ABSTRACT
RESUMEN El quitosano (QT) es un biopolímero que ha sido ampliamente utilizado en aplicaciones de ingeniería de tejido óseo, demostrando un gran potencial para este propósito. El presente estudio tiene como objetivo desarrollar un sistema de hidrogel entrecruzable in situ, compuesto de quitosano y nano-partículas de hidroxiapatita (HAP), un equivalente al componente mineral del hueso. El quitosano fue modificado, utilizando reacciones de carbodiimida, con ácido lactobiónico y ácido azidobenzoico para hacerlo soluble a pH fisiológico y foto-entrecruzable, respectivamente. El quitosano modificado fue mezclado en diferentes proporciones con HAP, y luego de una corta exposición a luz UV, se formaron hidrogeles. Células madre mesenquimales de médula ósea de rata (MSC) fueron sembradas sobre estos hidrogeles y cultivadas por 4, 10 y 16 días, bajo condiciones osteogénicas y no-osteogénicas. A través de ensayos de proliferación celular, actividad de fosfatasa alcalina, y microscopía confocal, se observó que la mayoría de las formulaciones soportan la adhesión y proliferación celular, mostrando importantes interacciones célula-biomaterial, y una diferenciación osteogénica temprana destacada en las formulaciones 70:30 y 50:50, QT:HAP. Algunas formulaciones del sistema foto-entrecruzable tienen potencial en aplicaciones de ingeniería de tejido óseo, y se propone estudios más detallados de diferenciación celular.
ABSTRACT Chitosan (QT) is a biopolymer that has been used in widely used in bone tissue engineering applications, demonstrating great potential for that purpose. Therefore, the present study aims to develop an in situ crosslinking hydrogel system, composed of chitosan and hydroxyapatite (HAP). Briefly, chitosan was modified, using carbodiimide chemistry, with lactobionic and azidobenzoic acid to make it soluble at physiological pH and photo-crosslinkable, respectively. The modified chitosan was mixed with HAP, in different proportions, and later exposed to UV light, yielding hydrogels. Mesenchymal stem cells, from rat bone marrow, were seeded onto the hydrogels and cultured for 4, 10 and 16 days, under osteogenic and non-osteogenic conditions. Through cell proliferation and alkaline phosphatase activity assays, and confocal microscopy, it was observed that the majority of formulations supported cell adhesion and proliferation, and a significant early osteogenic differentiation in formulations 70:30 and 50:50, QT:HAP. According to these results, the proposed photo-crosslinking system has potential for tissue engineering applications, and further specific studies are proposed for cell differentiation.
ABSTRACT
Treatment of a complex, wide neck aneurysm sometimes cannot be achieved in a single endovascular session. This case illustrates a planned stage endovascular treatment of a complex aneurysm with remodeling technique aiming to eliminate risk of rebleeding during acute phase in the first stage of treatment, and complete occlusion in the second stage of treatment. After first stage, separation between coil mass and neck remnant was clearly shown indicating presence of neointimal layer. Multiple sessions also provide proper planning and more controlled treatment of difficult aneurysms.