New artificial connective matrix made of fibrin monomers, elastin peptides and type I + III collagens: structural study, biocompatibility and use as tympanic membranes in rabbit

Technological advances in fibrin for tissue engineering

Fibrin is a promising natural polymer that is widely used for diverse applications, such as hemostatic glue, carrier for drug and cell delivery, and matrix for tissue engineering. Despite the significant advances in the use of fibrin for bioengineering and biomedical applications, some of its characteristics must be improved for suitability for general use. For example, fibrin hydrogels tend to shrink and degrade quickly after polymerization, particularly when they contain embedded cells. In addition, their poor mechanical properties and batch-to-batch variability affect their handling, long-term stability, standardization, and reliability. One of the most widely used approaches to improve their properties has been modification of the structure and composition of fibrin hydrogels. In this review, recent advances in composite fibrin scaffolds, chemically modified fibrin hydrogels, interpenetrated polymer network (IPN) hydrogels composed of fibrin and other synthetic or natural polymers are critically reviewed, focusing on their use for tissue engineering.

Type I Collagen-Fibrin Mixed Hydrogels: Preparation, Properties and Biomedical Applications

Type I collagen and fibrin are two essential proteins in tissue regeneration and have been widely used for the design of biomaterials. While they both form hydrogels via fibrillogenesis, they have distinct biochemical features, structural properties and biological functions which make their combination of high interest. A number of protocols to obtain such mixed gels have been described in the literature that differ in the sequence of mixing/addition of the various reagents. Experimental and modelling studies have suggested that such co-gels consist of an interpenetrated structure where the two proteins networks have local interactions only. Evidences have been accumulated that immobilized cells respond not only to the overall structure of the co-gels but can also exhibit responses specific to each of the proteins. Among the many biomedical applications of such type I collagen-fibrin mixed gels, those requiring the co-culture of two cell types with distinct affinity for these proteins, such as vascularization of tissue engineering constructs, appear particularly promising.

Hybrid elastin-like recombinamer-fibrin gels: physical characterization and in vitro evaluation for cardiovascular tissue engineering applications

In the field of tissue engineering, the properties of the scaffolds are of crucial importance for the success of the application. Hybrid materials combine the properties of the different components that constitute them. In this study hybrid gels of Elastin-Like Recombinamer (ELR) and fibrin were prepared with a range of polymer concentrations and ELR-to-fibrin ratios. The correlation between SEM micrographs, porosities, swelling ratios and rheological properties was discussed and a poroelastic mechanism was suggested to explain the mechanical behavior of the hybrid gels. Applicability as scaffold materials for cardiovascular tissue engineering was shown by the realization of cell-laden matrixes which supported the synthesis of collagens as revealed by immunohistochemical analysis. As a proof of concept, a tissue-engineered heart valve was fabricated by injection moulding and cultivated in a bioreactor for 3 weeks under dynamic conditions. Tissue analysis revealed the production of collagen I and III, fundamental proteins for cardiovascular constructs.

Chitosan/PEI patch releasing EGF and the EGFR gene for the regeneration of the tympanic membrane after perforation

EGF and EGFR gene-releasing PEI/chitosan patch (EErP-CPs) was developed to increase the regeneration of tympanic membrane perforations.

Fabricated Elastin

The mechanical stability, elasticity, inherent bioactivity, and self-assembly properties of elastin make it a highly attractive candidate for the fabrication of versatile biomaterials. The ability to engineer specific peptide sequences derived from elastin allows the precise control of these physicochemical and organizational characteristics, and further broadens the diversity of elastin-based applications. Elastin and elastin-like peptides can also be modified or blended with other natural or synthetic moieties, including peptides, proteins, polysaccharides, and polymers, to augment existing capabilities or confer additional architectural and biofunctional features to compositionally pure materials. Elastin and elastin-based composites have been subjected to diverse fabrication processes, including heating, electrospinning, wet spinning, solvent casting, freeze-drying, and cross-linking, for the manufacture of particles, fibers, gels, tubes, sheets and films. The resulting materials can be tailored to possess specific strength, elasticity, morphology, topography, porosity, wettability, surface charge, and bioactivity. This extraordinary tunability of elastin-based constructs enables their use in a range of biomedical and tissue engineering applications such as targeted drug delivery, cell encapsulation, vascular repair, nerve regeneration, wound healing, and dermal, cartilage, bone, and dental replacement.

Latent progenitor cells as potential regulators for tympanic membrane regeneration

Tympanic membrane (TM) perforation, in particular chronic otitis media, is one of the most common clinical problems in the world and can present with sensorineural healing loss. Here, we explored an approach for TM regeneration where the latent progenitor or stem cells within TM epithelial layers may play an important regulatory role. We showed that potential TM stem cells present highly positive staining for epithelial stem cell markers in all areas of normal TM tissue. Additionally, they are present at high levels in perforated TMs, especially in proximity to the holes, regardless of acute or chronic status, suggesting that TM stem cells may be a potential factor for TM regeneration. Our study suggests that latent TM stem cells could be potential regulators of regeneration, which provides a new insight into this clinically important process and a potential target for new therapies for chronic otitis media and other eardrum injuries.

Regeneration of chronic tympanic membrane perforation using an EGF-releasing chitosan patch

Most chronic tympanic membrane (TM) perforations require surgical interventions such as tympanoplasty because, unlike with acute perforations, it is very difficult for the perforations to heal spontaneously. The purpose of this study was to develop novel therapeutic techniques and scaffolds that release growth factors to treat chronic TM perforations. We evaluated the cell proliferation effects of the epidermal growth factor (EGF) and fibroblast growth factor (FGF) on in vitro cultures of TM cells using an MTT assay. They both showed similar efficacy, so we used EGF because of its lower cost. We then constructed an EGF-releasing chitosan patch scaffold (EGF-CPS) based on previous studies. We analyzed its toxicity and strength, and we studied it using scanning electron microscopy. EGF was released from the EGF-CPS for 8 weeks in an in vitro system. In animal studies, the EGF group, which was treated with EGF-CPS, showed healing in 56.5% of the animals (13/23), while the control group, which did not receive any treatment, revealed 20.8% healing (4/24) (p=0.04). Transmission electron microscopic studies of regenerated eardrums in the EGF group showed much greater preservation of histological features, and TMs of the EGF group were thinner than spontaneously healed TMs. In conclusion, this novel EGF-CPS can be used as a nonsurgical intervention technique for treatment of chronic TM perforations.

The biocompatibility of silk fibroin and acellular collagen scaffolds for tissue engineering in the ear

Recent experimental studies have shown the suitability of silk fibroin scaffold (SFS) and porcine-derived acellular collagen I/III scaffold (ACS) as onlay graft materials for tympanic membrane perforation repair. The aims of this study were to further characterize and evaluate the in vivo biocompatibility of SFS and ACS compared with commonly used materials such as Gelfoam and paper in a rat model. The scaffolds were implanted in subcutaneous (SC) tissue and middle ear (ME) cavity followed by histological and otoscopic evaluation for up to 26 weeks. Our results revealed that SFS and ACS were well tolerated and compatible in rat SC and ME tissues throughout the study. The tissue response adjacent to the implants evaluated by histology and otoscopy showed SFS and ACS to have a milder tissue response with minimal inflammation compared to that of paper. Gelfoam gave similar results to SFS and ACS after SC implantation, but it was found to be associated with pronounced fibrosis and osteoneogenesis after ME implantation. It is concluded that SFS and ACS both were biocompatible and could serve as potential alternative scaffolds for tissue engineering in the ear.

Regeneration of chronic tympanic membrane perforation using 3D collagen with topical umbilical cord serum

Chronic tympanic membrane (TM) perforation is one of the most common otology complications. Current surgical management of TM perforation includes myringoplasty and tympanoplasty. The purpose of this study was to evaluate the efficacy and feasibility of three dimensional (3D) porous collagen scaffolds with topically applied human umbilical cord serum (UCS) for the regeneration of chronic TM perforation in guinea pigs. To achieve this goal, we fabricated porous 3D collagen scaffolds (avg. strut diameter of 236 ± 51 μm, avg. pore size of 382 ± 67 μm, and a porosity of 96%) by using a 3 axis robot dispensing and low temperature plate systems. Guinea pigs were used in a model of chronic TM perforation. In the experimental group (n=10), 3D collagen scaffold was placed on the perforation and topically applied of UCS every other day for a period of 8 days. The control group ears (n=10) were treated with paper discs and phosphate buffered saline (PBS) only using the same regimen. Healing time, acoustic-mechanical properties, and morphological analysis were performed by otoendoscopy, auditory brainstem response (ABR), single-point laser Doppler vibrometer (LDV), optical coherence tomography (OCT), and light microscopic evaluation. The closure of the TM perforation was achieved in 100% of the experimental group vs. 43% of the control group, and this difference was statistically significant (p=0.034). The ABR threshold at all frequencies of the experimental group was significantly recovered to the normal level compared to the control group. TM vibration velocity in the experimental group recovered similar to the normal control level. The difference is very small and they are not statistically significant below 1 kHz (p=0.074). By OCT and light microscopic examination, regenerated TM of the experimental group showed thickened fibrous and mucosal layer. In contrast, the control group showed absence of fibrous layer like a dimeric TM.

Flash photolysis and pulse radiolysis studies on elastin hydrolysates

The formation of reactive species and free radicals in water soluble elastin hydrolysates have been investigated by pulse radiolysis and flash photolysis. Elastin hydrolysates were obtained by hydrolysis of elastin extracted from aorta. An investigation of the photochemical properties of elastin hydrolysates in water was carried out using nanosecond laser irradiation. The transient spectra of elastin hydrolysates solution excited at 266 nm showed two bands. One of them with maximum at 295 nm and the second one with maximum at 400 nm. The reactions of hydrated electrons and ˙OH radicals with elastin have been studied by pulse radiolysis. In the absorption spectra of products resulting from the reaction of elastin with e(aq)(-) small maximum absorption in UV and visible light was observed. In the absorption spectra of products resulting from the reaction of the hydroxyl radicals with elastin two bands were observed. The first one at 320 nm and the second one at 410 nm. Reaction of OH radicals with elastin hydrolysates lead to formation of Tyr phenoxyl radicals with absorption at 410 nm. The influence of the addition of sodium azide NaN3 on the formation of the transients was evaluated.

Tympanic membrane repair using silk fibroin and acellular collagen scaffolds

OBJECTIVES/HYPOTHESIS

To evaluate the efficacy of silk fibroin scaffolds (SFS) and acellular collagen scaffolds (ACS) for the repair of tympanic membrane (TM) in a guinea pig acute perforation model.

STUDY DESIGN

Experimental animal research.

METHODS

Seventy-two albino guinea pigs underwent perforation of the right TM and were divided into four experimental groups (n = 18). The perforations were repaired with SFS, ACS, and paper patch using onlay myringoplasty, or they were allowed to heal spontaneously (control). An additional group of 10 guinea pigs without perforation or scaffold was allocated as a normal TM group. Guinea pigs in each experimental group (n = 6) were evaluated at 7, 14, and 28 days following surgery. TM structural healing was evaluated by otomicroscopy and histology, and functional hearing was analyzed by auditory brainstem responses (ABR). Prior to the study, mechanical properties of SFS and ACS were investigated.

RESULTS

Tensile strength and elasticity of SFS and ACS were within the known range for human TM. Based on otologic and histologic evaluation, TMs treated with SFS or ACS showed complete closure of the perforation at an earlier stage, with a trilaminar structure and more uniform thickness compared to paper patch and control treated groups. ABR assessment demonstrated that SFS or ACS treatment facilitated a faster restoration of hearing function compared to paper patch and control groups.

CONCLUSION

The results of this study show that SFS and ACS are effective graft materials and may be utilized as alternatives to current grafts for TM repair.

The promotion of angiogenesis by growth factors integrated with ECM proteins through coiled-coil structures

An appropriate method to bind extracellular matrix (ECM) proteins and growth factors using advanced protein engineering techniques has the potential to enhance cell proliferation and differentiation for tissue regeneration and repair. In this study we developed a method to co-immobilize non-covalently an ECM protein to three different types of growth factors: basic fibroblast growth factor (bFGF), epidermal growth factor (EGF) and single-chain vascular endothelial growth factor (scVEGF121) through a coiled-coil structure formed by helixA/helixB in order to promote angiogenesis. The designed ECM was established by fusing two repeats of elastin-derived unit (APGVGV)(12), cell-adhesive sequence (RGD), laminin-derived IKVAV sequence and collagen-binding domain (CBD) to obtain CBDEREI2. HelixA was fused to each growth factor and helixB to the engineered ECM. Human umbilical vein endothelial cells (HUVECs) were cultured on engineered ECM and growth factors connected through the coiled-coil formation between helixA and helixB. Cell proliferation and capillary tube-like formation were monitored. Moreover, the differentiated cells with high expression of Ang-2 suggested the ECM remodeling. Our approach of non-covalent coupling method should provide a protein-release control system as a new contribution in biomaterial for tissue engineering field.

Scaffolds for tympanic membrane regeneration in rats

Tympanic membrane (TM) perforations lead to significant hearing loss and result in possible infection of the middle ear. Myringoplasty is commonly performed to repair chronic perforations. Although various grafts and materials have been used to promote TM regeneration, all have associated limitations. The aim of this study was to evaluate the efficacy and feasibility of two graft materials, silk fibroin scaffold (SFS) and porcine-derived acellular collagen type I/III scaffold (ACS), compared with two commonly used graft materials (paper patch and Gelfoam) for the promotion of TM regeneration. These scaffolds were implanted using on-lay myringoplasty in an acute TM perforation rat model. Surface morphology of the scaffolds was observed with scanning electron microscopy. The morphology of the TM was assessed at various time points postimplantation using otoscopy, light and electron microscopy, and functional outcomes by auditory brainstem responses. We found that SFS and ACS significantly accelerated the TM perforation closure, obtained optimal TM thickness, and resulted in better trilaminar morphology with well-organized collagen fibers and early restoration of hearing. However, paper patch and Gelfoam lost their scaffold function in the early stages and showed an inflammatory response, which may have contributed to delayed healing. This study indicates that compared with paper patch and Gelfoam, SFS and ACS are more effective in promoting an early TM regeneration and an improved hearing, suggesting that these scaffolds may be potential substitutes for clinical use.

Novel silk fibroin/elastin wound dressings

Silk fibroin (SF) and elastin (EL) scaffolds were successfully produced for the first time for the treatment of burn wounds. The self-assembly properties of SF, together with the excellent chemical and mechanical stability and biocompatibility, were combined with elastin protein to produce scaffolds with the ability to mimic the extracellular matrix (ECM). Porous scaffolds were obtained by lyophilization and were further crosslinked with genipin (GE). Genipin crosslinking induces the conformational transition from random coil to β-sheet of SF chains, yielding scaffolds with smaller pore size and reduced swelling ratios, degradation and release rates. All results indicated that the composition of the scaffolds had a significant effect on their physical properties, and that can easily be tuned to obtain scaffolds suitable for biological applications. Wound healing was assessed through the use of human full-thickness skin equivalents (EpidermFT). Standardized burn wounds were induced by a cautery and the best re-epithelialization and the fastest wound closure was obtained in wounds treated with 50SF scaffolds; these contain the highest amount of elastin after 6 days of healing in comparison with other dressings and controls. The cytocompatibility demonstrated with human skin fibroblasts together with the healing improvement make these SF/EL scaffolds suitable for wound dressing applications.

Experimental study of the tissue reaction caused by the presence of cellulose produced by Acetobacter xylinum in the nasal dorsum of rabbits

Several materials have been proposed for nasal reconstruction. There is no consensus on which is the best. The cellulose blanket produced by bacteria may be a possible cartilaginous addition element to the nose.

AIM

to study tissue reaction to cellulose in the dorsal nose of rabbits.

MATERIALS AND METHODS

22 New Zealand rabbits were used. In 20 a cellulose blanket was implanted in the nasal dorsum and 2 served as controls. They were followed up through a period of three and six months, after which their nostrils and nasal dorsums were removed and histological studies were carried out on them, considering defined parameters of inflammation such as vascular congestion, intensity of the inflammatory process and presence of purulent exudate.

RESULTS

The inflammatory process remained stable, showing its relationship with the surgical procedure and not with the presence of the cellulose blanket. There were no statistical differences in the other parameters.

CONCLUSION

The cellulose blanket produced by Acetobacter xylinum presented good biocompatibility, remained stable during the entire study period, and could be considered a good material for elevating the nasal dorsum.

Avaliação da resposta inflamatória traqueal ao curativo de celulose bacteriana após escarificação cirúrgica em coelhos

Dentre as causas de insucesso nas cirurgias para a estenose traqueal está a formação de tecidos de cicatrização exuberantes. O uso de curativos para evitar esta reação pode ser de grande valia nestes casos. A celulose bacteriana produzida por acetobacter xylinun pode ser útil nestes casos. Não há estudos na região laringotraqueal. OBJETIVO: Avaliar a resposta tecidual subglótica de coelhos após escarificação e colocação de curativo de celulose, comparando com grupo controle. FORMA DE ESTUDO: Experimental MATERIAL E MÉTODOS: Foram estudados 26 coelhos, submetidos a escarificação da região laringotraqueal e tratados com curativo e comparados com controle. Foram estabelecidos 4 tempos de seguimento. Os seguimentos laringotraqueais foram examinados histologicamente e os resultados foram avaliados estaticamente. RESULTADOS: O grupo de estudo evoluiu com o passar do tempo com resultados estatisticamente semelhantes ao do grupo controle, nos parâmetros Congestão vascular, Exsudato purulento, Inflamação aguda, Integridade do epitélio, Proliferação fibrosa e Reação granulomatosa. CONCLUSÃO: Não foram observadas diferenças entre os grupos controle e de estudo quanto aos parâmetros inflamatórios ou cicatriciais. Não houve sinais inflamatórios relacionados ao uso da membrana de celulose que não tivessem ocorrido devido ao traumatismo cirúrgico.

Tracheal inflammatory response to bacterial cellulose dressing after surgical scarification in rabbits

Exuberant scarring tissue formation is among the failure causes of tracheal stenosis surgery. Dressings that could avoid such reaction could be very helpful in these cases. Bacterial cellulose, produced by acetobacter xylinun can be useful in these cases. There are no studies in the laryngotracheal region.

Aim

to assess subglottic tissue response in rabbits after scarification and placement of cellulose dressing, and comparing it to a control group.

Study design

experimental.

Materials and Methods

26 rabbits underwent laryngotracheal scarification, received the dressing and were compared to the control group. We established four follow up periods. Laryngotracheal specimens underwent histological exam and the results were statistically assessed.

Results

the study group had statistically similar results when compared to the control group in the following parameters: vascular congestion, purulent oozing, acute inflammation, epithelial integrity, fibrous proliferation and granulous proliferation.

Conclusion

we did not observe differences between the study and control groups as far as inflammation and scarring are concerned. There were no inflammatory signs associated with the use of the cellulose membrane that did no occur because of surgery.

Spectroscopic studies into the influence of UV radiation on elastin in the presence of collagen

An investigation into the influence of UV irradiation on elastin hydrolysates in the presence of collagen was carried out using UV-Vis spectroscopy and spectrofluorometry. It was found that the absorbance of elastin hydrolysates in solution increased during irradiation more than the absorbance of the elastin/collagen blend. The fluorescence of elastin hydrolysates was observed at 305nm and at 380nm after excitation at 270nm. For the elastin/collagen mixture in solution, fluorescence spectrum shows only one maximum at 305nm. UV irradiation caused fluorescence fading at 305nm. For irradiated elastin the fluorescence at 305nm decreased faster than for the irradiated elastin/collagen mixture. The maximum of the fluorescence peak was shifted for elastin by 4nm, whereas for the elastin/collagen blends the shift was only 1-2nm. All the obtained results point out the ability of mixing elastin and collagen, and suggest that the elastin/collagen mixture in solution is less sensitive to UV irradiation than elastin hydrolysates alone.

Spectroscopic studies into the influence of UV radiation on elastin hydrolysates in water solution

An investigation into the influence of UV irradiation on elastin hydrolysates dissolved in water was carried out using UV-Vis spectroscopy and spectrofluorometry. It was found that the absorption of elastin hydrolysates in solution increased during irradiation of the sample. For fluorescence of elastin hydrolysates we observed both, a decrease and increase of this value during irradiation of the sample. After UV irradiation of the elastin solution we observed a minor increase of overall absorption, most notably between 250 nm and 280 nm. Moreover, after UV irradiation a wide peak emerged between 290 nm and 310 nm with maximum at about 305 nm. The new peak suggests that new photoproducts are formed during UV irradiation of elastin hydrolysates. The fluorescence of elastin hydrolysates was observed at 305 nm and at 380 nm after excitation at 270 nm. UV irradiation caused fluorescence fading at 305 nm and 380 nm. After 30 min of irradiation a new broad weak band of fluorescence, attributable to new photoproducts, emerged in the UV wavelength region with emission maximum between 400 nm and 500 nm.

Native fibrillar collagen membranes of micron-scale and submicron thicknesses for cell support and perfusion

Fibrillar type I collagen is nontoxic, biocompatible, and possesses considerable strength and stability. In a study of scaffolds for use in laminated tissue substitutes, we examined the properties of membranes made from air-dried hydrogels of collagen fibrils that were polymerized from native, monomeric collagen. Planar collagen membranes (CMs) of 0.1-5.3 microm dry thickness were made by variation of the collagen concentration and/or the volume of the hydrogel. The planar CMs, which were comprised of a dense feltwork of long collagen fibrils 70-100 nm in diameter, showed considerable resistance to rupture and retained their membranous character after 6 weeks in tissue culture medium at 37 degrees C. CMs that were relatively thick when dry exhibited a greater proportional increase in rehydrated thickness and a greater diffusivity (when rehydrated) to 4.3 kDa dextran than did CMs that were relatively thin when dry. Hollow, tubular CMs of several configurations were prepared by embedment of solid, removable forms into collagen hydrogels prior to drying. By use of special fixtures, a planar CM that incorporated multiple, parallel tubes was fabricated. In summary, hydrogels of fibrillar collagen can be transformed into membranous structures suitable for tissue engineering applications.

Properties of engineered vascular constructs made from collagen, fibrin, and collagen–fibrin mixtures

Vascular constructs were formed by embedding rat aortic smooth muscle cells in three-dimensional matrices of Type I collagen, fibrin, or a mixture of collagen and fibrin in a 1:1 ratio, at total matrix protein concentrations of 2 and 4 mg/ml. Morphological and mechanical properties were evaluated after 6 days in culture, and the effect of cyclic mechanical strain on collagen-fibrin mixture constructs was also studied. Constructs made with the lower protein concentration compacted to the greatest degree, and fibrin was found to enhance gel compaction. Each matrix type exhibited a characteristic stress-strain profile. Pure collagen had the highest linear modulus and pure fibrin had the lowest. The ultimate tensile stress was strongly dependent on the degree of gel compaction, and collagen-fibrin mixtures at 2mg/ml total protein content exhibited the highest values. Application of cyclic mechanical strain to collagen-fibrin mixture constructs caused a significant increase in gel compaction and a decrease in cell proliferation. The linear modulus, ultimate tensile stress and toughness of the constructs were all augmented by mechanical strain. These results demonstrate that the properties of engineered vascular tissues can be modulated by the combination of selected extracellular matrix components, and the application of mechanical stimulation.

Biodegradable biocomposite non-woven matrices based on PDLLA- and elastin-solubilized proteins/elastin

Poly(D,L-lactide) (PDLLA) was synthesized by ring-opening polymerization of D,L-lactide. Non-woven PDLLA matrices were prepared by an extrusion/winding process. The process conditions were optimized and the surfaces of these matrices were modified by glow-discharge treatment and/or glutaraldehyde incorporation for immobilization of elastin-derived proteins (ESP) to the matrix to increase the biocompatibility and also to improve the bioactivity of the matrix. Glow-discharge conditions were optimized. Ethylene diamine (EDA) and Ar were used as the active monomers in the plasma phase. When EDA was used, the glow-discharge treated PDLLA matrices were first allowed to be reacted with glutaraldehyde, although, when Ar used, the treated matrices were used directly for ESP immobilization. The higher degree of immobilization was obtained for EDA and glutaraldehyde. The ESP-incorporated PDLLA matrices were further treated with elastin by cross-reaction of the ESP molecules on the matrix surfaces with elastin. Scanning electron microscopy (SEM) studies showed that ESP were homogeneously deposited the surface of the matrix.

Evaluation of bioabsorbable elastin-fibrin matrix as a barrier in surgical periodontal treatment

The purpose of this investigation was to test clinically the efficiency of a recently described bioabsorbable matrix as a guided tissue regeneration membrane. This matrix was prepared from an original reaction between elastin and fibrin monomers and is now extensively used in several domains of surgery. The study group was composed of 26 patients, with a total of 35 lesions (22 intrabony defects, 8 Class II furcations and 5 Class III furcations) presenting moderate to advanced adult periodontitis. After initial therapy, measurements were made with a calibrated periodontal probe. Probing depth (PD) and gingival margin location (GM) measurements were taken twice: immediately before surgery and after 6 months before re-entry. Clinical attachment level (CAL), vertical osseous level (VOL) and alveolar crest location (AC) measurements were taken during surgery and after 6 months with re-entry procedures for all the patients. Color change of the gingival margin was only observed in 4 defects and device exposure occurred in the proportion of 2 out of the 35 defects. No foreign body reaction was observed in any case. At the intrabony defects mean PD reduction was 5 mm (P < 0.001), and mean gain of CAL was 4 mm (P < 0.001). Mean VOL was 4.3 mm (P < 0.001), mean gingival recession was 0.9 mm (P < 0.05) and mean AC was 0.2 mm (NS). At the Class II furcation defects the mean PD reduction was 4.5 mm (P < 0.001), mean gain CAL vertical was 3.2 mm and CAL horizontal was 4.5 mm (P < 0.001). Gingival recession averaged 1 mm (NS). A complete closure was observed in 2 out of the 8 defects. At the Class III furcation defects the mean PD reduction was 3.6 mm (P < 0.05) and mean CAL-V gain was 1.5 mm (P < 0.02). However the 5 sites showed no horizontal attachment gain and none were unchanged. A very low gingival recession, gingival reaction, crestal bone loss, and device exposure occurred during this study. This preliminary study suggests that the use of a biosynthetic barrier may have beneficial effects in the treatment of intrabony defects and Class II furcation defects. Randomized controlled trials are necessary to evaluate the efficacy and safety of this bioabsorbable membrane in periodontal therapy.

Use of a biodegradable elastin-fibrin material, Neuroplast, as a dural substitute

Since the new Neuroplast biomaterial is now commonly used in several domains of restorative and curative surgery, its preliminary evaluation as a dura mater substitute in the rabbit was performed and is described herein. Whereas the importance of prosthesis thickness was implicated and solved (0.2 rather than 1.0 mm), both macroscopic examination and histological studies revealed for the neotissue an effective patency, a good continuity and especially no or almost no adherence at all. As Neuroplast is now available for use everywhere in humans, this material is being developed in several fields of neurosurgery.