PGA-associated heterotopic chondrocyte cocultures: implications of nasoseptal and auricular chondrocytes in articular cartilage repair

The availability of autologous articular chondrocytes remains a limiting issue in matrix assisted autologous chondrocyte transplantation. Non-articular heterotopic chondrocytes could be an alternative autologous cell source. The aims of this study were to establish heterotopic chondrocyte cocultures to analyze cell-cell compatibilities and to characterize the chondrogenic potential of nasoseptal chondrocytes compared to articular chondrocytes. Primary porcine and human nasoseptal and articular chondrocytes were investigated for extracellular cartilage matrix (ECM) expression in a monolayer culture. 3D polyglycolic acid- (PGA) associated porcine heterotopic mono- and cocultures were assessed for cell vitality, types II, I, and total collagen-, and proteoglycan content. The type II collagen, lubricin, and Sox9 gene expressions were significantly higher in articular compared with nasoseptal monolayer chondrocytes, while type IX collagen expression was lower in articular chondrocytes. Only β1-integrin gene expression was significantly inferior in humans but not in porcine nasoseptal compared with articular chondrocytes, indicating species-dependent differences. Heterotopic chondrocytes in PGA cultures revealed high vitality with proteoglycan-rich hyaline-like ECM production. Similar amounts of type II collagen deposition and type II/I collagen ratios were found in heterotopic chondrocytes cultured on PGA compared to articular chondrocytes. Quantitative analyses revealed a time-dependent increase in total collagen and proteoglycan content, whereby the differences between heterotopic and articular chondrocyte cultures were not significant. Nasoseptal and auricular chondrocytes monocultured in PGA or cocultured with articular chondrocytes revealed a comparable high chondrogenic potential in a tissue engineering setting, which created the opportunity to test them in vivo for articular cartilage repair.

The improvement of middle ear ventilation by laser ablation of the epipharyngeal eustachian tube: a prospective study

A long-lasting dysfunction of the eustachian tube seems to be the etiologic origin for development of chronic otitis media (COM) with mesotympanic perforation, otitis media with effusion (OME), and chronic atelectasis of the middle ear. Surgical interventions in the middle ear generally treat the sequelae of the tube dysfunction but not the dysfunction itself. This prospective clinical study investigated how far fiber-guided laser ablation of the posterior half of the epipharyngeal tubal ostium led to better middle ear ventilation in the otologic disease patterns mentioned below. There were 38 adult patients included in the analysis. The patients in one group had a perforated tympanic membrane [COM before primary tympanoplasty (n = 14) or revision tympanoplasty (n = 5)]; the patients in a second group had an intact eardrum [OME resistant to therapy (n = 3), with an atelectasis of the middle ear (n = 2) or problems of pressure equalization with fast changes in ambient pressure (diving, flying) (n = 14)]. Laser ablation of the posterior half of the epipharyngeal tubal ostium was performed, generally with local anesthesia, if tubal function testing was pathologic (Valsalva maneuver, passive tube opening, tympanogram). In patients with COM the procedure was performed 8 weeks before the middle ear surgery. All patients were checked 8 weeks postoperatively and in the course of the following year. The intervention seemed to have had a positive effect on tube function in 68.4% of patients operated on (P = 0.001). In 26 of the 38 patients that had undergone operation, an improvement the results of tubal function tests could be seen in the postoperative follow-up. In the COM group the Valsalva maneuver improved in 14 of 19 patients (73.6%) (P = 0.001), and the passive tube opening improved in nine of 18 patients (50%). In the group with an intact eardrum the Valsalva maneuver improved in 13 of 18 patients (72.2%) (P = 0.001). The resulting condition remained stable after 1 year. None of the patients showed any complications as a result of the therapy. Minimally invasive shaping of the distal eustachian tube under topical anesthesia can be recommended for patients with the above-mentioned diagnoses who have pathologic middle ear ventilation. Especially prior to tympanoplasties, and especially in otologic revision procedures, where middle ear ventilation is a prerequisite for successful otologic surgery, the function of the eustachian tube can be optimized in 70% of the patients, particularly if there are pathological findings (tubal tonsil, narrow orifice of the tubal ostium, adenoids). The placement of permanent ear tubes in adults with recurrent OME can also be avoided by the procedure described. The resultant conditions remained stable for the next year. Patients with tympanic ventilation problems due to rapid pressure changes (flying, diving) can also benefit from this procedure.

Human mastoid periosteum-derived stem cells: promising candidates for skeletal tissue engineering

Currently, mesenchymal stem cells (MSCs) are considered as the most eligible cells for skeletal tissue engineering. However, factors such as difficult stimulation and control of differentiation in vivo hamper their clinical use. In contrast, periosteum or periosteum-derived cells (PCs) are routinely clinically applied for bone and cartilage repair. PCs have often been named MSCs but, although cells of osteochondrogenic lineages arise from MSCs, it is unclear whether periosteum really contains MSCs. Our aim was to investigate the MSC-like character of PCs derived from the periosteum of mastoid bone. Harvesting of periosteum from mastoid bone is easy, so mastoid represents a good source for the isolation of PCs. Therefore, we analysed the MSC-like growth behaviour and the expression of embryonic, ectodermal, endodermal and mesodermal markers by microarray and FACS technology, and the multilineage developmental capacity of human PCs. Regarding clinical relevance, experiments were performed in human serum-supplemented medium. We show that PCs do not express early embryonic stem cell markers such as Oct4 and Nanog, or the marker of haematopoietic stem cells CD34, but express some other MSC markers. Osteogenesis resulted in the formation of calcified matrix, increased alkaline phosphatase activity, and induction of the osteogenic marker gene osteocalcin. Staining of proteoglycans and deposition of type II collagen documented chondrogenic development. As shown for the first time, adipogenic stimulation of mastoid-derived PCs resulted in the formation of lipid droplets and expression of the adipogenic marker genes aP2 and APM1. These results suggest MSC-like PCs from mastoid as candidates for therapy of complex skeletal defects.

[Tissue engineering of respiratory epithelium. Regenerative medicine for reconstructive surgery of the upper airways]

Reconstruction of long tracheal defects remains an unsolved surgical problem. Tissue engineering of respiratory epithelium is therefore of utmost surgical and scientific interest. Successful cultivation and reproduction of respiratory epithelium in vitro is crucial to seed scaffolds of various biomaterials with functionally active respiratory mucosa. Most frequently, the suspension culture as well as the tissue or explant cultures are used. Collagenous matrices, synthetic and biodegradable polymers, serve as carriers in studies. It is essential for clinical practice that mechanically stable biomaterials be developed that are resorbable in the long term or that cartilaginous constructs produced in vitro be employed which are seeded with respiratory epithelium before implantation. Vascularization of a bioartificial matrix for tracheal substitution is also prerequisite for integration of the constructs produced in vitro into the recipient organism. Here, the state of the art of research, perspectives and limitations of tracheal tissue engineering are reviewed.

Intratympanic treatment of acute acoustic trauma with a cell-permeable JNK ligand: a prospective randomized phase I/II study

OBJECTIVES

Intratympanic administration of a cell-permeable JNK ligand has been shown to prevent hearing loss after acute acoustic trauma in animal models.

CONCLUSIONS

Functional and morphological analysis of the treated ears revealed that AM-111 had an excellent otoprotective effect, even when administered hours after the noise exposure. Blocking the signal pathway with D-JNKI-1 is therefore a promising way to protect the morphological integrity and physiological function of the inner ear in various conditions involving acute sensorineural hearing loss.

SUBJECTS AND METHODS

For the first application of AM-111 in humans, we organized a clinical phase I/II trial in patients with acute acoustic trauma after exposure to firecrackers in Berlin and Munich on New Year's Eve 2005/2006. We randomly selected 11 patients for intratympanic treatment with AM-111 at a concentration of 0.4 mg/ml or 2 mg/ml within 24 h after noise exposure. Pure tone audiometry and otoacoustic emissions were assessed before treatment and on days 3 and 30 thereafter.

RESULTS

Based on clinical experience and on a calculation using an empirically derived exponential hearing recovery function AM-111 seems to have had a therapeutic effect. A total of 13 adverse events were reported in 5 study participants. None of the adverse events were serious or severe.

[Hyperkeratotic inverted seborrheic keratosis of the outer auditory canal : a first description]

Seborrheic keratosis is one of the most common benign neoplasms seen at the trunk, extremities, head and neck of older individuals which rarely occurs in the auditory canal. Even rarer is the occurrence of an inverted or hyperkeratotic variant in this localization. We present the clinical picture of a 74-year-old man with a recurrent hyperkeratotic, partially inverted seborrheic keratosis of the right external auditory canal. This disease is sometimes difficult to diagnose, particulary to mark down malignant lesions. An uncritical diagnosis must be avoided, since these lesions and especially the irritated subtype might be falsely assessed as basal cell carcinomas which they may resemble histologically.

Differenzialdiagnosen einer beidseitigen akuten Hörminderung bei einem Patienten mit metastasierendem Bronchialkarzinom

The first symptom of an acoustic neuroma in about 50% of the patients is hearing loss, which occurs suddenly in about 5-10% of cases. Acute progressive hearing loss is associated with a broad spectrum of differential diagnoses. Cerebellar and hepatic metastases from a bronchial carcinoma were previously diagnosed in the case presented here, and the most probable causes of the progressive hearing loss, e.g. idiopathic sudden deafness, infection and tumor-associated factors, were considered and diagnostically analyzed. The discussion ultimately focused on the clinical and radiological signs of bilateral acoustic neuroma. The patient's history and clinical findings yielded no indication of neurofibromatosis (type 1/2). Nevertheless, the constellation of findings suggests that the bilateral hearing loss was caused by a bilateral acoustic neuroma.

Development and phenotypic characterization of a high density in vitro model of auricular chondrocytes with applications in reconstructive plastic surgery

Cultivation of phenotypically stable auricular chondrocytes will have applications in autologous chondrocyte transplantation and reconstructive surgery of cartilage. Chondrocytes grown in monolayer culture rapidly dedifferentiate assuming a fibroblast-like morphology and lose their cartilage-specific pattern of gene expression. Three-dimensional high-density culture models mimic more closely the in vivo conditions of cartilage. Therefore, this study was undertaken to test whether the high-density cultures might serve as a suitable model system to acquire phenotypically and functionally differentiated auricular chondrocytes from porcine cartilage. Freshly isolated porcine auricular chondrocytes were cultured for 7 passages in monolayer culture. From each passage (passage 0 and 1-7) cells were introduced to high-density cultures and examined by transmission electron microscopy. Western blotting was used to analyse the expression of cartilage-specific markers, such as collagen type II and cartilage specific proteoglycan, fibronectin, cell adhesion and signal transduction receptor beta1-integrin, matrix metalloproteinases (MMP-9, MMP-13), cyclo-oxygenase (COX)-2 and the apoptosis commitment marker, activated caspase-3. When dedifferentiated auricular chondrocytes from monolayer passages 0-4 were cultured in high-density culture, they recovered their chondrocytic phenotype and formed cartilage nodules surrounded by fibroblast-like cells and synthesised collagen type II, proteoglycans, fibronectin and beta1-integrins. However, chondrocytes from monolayer passages 5-7 did not redifferentiate to chondrocytes even when transferred to high-density culture, and did not synthesize a chondrocyte-specific extracellular matrix. Instead, they produced increasing amounts of MMP-9, MMP-13, COX-2, activated caspase-3 and underwent apoptosis. Three-dimensional high-density cultures may therefore be used to obtain sufficient quantities of fully differentiated auricular chondrocytes for autologous chondrocyte transplantation and reconstructive plastic surgery.

Photodynamic effect of argon and diode laser on cholesteatoma cell cultures after intravital staining with absorption enhancers

Chronic epitympanic otitis media, or chronic suppurative osteitis, is a destructive form of chronic middle-ear inflammation. The therapy of choice is complete surgical removal of the squamous epithelium from the middle ear. It is often impossible to inspect all areas of the middle ear with the posterior canal wall intact. Not all recesses can be reliably monitored with the microscope, particularly in the area of the antrum and hypotympanum. Residual squamous epithelium here causes frequent recurrences following cholesteatoma surgery. This study examines the effect of argon and diode lasers on cholesteatoma tissue. The aim is to develop a laser treatment selectively directed against cholesteatoma cells that can be performed after cholesteatoma surgery to eliminate any residual squamous epithelium. Intraoperatively harvested monolayer-cultured cholesteatoma cells stained in vivo with various absorption enhancers served as the in vitro examination model. Argon (499 nm) and diode lasers (810 nm) were applied since their irradiation has an appropriate tissue penetration depth and is absorbed by various chromophores such as neutral red (475-500 nm), fluorescein (488 nm), and indocyanine green (790-810). Intracellular staining of cultured cells increased the optical density at the wavelength corresponding to the dye. Neutral red damaged 50-60% of cultured cells merely by intracellular accumulation at high concentrations. An additive cell destruction of about 30% was achieved by also applying argon laser irradiation. Fluorescein diacetate caused no appreciable stain-induced damage to cultured cholesteatoma cells. Argon laser irradiation destroyed up to 60% of the cultures. Indocyanine green resulted in only minor damage to cultured cells. The diode laser destroyed up to 60% of the irradiated cells. Selective staining of cholesteatoma cells was not achieved with any of the dyes examined. Thus, other stained tissue could be damaged. Staining and subsequent laser irradiation destroys up to 60% of cultured cholesteatoma cells. Unstained irradiated cells are not affected. Indocyanine green and fluorescein are nontoxic and may thus be used as absorption enhancers. The diode and argon lasers appear to be basically suitable. Cell staining is not selective, i.e., other tissues would also be stained and damaged. To avoid such unwanted damage, it would be desirable to couple the chromophore to a specific antibody that binds only to cholesteatoma cells.

Tissue engineering in otorhinolaryngology

Tissue engineering is a field of research with interdisciplinary cooperation between clinicians, cell biologists, and materials research scientists. Many medical specialties apply tissue engineering techniques for the development of artificial replacement tissue. Stages of development extend from basic research and preclinical studies to clinical application. Despite numerous established tissue replacement methods in otorhinolaryngology, head and neck surgery, tissue engineering techniques opens up new ways for cell and tissue repair in this medical field. Autologous cartilage still remains the gold standard in plastic reconstructive surgery of the nose and external ear. The limited amount of patient cartilage obtainable for reconstructive head and neck surgery have rendered cartilage one of the most important targets for tissue engineering in head and neck surgery. Although successful in vitro generation of bioartificial cartilage is possible today, these transplants are affected by resorption after implantation into the patient. Replacement of bone in the facial or cranial region may be necessary after tumor resections, traumas, inflammations or in cases of malformations. Tissue engineering of bone could combine the advantages of autologous bone grafts with a minimal requirement for second interventions. Three different approaches are currently available for treating bone defects with the aid of tissue engineering: (1) matrix-based therapy, (2) factor-based therapy, and (3) cell-based therapy. All three treatment strategies can be used either alone or in combination for reconstruction or regeneration of bone. The use of respiratory epithelium generated in vitro is mainly indicated in reconstructive surgery of the trachea and larynx. Bioartificial respiratory epithelium could be used for functionalizing tracheal prostheses as well as direct epithelial coverage for scar prophylaxis after laser surgery of shorter stenoses. Before clinical application animal experiments have to prove feasability and safety of the different experimental protocols. All diseases accompanied by permanently reduced salivation are possible treatment targets for tissue engineering. Radiogenic xerostomia after radiotherapy of malignant head and neck tumors is of particular importance here due to the high number of affected patients. The number of new diseases is estimated to be over 500,000 cases worldwide. Causal treatment options for radiation-induced salivary gland damage are not yet available; thus, various study groups are currently investigating whether cell therapy concepts can be developed with tissue engineering methods. Tissue engineering opens up new ways to generate vital and functional transplants. Various basic problems have still to be solved before clinically applying in vitro fabricated tissue. Only a fraction of all somatic organ-specific cell types can be grown in sufficient amounts in vitro. The inadequate in vitro oxygen and nutrition supply is another limiting factor for the fabrication of complex tissues or organ systems. Tissue survival is doubtful after implantation, if its supply is not ensured by a capillary network.

[Bilateral spontaneous development of a frontal sinus pyocele--a rare diagnosis]

Due to the length and the narrowing of the sinus draining passage, mucoceles are typically located within the frontal sinus. This case report describes the pathology of a patient with bilateral formation of pyoceles of the frontal sinus without the history of trauma, sinus operation or nasal pathology. The patient visited an ophthalmologist and reported a slowly increasing visual loss and protrusion of the left bulbus in the course of one year. Coronal CT scan showed bilateral soft tissue densities within the frontal sinus with arrosion of the floor on the left side. Extranasal frontal sinus surgery with ethmoidectomy (Ritter-Jansen and Uffenorde mucosal plasty) was performed. Intraoperative view demonstrated bony defects of the floor and the posterior wall of the frontal sinus.

Human platelet supernatant promotes proliferation but not differentiation of articular chondrocytes

The objective of the study was to evaluate the growth-promoting activity of human platelet supernatant on primary chondrocytes in comparison with fetal calf serum (FCS) supplemented cell culture medium. Furthermore, the differentiation potential of platelet supernatant was determined in three-dimensional artificial cartilage tissues of bovine articular chondrocytes. Proliferation of articular and nasal septal chondrocytes was assayed by incorporation of BrdU upon stimulation with ten different batches of human platelet supernatant. On bovine articular chondrocytes, all these batches were at least as growth-promoting as FCS. On nasal septal chondrocytes, nine out of ten batches revealed increased or equivalent mitogenic stimulation compared with medium supplemented with FCS. Three-dimensional culture and subsequent histological analysis of matrix formation were used to determine the differentiation properties of platelet supernatant on articular chondrocytes. Human platelet supernatant failed to induce the deposition of typical cartilage matrix components, whereas differentiation and matrix formation were apparent upon cultivation of articular chondrocytes with FCS. Proliferation assays demonstrated that human platelet supernatant stimulates growth of articular and nasal septal chondrocytes; however, platelet supernatant failed to stimulate articular chondrocytes to redifferentiate in three-dimensional chondrocyte cultures. Therefore platelet lysate may be suitable for chondrocyte expansion, but not for maturation of tissue-engineered cartilage.

Mechanical quality of tissue engineered cartilage: results after 6 and 12 weeks in vivo

Traumatic events are a primary cause for local lesions of articular cartilage. If treated early, restoration of the initial joint geometry and integrity may be achieved. In large defects, sufficient material is not available to bridge the affected area. Heterologeous transplantation is not well accepted due to the risk of infection and immune response. Alternatives are cartilage-like structures, which may be cultured in vitro and transplanted into the defect site. Critical to the success of these new tissues are their mechanical properties. Goals of this study were to generate a hyaline-like cartilage structure, to evaluate its performance in vivo and to verify that its cellular and material properties meet those of native cartilage. Hyaline-like cartilage specimens were generated in vitro and implanted in the backs of nude mice. Specimens were explanted after 6 and 12 weeks, mechanically tested using an indentation test and histologically examined. In mechanical testing, stiffness and failure load significantly increased between weeks 6 and 12. At 12 weeks, mechanical properties of the hyaline-like cartilage were comparable to those of native nasal septal cartilage. Compared to native articular cartilage, the engineered tissue achieved up to 30-50% in strength and mechanical stiffness. In histological examination, specimens showed neocartilage formation. The mechanical testing procedure proved to be sufficiently sensitive to identify differences in properties between cartilage specimens of different origin and at different stages of healing. As an adjunct to histological analysis, mechanical testing may be a valuable tool for judging the utility of engineered cartilage prior to a broad clinical usage.

Preparation of a pure autologous biodegradable fibrin matrix for tissue engineering

Parallel to the growing role of tissue engineering, the need for cell embedding materials, which allow cells to stabilise in a three-dimensional distribution, has increased. Although several substances have been tested, fibrin is thus far the only one that permits the clinical application of cultured tissue. To date, autologous fibrinogen has usually been polymerised with bovine thrombin, which can cause severe immunological side effects. The objective of this study was to explore the practicability of obtaining autologous thrombin from a single patient in an adequate concentration and amount. Fibrinogen was cryoprecipitated from 200 ml of freshly-frozen plasma. Thrombin was isolated from the supernatant through ion-exchange chromatography. The thrombin was first bound to Sephadex A-50 and then eluated using 2 ml of a salt buffer (2.0 M NaCl in 0.015 M trisodiumcitrate, pH 7.0). The activity of the thrombin (51 NIH x ml(-1) to 414 NIH x ml(-1) reached levels comparable to those in commercially available fibrin glues (4-500 NIH x ml(-1)). The study has shown that it is possible to obtain a sufficient amount of autologous thrombin from a single donor to create a fibrin matrix of high efficiency without the risk of immunological and infectious side effects.

Macroencapsulation of human cartilage implants: pilot study with polyelectrolyte complex membrane encapsulation

Autogenous cartilage transplantation is a generally accepted method in reconstructive surgery. A promising alternative to this established method could be represented by in vitro engineering of cartilage tissue. In both methods of autogenous transplantation, host response induces reduction of transplant size and transplant instability to an unforeseeable extent. To investigate if polyelectrolyte complex (PEC) membranes were able to avoid host-induced effects on implanted tissues without neglecting the tissue metabolism, human septal cartilage was encapsulated with polyelectrolyte complex membranes and subcutaneously implanted on the back of nude mice. Septal cartilage implants, without encapsulation served as control group. Histochemical and electron microscopic investigations were performed 1, 4, 8 and 16 weeks after implantation. In the case of an intact PEC-membrane no interactions between the host and the implant could be observed. In some implants, the capsule was torn in several areas and signs of chronic inflammation with the cartilage having been affected mildly could be observed. Implanted cartilage protected with PEC-encapsulation showed no signs of degeneration and significantly lower level of after effects of chronic inflammation than implanted cartilage without PEC-encapsulation. Therefore, it could be expected, that PEC membrane encapsulation offers a novel approach to protect cartilage implants from host response after autogenous transplantation.

[Protection of autogenous cartilage transplants from resorption using membrane encapsulation]

In reconstruction of cartilage defects, autogenous transplantation is known as a reliable and experienced method. Although a clinical application has not been reported until now, tissue engineering permits in vitro production of autogenous cartilage transplants. Nevertheless, in both methods the cartilage is exposed to individually varying resorptive mechanisms. Among other methods for in vivo tissue protection, the encapsulation with a semipermeable polyelectrolytecomplex membrane could guarantee sufficient protection against resorptive influences. Human septal cartilage was encapsulated (group 1) with polyelectrolytecomplex membranes and subcutaneously implanted on the back of thymusaplastic nude mice. Cartilage implants without encapsulation (group 2) were used as control. Scanning electron microscopy and histochemical investigations were performed 1, 4, 8, 12 and 16 weeks after implantation. Group 1 showed no signs of resorption and chronic inflammation at all. In contrast, group 2 presented, correlating to the time of implanta-tion, increasing signs of cell death and fibrotic transformation, representing an increased activity of resorption. In conclusion, tissue encapsulation with a polyelectrolytecomplex membrane could ensure a sufficient protection of human cartilage transplants from resorptive influences. For the plastic-reconstructive surgeon the desired result becomes more calculable.

[Myoepithelial carcinoma (malignant myoepithelioma) of the salivary glands. A case report]

We report the rare development of a myoepithelial carcinoma in a pleomorphic adenoma involving the minor salivary glands in the buccal mucosa of a 78-year-old female. Tumor presented as a small asymptomatic left buccal mass. The initial dominant component of the neoplasm was a pleomorphic adenoma, while the minor component was a myoepithelial carcinoma. Recurrences of tumor after 2 and then 5 years were excised. Histopathological examination of the last tissue removed showed a pure myoepithelial carcinoma of the minor salivary glands without evidence for a pleomorphic adenoma. The clinical features, therapy, diagnosis, histopathology and literature are reviewed.

[Tissue engineering of human cartilage tissue for reconstructive surgery using biocompatible resorbable fibrin gel and polymer carriers]

Current practical approaches in cartilage engineering still face problems with three dimensional cell distribution or require components for cell immobilization, raising biocompatibility problems. In this study, we present a new model using cells cross-linked by fibrin within biocompatible resorbable polymers. Both components have been in clinical use for a long time. Immunohistochemical procedures showed that this model provides optimal requirements for in vitro cartilage production. Immunochemically, cartilage-specific extracellular components such as proteoglycan, chondroitin sulfate and collagen II were characterized. Histomorphological methods showed a mechanically stable tissue compound that lasted for at least 5 weeks. This model may be the first to provide all biocompatible requirements for in vitro production of autologous cartilage transplants for reconstructive surgery.