Miringoplastia com a utilização de um novo material biossintético

Natural rubber latex-based biomaterials for drug delivery and regenerative medicine: Trends and directions

Natural Rubber Latex (NRL) has shown to be a promising biomaterial for use as a drug delivery system to release various bioactive compounds. It is cost-effective, easy to handle, biocompatible, and exhibits pro-angiogenic and pro-healing properties for both soft and hard tissues. NRL releases compounds following burst and sustained release kinetics, exhibiting first-order release kinetics. Moreover, its pore density can be adjusted for tailored kinetics profiles. In addition, biotechnological applications of NRL in amblyopia, smart mattresses, and neovaginoplasty have demonstrated success. This comprehensive review explores NRL's diverse applications in biotechnology and biomedicine, addressing challenges in translating research into clinical practice. Organized into eight sections, the review emphasizes NRL's potential in wound healing, drug delivery, and metallic nanoparticle synthesis. It also addresses the challenges in enhancing NRL's physical properties and discusses its interactions with the human immune system. Furthermore, examines NRL's potential in creating wearable medical devices and biosensors for neurological disorders. To fully explore NRL's potential in addressing important medical conditions, we emphasize throughout this review the importance of interdisciplinary research and collaboration. In conclusion, this review advances our understanding of NRL's role in biomedical and biotechnological applications, offering insights into its diverse applications and promising opportunities for future development.

Application of a Purified Protein From Natural Latex and the Influence of Suture Type on Achilles Tendon Repair in Rats

BACKGROUND

The prolonged tendon-healing process, the high costs associated with treatment, the increase in the number of injuries over the past decades, and the lack of consensus on the optimal treatment of tendon injuries are a global problem. Restoring the normal tendon anatomy and decreasing the healing time are key factors for treatment advancement.

HYPOTHESIS

Application of a purified protein from natural latex (PPNL) accelerates the healing process, increasing collagen synthesis and decreasing metalloproteinases. PPNL associated with a simpler suture technique should decrease the healing time.

STUDY DESIGN

Controlled laboratory study.

METHODS

Injury, surgery, and treatment with PPNL were conducted with male Sprague-Dawley rats. Two suture techniques were used: U-suture, a simpler and lesser traumatic technique, and Kessler-Tajima, to avoid strangulation of the microcirculation. Achilles tendons were completely sectioned, and 100 µL of 0.1% PPNL was applied on the tendon during surgery. Tendon morphology, distribution, and quantity of collagen types I and III, as well as expression of TIMP-1, TIMP-2, MMP-2, and MMP-9 and ultrastructural aspects of cells and collagen fibrils, were assessed after 2 and 4 weeks.

RESULTS

PPNL treatment improved collagen type I synthesis and reduced MMP-2 expression. All groups showed a 6.8-times increase in tendon weight as compared with the control group after 2 weeks and a 5.2-times increase after 4 weeks. All groups showed an increase in diameter after 4 weeks, except for the ones treated with PPNL, which showed a slight reduction in diameter. The peak of concentration of collagen fibrils with a 80-nm diameter was 27.79% in the control group; all other experimental groups presented fibrils between 50 and 60 nm. However, the best results were observed with Kessler-Tajima suture associated with PPNL.

CONCLUSION/CLINICAL RELEVANCE

There are no known medicines or substances capable of aiding the tendon healing process besides surgery. The discovery of a substance able to improve this process and decrease its duration represents an important advancement in orthopaedic medicine.

In vitro evaluation of poly (lactic-co-glycolic acid)/polyisoprene fibers for soft tissue engineering

The polymeric blend of poly (lactic-co-glycolic acid) (PLGA) and polyisoprene (PI) has recently been explored for application as stents for tracheal stenosis and spring for the treatment of craniosynostosis. From the positive results presented in other biomedical applications comes the possibility of investigating the application of this material as scaffold for tissue engineering (TE), acquiring a deeper knowledge about the polymeric blend by exploring a new processing technique while attending to the most fundamental demands of TE scaffolds. PLGA/PI was processed into randomly oriented microfibers through the dripping technique and submitted to physical-chemical and in vitro characterization. The production process of fibers did not show an effect over the polymer's chemical composition, despite the fact that PLGA and PI were observed to be immiscible. Mechanical assays reinforce the suitability of these scaffolds for soft tissue applications. Skeletal muscle cells demonstrated increases in metabolic activity and proliferation to the same levels of the control group. Human dermal fibroblasts didn't show the same behaviour, but presented cell growth with the same development profile as presented in the control group. It is plausible to believe that PLGA/PI fibrous three-dimensional scaffolds are suitable for applications in soft tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2581-2591, 2017.

Angiogenic activity of latex from Euphorbia tirucalliLinnaeus 1753 (Plantae, Euphorbiaceae)

AbstractTo assess the pro-angiogenic activity of Euphorbia tirucalli, commonly known as “avelós” plant, we performed a series of tests by applying an aqueous E. tirucalli latex solution (10 mg/mL) to the chorioallantoic membranes (CAMs) of 80 fertilized chicken eggs incubated in a temperature- and humidity-controlled automatic incubator. The results indicated that the aqueous latex solution increased vascular network formation compared to that with the negative control (p < 0.05) and the inhibitor control (p < 0.05). This suggests that under the experimental conditions tested, the aqueous latex solution induced an inflammatory response leading to neoangiogenesis.

Ciprofloxacin release using natural rubber latex membranes as carrier

Natural rubber latex (NRL) from Hevea brasiliensis is easily manipulated, low cost, is of can stimulate natural angiogenesis and cellular adhesion, is a biocompatible, material and presents high mechanical resistance. Ciprofloxacin (CIP) is a synthetic antibiotic (fluoroquinolone) used in the treatment of infection at external fixation screws sites and remote infections, and this use is increasingly frequent in medical practice. The aim of this study was to develop a novel sustained delivery system for CIP based on NRL membranes and to study its delivery system behavior. CIP was found to be adsorbed on the NRL membrane, according to results of energy dispersive X-ray spectroscopy. Results show that the membrane can release CIP for up to 59.08% in 312 hours and the mechanism is due to super case II (non-Fickian). The kinetics of the drug release could be fitted with double exponential function X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy shows some interaction by hydrogen bound, which influences its mechanical behavior.

Avaliação macroscópica e microscópica de implante de Biomembrana em estômago de coelhos (Oryctolagus cuniculus)

Neste estudo foi implantado um retalho de biomembrana de látex natural em substituição a um fragmento da parede de estômago de coelhos albinos, raça Nova Zelândia, adultos, machos não castrados (n=12), com o intuito de avaliar o processo de reparação tecidual no que se refere à biocompatibilidade, à capacidade de reparação tecidual e a possíveis complicações. Aos 15, 30 e 60 dias de pós-operatório, os animais foram sacrificados, mediante o emprego de tiopental sódico (200mg kg-1), para posterior avaliação macroscópica e análise histopatológica da interface do implante com o tecido nativo. Macroscopicamente, aos 15, 30 e 60 dias de pós-operatório observou-se presença de aderências na face serosa. Aos 60 dias de pós-operatório, em todos os animais avaliados, a biomembrana não foi encontrada. Sob microscopia de luz, aos 15 e 30 dias, verificaram-se descontinuidade das camadas muscular e mucosa, presença de infiltrado inflamatório polimorfonuclear. Foram visualizados vasos sanguíneos e fibras musculares. Aos 60 dias, as camadas mucosa, muscular estavam completamente reconstituídas. O implante foi biocompatível e forneceu arcabouço para orientação e desenvolvimento das camadas teciduais do estômago, mediante processos de reparação, restabelecendo a estrutura do órgão.

Use of a latex biomembrane for bladder augmentation in a rabbit model: biocompatibility, clinical and histological outcomes

PURPOSE

To investigate histological features and biocompatibility of a latex biomembrane for bladder augmentation using a rabbit model.

MATERIAL AND METHODS

After a partial cystectomy, a patch of a non-vulcanized latex biomembrane (2x4 cm) was sewn to the bladder with 5/0 monofilament polydioxanone sulfate in a watertight manner. Groups of 5 animals were sacrificed at 15, 45 and 90 days after surgery and the bladder was removed. The 5-mum preparations obtained from grafted area and normal bladder were stained with hematoxylin-eosin. Immunohistochemical staining was performed with a primary antibody against alpha-actin to assess muscle regeneration.

RESULTS

No death, urinary leakage or graft extrusion occurred in any group. All bladders showed a spherical shape. Macroscopically, after 90 days, the latex biomembrane was not identifiable and the patch was indistinguishable from normal bladder. A bladder stone was found in one animal (6.6%). On the 90th day, histology revealed continuity of transitional epithelium of host bladder tissue on the patch area. At this time, the muscle layers were well organized in a similar fashion to native bladder muscle layers. The inflammatory process was higher on grafted areas when compared to controls: 15 days--p < 0.0001, 45 days--p < 0.001, and 90 days--p < 0.01. The anti alpha-actin immunoexpression peaked at 45 days, when the graft was observed covered by muscle cells.

CONCLUSION

The latex biomembrane is biocompatible and can be used in models for bladder augmentation in rabbits. It promotes epithelium and muscle regeneration without urinary leakage.

Analysis of biomaterial latex-derived flow mechanical controller

This paper describes the basic guidelines for developing an innovative biomedical device. It covers the issues of researching about a suitable material, developing a new device, and testing its proprieties to check its effectiveness. The goal of the device is to control food flow into the esophagus, reducing its volume and the speed of food intake to help in the treatment of obesity. This module, called Esophageal Flow Controller (EFC®), is made of latex. Three different models of prototypes were developed, and 10 units of each model had their constructive and mechanical characteristics evaluated. All of them have followed the same manufacturing cycle. The results showed that the Esophageal Flow Control module has all the essential characteristics of an effective device for flow control in the esophagus.

Plug cartilage tympanoplasty in children

The treatment of tympanic membrane perforations in the pediatric population with sequelae of chronic otitis media represents a challenge to otolaryngologists. Aim: to assess the clinical and audiometric results of the inlay technique with a tragus cartilage plug. Materials and Methods: we assessed 23 patients (ages between 1 and 15 years) who underwent plug tympanoplasty. Study design: clinical retrospective. Results: repair success rate was of 82.6%, with audiometric parameters improvement in 87.5% of the patients. Complications were minimum. Conclusion: considering the results attained, this method of tympanoplasty should be considered a good treatment option for tympanic membrane perforation in children.

Membranas de látex natural na herniorrafia diafragmática experimental em cães

Utilizaram-se membranas de látex para o reparo de defeitos diafragmáticos em 12 cães, distribuídos em três grupos: no G1 utilizou-se membrana comercial e no G2, membrana experimental. O G3 foi usado como controle. Foi feito um defeito retangular no músculo diafragma, com 4cm de comprimento por 3cm de largura, que nos grupos G1 e G2 foi substituído pelo implante da membrana de látex correspondente. Os animais foram avaliados por estudo radiográfico, hemograma, videocirurgia e análise histológica. Os resultados mostraram que a membrana de látex do grupo 2 foi eficiente na correção de defeito no diafragma, promovendo a reparação e neovascularização tecidual local, sem causar rejeição durante o período de avaliação.

Biocompatibility of natural latex implanted into dental alveolus of rats

The present study investigated the biocompatibility of a biopolymer based on vegetable latex extracted from the Hevea brasiliensis rubber tree, implanted into the bony alveolar cavity after dental extraction in rats. A granule of latex (area = 0.25 +/- 0.04 mm(2)) was implanted inside the alveolus immediately after extraction of the upper right incisor, and the animals were sacrificed 7, 21 and 42 days after the procedure. The hemi-maxillas were decalcified and processed for embedding in paraffin to obtain semi-serial longitudinal sections 5 mum thick, and then stained with hematoxylin-eosin. The latex granule was observed in the cervical third of the alveolus without any foreign body reaction, or persistence of the initial acute inflammatory reaction. Bone repair in the areas adjacent to the material was quantified, and a decrease was noted in the thickness of the fibrous capsule surrounding the implants from 92.8 +/- 9.3 microm on day 7 to 9.4 +/- 1.8 microm on day 42 (ANOVA, P = 0.01). The quantitative data confirmed acceleration of bone formation (statistically significant at 5%) in parallel with a decrease of connective tissue in the areas around the implants. These results show that the tested material is biologically compatible, and progressively integrated into the alveolar bone, simultaneously accelerating bone formation and playing an important role in the healing process.

Prótese vascular derivada do látex

CONTEXTO: O desenvolvimento de prótese vascular tem sido vital para os avanços e realizações da cirurgia vascular reconstrutora durante as últimas 5 décadas. OBJETIVOS: Desenvolver um novo modelo de prótese vascular microperfurada, confeccionada em tecido recoberto com um composto derivado do látex natural da seringueira (Hevea brasiliensis) e avaliar sua perviedade, trombogenicidade, biocompatibilidade e o processo de cicatrização, além de algumas propriedades mecânicas (adaptabilidade, elasticidade, impermeabilidade e possibilidade de sutura), utilizando como controle a prótese de politetrafluoretileno expandido no mesmo animal. MÉTODOS: Quinze cães foram separados em três grupos de cinco animais. Implantou-se a prótese de tecido e látex microperfurada e, no membro pélvico contralateral, a prótese de politetrafluoretileno expandido em todos os cães. O seguimento pós-operatório foi de 4, 8 e 12 semanas. A apreciação dos resultados foi feita segundo as avaliações clínicas dos pulsos, complicações (coleção líquida, deiscência, granuloma e infecção), arteriografias, análise macroscópica e elétron-micrografias de varredura. RESULTADOS: Os testes estatísticos aplicados não evidenciaram diferenças significativas (p > 0,05) em relação às complicações pós-operatórias e perviedade dos enxertos. Ambas as próteses integraram-se adequadamente aos tecidos circunvizinhos, com um tecido de incorporação formado por fibras colágenas. Constatou-se a presença de neoíntima recoberta por endotélio em toda a extensão da superfície luminal da prótese de tecido e látex microperfurada. Ao contrário, na prótese de politetrafluoretileno expandido, o desenvolvimento endotelial sobre a superfície neointimal limitou-se às regiões próximas às anastomoses. CONCLUSÕES: A prótese de tecido e látex microperfurada demonstrou qualidades estruturais (adaptabilidade, elasticidade, impermeabilidade e possibilidade de sutura) satisfatórias como substituto vascular. Estimulou o crescimento endotelial além das regiões de contato com a artéria nas anastomoses e foi biocompatível no sistema arterial do cão, apresentando adequada integração tecidual.

Latex biomembrane: A new method to coat the open cavity in tympanomastoidectomies

The new cavity created after an open cavity tympanomastoidectomy (OCTM) is filled with an antibiotic impregnated cotton pack (cotton tape, umbilical tape, gauze). The removal of this pack usually causes some bleeding and discomfort for the patient. We propose the use of a latex biomembrane to cover the cavity, which will act as an interface between the raw bone surface and the packing. Study design: clinical prospective. Aim: To study the performance of the latex biomembrane as an interface between the raw bone surface and the pack, and to analyze its role in cavity epithelization. Material and Methods: 64 ears of patients submitted to OCTM were studied. The biomembrane was used in the packing of 54 ears and in the 10 remaining ears the regular cotton tape packing was used. Results: In the majority of the cases where the biomembrane was used the packing was removed much easier with no bleeding or pain for the patient and also showed an earlier cavity epithelization. Conclusion: The use of the latex biomembrane has proven to be an effective method to cover the mastoid cavity facilitating epithelization and removal of mastoid cavity packing.

Healing of subacute tympanic membrane perforations in chinchillas treated with epidermal growth factor and pentoxifylline

HYPOTHESIS

The aims of the present study were to determine the effect of epidermal growth factor (EGF) and pentoxifylline on subacute tympanic membrane (TM) perforations and to quantify the healing rate of such perforations treated with these drugs alone or in combination.

BACKGROUND

It is known that EGF modulates in vitro and in vivo proliferation of epithelial and endothelial cells. Pentoxifylline is a methylxanthine that has been used to treat experimental skin flaps and venous leg ulcers. Data in the literature regarding this subject are contradictory, and quantitative data regarding the effects of EGF and pentoxifylline on TM perforation healing are scarce.

METHODS

We studied 50 chinchillas submitted to TM perforation. On postoperative Day 30, eight were selected for histologic analysis. Of the remaining 42, those presenting little or no healing were distributed into four groups: control, EGF, pentoxifylline, and EGF combined with pentoxifylline.

RESULTS

Histologic analysis showed that the observation period adopted was sufficient to consider the TM perforations subacute. We found significant differences between the study groups and the control group in the healing rate of subacute TM perforations during a 30-day period (analysis of variance; p < 0.001), which was 30.3% for the EGF group, 3.6% for the pentoxifylline group, 16.5% for the EGF-pentoxifylline group, and 8.7% for the control group.

CONCLUSIONS

The use of EGF promoted healing of subacute TM perforations in chinchillas, and the use of pentoxifylline did not. The combination of the two had no synergistic effect on the healing of these perforations.