Extracellular secretion of Escherichia coli alkaline phosphatase with a C-terminal tag by type I secretion system: purification and biochemical characterization

Type I secretion system (TISS) of Gram-negative bacteria permits proteins to be secreted directly from the cytoplasm to the external medium by a single, energy-coupled step. To examine whether this system can be used as an extracellular production system of recombinant proteins, Escherichia coli alkaline phosphatase (AP) was fused to a C-terminal region of Pseudomonas sp. MIS38 lipase (PML) and examined for secretion using the E.coli cells carrying the heterologous TISS. PML is one of the passenger proteins of TISS and contains 12 repetitive sequences and a secretion signal at the C-terminal region. The fusion protein was efficiently secreted to the extracellular medium, while AP was not secreted at all, indicating that the secretion of AP is promoted by a secretion signal of PML. The repetitive sequences were not so important for secretion of the fusion protein, because the secretion level of the fusion protein containing entire repeats ( approximately 10 mg/l culture) was only 2-fold higher than that of the fusion protein without repeats. The fusion protein purified from the culture supernatant existed as a homodimer, like AP, and was indistinguishable from AP in enzymatic properties and stability.

Multipotent progenitor cells isolated from adult human pancreatic tissue

The supply of islet cells is a limiting factor for the widespread application of islet transplantation of type-1 diabetes. Islets constitute 1% to 2% of pancreatic tissue, leaving approximately 98% as discard after islet isolation and purification. In this report we present our data on the isolation of multipotent progenitor cells from discarded adult human pancreatic tissue. The collected cells from discarded nonislet fractions, after enzymatic digestion and gradient purification of islets, were dissociated for suspension culture in a serum-free medium. The cell clusters grown to a size of 100 to 150 mum contained cells staining for stage-specific embryonic antigens, but not insulin or C-peptide. To direct cell differentiation toward islets, clusters were recultured in a pancreatic differentiation medium. Insulin and C-peptide-positive cells by immunocytochemistry appeared within a week, reaching over 10% of the cell population. Glucagon and somatostatin-positive cells were also detected. The cell clusters were found to secrete insulin in response to glucose stimulation. Cells from the same clusters also had the capacity for differentiation into neural cells, as documented by staining for neural and glial cell markers when cultured as monolayers in media containing neurotrophic factors. These data suggest that multipotent pancreatic progenitor cells exist within the human pancreatic tissue that is typically discarded during islet isolation procedures. These adult progenitor cells can be successfully differentiated into insulin-producing cells, and thus they have the potential for treatment of type-1 diabetes mellitus.

Destiny of autologous bone marrow-derived stromal cells implanted in the vocal fold

OBJECTIVES

The aim of this study was to investigate the destiny of implanted autologous bone marrow-derived stromal cells (BSCs) containing mesenchymal stem cells. We previously reported the successful regeneration of an injured vocal fold through implantation of BSCs in a canine model. However, the fate of the implanted BSCs was not examined. In this study, implanted BSCs were traced in order to determine the type of tissues resulting at the injected site of the vocal fold.

METHODS

After harvest of bone marrow from the femurs of green fluorescent transgenic mice, adherent cells were cultured and selectively amplified. By means of a fluorescence-activated cell sorter, it was confirmed that some cells were strongly positive for mesenchymal stem cell markers, including CD29, CD44, CD49e, and Sca-1. These cells were then injected into the injured vocal fold of a nude rat. Immunohistologic examination of the resected vocal folds was performed 8 weeks after treatment.

RESULTS

The implanted cells were alive in the host tissues and showed positive expression for keratin and desmin, markers for epithelial tissue and muscle, respectively. The implanted BSCs differentiated into more than one tissue type in vivo.

CONCLUSIONS

Cell-based tissue engineering using BSCs may improve the quality of the healing process in vocal fold injuries.

Morphological and histologic examination of the epiglottis: implications for improving epiglottic closure technique

OBJECTIVES

We conducted a histologic examination and measured the tension on the epiglottis to determine how dehiscence of the epiglottis can be prevented after epiglottic closure surgery.

METHODS

We classified configurations of the epiglottis into flat, intermediate, and omega types and studied the histology of each type. We also measured the tension in each of these 3 morphological types on 4 regions of the epiglottis (upper, middle, and lower points, and the cuneiform tubercle) at 3 different times: before incision, after median incision, and after reversed-Y incision.

RESULTS

No histologic differences were evident among the epiglottic types. In the flat and intermediate types, the tension measured before incision decreased significantly upon completion of the median incision at every point. In these 2 types, the reversed-Y incision resulted in a further significant decrease in tension at the middle and lower points. In the omega type, the tension was low before incision and was not significantly reduced by either incision.

CONCLUSIONS

We demonstrated that a median incision alone effectively decreased tension sufficiently to prevent dehiscence. The reversed-Y incision was even more effective for decreasing tension at the middle and lower points.

Cranial Bone Regeneration Using a Composite Scaffold of Beta-Tricalcium Phosphate, Collagen, and Autologous Bone Fragments

OBJECTIVE

The aim of our study was to examine the tissue response and new bone formation induced by beta-tricalcium phosphate (beta-TCP), collagen, and autologous bone fragments with fibrin glue implanted into a cranial bone defect.

MATERIALS AND METHODS

Granulated beta-TCP and collagen from porcine skin were mixed and freeze-dried. The weight ratio of both materials was 98:2. The composite scaffold for bone regeneration was composed of this artificial material and autologous bone fragments. Five adult beagle dogs were used. A cranial bone defect (2 cmx2 cm) was created in each dog. The animals were divided into two groups. In group 1 (n=3), the cranial bone defect was closed by replacing the original free bone flap, and the residual fissure and burr holes were filled with the composite scaffold with fibrin glue. In group 2 (n=2), the bone defect was closed only by replacing the original free bone flap. Three months after the treatment, computed tomography and histologic examinations were done in all animals.

RESULTS

In all dogs in group 1, the defects were almost closed by new bone; whereas in group 2, the defects were filled with fibrous tissues instead of bone.

CONCLUSION

This study showed that the composite scaffold made of beta-TCP, collagen, and autologous bone fragments with fibrin glue enabled reconstruction of cranial bone defects without the usual fixation materials.

Increased expression of cyclooxygenase-2 in human pancreatic islets treated with high glucose or ligands of the advanced glycation endproduct-specific receptor (AGER), and in islets from diabetic mice

AIMS/HYPOTHESIS

The cyclooxygenase-2 (PTGS2, previously known as COX2) enzyme and its products, such as prostaglandin E(2) (PGE(2)), have been implicated in the pathogenesis of several inflammatory diseases including islet dysfunction under diabetic conditions. In this study we evaluated whether diabetic conditions in vitro, such as high-glucose (HG) culture or AGE, or in vivo in animal models of diabetes can induce PTGS2 expression and activity in pancreatic islets.

MATERIALS AND METHODS

Isolated human pancreatic islets were treated for 24 h with HG (25 mmol/l) or with S100b (5 mg/l), a specific ligand for the AGE-specific receptor. PTGS2 and cyclooxygenase-1 (PTGS1, previously known as COX1) mRNA, protein expression and product PGE(2) were analysed by RT-PCR, Western blots and specific enzyme immunoassay respectively. Islet PTGS2 production in animal models was assessed by immunofluorescence.

RESULTS

Treatment of human pancreatic islets with HG and S100b led to a three-five-fold induction of PTGS2 mRNA (p<0.001). PTGS2 protein and its product PGE(2) (351.4+/-13.05 fg/ml vs control 39.4+/-0.11 fg/ml) were also increased (p<0.001). Pretreatment with specific inhibitors demonstrated the involvement of protein kinase C and oxidant stress in S100b- and HG-induced PTGS2 expression. However, insulin secretion was not significantly altered by S100b. Double immunofluorescent staining showed increased PTGS2 production in pancreatic islets from diabetic mice relative to corresponding controls.

CONCLUSION/INTERPRETATION

These results show for the first time that diabetes as well as diabetic conditions such as AGE and HG in vitro can directly upregulate the expression of the inflammatory PTGS2 gene in pancreatic islets. This might contribute to the pathogenesis of islet dysfunction in diabetes.

Maxacalcitol therapy decreases circulating osteoprotegerin levels in dialysis patients with secondary hyperparathyroidism

BACKGROUND

Osteoprotegerin is a natural glycoprotein which plays a critical role in osteoclast physiology. Elevated levels of circulating osteoprotegerin may account for the development of bone and mineral metabolic abnormalities in uremia. Little is known about the effects of vitamin D therapy on the circulating osteoprotegerin levels in dialysis patients.

PATIENTS AND METHODS

Fifty chronic dialysis patients whose plasma intact PTH levels were greater than 300 pg/ml were analyzed for the study. Following a four-week washout time during which all vitamin D administration was halted, 10 microg of maxacalcitol was intravenously injected thrice a week.

RESULTS

The circulating intact PTH, bone-specific alkaline phosphatase and intact osteocalcin levels were significantly lowered, while the serum calcium levels were elevated after the therapy. The osteoprotegerin levels significantly decreased after the therapy (p < 0.0001).

CONCLUSION

Maxacalcitol therapy reduced the circulating osteoprotegerin levels and improved secondary hyperparathyroidism. The observed effects were the opposite of those expected from previous in vitro studies. Osteoprotegerin may mediate and/or modify the effect of active vitamin D therapy in dialysis patients.

Isolation and analysis of lipase-overproducing mutants of Serratia marcescens

We have isolated a lipase-overproducing mutant, GE14, from Serratia marcescens 8000 after three rounds of N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. The mutant GE14 produced 95 kU/ml of extracellular lipase in the lipase medium, which was about threefold higher than that of produced by the original strain 8000. Enzymatic characteristics including specific activity of purified lipases from culture supernatants of GE14 and 8000 were almost same. The lipase gene (lipA) of GE14 contained two base substitutions; one in the promoter region and another in the N-terminal region of the lipA gene without an amino acid substitution. Promoter analysis using lipA-lacZ fusion plasmids revealed that these substitutions were responsible for the increase in the lipA expression level, independently. In contrast, no base substitution was found in the genes encoding the lipase secretion device, the Lip system. In addition, the genes coding for metalloprotease and the cell surface layer protein which are both secreted through the Lip system and associated with extracellular lipase production, also contained no base substitution. The strain GE14 carrying a high-copy-number lipA plasmid produced a larger amount of the extracellular lipase than the recombinant strains of 8000 and other mutants also did, indicating that GE14 was not only a lipase-overproducing strain, but also an advantageous host strain for overproducing the lipase by a recombinant DNA technique. These results suggest that the lipase-overproducing mutant GE14 and its recombinant strains are promising candidates for the industrial production of the S. marcescens lipase.

Inhibition of p38 Mitogen-Activated Protein Kinase Protects Human Islets From Cryoinjury and Improves the Yield, Viability, and Quality of Frozen-Thawed Islets

The development of an optimal islet cryopreservation method will permit transplantation of islets from multiple donors in a single procedure and contribute to alleviation of the islet shortage. In this study, we have improved human islet cryopreservation methods under serum-free conditions using an intracellular-based islet cryopreservation solution (ICS), especially supplemented with a p38 pathway inhibitor (p38IH) to suppress p38 mitogen-activated protein kinase (MAPK) activation. Three different solutions were compared for freezing and thawing of human islets (1) conventional RPMI1640 medium, (2) ICS, and (3) ICS supplemented with a p38IH, SD-282 (ICS-p38IH). Islet cryopreservation with ICS-p38IH significantly improved islet recovery, viability, and quality after thawing of cryopreserved islets. This improvement may allow the use of cryopreserved islets in clinical islet transplantation.

Schwannoma of the nasal septum removed with endoscopic surgery

A 50-year-old woman presented with a 30-year history of nasal obstruction. She had been treated for paranasal sinusitis at other hospitals and she was referred to our hospital for further examination. Flexible endoscopy revealed a mass in the posterior aspect of the right nasal cavity to the posterior aspect of the left nasal cavity around the posterior edge of the nasal septum.

Hyperfractionated radiotherapy for T2 glottic cancer for preservation of the larynx

To evaluate the effectiveness of hyperfractionation for T2 glottic cancer from a viewpoint of laryngeal preservation, we analyzed 21 patients (twice-a-day group) who were treated with hyperfractionation between 1992 and 1998 and compared the results with those of 27 patients (once-a-day group) treated with conventional once-a-day radiation between 1987 and 1992. In the twice-a-day group, radiation was performed with two fractions of 1.2 Gy/day up to a total dose of 72-74.4 Gy. In the once-a-day group, radiation was performed with a fraction of 2 Gy/day up to a total dose of 66 Gy. If radiation was ineffective at 40 Gy, it was stopped, and surgical treatment was carried out. Kaplan-Meier estimates were used for the analysis of the survival rate and laryngeal preservation rate, and the results were compared. In the once-a-day group, the 5-year survival rate was 92.3%. The 5-year laryngeal preservation rate was 51.8%, and it was 60.3% in 20 patients who had undergone full-dose radiation (once-a-day full-dose group). In the twice-a-day group, no major complication, such as laryngeal necrosis, was seen in any case, and the 5-year survival rate was 95.3%. The 5-year laryngeal preservation rate was 95.3%, and it was significantly better than that of both the once-a-day group and the once-a-day full-dose group. Hyperfractionation is considered to be useful for preserving the larynx for the treatment of T2 glottic cancer.

Successful laser ablation of diffuse laryngeal swelling in posttransplant lymphoproliferative disorder: the Japanese first case

Posttransplant lymphoproliferative disorder (PTLD) is a well-known complication of pediatric organ transplantation. The first symptoms are often in the ear, nose, or throat (ENT) area. We report the first Japanese case of an airway obstruction in PTLD. A 7-year-old boy who had a liver transplant at the age of 2 years presented with progressive stridor. Fiberoptic examination revealed enlarged epiglottis and swelling arytenoids. Highly suspicious of early-PTLD, he was treated with reduction of immunosuppression, but no improvement on his larynx was observed. Laser ablation of swelling arytenoids worked. Surgical debulking is effective to ease an airway obstruction in cases of PTLD.

Impact of sentinel node navigation technique for carcinoma of tongue with cervical node metastases

We attempted lymph node mapping for clinically positive neck using sentinel node navigation technique. Technetium labeled rhenium sulfide was injected as a radiotracer in 11 patients with squamous cell carcinoma of the tongue. After surgery, the radioactivity and the ratio of metastatic area (RMA) of the removed nodes were measured. Average RMA (57%) of 18 high radioactive metastatic nodes was significantly lower than the RMA (90%) of 16 low radioactive metastatic nodes. Average number of metastatic nodes (4.7 nodes) in the five cases with low radioactive metastatic nodes was significantly larger than that (1.8 nodes) in the six cases with only high radioactive metastatic nodes. There is no accumulation of radioactive tracer if a lymph node is totally or predominantly occupied by metastatic cells. When the sentinel node was mostly occupied by malignant cells, the injected colloid could not flow to the sentinel node and flowed to a different lymph node through another basin. Sentinel node navigation technique can show the actual time of lymphatic flow at the operation of positive neck cases.

Regeneration of Mastoid Air Cells in Clinical Applications by In Situ Tissue Engineering

OBJECTIVES

To regenerate of the mastoid air cells and their functions for the treatment of incurable otitis media.

MATERIALS AND METHOD

In situ tissue-engineered mastoid air cells using three-dimensional hydroxy apatite (3D-HA) of honeycomb-like structure were used as artificial pneumatic bones. This 3D-HA is made of calcium phosphate and has a high ratio of micropores, 90%. Its surface is coated with collagen. Ten patients (4 males, 6 females) for this clinical study were randomly selected among the patients with severe cholesteatoma, adhesive otitis media, and purulent chronic otitis media, and they were to be received a staged operation. At the first stage of tympanoplasty, collagen-coated 3D-HA was put into the newly opened mastoid cavity, and it was fixed by fibrin glue. Recovery of mastoid aeration and regeneration of the pneumatic air cells of the mastoid cavity were estimated by images of high-resolution computed tomography (HRCT) after the first operation. At the second stage of operation, histopathologic examinations of specimens of HA taken from the reopened mastoid cavity were performed.

RESULTS

Aerations in the mastoid cavity were observed in 9 of the 10 patients within 12 months after the second operation. Moreover, the pneumatic structure in the mastoid cavity was partially regenerated in five patients. In these successful cases, mucosa with newly formed capillaries was observed on the surface of the implanted HA at the second stage of operation. In the failure cases, however, connective tissues and granulations invaded the space of the 3D-HA. They were observed as soft-tissue density areas in the HRCT scan images.

CONCLUSIONS

This study indicates that mucosa can grow on the surface of implanted artificial 3D-HA and can have a gas exchange function in the newly opened mastoid cavity. These tissue-engineered mastoid air cells may be a possible treatment for intractable otitis media.

Expression of calretinin by fetal otocyst cells after transplantation into damaged rat utricle explants

Severe damage by acoustic overstimulation or ototoxins induces inner ear hair cell loss, resulting in permanent hearing loss and balance disorders because hair cell regeneration scarcely occurs in the inner ear sensory organs of mammals. In this study, to evaluate the possibilities of cell transplantation therapy for damaged inner ear sensory organs, dissociated cell cultures of fetal otocyst cells (FOCs) were established from embryonic day 12.5 (E12.5) rat inner ears, and transplanted into gentamicin-treated explants of vestibular sensory epithelia. Two weeks after transplantation, immunohistochemical analysis demonstrated that some of the grafted FOCs survived within the vestibular sensory epithelia and expressed epitopes of calretinin. one of the hair cell marker proteins. These findings indicate that FOCs have the potential to migrate into damaged vestibular epithelia and differentiate into hair cell immunophenotypes. Cell transplantation therapy may be available for functional regeneration in inner ear diseases.

Surgical techniques for cell transplantation into the mouse cochlea

This study investigated surgical procedures for cell transplantation into the mouse inner ear. Female C57BL/6 mice were used as recipient animals. Fetal mouse neural stem cells expressing green fluorescence were used as donor cells. Two methods, an injection of transplants from the lateral semicircular canal (LSCC) and from the cochlear lateral wall (CLW), were examined. Two weeks after transplantation, the distribution of transplant-derived cells in the cochlea was examined. Effects on auditory function were assessed by measurement of auditory brain stem responses (ABRs). Cochleae receiving cell transplantation from the LSCC exhibited robust survival of transplant-derived cells mainly in the scala vestibuli and scala tympani. Transplantation from the LSCC caused elevation of ABR thresholds by less than 10 dB SPL. However, transplantation from the CLW resulted in considerable hearing loss, even though transplant-derived cells settled in the scala media. These findings demonstrate that an approach from the LSCC can be utilized for cell transplantation into the perilymph without causing apparent auditory disorder, while an approach from the CLW delivers cells to the endolymph but appears to cause auditory dysfunction.

Transplantation of neural stem cells into the modiolus of mouse cochleae injured by cisplatin

This study aimed to examine the possibility of restoration of spiral ganglion neurons, which transmit sound stimulation to the brain, by transplantation of fetal neural stem cells (NSCs) into the modiolus of cochleae. Fetal mouse NSCs expressing green fluorescence were injected into the modiolus of cisplatin-treated cochleae of mice. The temporal bones were collected 14 days after transplantation, and provided histological examination. The cell fate of transplants was determined by immunohistochemistry for a neural or glial cell-marker. Histological analysis 2 weeks after transplantation revealed robust survival of transplant-derived cells in the modiolus of the cochlea. NSCs injected in the basal portion of cochleae migrated as far as the apical end of the modiolus Grafted NSCs expressing a neural cell marker were identified, but the majority of grafted NSCs differentiated into glial cells. These findings suggest the possible use of NSCs in cell therapy for restoration of spiral ganglion neurons. However, further treatments are required to increase the number of NSC-derived neurons in the modiolus to realize functional recovery.

Regeneration of mastoid air cells: clinical applications

The objective of this study was to establish a method for regenerating mastoid air cells and their functions for clinical use in incurable otitis media. For this clinical study three patients (one male, two female) were randomly selected from patients with severe cholesteatoma about to undergo staged operations. Hydroxy-apatite in three-dimensional, honeycomb-like structures (3D-HA) were used as artificial pneumatic bones. This 3D-HA is made of calcium phosphate and has a high percentage of micropores (90%). Its surface is coated with collagen. At the first stage of tympanoplasty, collagen-coated 3D-HA was put into the opened mastoid cavity and fixed by fibrin glue. Recovery of mastoid aeration and regeneration of the pneumatic air cells of the mastoid cavity were estimated on CT scan images after the first operation. Aeration was recovered in all cases. The mastoid air cells were regenerated in two cases. In the failed case, subcutaneous connective tissues and granulations invaded into the spaces of the 3D-HA. This study demonstrated that mucosa would grow on the surface of a 3D-HA implant and could provide gas exchange functions in the newly opened mastoid cavity. This tissue engineering method may be a possible treatment for intractable otitis media.

Tissue engineering for the regeneration of the mastoid air cells: a preliminary in vitro study

Mastoid is a pneumatic bone, composed of small interconnecting chambers covered by a mono-layer of mucosa with an abundant blood supply. One of its main functions is gas exchange according to the concentration/pressure gradient. The final goal of our research project is to regenerate mastoid air cells and their unique physiologic functions. The aim of the present study is to determine appropriate cultivating conditions for the cells cultured on the surface of artificial hydroxyapatite. In our in vitro experiment, to imitate the skeleton of mastoid bone, we used two types of three-dimensional hydroxyapatite (3D-HA), i.e. with a high (90%) and low (60%) percentage of micropores. The former type was divided into two groups: collagen-coated and non-coated. Canine mucosal- and bone marrow-derived stromal cells (BSCs), from the oral floor and femur respectively, were harvested and cultured on the 3D-HA under different conditions. To estimate the proliferation/distribution of the cultured cells over the surface of the 3D-HA, these cells were stained with the dye DiI and hematoxylin-eosin. There were no significant differences in the proliferation of cultured cells on the 3D-HA with high and low percentages of micropores. Collagen-coated HA was a better material for the cultured cells compared with the non-coated HA. Co-cultured mucosal and BSCs proliferated better than those cultured separately. In conclusion, this tissue engineering technique may be applied for the regeneration of mastoid air cells.

Expression of beta-catenin in developing auditory epithelia of mice

This study investigated the role of beta-catenin in the development of mouse auditory epithelia. Inner ears obtained from embryonic and newborn mice were used. Expression of beta-catenin was examined together with the expression of Ki-67, a marker for proliferating cells, or myosin VIIa, a marker for differentiated hair cells. In the early phase of development, intense expression of beta-catenin was found in auditory epithelia in which a number of Ki-67-positive cells were identified. Together with a decrease in proliferating cells, the intensity and area of beta-catenin expression were reduced. In addition, during differentiation and maturation of hair cells, the area of beta-catenin expression was further limited. These findings suggest that patterns of expression of beta-catenin are closely linked with the status of auditory epithelia development.

Induction of cell proliferation and beta-catenin expression in rat utricles in vitro

Limited regenerative response occurs in mammalian vestibular epithelia, although vestibular hair cell regeneration in mammals has been demonstrated under a variety of experimental conditions. Beta-catenin is known to play an important role in both cell-cell adhesion and signal transduction associated with cell proliferation. This study evaluated cell proliferation activity in mammalian vestibular epithelia in organotypic culture and examined the involvement of beta-catenin in cell proliferation in vestibular epithelia. After 72 h of culture, utricles with or without induction of cell proliferation were examined. Cell proliferation was induced by brief exposure to forskolin and supplementation with fetal bovine serum. Cell proliferation activity was assessed by bromodeoxyuridine (BrdU) labeling. Immunohistochemistry was employed for analysis of cellular distribution of beta-catenin. In utricles cultured without induction of cell proliferation. BrdU labeling was not found in vestibular epithelia. Expression of beta-catenin was found in the area corresponding to the distribution of adherens junctions in vestibular epithelia. However, BrdU labeling was identified in sensory epithelia of utricles following induction of cell proliferation, although the number of BrdU-positive cells in sensory epithelia was very limited. Accumulation of beta-catenin was occasionally found in proliferating cells in sensory epithelia; however, it was not always found in BrdU-positive cells. The present findings suggest that beta-catenin may play a role in the induction of cell proliferation in mammal vestibular epithelia.

Transplantation of neural stem cells into explants of rat inner ear

Damage and loss of hair cells in the inner ear is the most frequent cause of hearing loss and balance disorders. Mammalian hair cells do not regenerate in the conventional ways. To regenerate the hair cell in the mammalian inner ear we transplanted neural stem cells into explants of rat inner ear. The stem cells integrated successfully into the sensory epithelium of the vestibular organs, but not into the organ of Corti. This method is useful to investigate efficient ways to transplant stem cells into the inner ear.

Steroid injection to vocal nodules using fiberoptic laryngeal surgery under topical anesthesia

Since 1990, we have performed steroid injection into the vocal fold by fiberoptic laryngeal surgery (FLS) under local anesthesia. In this study, the usefulness of this method was evaluated in 28 patients with vocal nodules. Under monitoring using a fiberoptic laryngoscope, a curved injection needle was inserted via the oral cavity and steroid was injected. Endoscopic findings showed that the vocal nodule had disappeared in 17 patients of the 27 patients and decreased in 10 after injection. The maximum phonation time was 10.9 s before operation and 13.9 s after operation, showing a significant increase (P<0.05), and the mean flow rate also showed a significant improvement (P<0.05). The patients self-rating concerning hoarseness demonstrated great improvement after injection. This technique can be performed under local anesthesia in combination with voice therapy on an outpatient basis, and it is considered to be useful for treating vocal nodules.

Regeneration of the vocal fold using autologous mesenchymal stem cells

The aim of this study was to regenerate the injured vocal fold by means of selective cultured autologous mesenchymal stem cells (MSCs). Eight adult beagle dogs were used for this experiment. Selective incubation of MSCs from bone marrow was done. These MSCs were submitted to 3-dimensional incubation in 1% hydrochloric acid atelocollagen. Three-dimensional incubated MSCs were injected into the left vocal fold, and atelocollagen only was injected into the right vocal fold of the same dog as a control. Four days after injection, the posterior parts of the vocal folds were incised. The regeneration of the vocal fold was estimated by morphological and histologic evaluations. Our results showed that 3-dimensional incubated MSCs were useful in the regeneration of the injured vocal fold. This study shows that damaged tissues such as an injured vocal fold would be able to be regenerated by tissue engineering.