Carboxymethyl chitosan hydrogel formulations enhance the healing process in experimental partial-thickness (second-degree) burn wound healing

Purpose: This study aimed to elaborate a hydrogel constituted by carboxymethyl chitosan (CMC), hyaluronic acid (HA) and silver (Ag) and to evaluate its healing effect on partial-thickness burn wounds experimentally induced in rats. Methods: CMC was obtained by chitosan reacting with monochloroacetic acid. The carboxymethylation was confirmed by Fourier-transform infrared spectroscopy and hydrogen nuclear magnetic resonance (NMR). Scanning electron microscopy was used to determine the morphological characteristics of chitosan and CMC. After the experimental burn wound induction, the animals (n = 126) were treated with different CMC formulations, had their occlusive dressings changed daily and were followed through 7, 14 and 30 days. Morphometric, macroscopic and microscopic aspects and collagen quantification were evaluated. Results: Significative wound contraction, granulation tissue formation, inflammatory infiltration and collagen fibers deposit throughout different phases of the healing process were observed in the CMC hydrogels treated groups. Conclusion: The results showed that, in the initial phase of the healing process, the most adequate product was the CMC/HA/Ag association, while in the other phases the CMC/HA association was the best one to promote the healing of burn wounds.(AU)

Hidrogeles de polimerizacion in situ para la regeneracion de cartilago articular / In-situ hydrogel polymerization for articular cartilage regeneration

Una significativa cantidad de adultos jóvenes activos sufre lesiones condrales focales. Estas lesiones, si no se tratan, pueden progresar hacia la artrosis, que es una de las principales enfermedades musculoesqueléticas debilitantes y de gran carga económica que afectan a toda sociedad. Pese a los tratamientos quirúrgicos disponibles para la reparación de defectos condrales focales sintomáticos que mejoran la calidad de vida a mediano plazo, hay un mayor riesgo de progresión hacia la artrosis prematura. Los tratamientos biológicos (células madre, bioingeniería tisular) han avanzado a grandes pasos en los últimos años. La bioingeniería es un área que ha progresado en la regeneración de cartílago articular y que potencialmente podría progresar en el terreno de tratamientos articulares, promoviendo la regeneración y evitando la degeneración. Las células madre y los hidrogeles pueden proveer un tejido símil biológico de comportamiento dinámico-funcional equivalente que induce la regeneración tisular al ser degradado y reemplazado gradualmente. El abordaje consiste en colocar un hidrogel precursor o un biomaterial tridimensional impreso dentro del defecto condral por ocupar para inducir la regeneración. Esta revisión se focaliza en el uso actual y futuro de hidrogeles y bioimpresión tridimensional para la regeneración de cartílago articular en el tratamiento de lesiones condrales focales y proporciona datos preliminares de dos estudios piloto en animales. Nivel de Evidencia: V

A significant number of young active adults are affected by focal chondral lesions. These lesions, if left untreated, will progress to osteoarthritis (OA). OA is one of the main debilitating musculoskeletal diseases and leads to a high economic and social burden. Despite surgical cartilage repair for focal chondral lesions, which improve patient-reported outcomes at short- and mid-term, there is a risk of early OA progression. Biological treatments (i.e., stem-cell therapy, bioengineering) have made great progress in the last years. Tissue engineering is an evolving field for articular cartilage repair which could potentially be used for the treatment of focal chondral lesions, promoting regeneration and preventing joint surface degeneration. Stem cells and hydrogels may provide a functional, dynamic and biologically equivalent tissue that promotes tissue regeneration while being gradually degraded and replaced. The standard approach to tissue engineering consists in delivering cells within a hydrogel or a three-dimensional printed biomaterial scaffold into the chondral lesion to induce regeneration. This review focuses on the current and future use of hydrogels and tissue scaffold bioprinting for the treatment of focal chondral lesions, and provides preliminary data from two pilot animal studies. Level of Evidence: V

Effects of Hydrogel With Enriched Sodium Alginate in Wounds of Diabetic Patients.

Objective of this study was to evaluate the efficacy of the autolytic debridement promoted by hydrogel with sodium alginate enriched with fatty acids and vitamins A and E in the healing of foot wounds in diabetic patients. A clinical study was conducted at an outpatient clinic of medical specialties. The sample comprised 8 patients supervised for a 3-month period, from April to July 2017, by means of a clinical history, photographic record, planimetry, and classification of the wound severity by the Pressure Ulcer Scale for Healing (PUSH) system. Of the 8 patients supervised, 1 dropped out and 7 were followed up for 12 weeks. Only 2 had complete wound healing, but all presented a reduction of the lesion area of approximately 22.2% and PUSH score of 9.8 to 6.6. This study found that hydrogel showed good results for the treatment of diabetic feet, reducing the area and overall PUSH score of the wounds.

Prevention of peritoneal adhesion using a bacterial cellulose hydrogel, in experimental study.

PURPOSE: To analyze the effectiveness of bacterial cellulose hydrogel as a barrier in preventing postoperative peritoneal adhesion in rat model. METHODS: Experimental study with 45 Wistar rats (Rattus norvegicus) that were divided into three groups for the following treatments: A. Saline, B. Oxidized Regenerated Cellulose (ORC) barrier, and C Bacterial Cellulose Hydrogel (BCH) barrier. After 45 days of the surgery the adhesions were classified and graded according to the qualitative score. The histological parameters were evaluated using a modified semi-quantitative scale to rate the extent of fibrosis, inflammatory reaction and vascular proliferation. RESULTS: Compared with the saline group (A), the treatments with ORC barrier (B) and BHC barrier (C) resulted in a smaller number of adhesions (p=0.019 and p=0.003 on Fisher's exact test, respectively). Data from inflammation and neovascularization showed no statistically significant difference between the groups BHC and ORC (p=0.426 and 0.446 on chi-square test, respectively). CONCLUSION: Bacterial cellulose hydrogel is effective as a bio-re-absorbable barrier for preventing postoperative peritoneal adhesions.

Reconstruction of abdominal wall defects using small intestinal submucosa coated with gelatin hydrogel incorporating basic fibroblast growth factor.

PURPOSE: To construct a new biomaterial-small intestinal submucosa coated with gelatin hydrogel incorporating basic fibroblast growth factor, and to evaluate the new biomaterials for the reconstruction of abdominal wall defects. METHODS: Thirty six Sprague-Dawley rats were used in the animal experiments and randomly divided into three groups. The new biomaterial was constructed by combining small intestinal submucosa with gelatin hydrogel for basic fibroblast growth factor release. Abdominal wall defects were created in rats, and repaired using the new biomaterials (group B), compared with small intestinal submucosa (group S) and ULTRAPROTM mesh (group P). Six rats in each group were sacrificed at three and eight weeks postoperatively to examine the gross effects, inflammatory responses, collagen deposition and neovascularization. RESULTS: After implantation, mild adhesion was caused in groups B and S. Group B promoted more neovascularization than group S at three weeks after implantation, and induced significantly more amount of collagen deposition and better collagen organization than groups S and P at eight weeks after implantation. CONCLUSION: Small intestinal submucosa coated with gelatin hydrogel incorporating basic fibroblast growth factor could promote better regeneration and remodeling of host tissues for the reconstruction of abdominal wall defects.

A randomised comparative trial on the use of a hydrogel with tepescohuite extract (Mimosa tenuiflora cortex extract-2G) in the treatment of venous leg ulcers.

Tepescohuite is an extract obtained from the bark of the Mimosa tenuiflora tree and is used as an empirical treatment in wounds for its healing and antiseptic properties. Venous leg ulcers (VLUs) are a common health care problem in most countries with a high rate of morbidity. The standard of care is moist interactive healing and compression; however, the ideal topical treatment is yet to be established. This study is designed to evaluate the effectiveness and safety of M. tenuiflora cortex extract (MTC-2G) in the treatment of VLUs in an Interdisciplinary Wound and Ostomy Care Center (IWOCC). A randomised, placebo-controlled, double blind clinical trial was conducted to compare the use of a hydrogel containing MTC-2G with the hydrogel alone in VLUs. The study included all patients with venous ulcers referred to the IWOCC. Laboratory tests and tissue biopsies were performed at the beginning and at the end of the study. The patients were instructed to daily cleansing followed by topical application of the hydrogel and compression. Forty-one patients were included, 22 patients received the MTC-2G and 19 patients received the hydrogel only. Of the 41 patients, 32 completed the study, 18 in the experimental arm and 14 in the control group, 19 were women and 13 men. The mean age of the subjects was 60 years. The mean time from presentation was 38 months. The mean surface reduction was 6·29 cm(2) [confidence interval (IC) 95%: 3·28-9·29] (P = 0·0001) in the MTC-2G group and 5·85 cm(2) (95% CI: 3·58-8·12) (P = 0·001) in the hydrogel group. There was no significant difference between the groups (P = 0·815). No changes in the laboratory parameters were noted. In the histology, there were not any differences between groups either. A hydrogel containing MTC-2G was not superior to a hydrogel alone in the treatment of VLUs.

2-hydroxyethyl methacrylate composite - polypropylene mesh for preventing peritoneal adhesions in female dogs.

PURPOSE: To evaluate whether the lining facing the visceral side of polypropylene mesh made with 2-hydroxyethyl methacrylate (p(HEMA)) hydrogel could avoid peritoneal adhesion in female dogs. METHODS: Eight animals (group PP) had a polypropylene mesh implanted to correct a defect in the rectal abdominal muscle, whereas in the other group (group PH) the polypropylene mesh was coated with p(HEMA) composite on the surface facing the peritoneal area. RESULTS: Adhesions were observed on the mesh in 62.5% of the PP group. In the PH group adhesions were present only on the suture lines. CONCLUSION: p(HEMA) hydrogel was well tolerated and effective in avoiding visceral and omental adhesions on the surface of the polypropylene mesh.

Hydrogel protection: a novel approach to reduce bowel inflammation in experimental gastroschisis.

OBJECTIVE: In gastroschisis there is herniation of the fetal bowel into the amniotic cavity that results in severe intestinal dysfunction. In order to reduce bowel exposure to amniotic fluid we used a hydrogel of N-isopropylacrylamide copolymerized with acrylic acid (P(NIPAAm-co-AAc)) to coat the herniated bowel through the use of a fibrin adhesive (Beriplast). STUDY DESIGN: Gastroschisis was created in fetuses of 31 pregnant Sprague-Dawley rats by evisceration of the bowel through a right paramedian incision in the abdominal wall on day 18.5 of pregnancy. The fetuses were separated in four groups of 12 fetuses: control (C), gastroschisis (G), gastroschisis+fibrin adhesive (GA) and gastroschisis+fibrin adhesive+dry hydrogel (GAH). Animals were harvested at day 21.5 of pregnancy and the hydrogel was removed. Fetuses and bowels were weighed and morphometric analysis was performed. Isoelectric focusing of the amniotic fluid determined its electrical charge. We evaluated the hydrogel swelling ratio (Q) in the amniotic fluid. Histological analysis and scanning electronic microscopy (SEM) of the bowel and hydrogel were performed. Our primary outcome was bowel intactness after hydrogel removal and our secondary outcome was the effectiveness of the hydrogel in protecting the bowel against amniotic fluid and its components. Differences among the groups were tested by the ANOVA and Tukey-Kramer post-test method and the statistical significance accepted was for p values <0.05. RESULTS: The mass of swollen hydrogel was 34 times the mass of dry hydrogel. Isoelectric focusing of the amniotic fluid showed that most of its proteins are negatively charged as the hydrogel. SEM showed that removal of the hydrogel did not damage bowel serosa. Bowel weight, diameter and wall thickness were similar between groups C and GAH but bowel diameter and wall thickness was significantly reduced in C and GAH compared to G and GA (p<0.001). CONCLUSION: The P(NIPAAm-co-AAc) hydrogel does not harm the bowel and provides a safe effective protection with reduction of bowel damage in gastroschisis.

Evolución de las lentes intraoculares y los viscoelásticos / Intraocular lenses and viscoelastic evolution review

Se hace una revisión de la literatura y se relata la evolución de las lentes intraoculares, de sus materiales y diseños, así como de los viscoelásticos.

Ulceras venosas tratadas con apósitos de hidrogel de polimanosa, estudio comparativo con grupo control / Venous ulcers treated with polymanose hydrogel dressing, a comparative study with a control group

Objetivo: Comunicar la experiencia obtenida al tratar úlceras venosas con apósitos de hidrogel de polimanosa comparándola con un grupo control. Antecedentes: La frecuencia de presentación de úlceras venosas es muy alta y requieren tratamiento local efectivo para lograr su cicatrización. Un producto natural derivado del ALOE-VERA cuyo principio activo es la polimanosa, parece que favorece y acelera la cicatrización. Material y métodos: Se estudiaron 40 pacientes divididos en 2 grupos, 20 tratados con apósitos de hidrogel de polimanosa y 20 tratados sólo con solución físiológica y jabón a los cuales se les hizo seguimiento por 16 semanas y se valoró la velocidad de cicatrización. Resultados: El grupo tratado con polimanosa cicatrizó en un 50 por ciento más rápido que el tratado con agua y jabón. Conclusión: El hidrogel de polimanosa aumenta el doble la velocidad de cicatrización de las úlceras venosas comparado con la curación con solución fisiológica y jabón.

Biomechanical and histological evaluation of hydrogel implants in articular cartilage.

We evaluated the mechanical behavior of the repaired surfaces of defective articular cartilage in the intercondylar region of the rat femur after a hydrogel graft implant. The results were compared to those for the adjacent normal articular cartilage and for control surfaces where the defects remained empty. Hydrogel synthesized by blending poly(2-hydroxyethyl methacrylate) and poly(methyl methacrylate-co-acrylic acid) was implanted in male Wistar rats. The animals were divided into five groups with postoperative follow-up periods of 3, 5, 8, 12 and 16 weeks. Indentation tests were performed on the neoformed surfaces in the knee joint (with or without a hydrogel implant) and on adjacent articular cartilage in order to assess the mechanical properties of the newly formed surface. Kruskal-Wallis analysis indicated that the mechanical behavior of the neoformed surfaces was significantly different from that of normal cartilage. Histological analysis of the repaired defects showed that the hydrogel implant filled the defect with no signs of inflammation as it was well anchored to the surrounding tissues, resulting in a newly formed articular surface. In the case of empty control defects, osseous tissue grew inside the defects and fibrous tissue formed on the articular surface of the defects. The repaired surface of the hydrogel implant was more compliant than normal articular cartilage throughout the 16 weeks following the operation, whereas the fibrous tissue that formed postoperatively over the empty defect was stiffer than normal articular cartilage after 5 weeks. This stiffness started to decrease 16 weeks after the operation, probably due to tissue degeneration. Thus, from the biomechanical and histological point of view, the hydrogel implant improved the articular surface repair.