for the atelocollagen sponge-implanted vocal folds. Histologic analyses revealed favorable restoration of the extracellular matrix in the lamina propria. Increased distribution of hyaluronic acid and decreased dense collagen deposition were also noted. These improvements were enhanced by implantation of BMSCs.

CONCLUSIONS

Implantation of atelocollagen sponges with autologous BMSCs into scarred vocal folds significantly increased hyaluronic acid distribution and decreased dense collagen deposition in the lamina propria, leading to better mucosal vibration.

Implantation of atelocollagen sheet for vocal fold scar

PURPOSE OF REVIEW

This article reviews recent advances in scaffold-based interventions for the treatment of vocal fold scarring, with a particular emphasis on atelocollagen sheet implantation in the vocal fold lamina propria.

RECENT FINDINGS

Scaffold-based therapies have demonstrated therapeutic promise in both preclinical and early clinical studies. Recent research has begun to shed light on the interactions between scaffold material properties, encapsulated and infiltrating cells, stimulatory molecules such as growth factors, and external regulatory variables such as stress, strain, and vibration. The atelocollagen sheet, a cross-linked collagen material with abundant micropores, has an established clinical track record as a scaffold for dermal and epidermal repair and exhibited potential therapeutic benefit in a recent study of patients with vocal fold scarring and sulcus vocalis.

SUMMARY

Scaffolding is one of the useful tools in tissue engineering and atelocollagen sheet implantation has been shown to be effective in vocal fold regeneration. However, many of the scaffold materials under investigation still await clinical translation and those that have been investigated in human patients (such as the atelocollagen sheet) require additional research in appropriately powered placebo-controlled studies.

Adipose-Derived Mesenchymal Stem Cells in Collagen—Hyaluronic Acid Gel Composite Scaffolds for Vocal Fold Regeneration

Objectives:

We sought to characterize the changes in the extracellular matrix (ECM) of the lamina propria following the implantation of autologous adipose-derived mesenchymal stem cells (ADSCs) in composite scaffolds in a rabbit vocal fold wound model.

Methods:

The ADSCs were co-cultured with collagen or hyaluronic acid gel. Each vocal fold was injured by localized resection and injected with ADSC complexes, ADSCs, or scaffolds or left untreated. From 15 days to 12 months, the vocal fold shape and the characteristics of the ECM components were analyzed.

Results:

With implantation of the ADSC complexes, the collagen content was significantly increased and had a disorderly distribution at 3 months. Subsequently, it began to decrease and reached close to normal by 12 months. The hyaluronic acid content was increased at 40 days, but it was reduced to normal levels and was limited to the superficial and middle layers of the lamina propria over the following 12 months. Fibronectin continued to be scattered in the lamina propria, at peak levels at 40 days, and then decreased over the following 12 months to reach near-normal levels. At 12 months, the vocal folds had a normal surface.

Conclusions:

ADSC complexes can play a facilitatory role in vocal fold regeneration, regulating the generation and orderly distribution of ECM.