Cultivo condral in vitro bajo estímulos de compresión y cizallamiento. De las células troncales mesenquimales al cartílago hialino / In vitro chondral culture under compression and shear stimuli. From mesenchymal stem cells to hyaline cartilage

INTRODUCCIÓN: La creación in vitro de cartílago hialino articular supone un reto, ya que, a día de hoy, no se ha conseguido la síntesis ex vivo de un tejido estructurado con las mismas propiedades biomecánicas e histológicas del cartílago articular. Para simular las condiciones fisiológicas hemos diseñado un sistema de cultivo in vitro que reproduce el movimiento articular. MATERIAL Y MÉTODO: Hemos desarrollado un biorreactor de cultivo celular que imprime un estímulo mecánico sobre una matriz de elastina en la que están embebidas células troncales mesenquimales (MSC). La primera fase de estudio corresponde al desarrollo de un biorreactor para cultivo de cartílago hialino y la comprobación de la viabilidad celular en la matriz de elastina en ausencia de estímulo. La segunda fase del estudio engloba el cultivo de MSC bajo estímulo mecánico y el análisis del tejido resultante. RESULTADOS: Tras el cultivo bajo estímulo mecánico no obtuvimos tejido hialino por falta de celularidad y desestructuración de la matriz. CONCLUSIÓN: El patrón de estímulo utilizado no ha resultado efectivo para la generación de cartílago hialino, por lo que se deberán explorar otras combinaciones en futuras investigaciones

INTRODUCTION: The in vitro creation of hyaline joint cartilage is a challenge since, to date, the ex vivo synthesis of a structured tissue with the same biomechanical and histological properties of the joint cartilage has not been achieved. To simulate the physiological conditions we have designed an in vitro culture system that reproduces joint movement. MATERIAL AND METHOD: We have developed a cell culture bioreactor that prints a mechanical stimulus on an elastin matrix, in which mesenchymal stem cells (MSC) are embedded. The first phase of study corresponds to the development of a bioreactor for hyaline cartilage culture and the verification of cell viability in the elastin matrix in the absence of stimulus. The second phase of the study includes the MSC culture under mechanical stimulus and the analysis of the resulting tissue. RESULTS: After culture under mechanical stimulation we did not obtain hyaline tissue due to lack of cellularity and matrix destructuring. CONCLUSION: The stimulus pattern used has not been effective in generating hyaline cartilage, so other combinations should be explored in future research

In vitro chondral culture under compression and shear stimuli. From mesenchymal stem cells to hyaline cartilage. / Cultivo condral in vitro bajo estímulos de compresión y cizallamiento. De las células troncales mesenquimales al cartílago hialino.

INTRODUCTION: The in vitro creation of hyaline joint cartilage is a challenge since, to date, the ex vivo synthesis of a structured tissue with the same biomechanical and histological properties of the joint cartilage has not been achieved. To simulate the physiological conditions we have designed an in vitro culture system that reproduces joint movement. MATERIAL AND METHOD: We have developed a cell culture bioreactor that prints a mechanical stimulus on an elastin matrix, in which mesenchymal stem cells (MSC) are embedded. The first phase of study corresponds to the development of a bioreactor for hyaline cartilage culture and the verification of cell viability in the elastin matrix in the absence of stimulus. The second phase of the study includes the MSC culture under mechanical stimulus and the analysis of the resulting tissue. RESULTS: After culture under mechanical stimulation we did not obtain hyaline tissue due to lack of cellularity and matrix destructuring. CONCLUSION: The stimulus pattern used has not been effective in generating hyaline cartilage, so other combinations should be explored in future research.

Nuevo método de liberación de antibióticos del cemento óseo (polimetilmetacrilato): redefiniendo los límites / New method for antibiotic release from bone cement (polymethylmethacrylate): redefining boundaries

Introducción. La creciente resistencia a antimicrobianos está impulsando la adición de antibióticos con elevada actividad antiestafilocócica al polimetilmetacrilato (PMMA), para su uso en los espaciadores de cemento en la infección periprotésica. El linezolid o el levofloxacino ya han sido utilizados en estudios in vitro; sin embargo, la rifampicina ha demostrado un efecto deletéreo sobre las propiedades mecánicas del PMMA, inhibiendo su polimerización. El objetivo de nuestro estudio fue aislar la rifampicina durante el proceso de polimerización mediante técnicas de microencapsulación, con el fin de obtener un PMMA apto para la fabricación de espaciadores articulares. Material y método. Se sintetizaron microcápsulas de rifampicina con alginato y PHBV, utilizando Rifaldin®. Se estudió la concentración de rifampicina mediante espectrofotometría UV-visible. Se realizaron ensayos de compresión, dureza y tiempo de fraguado con probetas de cemento CMW®1 solo, con rifampicina y microcápsulas de PHBV y alginato. Resultados. El rendimiento de producción, la eficiencia y el rendimiento de microencapsulación fueron mayores con alginato (p=0,0001). El cemento con microcápsulas mostró mayor resistencia a la compresión que el cemento con rifampicina (91,26±5,13, 91,35±6,29 y 74,04±3,57MPa en alginato, PHBV y rifampicina, respectivamente) (p=0,0001). El tiempo de fraguado disminuyó, siendo la curva de dureza del cemento con microcápsulas de alginato similar a la de control. Discusión y conclusiones. La microencapsulación con alginato es una técnica adecuada para introducir rifampicina en el PMMA preservando las propiedades de compresión y el tiempo de fraguado. Su obtención permitiría fabricar espaciadores que liberasen localmente rifampicina para el tratamiento de la infección periprotésica (AU)

Introduction. The increasing antimicrobial resistance is promoting the addition of antibiotics with high antistaphylococcal activity to polymethylmethacrylate (PMMA), for use in cement spacers in periprosthetic joint infection. Linezolid and levofloxacin have already been used in in-vitro studies, however, rifampicin has been shown to have a deleterious effect on the mechanical properties of PMMA, because it inhibits PMMA polymerization. The objective of our study was to isolate the rifampicin during the polymerization process using microencapsulation techniques, in order to obtain a PMMA suitable for manufacturing bone cement spacers. Material and method. Microcapsules of rifampicin were synthesized with alginate and PHBV, using Rifaldin®. The concentration levels of rifampicin were studied by UV-visible spectrophotometry. Compression, hardness and setting time tests were performed with CMW®1 cement samples alone, with non-encapsulated rifampicin and with alginate or PHBV microcapsules. Results. The production yield, efficiency and microencapsulation yield were greater with alginate (P = .0001). The cement with microcapsules demonstrated greater resistance to compression than the cement with rifampicin (91.26±5.13, 91.35±6.29 and 74.04±3.57 MPa in alginate, PHBV and rifampicin, respectively) (P = .0001). The setting time reduced, and the hardness curve of the cement with alginate microcapsules was similar to that of the control. Discussion and conclusions. Microencapsulation with alginate is an appropriate technique for introducing rifampicin into PMMA, preserving compression properties and setting time. This could allow intraoperative manufacturing of bone cement spacers that release rifampicin for the treatment of periprosthetic joint infection (AU)

New method for antibiotic release from bone cement (polymethylmethacrylate): Redefining boundaries. / Nuevo método de liberación de antibióticos del cemento óseo (polimetilmetacrilato): redefiniendo los límites.

INTRODUCTION: The increasing antimicrobial resistance is promoting the addition of antibiotics with high antistaphylococcal activity to polymethylmethacrylate (PMMA), for use in cement spacers in periprosthetic joint infection. Linezolid and levofloxacin have already been used in in-vitro studies, however, rifampicin has been shown to have a deleterious effect on the mechanical properties of PMMA, because it inhibits PMMA polymerization. The objective of our study was to isolate the rifampicin during the polymerization process using microencapsulation techniques, in order to obtain a PMMA suitable for manufacturing bone cement spacers. MATERIAL AND METHOD: Microcapsules of rifampicin were synthesized with alginate and PHBV, using Rifaldin®. The concentration levels of rifampicin were studied by UV-visible spectrophotometry. Compression, hardness and setting time tests were performed with CMW®1 cement samples alone, with non-encapsulated rifampicin and with alginate or PHBV microcapsules. RESULTS: The production yield, efficiency and microencapsulation yield were greater with alginate (P = .0001). The cement with microcapsules demonstrated greater resistance to compression than the cement with rifampicin (91.26±5.13, 91.35±6.29 and 74.04±3.57 MPa in alginate, PHBV and rifampicin, respectively) (P = .0001). The setting time reduced, and the hardness curve of the cement with alginate microcapsules was similar to that of the control. DISCUSSION AND CONCLUSIONS: Microencapsulation with alginate is an appropriate technique for introducing rifampicin into PMMA, preserving compression properties and setting time. This could allow intraoperative manufacturing of bone cement spacers that release rifampicin for the treatment of periprosthetic joint infection.