[Evaluation of the biocompatibility and cell segregation performance of acellular dermal matrix as barrier membrane on guided tissue regeneration in vitro]

PURPOSE

To investigate the proliferation of human periodontal ligament cell on acellular dermal matrix (ADM) and the epithelial cell segregation performance of ADM and evaluate the feasibility of ADM as barrier membrane of guided tissue regeneration.

METHODS

Human periodontal ligament cells(HPDLCs) of the 3rd to 5th passage were seeded onto 96-well plates(with ADM and e-PTFE inside) with 2000 cells per well. The cells were cultured in Dulbecco's modified eagle medium (DMEM). The MTT colorimetric assay method was performed at day 1, 3, 5 and 7 after incubation. The optical density(OD) of each well was measured spectrophotometrically at 490 nm to monitor effects on cell proliferation. The data was analyzed using Student's t test by SPSS13.0 software package. In addition, Tca8113 cells were placed in 24-well plates (with ADM and e-PTFE inside) with 2×10(4) cells per well. The DAPI staining was done 5, 10 d after incubation. Fluorescence microscope was used to observe the number of cells which lied on the two sides of the materials. Visual field was randomly selected to record the number of cells. The cell inoculated surface was recorded as ADM group and e-PTFE group, the other surface was recorded as ADM group and e-PTFE group. Student's t test was used to analyse the cell segregation of the two membranes.

RESULTS

At 3-, 5-, 7 d, the OD value of ADM group and blank control group was significantly higher than that in e-PTFE group (P<0.05), no significant difference was found between ADM group and blank control group (P>0.05). At 5-, 10 d, the cell number in ADM group was much more than that in ADM group, similar between e-PTFE group and e-PTFE group (P<0.05), while no significant difference was noted between the ADM group and e-PTFE group (P>0.05).

CONCLUSIONS

ADM is more conducive to the proliferation of HPDLCs than e-PTFE, and has the similar cell segregation performance on the epithelial cells. Compared with e-PTFE, ADM is more suitable for guided periodontal tissue regeneration. Supported by Health Science and Technology Projects of Jiangsu Province(H201231) and Priority Academic Program Development of Jiangsu Higher Education Institutions (2011-137).

Guided tissue regeneration using rigid absorbable membranes in the dog model of chronic furcation defect

OBJECTIVE

Absorbable membranes are used to promote the regeneration of periodontal defects by Guided Tissue Regeneration (GTR). However, their collapse into the defect is commonly reported, impairing regeneration. Therefore, absorbable but rigid membranes aiming at preventing such collapse were developed and analyzed in periodontal regeneration.

MATERIALS AND METHODS

Membranes were analyzed in class II furcation defects in dogs; procedures included periodontal disease induction, prophylaxis and GTR (treated groups) or open flap debridement alone (control group). For GTR, the membranes were made of either 25% hydroxyapatite (HA) in polyhydroxybutyrate matrix (PHB) or 35% HA in PHB. Animals were clinically evaluated for gingival recession, clinical attachment level (CAL) and biopsies were collected at 60 and 120 days. Bone volume, trabeculae number, trabecular thickness and trabecular separation were quantified by micro-computed tomography, followed by histology.

RESULTS

Membrane exposure was observed in both treated groups (25 and 35% HAP) from the 8(th) day after surgery, continuously progressing until 120 days. Mean CAL for all groups remained above normal values for dogs. Bone volumetric values were not significantly different. Partial formation of bone, cementum and periodontal ligament was observed in treated groups. An inflammatory infiltrate was observed in the dense connective tissue that partially filled the center of the treated defects with active osteoclasts on bone surface.

CONCLUSION

Although partial regeneration of the defect was observed, it was limited by wound contamination. Consequently, rigid absorbable membranes made of HA and PHB failed to improve the regeneration of class II furcation defects in dogs.

Induced collagen cross-links enhance cartilage integration

Articular cartilage does not integrate due primarily to a scarcity of cross-links and viable cells at the interface. The objective of this study was to test the hypothesis that lysyl-oxidase, a metalloenzyme that forms collagen cross-links, would be effective in improving integration between native-to-native, as well as tissue engineered-to-native cartilage surfaces. To examine these hypotheses, engineered cartilage constructs, synthesized via the self-assembling process, as well as native cartilage, were implanted into native cartilage rings and treated with lysyl-oxidase for varying amounts of time. For both groups, lysyl-oxidase application resulted in greater apparent stiffness across the cartilage interface 2–2.2 times greater than control. The construct-to-native lysyl-oxidase group also exhibited a statistically significant increase in the apparent strength, here defined as the highest observed peak stress during tensile testing. Histology indicated a narrowing gap at the cartilage interface in lysyl-oxidase treated groups, though this alone is not sufficient to indicate annealing. However, when the morphological and mechanical data are taken together, the longer the duration of lysyl-oxidase treatment, the more integrated the interface appeared. Though further data are needed to confirm the mechanism of action, the enhancement of integration may be due to lysyl-oxidase-induced pyridinoline cross-links. This study demonstrates that lysyl-oxidase is a potent agent for enhancing integration between both native-to-native and native-to-engineered cartilages. The fact that interfacial strength increased manifold suggests that cross-linking agents should play a significant role in solving the difficult problem of cartilage integration. Future studies must examine dose, dosing regimen, and cellular responses to lysyl-oxidase to optimize its application.

[Three dimensional bioprinting technology of human dental pulp cells mixtures]

OBJECTIVE

To explore the three dimensional(3D)bioprinting technology, using human dental pulp cells (hDPCs) mixture as bioink and to lay initial foundations for the application of the 3D bioprinting technology in tooth regeneration.

METHODS

Imageware 11.0 computer software was used to aid the design of the 3D biological printing blueprint. Sodium alginate-gelatin hydrosol was prepared and mixed with in vitro isolated hDPCs. The mixture contained 20 g/L sodium alginate and 80 g/L gelatin with cell density of 1×10(6)/mL. The bioprinting of hDPCs mixture was carried out according to certain parameters; the 3D constructs obtained by printing were examined; the viability of hDPCs after printing by staining the constructs with calcein-AM and propidium iodide dye and scanning of laser scanning confocal microscope was evaluated. The in vitro constructs obtained by the bioprinting were cultured, and the proliferation of hDPCs in the constructs detected.

RESULTS

By using Imageware 11.0 software, the 3D constructs with the grid structure composed of the accumulation of staggered cylindrical microfilament layers were obtained. According to certain parameters, the hDPCs-sodium alginate-gelatin blends were printed by the 3D bioprinting technology. The self-defined shape and dimension of 3D constructs with the cell survival rate of 87%± 2% were constructed. The hDPCs could proliferate in 3D constructs after printing.

CONCLUSION

In this study, the 3D bioprinting of hDPCs mixtures was realized, thus laying initial foundations for the application of the 3D bioprinting technology in tooth regeneration.

Keratinocytes in the treatment of severe burn injury: an update

Burns are among the most life-threatening physical injuries, in which fast wound closure is crucial. The surgical burn care has evolved considerably throughout the past decennia resulting in a shift of therapeutic goals. Therapies aiming to provide coverage of the burn have been replaced by treatments that have both functional as aesthetic outcomes. The standard in treating severe burns is still early excision followed by skin grafting. The use of cultured keratinocytes to cover extensive burn wounds appeared very promising at first, but the technique still has several limitations of which the long time to culture, the major costs, the risk of infection and the need for an adequate dermal layer limit clinical application. The introduction of dermal substitutes, composite grafts, tissue engineering based on stem cell application have been advocated. The aim of this review is to assess the use of cultured keratinocytes in terms of technical aspects, clinical application, limitations and future perspectives. Cultured keratinocytes are expected to keep playing a role in wound healing, especially in the field of chronic wounds. In severe burns, despite its limitations, keratinocytes can be beneficial if implemented as one of the elements in a broader wound management.

Novel macro-microporous gelatin scaffold fabricated by particulate leaching for soft tissue reconstruction with adipose-derived stem cells

The restoration of body contours as shaped by adipose tissue remains a clinical challenge specifically in patients who have experienced loss of contour due to trauma, surgical removal of tumours or congenital abnormalities. We have developed a novel macro-microporous biomaterial for use in soft tissue re-bulking and augmentation. Alginate beads provided the pore template for the construct. Incorporation, and subsequent dissolution, of the beads within a 7 % (w/v) gelatin matrix, produced a highly porous scaffold with an average pore size of 2.01 ± 0.08 mm. The ability of this scaffold to support the in vitro growth and differentiation of human adipose-derived stem cells (ADSCs) was then investigated. Histological analysis confirmed that the scaffold itself provided a suitable environment to support the growth of ADSCs on the scaffold walls. When delivered into the macropores in a fibrin hydrogel, ADSCs proliferated and filled the pores. In addition, ADSCs could readily be differentiated along the adipogenic lineage. These results therefore describe a novel scaffold that can support the proliferation and delivery of ADSCs. The scaffold is the first stage in developing a clinical alternative to current treatment methods for soft tissue reconstruction.

Socket grafting with or without buccal augmentation with anorganic bovine bone at immediate post-extractive implants: 6-month after loading results from a multicenter randomised controlled clinical trial

PURPOSE

To evaluate whether grafting with additional anorganic bovine bone to augment horizontally the buccal plate (internal and external grafting [IEG]) at single post-extractive implants preserves the alveolar ridge, improving aesthetics, better than internal socket grafting alone (ISGA).

MATERIAL AND METHODS

A total of 78 patients, treated in four Italian private practices, requiring a single immediate post-extractive implant, having at least 1 mm of implant-to-buccal bone gap after implant insertion and a preserved buccal bone, had the residual bone-to-implant gap filled with anorganic bovine bone. Thirty-nine randomly allocated patients received additional buccal horizontal augmentation of about 2 mm thickness with the same bone substitute (IEG group) covered with collagen resorbable membranes. Implants were submerged for 4 months before being loaded with provisional acrylic crowns. Definitive crowns were delivered after 6 months. Outcome measures were crown/implant failures, complications and aesthetics recorded by blinded assessors 6 months after initial loading, at delivery of definitive crowns.

RESULTS

Six months after initial loading, 8 patients dropped out, did not complete the treatment or were treated twice and therefore had to be excluded (4 from each group). There were no statistically significant differences for implant failures and complications between the two groups. Two implants failed in the IEG group versus 1 in the ISGA group. Four complications occurred, 2 in each group. The mean implant aesthetic score (IAS) was 7.8 at ISGA sites and 8.0 at IEG sites. There were no statistically significant differences between the two groups (P = 0.492; difference 0.2 mm; 95% CI -0.769, 0.369) for IAS score. There were no statistically significant differences in the outcomes between the centres.

CONCLUSIONS

The use of adjunctive anorganic bovine bone placed buccally at preserved buccal sites of immediate post-extractive implants may not improve the aesthetic outcome, however additional research is needed to confirm or reject these preliminary findings.

Complement anaphylatoxin C3a is a potent inducer of embryonic chick retina regeneration

Identifying the initiation signals for tissue regeneration in vertebrates is one of the major challenges in regenerative biology. Much of the research thus far has indicated that certain growth factors have key roles. Here we show that complement fragment C3a is sufficient to induce complete regeneration of the embryonic chick retina from stem/progenitor cells present in the eye, independent of fibroblast growth factor receptor signaling. Instead, C3a induces retina regeneration via STAT3 activation, which in turn activates the injury- and inflammation-responsive factors, IL-6, IL-8 and TNF-α. This activation sets forth regulation of Wnt2b, Six3 and Sox2, genes associated with retina stem and progenitor cells. Thus, our results establish a mechanism for retina regeneration based on injury and inflammation signals. Furthermore, our results indicate a unique function for complement anaphylatoxins that implicate these molecules in the induction and complete regeneration of the retina, opening new avenues of experimentation in the field.

Adult stem cells in small animal wound healing models

This chapter broadly reviews the use of stem cells as a means to accelerate wound healing, focusing first on the properties of stem cells that make them attractive agents to influence repair, both alone and as vehicles for growth factor delivery. Major stem cell reservoirs are described, including adult, embryonic, and induced pluripotent cell sources, outlining the advantages and limitations of each source as wound healing agents, as well as the possible mechanisms responsible for wound healing acceleration. Finally, the chapter includes a materials and methods section that provides an in-depth description of adult tissue harvest techniques.

The impact of thickness of resorbable membrane of human origin on the ossification of bone defects: a pathohistologic study

BACKGROUND/AIM

A wide range of resorbable and non-resorbable membranes have been investigated over the last two decades. The barrier membrane protects the defect from ingrowth of soft tissue cells and allows bone progenitor cells to develop bone within a blood clot that is formed beneath the barrier membrane. The membranes are applied to reconstruct small bony defect prior to implantation, to cover dehiscences and fenestrations around dental implants. The aim of this study was to evaluate the influence of human resorbable demineralized membrane (RHDM) thickness on bone regeneration.

METHODS

The experiment, approved by Ethical Committee, was performed on 6 dogs and conducted into three phases. Bone defects were created in all the 6 dogs on the left side of the mandible, 8 weeks after extraction of second, third and fourth premolars. One defect was covered with RHDM 100 micro thick, one with RHDM 200 micro thick, and the third defect left empty (control defect). The histopathological analysis was done 2, 4 and 6 months after the surgery. In the third phase samples of bone tissue were taken and subjected to histopathological analysis.

RESULTS

In all the 6 dogs the defects treated with RHDM 200 micro thick showed higher level of bone regeneration in comparison with the defect treated with RHDM 100 micro thick and especially with empty defect.

CONCLUSION

Our results demonstrated that the thicker membrane showed the least soft tissue ingrowths and promoted better bone formation at 6 months compared with a thinner one.

Effects of small intestinal submucosa (SIS) on the murine innate immune microenvironment induced by heat-killed Staphylococcus aureus

The use of biological scaffold materials for wound healing and tissue remodeling has profoundly impacted regenerative medicine and tissue engineering. The porcine-derived small intestinal submucosa (SIS) is a licensed bioscaffold material regularly used in wound and tissue repair, often in contaminated surgical fields. Complications and failures due to infection of this biomaterial have therefore been a major concern and challenge. SIS can be colonized and infected by wound-associated bacteria, particularly Staphylococcus aureus. In order to address this concern and develop novel intervention strategies, the immune microenvironment orchestrated by the combined action of S. aureus and SIS should be critically evaluated. Since the outcome of tissue remodeling is largely controlled by the local immune microenvironment, we assessed the innate immune profile in terms of cytokine/chemokine microenvironment and inflammasome-responsive genes. BALB/c mice were injected intra-peritoneally with heat-killed S. aureus in the presence or absence of SIS. Analyses of cytokines, chemokines and microarray profiling of inflammasome-related genes were done using peritoneal lavages collected 24 hours after injection. Results showed that unlike SIS, the S. aureus-SIS interactome was characterized by a Th1-biased immune profile with increased expressions of IFN-γ, IL-12 and decreased expressions of IL-4, IL-13, IL-33 and IL-6. Such modulation of the Th1/Th2 axis can greatly facilitate graft rejections. The S. aureus-SIS exposure also augmented the expressions of pro-inflammatory cytokines like IL-1β, Tnf-α, CD30L, Eotaxin and Fractalkine. This heightened inflammatory response caused by S. aureus contamination could enormously affect the biocompatibility of SIS. However, the mRNA expressions of many inflammasome-related genes like Nlrp3, Aim2, Card6 and Pycard were down-regulated by heat-killed S. aureus with or without SIS. In summary, our study explored the innate immune microenvironment induced by the combined exposure of SIS and S. aureus. These results have practical implications in developing strategies to contain infection and promote successful tissue repair.

Immunoregulatory effects of glutathione during mesenchymal stem cell differentiation to hepatocyte-like cells

BACKGROUND

The role of mesenchymal stem cell in cellular therapy is the subject of interest for many researchers. The differentiation potential of MSCs and abilities in modulations of the recipient's immune system makes them important cells in tissue regenerative studies. MSCs by releasing the proinflammatory cytokines play important role in immunomodulatory systems; however the signaling pathways for releasing of these mediators are not well understood. Glutathione has been shown to play a role in modulation of cytokines in hepatogenic differentiation.

OBJECTIVE

In the current study we aimed to investigate the effects of buthionine sulfoximine (BSO, inhibitor for glutathione synthesis) and N-acetylecystin (NAC, an inhibitor for ROS generation) on proinflammatory cytokines production in a hepatogenic differentiation model.

RESULTS

BSO and NAC significantly decreased IL-6 and TNF-α levels at 14 days of differentiation, whereas, NAC decreased the levels of IL-8 at days 2 and 14 of differentiation. Moreover, intracellular glutathione level during the differentiation was depleted.

CONCLUSION

Our current study suggests a novel role of GSH as an immunopharmacological regulatory molecule during hepatogenic differentiation. Finally, this information may shed some light on the understanding of MSCs responses in transplantation and cell therapy in diseases such as chronic hepatic diseases.

[Advances of research on preparation of tendon tissue engineered scaffolds using electrospinning]

OBJECTIVE

To review the application of electrospinning in preparation of tendon tissue engineered scaffolds, to describe its application effect and prospects.

METHODS

Recent literature was extensively reviewed and summarized from various aspects, concerning the application of electrospinning in preparing tendon tissue engineered scaffolds.

RESULTS

Because of its huge surface and high porosity, the electrospun fibers prepared by electrospinning technology have been widely used in the manufacture of tendon tissue engineered scaffolds in recent years. A variety of materials, including polylactic acid, have been successfully electrospun into various types of tendon tissue engineered scaffolds, and good results in the repair of tendon defect were achieved.

CONCLUSION

The electrospinning technology has provide a new way for the preparation of the tendon tissue engineered scaffolds, with the perfection of the technology they will have broad application prospects in the field of tendon tissue engineering.

Reconstruction of corneal stroma with decellularized porcine xenografts in a rabbit model

PURPOSE

To evaluate the potential use of decellularized porcine stromal matrix (PSM) for reconstruction of corneal stroma in a rabbit model.

METHODS

Ten chinchilla bastard rabbit corneas were exposed to a circular half-thickness keratotomy with a 3.0 mm diameter at the central cornea. Porcine corneas were decellularized using hypotonic tris buffer, ethylene diamine tetra-acetic acid (EDTA, 0.1%), aprotinin (10 K IU/ml) and 0.3% sodium dodecyl sulphate (SDS). The 3.0 mm in diameter decellularized corneal stromal xenograft was inserted into the pocket, and the incision was closed with four 10.0 nylon sutures. Clinical photographs were taken at day 1, day 7, day 30 and on a monthly basis for up to 6 months after transplantation. Six months after surgery, the rabbits were killed and eyes were enucleated. Haematoxylin-eosin (HE) and 4,6-diamidino-2-phenylindole (DAPI) staining were performed to confirm the complete removal of the corneal cells after decellularization of porcine corneas and repopulation with rabbit cells. Alcian blue staining was performed for analysing the structure of the extracellular matrix (ECM).

RESULTS

Efficient elimination of porcine cells was achieved by our decellularization protocol and confirmed via HE and DAPI stainings. Moreover, the major histoarchitectural ECM structure had been maintained as visualized by the alcian blue stain. Finally, the PSM was biocompatible with the host's epithelium evidenced as a regrowth covering the exposed xenograft.

CONCLUSIONS

This novel technique of tissue engineering may provide one of many solutions to addressing anterior corneal pathological conditions in the face of a shortage of human corneal material.

[Analysis of an acellular pigskin based nerve scaffold]

A scaffold fabricated with lysine/nerve growth factor (NGF)/poly (lactic acid coglycolic acid) copolymer (PLGA) and acellular pigskin was evaluated in vitro as a potential artificial nerve scaffold. Properties of the scaffold such as microstructure, mechanical property, degradation behavior in PBS and water, Schwann cell adhesion property, and release of NGF were investigated. Results showed PLGA had permeated into the porous structure of acellular pigskin; its breaking strength was 8.308 MPa, breaking extensibility was 38.98%, elastic modulus was 97.27 MPa. The porosities of the scaffold ranged from 68.3% to 81.2% with densities from 0.62 g/cm3 to 0.68 g/cm3. At 4 weeks of degradation in vitro, maximum mass loss ratio was 43.3%. The release of NGF could still be detected on the 30th day, and its accumulative release rate was 38%. Lysine added into the scaffold neutralized the acidoid preventing degradation of PLGA to maintain a solution pH value. Schwann cells had grown across the scaffold after co-cultivation for 15 days. These in vitro properties of the pigskin based composite might indicate its potentiality to be an artificial nerve scaffold.

Emerging concepts of laser-activated nanoparticles for tissue bonding

We report recent achievements and future perspectives of minimally invasive bonding of biological tissues triggered by laser light. In particular, we review new advancements in the biomedical exploitation of near-infrared absorbing gold nanoparticles as an original solution for the photothermal closure of surgical incisions. Advanced concepts of laser tissue bonding involving the application of hybrid nanocomposites obtained by inclusion of nanochromophores into biopolymer scaffolds are also introduced. The perspectives of tissue bonding are discussed in the following aspects: (1) tissue bonding with highly-stabilized nanochromophores, (2) enhanced tissue bonding with patterned nanocomposites, (3) real-time monitoring of temperature distributions, (4) tracking of tissue regeneration based on the optical resonances of gold nanoparticles.

[Electrospinning technology in tissue engineering scaffolds]

Tissue engineering technology provides a new method to repair ill tissue and worn-out organs. In tissue engineering, scaffolds play an important role in supporting cell growth, inducing tissue regeneration, controlling tissue structure and releasing active factor. In the last decade, electrospinning technology developed rapidly and opened vast application fields for scaffolds. In this review, we summarized the technological conditions of electrospinning for scaffolds, the study of electrospun fiber scaffolds applied in tissue cell cultivation, and some new directions of electrospinning technology for scaffolds. We also addressed development directions of electrospinning research for scaffolds.

[Improved mechanical strength and cell occlusivity of electrospun L-polylactic acid aligned nanofibrous membranes by post heat treatment]

Electrospun nanofibrous materials are considered as ideal scaffolds for tissue engineering because their fibrous structure is quite similar to the morphology of natural extracellular matrix, and they can offer biomimetic microenvironment for cell growth. However, the highly porous scaffolds are too weak to meet the mechanical requirement of guided tissue regeneration (GTR). In the present investigation, electrospun L-polylactic acid (PLLA) nanofibrous membranes were collected with high speed rolling method, and then hot stretched and annealed to improve the tensile strength and cell occlusivity. The membrane with the maximum tensile strength (strength 103MPa and modulus 1.83GPa) was obtained by hot-stretching for twice at 100 degrees C and further annealed for 10min at the same temperature. Cytotoxicity test showed that the heat treated membrane supported well the attachment and growth of human periodontal ligament cells, but inhibited the cell proliferation. The cell occlusivity of the membrane was also significantly improved as the porosity decreased after heat treatment. It could be used as the enhancement interlayer of barrier materials for GTR.

Performance of novel nanofibrous biopolymer membrane for guided bone regeneration within rat mandibular defect

BACKGROUND/AIM

A novel nanofibrous membrane of a degradable biopolymer poly (lactide-co-ε-caprolactone) (PLCL) for guided bone regeneration (GBR) was designed and its tissue compatibility and ability to promote the regeneration of new bone were investigated in a rat mandibular defect model.

MATERIALS AND METHODS

The nanofibrous structuring of the PLCL polymer was facilitated by a solvent-induced phase separation method using camphene as the porogen. The PLCL membrane was implanted in a critical-sized (5 mm diameter) defect of the rat mandible.

RESULTS

The assessment of cell compatibility conducted using undifferentiated pre-osteoblast cells (MC3T3-E1) showed favorable cell adhesion and growth on the nanofiber PLCL membrane with an active cytoskeletal processes and increment in the cell population with culture time. In vivo results at four weeks post-operation demonstrated that the PLCL nanofibrous membrane induced better guided new bone formation than the defect control group while protecting the bone defect against the ingrowth of fibrous tissues.

CONCLUSION

Based on these results, the newly-developed PLCL nanofibrous biopolymer may be useful as a biocompatible and bone regenerative guidance membrane in dentistry.

Hard and soft tissue augmentation in implant surgery: a case report

Correct pre- and postimplant hard and soft tissue management is prerequisite to achieving optimal esthetic and functional outcomes after implant-prosthesis treatment. Various different methods for preimplant hard tissue augmentation in alveolus maxillary atrophy are described. In some cases, non-resorbable titanium-reinforced membranes are employed for vertical augmentation of the edentulous crest. Also well documented is soft tissue management through mucus-gingival surgery techniques that increase the thickness of peri-implant keratinized gingiva, enhancing soft tissue esthetic and health. These methods also include the use of epithelial-connectival grafts collected from the palate. Here we present a clinical case of severe bone vertical resorption in edentulous areas treated with two vertical ridge augmentations by means of non-resorbable membranes in the retromandibular area and deferred insertion of six implants. Peri-implant plastic surgery techniques to improve the quantity of keratinized mucosa during the second surgery phase are also discussed. Combination of the two techniques resulted in harmonic tissue architecture and adequate presence of keratinized gingiva.

Adipose-derived stem cells: current findings and future perspectives

Adipose tissue is an abundant source of mesenchymal stem cells, which have shown promise in the field of regenerative medicine. Furthermore, these cells can be readily harvested in large numbers with low donor-site morbidity. During the past decade, numerous studies have provided preclinical data on the safety and efficacy of adipose-derived stem cells, supporting the use of these cells in future clinical applications. Various clinical trials have shown the regenerative capability of adipose-derived stem cells in subspecialties of medical fields such as plastic surgery, orthopedic surgery, oral and maxillofacial surgery, and cardiac surgery. In addition, a great deal of knowledge concerning the harvesting, characterization, and culture of adipose-derived stem cells has been reported. This review will summarize data from in vitro studies, pre-clinical animal models, and recent clinical trials concerning the use of adipose-derived stem cells in regenerative medicine.

Transplantation of nanostructured composite scaffolds results in the regeneration of chronically injured spinal cords

The destruction and hollowing of entire tissue segments represent an insurmountable barrier to axonal regeneration and therapeutics in chronic spinal cord injury. To circumvent this problem, we engineered neural prosthetics, by assembling electrospun nanofibers and self-assembling peptides into composite guidance channels and transplanted them into the cysts of a postcontusive, chronic spinal cord injury rat model, also providing delivery of proregenerative cytokines. Six months later conspicuous cord reconstruction was observed. The cyst was replaced by newly formed tissue comprising neural and stromal cells. Nerve fibers were interspersed between and inside the guidance channels, spanning the lesion, amidst a well-developed vascular network, basal lamina, and myelin. This was accompanied by a significant improvement in the activity of ascending and descending motor pathways and the global locomotion score. Thus by engineering nanostructured matrices into neuroprosthetics, it is possible to recreate an anatomical, structural, and histological framework, which leads to the replacement of large, hollow tissue gaps in the chronically injured spinal cord, fostering axonal regeneration and neurological recovery.

In vitro and in vivo chitosan membranes testing for peripheral nerve reconstruction

Tissue regeneration over a large defect with a subsequent satisfactory functional recovery still stands as a major problem in areas such as nerve regeneration or bone healing. The routine technique for the reconstruction of a nerve gap is the use of autologous nerve grafting, but still with severe complications. Over the last decades several attempts have been made to overcome this problem by using biomaterials as scaffolds for guided tissue regeneration. Despite the wide range of biomaterials available, functional recovery after a serious nerve injury is still far from acceptable. Prior to the use of a new biomaterial on healing tissues, an evaluation of the host's inflammatory response is mandatory. In this study, three chitosan membranes were tested in vitro and in vivo for later use as nerve guides for the reconstruction of peripheral nerves submitted to axonotmesis or neurotmesis lesions. Chitosan membranes, with different compositions, were tested in vitro, with a nerve growth factor cellular producing system, N1E-115 cell line, cultured over each of the three membranes and differentiated for 48h in the presence of 1.5% of DMSO. The intracellular calcium concentrations of the non-differentiated and of the 48h-differentiated cells cultured on the three types of the chitosan membranes were measured to determine the cell culture viability. In vivo, the chitosan membranes were implanted subcutaneously in a rat model, and histological evaluations were performed from material retrieved on weeks 1, 2, 4 and 8 after implantation. The three types of chitosan membranes were a viable substrate for the N1E-115 cell multiplication, survival and differentiation. Furthermore, the in vivo studies suggested that these chitosan membranes are promising candidates as a supporting material for tissue engineering applications on the peripheral nerve, possibly owing to their porous structure, their chemical modifications and high affinity to cellular systems.