In vitro degradation of porous poly(l-lactic acid) foams

Lu, Lichun; Peter, Susan J.; Lyman, Michelle D.; Lai, Hui Lin; Leite, Susan M.; Tamada, Janet A.; Vacanti, Joseph P.; Langer, Robert; Mikos, Antonios G.

doi:10.1016/s0142-9612(00)00048-x

Cited by 223 publications

(150 citation statements)

References 25 publications

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“…Lu et al [36] descrevem o estudo da degradação in vitro, em tampão fosfato (pH=7,4), de estruturas porosas de PLLA preparadas pela adição de sal em diferentes granulometrias e concentrações. Os autores concluem que a influência do tamanho do poro (e distribuição do tamanho de poros) não tem influên-cia na morfologia porosa durante 46 semanas de degradação, entretanto, o efeito autocatalítico é observado e descrito como sendo uma função da espessura da parede do poro.…”

Section: Morfologia Morfologia Morfologia Morfologia Morfologiaunclassified

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Polímeros bioreabsorvíveis na engenharia de tecidos

Barbanti

Zavaglia

Duek³

2005

Polímeros

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[3] , sistemas para liberação controlada de drogas [4] , stents [5] e dispositivos ortopédicos [6] . Atualmente fazem parte do cotidiano dos centros cirúrgicos no mundo inteiro.Embora muitos dispositivos protéticos artificiais estejam disponíveis, poucos podem substituir completamente todas as complexas funções biológicas. Em situações clíni-cas mais severas somente o transplante do órgão retoma as atividades orgânicas. Assim, de uma forma idealizada, a melhor alternativa seria obter um novo órgão ou tecido, substituindo aquele que não desempenha normalmente suas funções. Nos dias de hoje, a idéia da reconstrução de órgãos e tecidos criados em laboratório é amplamente difundida e investigada no mundo todo [7,8] . Resumo: A Engenharia de Tecidos consiste em um conjunto de conhecimentos e técnicas para a reconstrução de novos órgãos e tecidos. Baseada em conhecimentos das áreas de ciência e engenharia de materiais, biológica e médica, a técnica envolve a expansão in vitro de células viáveis do paciente doador sobre suportes de polímeros bioreabsorvíveis. O suporte degrada enquanto um novo órgão ou tecido é formado. Os poli(α-hidróxi ácidos) representam a principal classe de polímeros sintéticos bioreabsorvíveis e biodegradáveis utilizados na engenharia de tecidos. No desenvolvimento e na seleção desses materiais, o tempo de degradação é fundamental para o sucesso do implante. Os estudos e os desafios atuais são normalmente direcionados ao entendimento das relações entre composição química, cristalinidade, morfologia do suporte, e o processamento desses materiais. Este artigo faz uma revisão dos trabalhos recentes sobre a utilização dos polímeros sintéticos bioreabsorvíveis como suportes na engenharia de tecidos. Engenharia de tecidos Palavras-chave: Engenharia de tecidos, polímeros bioreabsorvíveis, poli(α-hidróxi ácidos). Bioresorbable Polymers in Tissue EngineeringAbstract: Tissue Engineering is based on a group of techniques for the reconstruction of new organs and tissues. Based on knowledge of materials science and engineering, biology and medicine, the technique involves the in vitro expansion of viable cells obtained from the patient on the polymeric scaffolds. The scaffold degrades while a new organ or tissue is formed. The poly(α-hydroxy acids) are the principal biodegradable and bioresorbable polymers used in tissue engineering. In developing and selecting bioresorbable scaffolds, the degradation time is fundamental for successful biocompatibility and biofuncionality. Hence, degradation studies often address variables such as the chemical composition, crystallinity, morphology of the scaffold and the processing of these materials. This paper reviews recent work in bioresorbable polymers used as scaffolds in the tissue engineering. Keywords: Tissue engineering, bioresorbable polymers, poly(α-hydroxy acids). IntroduçãoQuando a estrutura biológica de um órgão ou tecido não pode ser reparada, a alternativa viável para o restabelecimento das funções normais do paciente é repô-la com um implante feito de um b...

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Section: Morfologia Morfologia Morfologia Morfologia Morfologiaunclassified

“…Lu et al [40] avaliaram a composição química e a morfologia durante a degradação in vitro e in vivo de copolímeros de PLGA. Foram preparadas estruturas porosas de PLGA (85/15) e PLGA(50/50) através do processo de adição de sal e subseqüente evaporação do solvente.…”

Section: Morfologia Morfologia Morfologia Morfologia Morfologiaunclassified

Polímeros bioreabsorvíveis na engenharia de tecidos

Barbanti

Zavaglia

Duek³

2005

Polímeros

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“…With increase in hydrolytic degradation, PLLA tends to show a decrease in average molecular weight, a slow rise in melting point, and an increase in degree of crystallization 7,8,13,15 . In this study, a decrease in average molecular weight and an increase in degree of crystallization also occurred over time, indicating on increase in hydrolytic degradation and embrittlement.…”

Section: Discussionmentioning

confidence: 99%

“…Some have evaluated the stability of bone segments after employment of PLLA in oral and maxillofacial surgery 1,17,18 . Others have evaluated the dynamic and chemical properties of these materials 2,8,13 , or changes in their physical properties with hydrolytic degradation 7,8,13,15 .…”

Section: Introductionmentioning

confidence: 99%

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Changes in mechanical properties of poly-l-lactic acid mini-plate under functional load simulating sagittal splitting ramus osteotomy

Mizuhashi

Suga

Uchiyama

et al. 2008

International Journal of Oral and Maxillofacial Surgery

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The purpose of this study was to investigate how the characteristics of a poly-L-lactic acid mini-plate changed with dynamic loading in an environment with hydrolytic degradation.We prepared a mandible osteosynthesis model with specimen poly-L-lactic acid mini-plates to simulate sagittal splitting ramus osteotomy. The model was then subjected to dynamic loading, and changes in specimen shape and surface quality were observed. Specimen bending strength was then measured, and degree of hydrolytic degradation estimated. Statistical studies included an analysis of variance (ANOVA).Neither dynamic loading nor degree of load clearly affected degree of hydrolytic degradation. The specimens maintained their original shape and bending strength for up to 4 weeks with dynamic loading of 40 N or less in an environment with hydrolytic degradation. However, at 8 weeks, under the same conditions, the specimens showed cracks or fractures, or both, together with a clear decrease in bending strength.The results suggest that dynamic loading causes cracking in a poly-L-lactic acid mini-plate, and that growth of those cracks decreases bending strength over time, leading to fatigue fracture.--2

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Degradation behaviors of biodegradable macroporous scaffolds prepared by gas foaming of effervescent salts

Yoon¹,

Park²

2001

J. Biomed. Mater. Res.

233

139

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Biodegradable polymeric scaffolds for tissue engineering were fabricated by a gas-foaming/salt-leaching method using a combination of two effervescent salts, ammonium bicarbonate and citric acid. Poly(D,L-lactic-co-glycolic acid) (PLGA) in a state of gel-like paste was first produced by precipitation of PLGA dissolved in chloroform into ethanol. The polymer slurry was mixed with sieved particles of ammonium bicarbonate, molded, and then immersed in an aqueous solution of citric acid to generate macroporous scaffolds. The scaffolds had relatively homogeneous pore structures throughout the matrix and showed an average pore size of 200 microm and over 90% porosity. By adjusting the concentration of citric acid in the aqueous medium, it was possible to control porosity as well as mechanical strength of the scaffolds. In vitro degradation studies of three different scaffolds having lactic/glycolic acid molar ratios of 75/25, 65/35, and 50/50 exhibited marked swelling behaviors at different critical time points. The swollen matrices had a hydrogel-like internal structure. It was found that massive water uptake into the degrading scaffolds induced matrix swelling, which facilitated the hydrolytic scission of PLGA chains with concomitant disintegration of the matrices.

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In vitro degradation of porous poly(l-lactic acid) foams

Cited by 223 publications

References 25 publications

Polímeros bioreabsorvíveis na engenharia de tecidos

Polímeros bioreabsorvíveis na engenharia de tecidos

Changes in mechanical properties of poly-l-lactic acid mini-plate under functional load simulating sagittal splitting ramus osteotomy

Degradation behaviors of biodegradable macroporous scaffolds prepared by gas foaming of effervescent salts

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