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1.
J Biomater Sci Polym Ed ; 24(15): 1794-813, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23746285

RESUMO

Recent insight into the critical role of pro-inflammatory cytokines, particularly tumor necrosis factor-α (TNF-α), in bone regeneration has heralded a new direction in the design of tissue engineering constructs. Previous studies have demonstrated that continuous delivery of 50 ng/ml TNF-α to mesenchymal stem cells (MSCs) cultured on three-dimensional (3D) biodegradable electrospun poly(ϵ-caprolactone) (PCL) microfiber meshes stimulates mineralized matrix deposition, a marker of osteogenic differentiation. Since TNF-α exhibits a biphasic pattern of expression following bone fracture in vivo, this study aimed to investigate the effects of temporal patterns of TNF-α delivery on in vitro osteogenic differentiation of MSCs cultured on 3D electrospun PCL scaffolds. MSCs were cultured for 16 days and exposed to continuous, early, intermediate, or late TNF-α delivery. To further elucidate the effects of TNF-α on osteogenic differentiation, the study design included MSCs precultured both in the presence and absence of typically required osteogenic supplement dexamethasone. Mineralized matrix deposition was not observed in constructs with dexamethasone-naïve MSCs, suggesting that TNF-α is not sufficient to trigger in vitro osteogenic differentiation of MSCs. For MSCs precultured with dexamethasone, TNF-α suppressed alkaline phosphatase activity, an early marker of osteogenic differentiation, and stimulated mineralized matrix deposition, a late stage marker of MSC osteogenic differentiation. By elucidating the impact of temporal variations in TNF-α delivery on MSC osteogenic differentiation, our results offer insight into the regenerative mechanism of TNF-α and provide the design parameters for a novel tissue engineering strategy that rationally controls TNF-α signaling to stimulate bone regeneration.


Assuntos
Células-Tronco Mesenquimais/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Poliésteres/química , Alicerces Teciduais/química , Fator de Necrose Tumoral alfa/administração & dosagem , Animais , Regeneração Óssea/efeitos dos fármacos , Regeneração Óssea/imunologia , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/imunologia , Histocitoquímica , Masculino , Células-Tronco Mesenquimais/citologia , Microscopia Eletrônica de Varredura , Osteogênese/imunologia , Ratos , Ratos Endogâmicos F344 , Engenharia Tecidual/métodos , Fator de Necrose Tumoral alfa/imunologia
2.
J Biomed Mater Res A ; 100(5): 1097-106, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22345065

RESUMO

As an initial step in the development of a bone tissue engineering strategy to rationally control inflammation, we investigated the interplay of bone-like extracellular matrix (ECM) and varying doses of the inflammatory cytokine tumor necrosis factor alpha (TNF-α) on osteogenically differentiating mesenchymal stem cells (MSCs) cultured in vitro on 3D poly(ε-caprolactone) (PCL) microfiber scaffolds containing pregenerated bone-like ECM. To generate the ECM, PCL scaffolds were seeded with MSCs and cultured in medium containing the typically required osteogenic supplement dexamethasone. However, since dexamethasone antagonizes TNF-α, the interplay of ECM and TNF-α was investigated by culturing naïve MSCs on the decellularized scaffolds in the absence of dexamethasone. MSCs cultured on ECM-coated scaffolds continued to deposit mineralized matrix, a late stage marker of osteogenic differentiation. Mineralized matrix deposition was not adversely affected by exposure to TNF-α for 4-8 days, but was significantly reduced after continuous exposure to TNF-α over 16 days, which simulates the in vivo response, where brief TNF-α signaling stimulates bone regeneration, while prolonged exposure has damaging effects. This underscores the exciting potential of PCL/ECM constructs as a more clinically realistic in vitro culture model to facilitate the design of new bone tissue engineering strategies that rationally control inflammation to promote regeneration.


Assuntos
Osso e Ossos/metabolismo , Diferenciação Celular , Matriz Extracelular/metabolismo , Células-Tronco Mesenquimais/citologia , Osteogênese , Transdução de Sinais , Fator de Necrose Tumoral alfa/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Distinções e Prêmios , Materiais Biocompatíveis , Pesquisa Biomédica , Calcificação Fisiológica/efeitos dos fármacos , Cálcio/metabolismo , Contagem de Células , Diferenciação Celular/efeitos dos fármacos , Congressos como Assunto , Matriz Extracelular/efeitos dos fármacos , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/enzimologia , Microscopia Eletrônica de Varredura , Osteogênese/efeitos dos fármacos , Poliésteres/farmacologia , Ratos , Transdução de Sinais/efeitos dos fármacos , Estudantes
3.
Biomaterials ; 31(7): 1666-75, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19963268

RESUMO

This study presents a first step in the development of a bone tissue engineering strategy to trigger enhanced osteogenesis by modulating inflammation. This work focused on characterizing the effects of the concentration of a pro-inflammatory cytokine, tumor necrosis factor alpha (TNF-alpha), on osteogenic differentiation of mesenchymal stem cells (MSCs) grown in a 3D culture system. MSC osteogenic differentiation is typically achieved in vitro through a combination of osteogenic supplements that include the anti-inflammatory corticosteroid dexamethasone. Although simple, the use of dexamethasone is not clinically realistic, and also hampers in vitro studies of the role of inflammatory mediators in wound healing. In this study, MSCs were pre-treated with dexamethasone to induce osteogenic differentiation, and then cultured in biodegradable electrospun poly(epsilon-caprolactone) (PCL) scaffolds, which supported continued MSC osteogenic differentiation in the absence of dexamethasone. Continuous delivery of 0.1 ng/mL of recombinant rat TNF-alpha suppressed osteogenic differentiation of rat MSCs over 16 days, which was likely the result of residual dexamethasone antagonizing TNF-alpha signaling. Continuous delivery of a higher dose, 5 ng/mL TNF-alpha, stimulated osteogenic differentiation for a few days, and 50 ng/mL TNF-alpha resulted in significant mineralized matrix deposition over the course of the study. These findings suggest that the pro-inflammatory cytokine TNF-alpha stimulates osteogenic differentiation of MSCs, an effect that can be blocked by the presence of anti-inflammatory agents like dexamethasone, with significant implications on the interplay between inflammation and tissue regeneration.


Assuntos
Materiais Biocompatíveis/farmacologia , Diferenciação Celular/efeitos dos fármacos , Células-Tronco Mesenquimais/citologia , Osteogênese/efeitos dos fármacos , Polímeros/farmacologia , Alicerces Teciduais/química , Fator de Necrose Tumoral alfa/farmacologia , Fosfatase Alcalina/metabolismo , Animais , Cálcio/metabolismo , Relação Dose-Resposta a Droga , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/enzimologia , Células-Tronco Mesenquimais/ultraestrutura , Microscopia Eletrônica de Varredura , Poliésteres/farmacologia , Ratos
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