The use of selective barriers as resorbable membranes has become a routine clinical procedure for guided bone regeneration. Therefore, the production of membranes with a low inflammatory potential during their resorption process has become the goal of a considerable number of researches. Aim The purpose of the present study was to evaluate the biocompatibility of poly (L- lactic acid) (PLLA) and biocelulose membranes (BC) inserted in the subcutaneous tissue on the dorsum of rats. Methods Fifteen animals underwent surgical procedures for the insertion of 4 types of membranes: COL (Collagen membrane) – Control Group; BC (Biocellulose membrane); BCAg (Biocellulose membrane impregnated with Silver); PLLA (Poly (L-lactic acid) membrane). All membrane types were inserted into each animal. Animals were euthanized after 3, 7, and 15 days of the surgical procedure. Descriptive histological analyses were carried out to investigate host tissue reaction to membrane presence by assessing the anti-inflammatory process composition associated with the membrane resorption and the presence of foreign-body reaction or encapsulation. Results The BC membranes showed a higher degree of inflammation and poor pattern of integration with the surrounding tissues than the PLLA and COL membranes. Conclusion The PLLA and COL membranes present better biocompatibility than the BC membranes.

Abstract The importance of monitoring in vivo interaction that occurs between cells /bio/tissue recipient in the understanding of tissue regeneration processes becomes ever greater. This study aims to monitor and evaluate the influence of scaffold implants of poly (L-co-D, L lactic acid) - PLDLA synthesized in the laboratory, previously cultured with primary osteoblastic cells heterologously stained with the fluorescent vital dye, PKH26, on the tissue regeneration process in 8 mm central critical defects of the Wistar rat calvaria. The results obtained by MTT assay and monitoring of cells stained with PKH26 dye over 14 days of culture showed that the dye was cytocompatible with osteoblastic cells and did not exert a negative influence on the growth of unstained cells. In the in vivo study, macroscopic observations made during deployment times corroborate the results in vitro, as no apparent signs of toxicity were observed in the implanted bone defect area. The use of mobile monitoring with the dye, PKH26 in vivo is an effective strategy for the understanding of cell behaviour in the presence of PLDLA polymer.

RESUMO OBJETIVO: Trabalho experimental para avaliar o desempenho biológico de arcabouços de hidrogel poli (L-co-D, L ácido lático)-co-trimetileno carbonato/poli (álcool vinílico) (PLDLA-co-TMC/PVA) como implante no preenchimento, e não no reparo, de defeito osteocondral em coelhos Nova Zelândia e verificar a influência do material na proteção tecidual in vivo. MÉTODOS: Foram usados 12 coelhos divididos em grupos de nove e 16 semanas. Em cada animal foi criado um defeito osteocondral em ambos os côndilos femorais mediais, em um foi implantado um arcabouço de hidrogel (grupo pino) e no outro foi mantido o defeito (grupo controle). Após o sacrifício dos animais, foi feita análise histológica do material. RESULTADOS: Os côndilos do grupo pino não evidenciaram reação inflamatória e estavam rodeados por cápsula fibrosa. Já no grupo controle, uma maior proliferação óssea foi observada nas áreas do defeito, porém com cartilagem articular desorganizada, fibrose evidente, atrofia com exposição óssea e proliferação de membrana sinovial. CONCLUSÃO: Os pinos de hidrogel são promissores na função de preenchimento de defeitos osteocondrais, não ocasionam, de modo geral, reação inflamatória e não são eficazes no reparo de defeitos osteocondrais.

ABSTRACT OBJECTIVE: This experimental study aimed to evaluate the biological performance of poly (l-co-D, l-lactic acid)-co-trimetilene carbonate/poly (vinyl alcohol) (PLDLA-co TMC/PVA), hydrogel scaffolds, as an implant in the filling (and not in the repair) of osteochondral defects in New Zealand rabbits, assessing the influence of the material in tissue protection in vivo. METHODS: Twelve rabbits were divided into groups of nine and 16 weeks. In each animal, an osteochondral defect was created in both medial femoral condyles. In one knee, a hydrogel scaffold was implanted (pin group) and in the other, the defect was maintained (control group). A histological analysis of the material was performed after euthanasia. RESULTS: The condyles of the pin group showed no inflammatory reaction and were surrounded by a fibrous capsule. The control group presented higher bone growth in the areas of the defect, but with disorganized articular cartilage, evident fibrosis, bone exposure, atrophy, and proliferation of synovial membrane. CONCLUSION: The hydrogel pins are promising in filling osteochondral defects, generally do not cause inflammatory reactions, and are not effective in the repair of osteochondral defects.

Resumo Os dispositivos de fixação óssea, metálicos convencionais, usados em cirurgia crâniomaxilofacial têm apresentado alguns problemas, tais como, corrosão, inflamação e infecção, além de neoformação de estrutura óssea mecanicamente inferior devido à atrofia gerada pela diferença de módulo elástico entre metal e osso, razões que têm levado ao aumento do interesse por dispositivos poliméricos bioarreabsorvíveis. Os polímeros biorreabsorvíveis mais utilizados nesta aplicação pertencem à família dos poli (α-hidroxi ácidos), que têm como característica degradarem por hidrólise de suas ligações ésteres, tal como copolímero poli (L-ácido láctico-co-D, L ácido láctico), PLDLA. Neste trabalho foram investigados alguns efeitos da adição de poli (caprolactona triol), PCL-T sobre PLDLA. Foram preparados pinos por fusão de blendas nas seguintes composições 100/0, 90/10, 70/30 and 50/50 (m/m), PLDLA/PCL-T. Os pinos foram caracterizados por diferentes técnicas (DSC, MEV e ensaio mecânico). A degradação in vitro dos pinos foi investigada, sendo observado que a adição de PCL-T no PLDLA modificou suas propriedades mecânicas e morfológicas. Tais mudanças podem apresentar potencial para outras aplicações do material, onde a questão da flexibilidade se faça necessária.

Abstract The bone fixation devices, conventional metallic cranium used in surgery have presented some problems, such as corrosion, inflammation and infection, and a lower mechanically newly formed bone structure due to the atrophy caused by the difference in stiffness between metal and bone. These reasons have led to increased interest in bioreabsorbable polymeric devices. The most bioresorbable polymers used in this application belong to the family of poly (α-hydroxy acids), which are characterized degrade by hydrolysis of its ester linkages, such as copolymer poly (L-lactic acid-co-D, L lactic acid) (PLDLA). In this work was investigated some effects of the addition poly (caprolactone triol), PCL-T in the PLDLA. Pins were prepared by melting in the 100/0, 90/10, 70/30 and 50/50 (w/w) compositions, PLDLA/PCL-T. The pins were characterized by different methods (DSC, SEM and mechanical test). The in vitro pins degradation was investigated. It was observed that the addition of PCL-T of PLDLA modifies the mechanical properties, morphological, we conclude that PLDLA/PCL-T can be a potential material for various applications, where the question of flexibility to make necessary.

In bone tissue engineering, cell-scaffold constructs are used to stimulate complete, functional tissue replacement that does not occur naturally in critical-size defects. In this report, we describe the application potential of poly (L-co-D,L lactic acid)-PLDLA 70/30, synthesized in house as constructs loaded with osteoblast-like cells on bone tissue engineering. In vitro biological results show that the porogen leached PLDLA scaffolds are cytocompatible with osteoblast cells, able to stimulate significant cells growth during the first 14 days of culture, during which the morphology and cell behavior of osteoblasts cultured on the scaffolds were monitored by scanning electron microscopy (SEM). In vivo, PLDLA constructs were implanted in 5 mm bilateral critical-size defects created in rat-calvariae and then evaluated histologically 8 and 12 weeks after implantation. The histological results showed that PLDLA constructs supported the growth of new tissue, with a degradation rate close to that of native bone formation and decrease of inflammatory response over time of implantation. These data provide evidences that the synthesized PLDLA polymer has application potential as construct for bone tissue engineering.

Carbon nanotubes (CNT) have been studied for biomedical applications due to their unique properties. However, pristine CNT have structural features and impurities that can cause toxicity to biological systems. In this work, we describe a method to purify multiwalled carbon nanotubes (MWCNT) by chemical modification and subsequent attachment of hydroxyl and carboxyl groups to improve dispersion and to decrease toxic effects. Nanocomposites from poly (L-lactic acid) (PLLA) and nanotubes were produced by the solvent casting method and characterized and evaluated for cytocompatibility with Vero cells. The nanocomposite interactions with Vero cells demonstrated that the cells were able to adhere and sustain proliferation and showed favorable cytocompatibility. In vitro studies also revealed an increase in fibroblast cell viability in the nanocomposites, compared with neat PLLA.

Bionanocomposites derived from poly(L-Lactide) (PLLA) were reinforced with chemically modified cellulose nanocrystals (m-CNCs). The effects of these modified cellulose nanoparticles on the mechanical and hydrolytic degradation behavior of polylactide were studied. The m-CNCs were prepared by a method in which hydrolysis of cellulose chains is performed simultaneously with the esterification of hydroxyl groups to produce modified nanocrystals with ester groups. FTIR, elemental analysis, TEM, XRD and contact angle measurements were used to confirm and characterize the chemical modifications of the m-CNCs. These bionanocomposites gave considerably better mechanical properties than neat PLLA based on an approximately 100% increase in tensile strength. Due to the hydrophobic properties of the esterified nanocrystals incorporated into a polymer matrix, it was also demonstrated that a small amount of m-CNCs could lead to a remarkable decrease in the hydrolytic degradation rate of the biopolymer. In addition, the m-CNCs considerably delay the degradation of the nanocomposite by providing a physical barrier that prevents the permeation of water, which thus hinders the overall absorption of water into the matrix. The results obtained in this study show the nanocrystals can be used to reinforce polylactides and fine-tune their degradation rates in moist or physiological environments.

The present study reports the deposition of coating using Plasma Electrolytic Oxidation (PEO) onto grade 4 titanium to produce novel surface features. Samples were treated in an electrolytic solution of calcium acetate and sodium glycerolphosphate. The temporal evolution of hydroxyapatite coatings with high Ra roughness and a maximum thickness of 120 µm was obtained. X-ray spectra revealed the presence of hydroxyapatite, rutile and calcium phosphate. Cell growth measurement by MTT assay showed that the coatings were not toxic because cells grew on all samples.

Surface modification techniques based on the grafting of chemical functional groups and immobilization of bioactive molecules have been used to improve biocompatibility and clinical performance of bioabsorbable scaffolds in tissue engineering and medicine regenerative applications. This study aimed at developing and characterizing a biomimetic surface to stimulate bone regeneration by a simple and low-cost method of surface biofunctionalization of the poly (L-co-D,L lactic acid)-PLDLA scaffolds. The method was obtained by grafting reaction of carboxyl groups (-COOH) on their surface via acrylic acid (AAc) polymerization process, followed by immobilization of collagen type I (Col). Such approach resulted in a surface morphology markedly modified after treatment, with increase of pores and roughness on PLDLA-AAc surfaces and a network of fibrillar collagen deposition in non-specific areas of PLDLA-Col surfaces. The cytocompatibility of collagen-immobilized scaffolds was significantly improved in terms of cellular adhesion, proliferation, collagen synthesis and maintenance of osteoblast-like phenotype, indicating, therefore, the fundamental role of collagen protein over the biological interactions that occur by bio-recognition mimetic mechanisms at biomaterials interface. These results indicate that the surface modification method used here may be useful as a strategy to develop biofunctional scaffolds, which provide a more successful clinical application of biomaterials in the tissue engineering field.

Os biomateriais poli L-ácido lático (PLLA) e o poli caprolactona (PCL) são os polímeros mais estudadas na área dos materiais bioreabsorvíveis. Dentre as suas principais características que contribuem para a interação celular, temos a especificidade química da superfície, elétrica, hidrofobicidade e topografia. Ainda, observa-se o tempo de degradação, porosidade, biocompatibilidade com o tecido biológico, bem como, a confecção com as mais variadas formas e dimensões. Já a prática da cultura celular, tem como objetivo estudar a adesão, migração, diferenciação e a proliferação celular utilizando-se um determinado material ou substância. Contudo, poucos trabalhos utilizando os biomateriais ora supracitados e a aplicação em células neuro2A foram realizados. Sabe-se que este tipo celular é derivado de células embrionárias da crista neural, as quais originam em neurônios simpáticos e apresentam como característica a imortalidade, portanto, são excelentes modelos em ensaios in vitro. Nesse sentido, o presente estudo avalia a adesão e a proliferação desta linhagem celular sobre os biopolímeros poli caprolactona (PCL) e poli L-ácido lático (PLLA).

Biomaterials poly L-lactic acid (PLLA) and poly caprolactone (PCL) are the most studied in the area of bioresorbable materials. Among the main features that contribute to cell interaction, we have the specific surface chemistry, electrical, hydrophobicity and topography. Also, is observed the degradation time, porosity, biocompatibility with biological tissue, as well as the preparation of the most varied shapes and sizes. The practice of cell culture, aims to study the adhesion, migration, differentiation and cell proliferation using a given material or substance. However, few studies were performed using these biomaterials and the application of neuro2A cells. It is known that this cell type is derived from the embryonic neural crest cells, which originate in sympathetic neurons and have the characteristic of immortality, therefore, are excellent models in vitro assays. Accordingly, the present study evaluates the adhesion and proliferation of this cell line on the biopolymers poly caprolactone (PCL) and poly L-lactic acid (PLLA).

Terpolymers of L-lactide, D,L-lactide and trimethylene carbonate (TMC) were synthesized via the ring-opening polymerization reaction for cyclic monomers using stannous octoate as the initiator at a ratio of ~0.05 mol% (monomers/(SnOct)2). Synthesis was done at 130 ºC for 48 h. The inclusion of TMC, an aliphatic elastomeric polycarbonate, alongside polymer chain segments containing L-lactide and D,L-lactide, was expected to yield a material with improved properties such as increased elongation; this would overcome the limitation of copolymers consisting entirely of lactide and D,L-lactide. The terpolymer properties were assessed by Nuclear magnetic resonance spectroscopy ¹H and 13C NMR, infrared spectroscopy, differential scanning calorimetry and thermogravimetry, with particular attention being given to the effect of TMC on the copolymer of L-lactide-co-D,L-lactide. The mixing of these polymers resulted in material with a high molar mass (10(5) g/mol). The mechanical properties of the terpolymer were assessed using pins of this material that were tested by mechanical flexion at three points. When compared with results for the copolymer PLDLA there was a decrease in Young's modulus for the TMC-containing terpolymer.

Um dos maiores problemas da cirurgia restauradora dos tendões flexores é evitar a formação de aderências, pois limita seu deslizamento. Assim, é muito desejável que a cicatrização ocorra o mais rápido possível, restaurando a capacidade de deslizamento dos tendões, sem limitações dos movimentos. O objetivo deste trabalho foi analisar a resistência do Tendão calcâneo, utilizando membrana de PLDLA-TMC como protetor da aderência dos tecidos adjacentes após implantes em coelhos New Zeland. Foram utilizados 20 coelhos, divididos em dois grupos, os quais foram submetidos à secção do tendão calcâneo e posterior sutura com técnica de Kessler modificada. No grupo A, logo após sutura o animal foi sacrificado e o tendão foi enviado para ensaio mecânico. Já no grupo B, após três semanas, os animais foram sacrificados e o material foi submetido à análise histológica. Os resultados obtidos a partir do ensaio mecânico mostraram melhora nos valores da resistência à tração dos implantes com a membrana, comparados aos apenas suturados. Na cicatrização da lesão, ocorreu melhor organização das fibras colágenas quando foi utilizado o polímero PLDLA-TMC, além de uma menor aderência cicatricial. Conclui-se que a membrana de PLDLA-TMC é promissora na reparação de lesões tendíneas.

The most common problem in reconstructive surgery of the flexor tendons is prevent adhesion formation by limiting its movement. Thus, it is very desirable that healing occurs as quick as possible, restoring tendons sliding capability, without limitation of movement. The objective of this study was to analyze the strength of the Achilles tendon, using PLDLA-TMC membrane as protector of the adhesion of adjacent tissues implanted in New Zealand rabbits. Twenty rabbits were used, divided into two groups, which were submitted to the section of the Achilles tendon and posterior suture with modified Kessler technique. In group A, after suturing, the animals were sacrificed and the tendon was sent for mechanical tests. In group B, after three weeks, the animals were sacrificed and the material was subjected to histological analysis. The results of the mechanical tests showed improvement in the values of the tensile strength of the implants with the membrane, compared to the sutured ones. In the injury healing process, better organization of collagen fibers occurred when the PLDLA-TMC polymer was used, and a smaller scar tissue adhesion was developed. In conclusion, the PLDLA-TMC membrane is promising in the repair of tendon injures.

The application of polymer-based bioresorbable temporary devices in the medical field grows continuously, and professionals from several areas act to solve problems related to body functions lost due to diseases, accidents or natural wear. Here we study the influence from poly(caprolactonetriol) (PCL-T) on the degeneration process in the copolymer poly(L-co-DL-lactic acid) (PLDLA) membrane, by producing PLDLA/PCL-T blends with 90/10, 70/30 and 50/50 relative concentrations. The data for in vitro degradation showed that PCL-T decreases the rate of PLDLA. This was obtained with the following techniques: Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Gel Permeation Chromatography (GPC) and Scanning Electron Microscopy (SEM). Therefore, it is possible to vary the membrane degradation rate by changing the blend composition, which is a tool to tailor a biomaterial.

Cell adhesion on materials surface is critical because this phenomenon occurs before other events, as cell spreading, cell migration and cell differentiation. it is commonly accepted that the adhesion of cells on solid substrate is influenced by several substratum surface properties, such as wettability, surface charge, roughness and topography. plasma technique is a convenient method for modifying surface properties of materials without affecting physical properties. in this study, poly(lactide-co-glycolide), plga, membranes were modified by oxygen and nitrogen plasma to improve polymer hydrophilicity and verify their effect on vero cells culture. the plga membranes, which were characterized by sem and contact angle, showed increased surface rugosity and narrower contact angles. cell adhesion, cytotoxicity assay, sem and cytochemistry analysis showed that plasma treatment was beneficial to cell growth by improving cell-polymer interaction. Cell adhesion on materials surface is critical because this phenomenon occurs before other events, as cell spreading, cell migration and cell differentiation. It is commonly accepted that the adhesion of cells on solid substrate is influenced by several substratum surface properties, such as wettability, surface charge, roughness and topography. Plasma technique is a convenient method for modifying surface properties of materials without affecting physical properties. In this study, poly(lactide-co-glycolide), PLGA, membranes were modified by oxygen and nitrogen plasma to improve polymer hydrophilicity and verify their effect on Vero cells culture. The PLGA membranes, which were characterized by SEM and contact angle, showed increased surface rugosity and narrower contact angles. Cell adhesion, cytotoxicity assay, SEM and cytochemistry analysis showed that plasma treatment was beneficial to cell growth by improving cell-polymer interaction.

Poly (L-co-D,L lactic acid) (PLDLA) is an important biomaterial because of its biocompatibility properties that promote cellular regeneration and growth. The aim of this study was to evaluate the polymer-tissue interaction of PLDLA implants in the dorsal subcutaneous tissue of male Wistar rats at various intervals (2, 7, 15, 30, 60 and 90 days) after implantation. Physical properties such as the glass transition point (Tg), degradation behavior and other mechanical properties were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), scanning electron microscopy (SEM) and tension tests. Analysis of the degradation of PLDLA membranes in vitro showed that the polymer became crystalline as a function of the degradation time. Mechanical tension tests showed that the polymer behaved like a ductile material: when subjected to constant tension it initially suffered deformation, then elongation and finally ruptured. TGA/MEV provided evidence of PLDLA membrane degradation. For histological analysis, samples from each group were processed in xylol/paraffin, except for the 60 - and 90 - day samples. Each of the latter samples was divided in two: one half was treated with xylol/paraffin and the other with historesin. Light microscopy showed the adhesion of cells to the biomaterial, the formation of a conjunctive capsule around the implant, the presence of epithelioid cells, the formation of foreign body giant cells and angiogenesis. During degradation, the polymer showed a 'lace' - like appearance when processed in xylol/paraffin compared to the formation of "centripetal cracks in the form of glove fingers" when embedded in historesin.