Efecto angiogénico comparado del celecoxib microencapsulado en PLGA v/s no encapsulado en un ensayo in vivo de angiogénesis / Comparative angiogenic effect of microencapsulated celecoxib in PLGA v/s non-encapsulated in an in vivo angiogenesis assay

RESUMEN: La angiogénesis es el proceso de formación de vasos sanguíneos a partir de otros formados previamente. Existen varios factores que están involucrados en el proceso, así como agentes capaces de modular distintas etapas de esta. Si bien, se ha observado que Celecoxib es capaz de inhibir la angiogénesis en distintos modelos, aún no se ha observado la potencial capacidad antiangiogénica de este agente cuando es microencapsulado en PLGA. Se incubaron huevos fertilizados y a las 48 horas se dividieron en 4 grupos para ser instilados con PBS (control), PLGA, Celecoxib 1000 ppm o Celecoxib 1000 ppm + PLGA. Se realizó un conteo de los vasos sanguíneos a las 48, 72 y 96 horas post aplicación de la solución a estudiar. Los resultados muestran que tanto Celecoxib como Celecoxib+PLGA reducen los vasos sanguíneos, manteniendo el mismo efecto a las 48, 72 y 96 horas y no existen diferencias significativas entre los dos tratamientos. Esto podría ser explicado por la concentración de Celecoxib usada o el margen de tiempo analizado, pudiendo encontrarse diferencias posteriores a este rango de tiempo o con concentraciones distintas.

SUMMARY: Angiogenesis is the process of blood vessel formation from previously formed ones. There are several factors involved in the process, as well as agents capable of modulating different stages of it. Although, it has been observed that Celecoxib is capable of inhibiting angiogenesis in different models, the potential antiangiogenic capacity of this agent has not yet been observed when it is microencapsulated in PLGA. Fertilized eggs were incubated and at 48 hours they were divided into 4 groups to be instilled with PBS (control), PLGA, Celecoxib 1000ppm or Celecoxib 1000 ppm + PLGA. A blood vessel count was performed at 48, 72 and 96 hours after application of the solution to be studied. The results show that both Celecoxib and Celecoxib + PLGA reduce blood vessels, maintaining the same effect at 48, 72 and 96 hours and there are no significant differences between the two treatments. This could be explained by the concentration of Celecoxib used or the time frame analyzed, being able to find differences after this time range or with different concentrations.

VPA/PLGA microfibers produced by coaxial electrospinning for the treatment of central nervous system injury

The central nervous system shows limited regenerative capacity after injury. Spinal cord injury (SCI) is a devastating traumatic injury resulting in loss of sensory, motor, and autonomic function distal from the level of injury. An appropriate combination of biomaterials and bioactive substances is currently thought to be a promising approach to treat this condition. Systemic administration of valproic acid (VPA) has been previously shown to promote functional recovery in animal models of SCI. In this study, VPA was encapsulated in poly(lactic-co-glycolic acid) (PLGA) microfibers by the coaxial electrospinning technique. Fibers showed continuous and cylindrical morphology, randomly oriented fibers, and compatible morphological and mechanical characteristics for application in SCI. Drug-release analysis indicated a rapid release of VPA during the first day of the in vitro test. The coaxial fibers containing VPA supported adhesion, viability, and proliferation of PC12 cells. In addition, the VPA/PLGA microfibers induced the reduction of PC12 cell viability, as has already been described in the literature. The biomaterials were implanted in rats after SCI. The groups that received the implants did not show increased functional recovery or tissue regeneration compared to the control. These results indicated the cytocompatibility of the VPA/PLGA core-shell microfibers and that it may be a promising approach to treat SCI when combined with other strategies.

In vitro and in vivo biocompatibility of reoss® in powder and putty configurations

Article This study evaluated comparatively two configurations (powder and putty) of a composite biomaterial based on PLGA (Poly(lactide-co-glycolide)/nanoescale hydroxyapatite (ReOss®, Intra-Lock International) through microscopic morphology, in vitro cytotoxicity, biocompatibility and in vivo response as a bone substitute. SEM and EDS characterized the biomaterials before/after grafting. Cytocompatibility was assessed with murine pre-osteoblasts. Osteoconductivity and biocompatibility were evaluated in White New Zealand rabbits. Both configurations were implanted in the calvaria of eighteen animals in non-critical size defects, with blood clot as the control group. After 30, 60 and 90 days, the animals were euthanized and the fragments containing the biomaterials and controls were harvested. Bone blocks were embedded in paraffin (n=15) aiming at histological and histomorphometric analysis, and in resin (n=3) aiming at SEM and EDS. Before implantation, the putty configuration showed both a porous and a fibrous morphological phase. Powder revealed porous particles with variable granulometry. EDS showed calcium, carbon, and oxygen in putty configuration, while powder also showed phosphorus. After implantation EDS revealed calcium, carbon, and oxygen in both configurations. The materials were considered cytotoxic by the XTT test. Histological analysis showed new bone formation and no inflammatory reaction at implant sites. However, the histomorphometric analysis indicated that the amount of newly formed bone was not statistically different between experimental groups. Although both materials presented in vitro cytotoxicity, they were biocompatible and osteoconductive. The configuration of ReOss® affected morphological characteristics and the in vitro cytocompatibility but did not impact on the in vivo biological response, as measured by the present model.

Resumo Este estudo avaliou comparativamente duas configurações (pó e massa) de um biomaterial composto com base de PLGA (Poli(láctico-co-glicólico)/hidroxiapatita em nanoescala (ReOss®, Intra-Lock International) através da morfologia microscópica, citotoxicidade in vitro, biocompatibilidade e resposta in vivo como substituto ósseo. MEV e EDS caracterizaram os biomateriais antes/após o enxerto. A citocompatibilidade foi avaliada em pré-osteoblastos murinos. A osteocondutividade e a biocompatibilidade foram avaliadas em coelhos Branco da Nova Zelândia. Ambas as configurações foram implantadas na calvária de dezoito animais em defeitos não-críticos, com coágulo sanguíneo como grupo controle. Após 30, 60 e 90 dias, os animais foram eutanasiados e os fragmentos contendo os biomateriais e controles coletados. Blocos ósseos foram embebidos em parafina (n=15) destinados às análises histológica e histomorfométrica, e em resina (n=3) destinadas à MEV e EDS. Antes da implantação, a configuração massa mostrou ambas fases morfológicas porosa e fibrosa. O pó revelou partículas porosas com granulometria variável. EDS mostrou cálcio, carbono e oxigênio na configuração massa, enquanto o pó mostrou também fósforo. Após a implantação a EDS revelou cálcio, carbono e oxigênio em ambas configurações. Os materiais foram considerados citotóxicos pelo teste XTT. A análise histológica mostrou nova formação óssea e nenhuma reação inflamatória nos sítios de implante. Entretanto, a análise histomorfométrica indicou que a quantidade de osso neoformado não foi estatisticamente diferente entre os grupos experimentais. Embora ambos os materiais tenham apresentado citotoxicidade in vitro, foram biocompatíveis e osteocondutores. A configuração do ReOss® afetou as características morfológicas e a citocompatibilidade in vitro, porém não impactou a resposta biológica in vivo, como medido pelo presente modelo.