The efficacy of immediate implantation of macroporous poly(N-[2-hydroxypropyl]-methacrylamide) hydrogel after laceration spinal cord injury in young rats / Eficacia de la implantación inmediata de hidrogel macroporoso de poli (N- [2-hidroxipropil] - metacrilamida) después de una lesión de la médula espinal en ratas jóvenes

SUMMARY: Spinal cord regeneration after mechanical injury is one of the most difficult biomedical problems. This article evaluates the effect of poly(N-[2-hydroxypropyl]-methacrylamide) hydrogel (PHPMA-hydrogel) on spinal cord regeneration in young rats after lateral spinal cord hemi-excision (laceration) at the level of segments T12-T13 (TrGel group). The locomotor function score (FS) and the paretic hindlimb spasticity score (SS) were assessed according to Basso-Beattie-Bresnahan (BBB) and Ashworth scales, respectively, and compared to a group of animals with no matrix implanted (Tr group). Regeneration of nerve fibers at the level of injury was evaluated at ~5 months after spinal cord injury (SCI). One week after the SCI induction, the FS on the BBB scale was 0.9±0.5 points in the Tr group and 3.6±1.2 points in the TrGel group. In the Tr group, the FS in 5 months was significantly lower than in 2 weeks after SCI, while no significant changes in FS were detected in the TrGel group over the entire observation period. The final FS was 0.8±0.3 points in the Tr group and 4.5±1.8 points in the TrGel group. No significant changes in SS have been observed in the TrGel group throughout the experiment, while the Tr group showed significant increases in SS at 2nd week, 6th week, 3th month and 5th month. The SS in 5 months was 3.6±0.3 points on the Ashworth scale in the Tr group and 1.8±0.7 points in the TrGel group. Throughout the observation period, significant differences in FS between groups were observed only in 5 weeks after SCI, whereas significant differences in SS were observed in 2, 3 and 6-8 weeks post-injury. Glial fibrous tissue containing newly formed nerve fibers, isolated or grouped in small clusters, that originated from the surrounding spinal cord matter have been found between the implanted hydrogel fragments. In conclusion, PHPMA-hydrogel improves recovery of the hindlimb locomotor function and promotes regenerative growth of nerve fibers. Further research is needed to clarify the mechanism of this PHPMA-hydrogel effect.

RESUMEN: La regeneración de la médula espinal después de una lesión mecánica es uno de los problemas biomédicos más difíciles. Este artículo evalúa el efecto del hidrogel de poli (N- [2-hidroxipropil] -metacrilamida) (PHPMA-hidrogel) sobre la regeneración de la médula espinal en ratas jóvenes después de la hemiescisión lateral de la médula espinal (lesión) a nivel de los segmentos T12 - T13 (Grupo TrGel). La puntuación de la función locomotora (FS) y la puntuación de espasticidad parética de las patas traseras (SS) se evaluaron de acuerdo con las escalas de Basso- Beattie-Bresnahan (BBB) y Ashworth, respectivamente, y se compararon con un grupo de animales sin matriz implantada (grupo Tr). Se evaluó la regeneración de las fibras nerviosas al nivel de la lesión ~ 5 meses después de la lesión de la médula espinal (LME). Una semana después de la inducción de SCI, el FS en la escala BBB fue 0,9 ± 0,5 puntos en el grupo Tr y 3,6 ± 1,2 puntos en el grupo TrGel. En el grupo Tr, el FS en 5 meses fue significativamente menor que en 2 semanas después de SCI, mientras que no se detectaron cambios significativos en FS en el grupo TrGel durante el período de observación. El FS final fue de 0,8 ± 0,3 puntos en el grupo Tr y de 4,5 ± 1,8 puntos en el grupo TrGel. No se han obser- vado cambios significativos en SS en el grupo TrGel durante el experimento, mientras que el grupo Tr mostró aumentos significativos en SS en la 2ª semana, 6ª semana, 3º mes y 5º mes. La SS en 5 meses fue de 3,6 ± 0,3 puntos en la escala de Ashworth en el grupo Tr y de 1,8 ± 0,7 puntos en el grupo TrGel. A lo largo del período de observación, se observaron diferencias significativas en FS entre los grupos solo en 5 semanas después de la LME, mientras que se observaron diferencias significativas en SS en 2, 3 y 6-8 semanas después de la lesión. Entre los fragmentos de hidrogel implantados se observó tejido fibroso glial que contenía fibras nerviosas recién formadas, aisladas o agrupadas en pequeños grupos, que se originaban a partir de la materia de la médula espinal circundante. En conclusión, PHPMA-hydrogel mejora la recuperación de la función locomotora de las patas traseras y promueve el crecimiento regenerativo de las fibras nerviosas. Se requieren más estudios para aclarar el mecanismo del efecto de hidrogel PHPMA.

Three-Dimensional Spheroid Culture Increases Exosome Secretion from Mesenchymal Stem Cells

BACKGROUND: Mass production of exosomes is a prerequisite for their commercial utilization. This study investigated whether three-dimensional (3D) spheroid culture of mesenchymal stem cells (MSCs) could improve the production efficiency of exosomes and if so, what was the mechanism involved. METHODS: We adopted two models of 3D spheroid culture using the hanging-drop (3D-HD) and poly(2-hydroxyethyl methacrylate) (poly-HEMA) coating methods (3D-PH). The efficiency of exosome production from MSCs in the 3D spheroids was compared with that of monolayer culture in various conditions. We then investigated the mechanism of the 3D spheroid culture-induced increase in exosome production. RESULTS: The 3D-HD formed a single larger spheroid, while the 3D-PH formed multiple smaller ones. However, MSCs cultured on both types of spheroids produced significantly more exosomes than those cultured in conventional monolayer culture (2D). We then investigated the cause of the increased exosome production in terms of hypoxia within the 3D spheroids, high cell density, and non-adherent cell morphology. With increasing spheroid size, the efficiency of exosome production was the largest with the least amount of cells in both 3D-HD and 3D-PH. An increase in cell density in 2D culture (2D-H) was less efficient in exosome production than the conventional, lower cell density, 2D culture. Finally, when cells were plated at normal density on the poly-HEMA coated spheroids (3D-N-PH); they formed small aggregates of less than 10 cells and still produced more exosomes than those in the 2D culture when plated at the same density. We also found that the expression of F-actin was markedly reduced in the 3D-N-PH culture. CONCLUSION: These results suggested that 3D spheroid culture produces more exosomes than 2D culture and the non-adherent round cell morphology itself might be a causative factor. The result of the present study could provide useful information to develop an optimal process for the mass production of exosomes.

Evaluation of stability and biocompatibility of PHEMA-PMMA keratoprosthesis by penetrating keratoplasty in rabbits / 한국실험동물학회지

Artificial corneas have been developed as an alternative to natural donor tissue to replace damaged or diseased corneas. This study was conducted to evaluate the stability and biocompatibility of PHEMA-PMMA [poly (2-hydroxyl methacrylate)-poly (methyl methacrylate)] keratoprostheses in rabbits following penetrating keratoplasty. Sixteen male New Zealand White rabbits aged 16 weeks were divided into three groups. Group I and group II contained six rabbits each, while the control group had four rabbits. Experimental surgery was conducted under general anesthesia. The cornea was penetrated using an 8 mm diameter biopsy punch. In group I (core 5 mm & skirt 3 mm) and group II (core 6 mm & skirt 2 mm), the keratoprosthesis was placed into the recipient full thickness bed and sutured into position with double-layer continuous. In the control group, corneal transplantation using normal allogenic corneal tissue was performed with the same suture method. After four and eight weeks, keratoprosthesis devices were evaluated by histopathological analysis of gross lesions. Post-operative complications were observed, such as extrusion and infection in experimental groups. Most corneas were maintained in the defect site by double-layer continuous suture materials for 4 weeks and kept good light transmission. However, most artificial cornea were extruded before 8 weeks. Overall, combined PHEMA and PMMA appears to have sufficient advantages for production of artificial corneas because of its optical transparency, flexibility and other mechanical features. However, the stability and biocompatibility were not sufficient to enable application in humans and animals at the present time using penetrating keratoplasty. Further studies are essential to improve the stability and biocompatibility with or without other types of keratoplasty.

Adhesión a tejidos dentarios / Bonding to dental tissues

En las últimas décadas, la odontología restauradora ha logrado un avance significativo que permite preservar tejido dentario mediante la realización de restauraciones adheridas, directas e indirectas. Este enfoque moderno de “Odontología Mínimamente Invasiva”, se centra en obtener preparaciones dentarias con un diseño más conservador, basándose en la eficacia de la adhesión al tejido remanente de los biomateriales utilizados. El conocimiento de las características de los sustratos y de los materiales adhesivos, y la comprensión del mecanismo de adhesión es un factor fundamental para alcanzar el éxito clínico...

Preparation of novel biodegradable pHEMA hydrogel for a tissue engineering scaffold by microwave-assisted polymerization

OBJECTIVE@#To prepare a novel biodegradable poly(2-hydroxyethylmethacrilate) (pHEMA) hydrogel as tissue engineering scaffold.@*METHODS@#The pHEMA hydrogel was synthesized by microwave-assisted polymerization using 2-hydroxyethyl methacrylate (HEMA) as the raw material, potassium persulfate as the initiator, and PCLX as the cross-linking additive. The hydrogels was characterized with FTIR and NMR spectroscopy. The physical and chemical properties of the prepared hydrogel were evaluated, and its degradation performance was tested. The cytotoxicity of the optimum composite hydrogel was measured by an MTT assay to confirm the feasibility of its use in tissue engineering.@*RESULTS@#The optimum conditions under which the hydrogel was prepared by microwave-assisted polymerization are as follows: 1.5 g cross-linking additive, 0.3 g initiator, reaction temperature of 80 °C, and microwave power of 800 W. Degradation studies showed good degradation profiles with 75% in 17 days. Additionally, the hydrogels did not elicit any cytotoxic response in in vitro cytotoxic assays.@*CONCLUSION@#A biodegradable pHEMA hydrogel was successfully prepared by microwave-assisted polymerization, as confirmed from FTIR and NMR results. The hydrogel shows promising applications in tissue engineering, and its healing ability and biocompatibility will be evaluated in detail in the future.

Evaluation of peritoneal adhesions formation and tissue response to polypropylene - poli (2-hydroxyethyl methacrylate)-(polyHEMA) implant on rats' abdominal wall / Avaliação da formação de aderências peritoneais e da resposta tecidual ao implante de poli (2-hidroxietil dimetacrilato)-(poliHEMA) na parede abdominal de ratos

PURPOSE: To verify if the composit poli (2-hydroxyethyl methacrylate)-PolyHEMA/polypropylene mesh implanted in the female rat's abdominal wall could be suitable for the prevention of peritoneal adhesions, and for the evaluation of the tecidual response produced by this biomaterial. METHODS: Polypropylene meshes (Group PP, n=20) and polypropylene meshes coated with a layer of poli (2-hydroxyethyl methacrylate)-PolyHEMA (Group PH, n=20) were implanted on the abdominal wall of Wistar female rats. Ten animals from each group were submitted to euthanasia at 15 and 30 days of the postoperative period. RESULTS: The animals from the group PP presented visceral adhesions on the mesh surface, which was not observed in the ones from group PH. At the histopathological examination foreign body response was observed in both groups, whilst there was a greater intensity of inflammatory response in group PH on both moments. CONCLUSION: The poli (2-hydroxyethyl methacrylate) polyHEMA hydrogel associated to polypropylene mesh reduces visceral adhesion formation in rats, although it may be associated to greater inflammatory reaction.

OBJETIVO: Verificar se compósito poli 2-hidroxietil dimetacrilato (PoliHEMA) / tela de polipropileno implantado na parede abdominal de ratas seria adequado para prevenção de aderências peritoneais e avaliar a resposta tecidual desencadeada por este biomaterial. MÉTODOS: Foram implantadas telas de polipropileno - Grupo PP (n=20) e telas de polipropileno revestidas por uma camada de poli 2 (hidroxietil dimetacrilato)-PolyHEMA - Grupo PH (n=20) na parede abdominal de ratas da linhagem Wistar. Dez animais de cada grupo foram submetidos à eutanásia aos 15 e 30 dias de pós-operatório. RESULTADOS: Os animais do grupo PP apresentaram aderências viscerais na superfície da tela, o que não foi observado nos do grupo PH. Observou-se no exame histopatológico resposta tipo corpo estranho nos dois grupos sendo que no grupo PH houve maior intensidade de resposta inflamatória nos dois momentos. CONCLUSÃO: O hidrogel de poliHEMA quando associado à tela de polipropileno reduz a formação de aderências viscerais em ratos, embora possa estar associado à reação inflamatória mais intensa.

Preparation and properties of poly (acrylic ester) hydrogel as basic materials for intraocular lens / 生物医学工程学杂志

Poly (acrylic ester) hydrogel materials were widely used in intraocular lens and contact lens because of their excellent optical performance and biocompatibility. In this paper, the bulk copolymerization behavior of hydrophilic hydroxyethyl methacrylat with hydrophobic methyl metharylate was studied; and the optical performance, calcium deposits, equilibrium water content of polymers and its hydrogels obtained by different ratios of monomers were systematically investigated. The experimental results showed that the average light transmittance and the equilibrium water content of the obtained hydrogels increased with the increasing of the hydrophilic monomer content from 0 to 100%; however, the hardness decreased. The highest light transmittance reached 97% and the hardness of Shore A fell from 92 to 25, the equilibrium water content of hydrogel increased from 16% to 64%. The absorbent capacity of copolymers reduced with the adding of cross-linking monomer. When m(hydrophilic monomer): m(hydrophobic monomer) = 90 : 10, the combination property of the polymer and its hydrogel obtained is optimum.

Effect of renal artery embolization using 2-poly-hydroxyethyl-methacrylate as a liquid embolic agent: a study in rabbits / 南方医科大学学报

<p><b>OBJECTIVE</b>To assess the effect of a liquid embolic agent 2-poly-hydroxyethyl -methacrylate (2-P-HEMA) for renal artery embolization in rabbits.</p><p><b>METHODS</b>The precipitation time of different concentrations (2%, 3.5%, 5%, 6.5%, 8% and 9.5%) of 2-P-HEMA dissolved in different solutions (ethanol, ethanol/iobitridol, and ethanol/Bi2O3) were determined in flowing water. The mixtures of 2-P-HEMA (2%, 5%, and 8%) with ethanol/ Bi2O3 were injected into the renal arteries of the rabbits, and the artery-embolizing effects were assessed using angiography at 2 and 12 weeks after the injection, with also macroscopic and microscopic examination of the embolized kidneys.</p><p><b>RESULTS</b>The mixtures of 2-P-HEMA and ethanol formed flocculent precipitation a few seconds after injection into flowing water, and the precipitation time showed no significant variations with the concentration of 2-P-HEMA in the mixture. Low and moderate concentrations of 2-P-HEMA could pass through the microcatheter smoothly with little injection resistance, and resulted in complete occlusion of the renal arteries without adhesion to the microcatheter. Angiography at 2 and 12 weeks detected no recanalization of the occluded renal arteries. Macroscopically, the lumen of the renal arteries was found to be occluded by the embolic agents, and deep penetration of the embolic agents into the glomerular arteries was observed microscopically. The mixture containing high-concentration 2-P-HEMA was difficult to deliver through the microcatheter due to high injection resistance.</p><p><b>CONCLUSION</b>2-P-HEMA can be rapidly precipitated after injection into flowing water, and allows complete embolization of the renal arteries of rabbits at proper concentrations, suggesting its great potential as an endovascular liquid embolic agent.</p>

Reconstrucción mandibular a medida con prótesis HTR-PMI con esqueleto de titanio / Patient matched mandibular reconstruction with HTR-PMI prosthesis with titanium framework

La prótesis HTR-PMI (hard tissue replacement - patient matched implant) es una prótesis reconstructiva compuesta por una combinación de materiales: un polímero de polimetilmetacrilato y polihidroxietilmetacrilato, no reabsorbible, biocompatible, aloplástico, indicado para la reparación de defectos esqueletales. El objetivo de este trabajo es presentar un caso clínico de reconstrucción mandibular post-osteomielitis de injerto libre de cresta ilíaca, por resección de un ameloblastoma invasivo, con un seguimiento de 7 años. El uso de este tipo de prótesis ofrece una alternativa más para la reconstrucción de grandes defectos.

Synthesis and properties of poly(hydroxyethyl methacrylate) hydrogel for IOL materials / 生物医学工程学杂志

Poly (hydroxyethyl methacrylate) (PHEMA) hydrogel for intraocular lens (IOL) materials was synthesized by solution polymerization using 2-hydroxyethyl methacrylate (HEMA) as raw material, ammonium persulfate and sodium pyrosulfite (KPS/SMBS) as catalyst, and trietyleneglycole dimethacrylate (TEGDMA) as cross-linking additive. Effects of reaction time, temperature, dosage of catalyst and cross-linking additive on mechanical strength and the equilibrium water content (EWC) of the PHEMA hydrogel were systematically investigated and their structure and optical property were also characterized. The experimental results showed that the optimum conditions for preparing PHEMA hydrogel are: catalyst 0.5 wt%, cross-linking additive 1.0 wt%, reaction temperature 40 degrees C, reaction time 36 h. Under the optimum conditions, the tensile strength of PHEMA hydrogel prepared is as high as 0.57 MPa, hardness of Shore A is 23.0, EWC is over 40%, and light transmittance is over 97%.

Biological dressing with human hair keratin-collagen sponge-poly 2-hydroxyethyl methacrylate composite promotes burn wound healing in SD rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop a composite material containing human hair keratin (HHK), collagen sponge (inner layer) and poly 2-hydroxyethyl methacrylate (PHEMA) film that allows sustained release of polydatin and test its effect as a biological dressing in promoting burn wound healing in SD rats.</p><p><b>METHODS</b>Three HHK materials with fast, moderate, and low degradation rates were mixed at the ratio of 4:3:3 to prepare a reticular structure, which was processed into a composite material with bovine tendon-derived collagen sponge, and further complexed with HEMA film containing PD prepared by polymerization. Degree II burn wound was induced in SD rats by scalding and within postburn day 2-5, the wounds were cleansed and covered with the composite material or with glutaraldehyde-treated porcine skin (positive control). At week 1, 2, 4, 6 and 8 following wound dressing, 6 full-thickness skin samples were harvested from the wounds for histological observation and immunohistochemical detection of collagen and elastic fibers, and the wound healing time and healing rate were recorded.</p><p><b>RESULTS</b>The prepared collagen sponge film was transparent and porous (50-300 microm in diameter) and allowed sustained PD release into normal saline within 48 h. Compared with the porcine skin, the composite material reduced exudation and maintained ideal moisture of the wound, and significantly shortened the wound healing time (P=0.000). On day 7, 14, and 21 following dressing, the composite material and porcine skin significantly increased the wound healing rate as compared with the negative control group (P=0.000), and on day 14, the composite achieved significantly greater healing rate than the porcine skin (P<0.05).</p><p><b>CONCLUSION</b>HHK-collagen sponge-PHEMA/PD composite as a dressing material promotes burn wound healing in rats by allowing in vivo construction of tissue engineered epidermis. PHEMA is feasible for sustained drug delivery in this composite.</p>

Diplopia and Periorbital Mass Associated with Miragel Buckling Explant

A 28-year-old female presented with a palpable mass lesion on the superonasal aspect of her right globe and she had a progressive diplopia. She had a scleral encircling surgery with a Miragel explant (MIRA, Waltham, Mass, USA) for the tractional retinal detachment associated with pars planitis 9 years previously. On examination, she revealed restricted eye movements of her right eye. The magnetic resonance imaging documented a swelling of the Miragel explant that mimicked a periorbital mass lesion. The Miragel explant was removed and fragmentation of the explant was found intraoperatively. The removed Miragel explant was examined by a scanning electron microscopy, and this demonstrated a disintergrated and swollen structural composition of the Miragel explant. Postoperatively, her extraocular movement was almost restored and the retina remained well attached. Alterations in the structural composition of the Miragel explant results in an excessive swelling that causes a restriction of the extraocular movement, and this can mimick a periorbital mass lesion.

Compómero: ¿vidrio ionomérico modificado con resina o resina modificada con vidrio ionomérico?: revisión de la literatura / Compomer: resin-modified glass ionomer or glass ionomer-modified composite resin?

Quizás ningún otro material ha experimentado tantas modificaciones desde su presentación como el vidrio ionomérico. Este cemento ha presentado modificaciones no sólo en su composición y estructura original, sino también en sus indicaiciones y sus aplicaciones clínicas, lo que ha traído como consecuencia confusión cuando se habla de vidrio ionomérico, compómero o de cualquiera otra modificación realizada a dicho material. El cemento de vidrio ionomérico es un cemento de reacción ácido-base, siendo el ácido un homopolímero o copolímero de ácidos alquenoicos. El componente básico es un aluminio silicato de vidrio que contiene flúor. La introducción de las versiones modificadas con resina representan un intento más reciente de obtener algunas mejoras sobre las desventajas de los vidrios ionoméricos convencionales. La modificación implica grupos acrilatos en la parte poliácida del cemento convencional. La reacción de establecimiento ácido-base del cemento de vidrio ionomérico es suplementada por una reacción de polimerización de la resina de los monómeros como el HEMA y el bis-GMA o de cadenas sobre la molécula de poliácidos iniciada por la luz visible. El primer compómero comercialmente disponible estaba combinado con un imprimador de autograbado, que contenía un promotor de adhesión basado en la acetona con un componente activo PENTA (ácido ésterdipentaericitol pentacrilato fosfórico) y monómeros dimetacrilatos elastoméricos e iniciadores. El contenido restaurativo polimerizable ácido y otros monómeros como UDMA y resina TCB (un biéster de 2 HEMA y ácido tetracarboxílico butano) y vidrio de sodiofluorurosilicato de aluminio estroncio. En consecuencia, los compómeros constituyen un grupo de materiales sin relación con los vidrios ionoméricos; los compómeros no son vidrios ionoméricos, sino resinas reforzadas fotopolimerizables con algunas diferencias respecto a las resinas tradicionales. La terminología de algunas de las combinaciones de vidrio ionomérico/resina más nuevas es muy contradictoria y confusa. En esta revisión se han conseguido términos diferentes para agentes de cementación y materiales restauradores con una combinación de vidrio ionomérico y la química de la resina entre los cuales se incluye al compómero