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1.
Stem Cells ; 39(9): 1166-1177, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33837584

RESUMO

The expansion of pluripotent stem cells (PSCs) as aggregates in stirred suspension bioreactors is garnering attention as an alternative to adherent culture. However, the hydrodynamic environment in the bioreactor can modulate PSC behavior, pluripotency and differentiation potential in ways that need to be well understood. In this study, we investigated how murine embryonic stem cells (mESCs) sense fluid shear stress and modulate a noncanonical Wnt signaling response to promote pluripotency. mESCs showed higher expression of pluripotency marker genes, Oct4, Sox2, and Nanog in the absence of leukemia inhibitory factor (LIF) in stirred suspension bioreactors compared to adherent culture, a phenomenon we have termed mechanopluripotency. In bioreactor culture, fluid shear promoted the nuclear translocation of the less well-known pluripotency regulator ß-catenin and concomitant increase of c-Myc expression, an upstream regulator of Oct4, Sox2, and Nanog. We also observed similar ß-catenin nuclear translocation in LIF-free mESCs cultured on E-cadherin substrate under defined fluid shear stress conditions in flow chamber plates. mESCs showed lower shear-induced expression of pluripotency marker genes when ß-catenin was inhibited, suggesting that ß-catenin signaling is crucial to mESC mechanopluripotency. Key to this process is vinculin, which is known to rearrange and associate more strongly with adherens junctions in response to fluid shear. When the vinculin gene is disrupted, we observe that nuclear ß-catenin translocation and mechanopluripotency are abrogated. Our results indicate that mechanotransduction through the adherens junction complex is important for mESC pluripotency maintenance.


Assuntos
Mecanotransdução Celular , beta Catenina , Animais , Reatores Biológicos , Diferenciação Celular/genética , Células-Tronco Embrionárias/metabolismo , Camundongos , Células-Tronco Embrionárias Murinas/metabolismo , Vinculina/metabolismo , beta Catenina/metabolismo
2.
J Emerg Med ; 52(1): 74-76, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27745915

RESUMO

BACKGROUND: Ocular chemical injuries due to accidental exposure or application of cyanoacrylate, commonly known as "superglue," have increased over the past 30 years. However, current treatment options to relieve eyelid adhesions due to cyanoacrylate applications are difficult to successfully execute and can require sedation or general anesthesia. Here we describe a simple technique to release eyelid adhesions due to cyanoacrylate, or other adhesive agents, that can be successfully performed at bedside without sedation. DISCUSSION: Topical anesthetic is instilled in the involved eye through an opening identified in the lid fissure. A Jameson muscle hook is inserted through the opening with the distal element of the hook normal to the surface of the eye. The hook is then pulled parallel to the lid margins and through the site of adhesion while counter pressure is applied with the fellow hand in the opposite motion of the hook. Residual glue from the eyelashes can be trimmed with blunt-tip scissors. Examination of the eyelids and ocular surface after application of the technique to open the eyelids showed successful release of adhesion sites with no additional injuries to the eye itself. CONCLUSIONS: A Jameson muscle hook can be used in emergency departments to safely and successfully relieve eyelid adhesions due to the inadvertent application of cyanoacrylate glue without the use of general anesthesia.


Assuntos
Adesivos/efeitos adversos , Queimaduras Químicas/terapia , Pálpebras/lesões , Administração Tópica , Anestésicos/administração & dosagem , Anestésicos/farmacologia , Anestésicos/uso terapêutico , Cianoacrilatos/administração & dosagem , Cianoacrilatos/efeitos adversos , Serviço Hospitalar de Emergência/organização & administração , Humanos
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