Differentiation potential of the cells in the macula flava of the human vocal fold mucosa

Platelet Rich plasma injection of the vocal folds in benign vocal pathologies

PURPOSE

There are few options for treatment of dysphonia secondary to vocal pathology related to lamina propria scar, atrophy, sulcus, or inflammatory disorders. Platelet rich plasma (PRP) may provide anti-inflammatory and regenerative properties seen with other tissue engineering therapies without the risks associated with these treatments. We evaluated vocal fold (VF) injection of PRP for feasibility, phonatory effects, patient satisfaction and durability.

METHODS

Patients with dysphonia secondary to vocal fold scar, atrophy, sulcus and inflammatory lesions were included. PRP injections were administered in office, to bilateral vocal folds. Patients were followed up at 1 week, 1 month, 3 months and 6 months to assess outcomes (GRBAS scale, maximum phonation time, vocal fatigue index (VFI), voice handicap index (VHI-10) and stroboscopy).

RESULTS

75 intracordal PRP injections were administered to 48 patients. All injections were completed, and no adverse reactions were experienced. Improvements in VHI-10 scores at 1,3,6 months were seen (mean VHI 21.73 at baseline, 15.62 at six months, p < 0.001). 72.3% rated improvement at 7 or above on Likert scale. 95.7% of patients would consider a future PRP injection. Secondary outcomes VFI, MPT, and GRBAS also demonstrated significant improvements over time. Patients receiving a single PRP injection (n = 26) still demonstrated significant VHI-10 improvements at 1,3 and 6 months.

CONCLUSIONS

VF office PRP injections are feasible and safe and can provide phonatory benefit and reduce vocal effort in benign VF disorders. A single PRP injection is sufficient to provide sustained benefit in some cases.

LEVEL OF EVIDENCE

Level III: prospective cohort study.

Glycolytic Metabolism of the Tissue Stem Cells in the Maculae Flavae of the Human Vocal Fold

OBJECTIVES

Metabolic programs in the stem cells are essential for maintaining homeostasis and protecting against stem cell aging. There is growing evidence that the tissue stem cells reside in the anterior and posterior maculae flavae of the human vocal fold mucosa. Our previous studies observed that the glycolysis of the cell in the human maculae flavae seems to rely more on anaerobic glycolysis for energy supply in comparison with oxidative phosphorylation. However, previous studies showed only the metabolic enzymes of glycolysis and functional morphology of the mitochondria, therefore, it has not yet been determined whether anaerobic glycolysis actually took place. The purpose of this study is to investigate the glycolytic metabolites of the cells in the maculae flavae of the human vocal fold in vitro.

METHODS

Four normal human vocal folds were used. After extraction of the anterior maculae flavae, cells in the maculae flavae were cultured and proliferated. Glucose transporter-1 was assessed using immunocytochemistry and metabolites of glycolysis (lactate and NADPH) were measured.

RESULTS

The cells in the maculae flavae expressed glucose transporter-1 in the cytoplasm and the cell membranes. In addition, the cultured cells produced lactate (metabolites of anaerobic glycolysis) and NADPH (metabolites of the pentose phosphate pathway).

CONCLUSIONS

The cells in the maculae flavae of the human vocal folds were found to undergo anaerobic glycolysis via the pentose phosphate pathway. This suggests that the cells in the maculae flavae of the human vocal fold have a metabolism that favors the maintenance of stemness and undifferentiated states.

Metabolic Roles of Colony-Forming Tissue Stem Cells in the Maculae Flavae of Newborn Vocal Fold In Vivo

OBJECTIVES

Tissue stem cells in the maculae flavae (a stem cell niche) of the human vocal fold form colonies in vivo like stem cells in vitro. However, the roles of colony-forming aggregated cells in the maculae flavae in vivo have not yet been determined. This study investigated the glycolysis, of the colony-forming aggregated cells in the maculae flavae of the human newborn vocal fold in vivo.

METHODS

Three normal newborn vocal folds were investigated under light microscopy with immunohistochemistry and transmission electron microscopy.

RESULTS

Colony-forming aggregated cells in the newborn maculae flavae strongly expressed glucose transporter-1 and glycolytic enzymes (hexokinase II, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase A). The colony-forming aggregated cells did not express phosphofructokinase-1 (rate-limiting enzyme of regular glucose metabolism pathway) but expressed glucose-6-phosphate dehydrogenase (rate-limiting enzyme) indicating the cells relied more on the pentose phosphate pathway. The colony-forming aggregated cells' strong expression of lactate dehydrogenase A indicated that they rely more on anaerobic glycolysis in an anaerobic microenvironment. Mitochondrial cristae of the colony-forming aggregated cells in the newborn maculae flavae were sparse. Consequently, the microstructural features of the mitochondria suggested that their metabolic activity and oxidative phosphorylation were low.

CONCLUSIONS

The colony-forming aggregated cells in the maculae flavae of the newborn vocal fold seemed to rely more on anaerobic glycolysis using the pentose phosphate pathway for energy supply in vivo. Microstructural features of the mitochondria and the glycolytic enzyme expression of the colony-forming aggregated cells suggested that the oxidative phosphorylation activity was low. Already at birth, in the anaerobic microenvironment of the macular flavae in vivo, there is likely a complex cross-talk regarding metabolism between the colony-forming aggregated cells along the adhesion machinery and chemical signaling pathways which reduces toxic oxygen species and is favorable to maintaining the stemness and undifferentiated states of the tissue stem cells.

Vascularity in the macula flava of human vocal fold as a stem cell niche

OBJECTIVES

There is growing evidence that the maculae flavae of the human vocal fold are a stem cell niche, which is a microenvironment nurturing tissue stem cells. This study investigated the microenvironment, especially vascularity, in the maculae flavae of the human vocal fold.

METHODS

Three normal human adult, three normal newborn vocal folds obtained from autopsy cases and three surgical specimens of glottic carcinoma were investigated using light and electron microscopy. For scanning electron microscopy, a chemical digestion method (modified sodium hydroxide maceration method) was used to observe the inner 3-dimensional structure of the macula flava.

RESULTS

Capillaries ran around the anterior and posterior maculae flavae in adults and newborns. However, there was no vascularity in the maculae flavae of the vocal fold. The inner 3-dimensional electron microscopic structure of the macula flava showed there were no blood vessels in the maculae flavae of the vocal fold. Glottic carcinoma (squamous cell carcinoma) surrounded and was in contact with the macula flava, however, the carcinoma did not invade the macula flava indicating there was no vascular supply into the macula flava from the surrounding tissue.

CONCLUSIONS

There was no vascularity in the anterior and posterior maculae flavae in the human adult and newborn vocal folds. The present study is consistent with the hypothesis that the hypoxic microenvironment in the maculae flavae of the adult and newborn vocal fold as a stem cell niche is likely favorable to maintaining the stemness and undifferentiated states of the tissue stem cells in the stem cell system.

Three-dimensional fine structures of the maculae flavae of the human vocal fold using correlative light and electron microscopy

Objectives

To analyze various aspects of complex tissue, there is increasing demand to study each sample at different length scales in biology. Correlative light and electron microscopy (CLEM) is the latest technique to correlate two different types of information on the exact same histological area of interest: histology (from light microscopy) and ultrastructure (from electron microscopy). The three-dimensional fine structures of the maculae flavae (MFe) of the human vocal fold were investigated using CLEM.

Methods

Five normal human adult vocal folds as specimens embedded in paraffin, sectioned, and mounted on glass slides with/without a chemical digestion method (modified sodium hydroxide maceration method) were investigated. Observations using CLEM were performed.

Results

The fine structures of cells and extracellular matrices in the MFe and their peripheral regions were able to be observed on the exact same histological area of interest with the light microscope and field emission-scanning electron microscope. Cobblestone-like polygonal cells, vocal fold stellate cell-like cells, and fibroblast-like spindle cells were intermingled in the MFe of the human vocal fold. The extracellular matrices surrounding each three types of cell in the MFe differed, suggesting the cells were different in functional property.

Conclusion

CLEM is a useful technique to observe the three-dimensional fine structures of the human vocal fold mucosa. The results of the present study are consistent with the hypothesis that the cells in the MFe of the human vocal fold have heterogeneity and each three types of cell have different properties.

Epstein-Barr virus-associated leiomyosarcoma of the larynx in an adult patient with human immunodeficiency virus infection: Case report and review of the literature

We investigated the clinical features, treatment, and prognosis of laryngeal leiomyosarcoma (LLMS) and Epstein-Barr virus-associated (EBV-associated) LMS. We report a case of EBV-associated LLMS in an adult patient with HIV infection. We also conducted a review of the English-language literature on LLMS and EBV-associated leiomyosarcoma. To the best of our knowledge, 62 cases of LLMS and EBV-associated leiomyosarcoma have been reported to date. Of patients with LLS, 18.9% had distant metastases and 17.0% had local recurrence. The overall 5-year survival rate was 64.0%. Distant metastases affected the survival of patients with LLMS (p = 0.04). EBV-positive patients had a low survival rate (p = 0.01). Among patients with EBV-associated LMS, 8.2% had distant metastases and recurrence and the overall 5-year survival rate was 50.0%. EBV-associated LLMS is rare. The EBV infection might be a poor prognostic factor of LLMS.

Glycolysis of Tissue Stem Cells in the Macula Flava of Newborn Vocal Fold

OBJECTIVES

There is growing evidence that the cells in the maculae flavae are tissue stem cells and the maculae flavae are a stem cell niche of the human vocal fold mucosa. This study investigated the metabolic activity, especially glycolysis, of the tissue stem cells in the maculae flavae of the human newborn vocal fold.

METHODS

Three normal human newborn vocal folds obtained from autopsy cases were investigated using immunohistochemistry.

RESULTS

Among the three phenotypes of cells (cobblestone-like polygonal cells, vocal fold stellate cell-like cells and fibroblast-like spindle cells) in the newborn maculae flavae, a small number of cobblestone-like polygonal cells strongly expressed glucose transporter-1. All three phenotypes of cells in the newborn maculae flavae expressed glycolytic enzymes (hexokinase II, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase A). The cells did not express phosphofructokinase-1 (rate-limiting enzyme of regular glucose metabolism pathway) but sparsely express glucose-6-phosphate dehydrogenase (rate-limiting enzyme) indicating the cells relied more on the pentose phosphate pathway. The cells' expression of lactate dehydrogenase A suggests the maculae flavae of the newborn vocal fold is likely to be an anaerobic microenvironment where cells perform anaerobic glycolysis.

CONCLUSIONS

The present study is consistent with the hypothesis that the tissue stem cells in the maculae flavae of the newborn vocal fold seem to rely more on anaerobic glycolysis, especially by the pentose phosphate pathway, for energy supply. Already at birth, the metabolism of the tissue stem cells in the maculae flavae of the newborn vocal fold is likely to prevent the formation of toxic reactive oxygen species and is likely favorable to maintaining the stemness and undifferentiated states of the tissue stem cells in the stem cell system.

Current approaches to management of vocal fold scar

PURPOSE OF REVIEW

Vocal fold (VF) fibrosis remains an insoluble problem in most cases, with a severe impact on vocal quality and effort. This review examines current investigations and research strands that explore the understanding of VF wound healing and applied treatments for the management of VF scar.

RECENT FINDINGS

Recent work focused on VF fibrosis has examined wound healing in the glottis, fibrosis-modifying medication, and tissue engineering approaches that span cytokine and growth factor therapy, scaffold and cell delivery platforms, seeded scaffolds, conditioned media and stem cell therapy. Many show promise and may deliver improvements in the wound bed favouring less fibrogenic healing patterns, ultimately with the goal of preserving or restoring VF vibration. Further collaborative research is required that examines combined approaches, long term outcomes, better three-dimensional modelling of cell-cell interactions and delivery modalities for molecular therapies.

SUMMARY

VF fibrosis research continues to expand and explore a variety of mechanistic pathways in order to understand VF healing and identify novel and complementary targets for manipulation. Many different approaches show promise and may also offer synergistic benefits. Research continues to strive for healing that more closely resembles true VF architecture and function.

Energy metabolism of cells in the macula flava of the newborn vocal fold from the aspect of mitochondrial microstructure

OBJECTIVE

Cells in the vocal fold of maculae flavae are likely to be tissue stem cells. Energy metabolism of the cells in newborn maculae flavae was investigated from the aspect of mitochondrial microstructure.

METHOD

Five normal newborn vocal folds were investigated under transmission electron microscopy.

RESULTS

Mitochondria consisted of a double membrane bounded body containing matrices and a system of cristae. However, these membranes were ambiguous. In each mitochondrion, the lamellar cristae were sparse. Intercristal space was occupied by a mitochondrial matrix. Some mitochondria had fused to lipid droplets and rough endoplasmic reticulum, and both the mitochondrial outer and inner membranes had incarcerated and disappeared.

CONCLUSION

The features of the mitochondria of the cells in the newborn maculae flavae showed that their metabolic activity and oxidative phosphorylation were low. The metabolism of the cells in the newborn maculae flavae seems to be favourable to maintain the stemness and undifferentiation of the cells.

Distribution of Label-Retaining Cells and their Properties in the Newborn Vocal Fold Mucosa

OBJECTIVES

There is growing evidence that the cells in the maculae flavae (MFe) are candidates for tissue stem cells of the vocal fold mucosa and the MFe are a stem cell niche. Distribution of label-retaining cells and their properties in the postnatal vocal fold mucosa were investigated.

METHODS

Oral administration of bromodeoxyuridine (BrdU) was given to pregnant Sprague-Dawley rats and the label-retaining cells in the postnatal vocal fold mucosa were observed by immunohistochemistry. Immunoreactivity to antibodies directed to Ki-67 was studied to investigate the cell cycle.

RESULTS

At day 1 after birth, BrdU positive cells were identified in the MFe (60.1 ± 1.7%), epithelium (58.7 ± 10.6%) and lamina propria (52.4 ± 7.8%) of the vocal fold mucosa. At day 56 after birth, the number of BrdU positive cells in the epithelium (4.8 ± 2.2%) and lamina propria (32.3 ± 16.5%) were significantly lower compared to day 1 after birth (P < 0.05). However, the number of BrdU positive cells remaining in the MFe was still high (56.2 ± 2.5%). The label-retaining cells were distributed throughout the MFe. Few Ki-67 positive cells were identified in the MFe indicating they were resting cells.

CONCLUSIONS

The results of this study are consistent with the hypothesis that the cells in the postnatal MFe are candidates for tissue stem cells. At birth, these cells are already present in the MFe of the newborn vocal fold and they are likely ready to start the growth and development of the vocal fold mucosa.

Role of colony-forming tissue stem cells in the macula flava of the human vocal fold in vivo

OBJECTIVES

Our previous investigations showed that tissue stem cells in the maculae flavae (a stem cell niche) form colonies in vivo like stem cells in vitro. However, the roles of colony-forming cells in the maculae flavae in vivo have not yet been determined.This study investigated the metabolism of the colony-forming tissue stem cells in the maculae flavae of the human adult vocal fold.

STUDY DESIGN

Histologic analysis of the human vocal folds.

METHODS

Three normal human adult vocal folds were investigated under transmission electron microscopy and light microscopy including immunohistochemistry.

RESULTS

Mitochondrial cristae of the colony-forming cells in the maculae flavae were sparse. Hence, the microstructural features of the mitochondria suggested that their metabolic activity and oxidative phosphorylation were low. Colony-forming cells strongly expressed glucose transporter-1 and glycolytic enzymes (hexokinase II, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase A). The colony-forming cells did not express phosphofructokinase-1 but did express glucose-6-phosphate dehydrogenase indicating the cells relied more on the pentose phosphate pathway. Since the colony-forming cells expressed lactate dehydrogenase A, cells seemed to rely more on anaerobic glycolysis in an anaerobic microenvironment.

CONCLUSIONS

The present study is consistent with the hypothesis that the colony-forming tissue stem cells in the maculae flavae of the human adult vocal fold seemed to rely more on anaerobic glycolysis using the pentose phosphate pathway for energy supply in vivo. Microstructural features of the mitochondria and expressed glycolytic enzymes of the colony-forming cells in the maculae flavae suggested that the oxidative phosphorylation activity was low.In an anaerobic microenvironment in vivo, there is likely a complex cross-talk regarding the metabolism between the colony-forming aggregated cells along the adhesion machinery and chemical signaling pathways, which reduces toxic oxygen species and is favorable to maintaining the stemness and undifferentiated states of the tissue stem cells.

LEVEL OF EVIDENCE

NA.

Glycolytic activity of the tissue stem cells in the macula flava of the human vocal fold

OBJECTIVES

In our previous studies, the features of the mitochondria of tissue stem cells in the maculae flavae of the human vocal fold suggested that their metabolic activity and oxidative phosphorylation was low. This study investigated the metabolic activity, especially glycolysis of the tissue stem cells in the maculae flavae of the human adult vocal fold.

STUDY DESIGN

Histologic analysis of the human vocal folds.

METHODS

Three normal human adult vocal folds obtained from autopsy cases were investigated using immunohistochemistry.

RESULTS

Among the three phenotypes of cells in the human adult maculae flavae, the vocal fold stellate cell-like cells strongly expressed glucose transporter-1. Three phenotypes of cells in the human adult maculae flavae expressed glycolytic enzymes (hexokinase II, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase A) indicating the tissue stem cells in the maculae flavae relied more on glycolysis. The cells did not express phosphofructokinase-1 but did express glucose-6-phosphate dehydrogenase indicating the cells relied more on the pentose phosphate pathway. The cells expressed lactate dehydrogenase A indicating the maculae flavae of the human adult vocal fold was likely to be an anaerobic microenvironment.

CONCLUSIONS

The present study is consistent with the hypothesis that the tissue stem cells in the maculae flavae of the human vocal fold seem to rely more on anaerobic glycolysis, especially by the pentose phosphate pathway, for energy supply. The metabolism of the tissue stem cells in the maculae flavae of the human adult vocal fold is likely to prevent toxic reaction oxygen species and be favorable to maintaining the stemness and undifferentiated states of the tissue stem cells in the stem cells system.

LEVEL OF EVIDENCE

NA.

Heterogeneity and hierarchy of the tissue stem cells in the human newborn vocal fold mucosa

OBJECTIVES

There is growing evidence that the cells in the maculae flavae (MFe) are tissue stem cells and the MFe are a stem cell niche of the human vocal fold mucosa. Heterogeneity and hierarchy of tissue stem cells in the MFe of newborn vocal fold were investigated in vivo.

STUDY DESIGN

Histologic analysis of the human vocal folds.

METHODS

Five normal human newborn vocal folds were investigated under transmission electron microscopy and light microscopy.

RESULTS

Cobblestone-like polygonal cells, vocal fold stellate cell-like cells, and fibroblast-like spindle cells were intermingled in the newborn MFe in vivo, indicating that the cells in the MFe had heterogeneity. However, cobblestone-like polygonal cells were predominant. Free ribosomes were well developed in the cytoplasm. The cells in some cases formed gap junctions with each other. The cells in some cases were attached to other cells and formed cell junctions with each other. These findings indicated cells in the newborn maculae flavae possessed features of mesenchymal cells (cells in mesenchyme). Colony-forming-unit-like cell aggregate was observed, indicating the cells in the newborn MFe had stemness. The cobblestone-like polygonal cells expressed SSEA-3 (a human pluripotent stem cell marker), indicating they were at the top of a cellular hierarchy in the stem cell system.

CONCLUSIONS

The cells in the MFe of the human newborn vocal fold mucosa had heterogeneity and hierarchy in the stem cell system in vivo. At birth, newborn maculae flavae are ready to start the growth of the vocal fold mucosa as a vibrating tissue.

Cytoskeleton of cells in vocal fold macula flava unphonated for a long period

Cells in the maculae flavae (MFe) are inferred to be involved in the metabolism of extracellular matrices of the human vocal fold mucosa. The latest research has supported the hypothesis that the tension caused by phonation (vocal fold vibration) regulates the behavior of these cells in the MFe of the human vocal fold. Tensile and compressive strains have direct effects on cell morphology and structure including changes in cytoskeletal structure and organization. Cytoskeletons are one of the structures which play a role as mechanoreceptors for the cells. The microstructure of the intermediate filaments and the expression of their proteins were investigated regarding the cells in the MFe of the human vocal fold unphonated over a decade. The adult vocal fold mucosa of a 64-year-old male with cerebral hemorrhage unphonated for 11 years was investigated by immunohistochemistry and electron microscopy. The intermediate filaments in the cytoplasm of the cells had become fewer in number. And the expression of their characteristic proteins (vimentin, desmin, GFAP) was also reduced. The results of this study are consistent with the hypothesis that mechanotransduction caused by vocal fold vibration could possibly be a factor in regulating the function and fate of the cells in the MFe.

Metabolic activity of cells in the macula flava of the human vocal fold from the aspect of mitochondrial microstructure

OBJECTIVES

There is growing evidence to suggest that the cells in the maculae flavae of the vocal fold mucosa are tissue stem cells of the human vocal fold. This study investigated the metabolic activity of the cells in the maculae flavae of the human vocal fold from the aspect of mitochondrial microstructure.

STUDY DESIGN

Histologic analysis of the human vocal folds.

METHODS

Five normal human adult vocal folds obtained from autopsy cases were investigated under transmission electron microscopy.

RESULTS

Mitochondria were randomly distributed in the cytoplasm of the cells. The morphological features of the mitochondria consisted of a double-membrane-bounded body containing matrices and a system of cristae. In each mitochondria, the lamellar cristae were sparse. The intercristal space was occupied by a mitochondrial matrix which contained electron-dense matrix granules, mitochondrial DNA, and ribonucleoprotein granules. Some mitochondria spread out over or fused to the surface of a lipid droplet in the cytoplasm. In addition, both the mitochondrial outer and inner membranes and the membranes of the lipid droplets had disappeared. Some close association between mitochondria and rough endoplasmic reticulum was present.

CONCLUSIONS

The features of the mitochondria of the cells in the maculae flavae of the human vocal fold suggested that their metabolic activity and oxidative phosphorylation were low and that they may have shifted to the utilization of lipids to some extent for their metabolic needs.

LEVEL OF EVIDENCE

NA.