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.

Rotary jet spinning (RJS) and electrospinning are techniques to obtain fibrous scaffolds. RJS is a simple method, which fabricates three-dimensional fibers by exploiting a high-speed rotating nozzle, creating a polymer jet which stretches until solidification, and does not require high voltage. In opposite, electrospinning technique needs the presence of an external electric field to create fiber from the polymeric jet solution. This article investigates both processes using two different biocompatible polymers: Poly(L-lactic acid) (PLLA) and Poly(ε-caprolactone) (PCL). Samples were characterized by scanning electron microscopy, thermogravimetric analysis, differential scanning calorimeter, and Fourier-transform infrared spectroscopy. Morphological observations showed the efficiency of both techniques in obtaining nanofibers. Thermal analyses of data indicate immiscible property of different blends and the total solvent evaporation. In vitro cytocompatibility test showed that RJS and electrospinning samples exhibited good cytocompatibility. Based on these results, it may be concluded that the fibers obtained with both technologies are non-cytotoxicity and with good biocompatibility, and might be suitable for applications as scaffold for cell growth.

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.

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.

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.