ABSTRACT
El sistema intestinal posee una capacidad regenerativa intrínseca y fisiológica que tiene lugar a partir de las células madreLgr5+ ubicadas en el fondo de las criptas intestinales, las cuales se diferencian hacia las células progenitoras secretoras y absortivas con sus respectivas células especializadas mediante la activación de señalizaciones intracelulares como Wnt, Hippo y Notch. Condiciones adversas como lesiones e infecciones tisulares inducen esta actividad regenerativa promovida por variados mecanismos que influyen en el microambiente celular. El sistema inmunológico detecta alteraciones en el tejido intestinal y, a través de la activación de células inmunocompetentes y la secreción de citoquinas proinflamatorias, favorece la desdiferenciación de células especializadas hacia células madre para desencadenar la respuesta regenerativa. En cuanto al sistema nervioso entérico, su influencia está sujeta a modificaciones en la microbiota y los hábitos alimenticios, y se encuentra determinada en gran parte, por las células gliales entéricas y la expresión de distintos marcadores de plasticidad, que permiten limitar la lesión y reparar el tejido. Por su parte, la epigenéticamodifica la expresión genética y consecuentemente, la capacidadregenerativa intestinal, variando de acuerdo a cada paciente porla influencia de factores externos como la dieta o el estadopsicobiológico. De esta forma, la respuesta regenerativa intestinalinducida por lesiones, integra múltiples mecanismos y poseeimportantes repercusiones clínicas en cuanto a EII, disbiosise incluso tumorogénesis; conocer los mecanismos que regulanesta actividad puede sentar las bases para la creación de terapias innovadoras en el mismo ámbito(AU)
The intestinal system has an intrinsic and physiological regenerative capacity that takes place from the Lgr5+ stem cells located at the bottom of the intestinal crypts, which differentiate into secretory and absorptive progenitor cells with their specialized cells by activating intracellular signalslike Wnt, Hippo and Notch. Adverse conditions such asinjuries and tissue infections induce this regenerative activity promoted by various mechanisms that influence the cellular microenvironment. The immune system senses disturbances in the intestinal tissue and, through the activation of immunocompetent cells and the secretion of proinflammatorycytokines, favors the dedifferentiation of specialized cells intostem cells to trigger the regenerative response. Regarding theenteric nervous system, its influence is subject to modificationsin the microbiota and dietary habits, and is largely determinedby enteric glial cells and the expression of different plasticitymarkers, which enable to limit injuries and repair tissue. On the other hand, epigenetics modifies genetic expressionand, consequently, intestinal regenerative capacity, varying according to each patient due to the influence of external factors such as diet or psychobiological status. There fore, the intestinal regenerative response induced by lesions integrates multiple mechanisms and has important clinical repercussions in terms of IBD, dysbiosis, and even tumorigenesis; knowing themechanisms that regulate this activity can lay the foundations for the creation of innovative therapies in the same field (AU)
Subject(s)
Humans , Male , Female , Intestinal MucosaABSTRACT
In this study, binary SiO2-CaO hollow mesoporous bioactive glass nanoparticles (HMBGNs) are prepared by combing selective etching and impregnation strategies. Spherical silica particles (SiO2 NPs) are used as hard cores to assemble cetyltrimethylammonium bromide (CTAB)/silica shells, which are later removed by selective etching to generate a hollow structure. After the removal of CTAB by calcination, the mesoporous shell of particles is formed. Calcium (Ca) is incorporated into the particles using impregnation by soaking the etched SiO2 NPs in calcium nitrate aqueous solution. The amount of incorporated Ca is tailorable by controlling the ratio of SiO2 NPs:calcium nitrate in the soaking solution. The produced HMBGNs are bioactive, as indicated by the rapid formation of hydroxyapatite on their surfaces after immersion in simulated body fluid. In a direct culture with MC3T3-E1 cells, HMBGNs were shown to exhibit concentration-dependent cytotoxicity and can stimulate osteogenic differentiation of MC3T3-E1 cells at concentrations of 1, 0.5, and 0.25 mg/mL. Our results indicate that the combination of selective etching and impregnation is a feasible approach to produce hierarchical HMBGNs. The produced hollow particles have potential in drug delivery and bone tissue regeneration applications, and should be further investigated in detailed in vitro and in vivo studies.
