The applications of conductive nanomaterials in the biomedical field

Bone tissue engineering using bone mesenchymal stromal cells (BMSCs) is a multidisciplinary strategy that requires biodegradable scaffold, cell, various promoting cues to work simultaneously. Electrical stimulation (ES) is known able to promote osteogenic differentiation of BMSCs, but it is interesting to know how can it play the strongest promotion effect. To strengthen local ES on BMSCs, parallel-aligned conductive nanofibers were electrospun from the mixtures of poly(L-lactide) (PLLA) and multi-walled carbon nanotubes (MWCNTs), and used for cell culture. Osteogenic differentiation of BMSCs was conducted by applying ES (direct current, 1.5 V, 1.5 h/day) perpendicular to the fiber direction during the day 1-7, day 8-14, or day 15-21 period of the osteoinductive culture. In comparison with ES-free groups, bone-related markers and genes were found significantly up-regulated when ES was applied on BMSCs growing on nanofibers having higher conductivity. When the ES was applied at the earlier stage of osteoinductive culture, the promotion effect on osteogenic differentiation would be stronger. In the presence of a BMP blocker, the down-regulated expressions of bone-related genes were able to be slightly recovered by ES, especially when the ES was applied at the beginning of osteoinductive culture (i.e. day 1-7). The promotion effect generated by ES in the early stage was found sustainable to later stages of differentiation, while those ES applied at later stages of differentiation should have missed the optimal point. In other words, later ES was not so necessary in inducing the osteogenic differentiation of BMSCs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3369-3383, 2017.

Section: Introductionmentioning

confidence: 99%

Time‐dependent effect of electrical stimulation on osteogenic differentiation of bone mesenchymal stromal cells cultured on conductive nanofibers

Zhu

Wei

et al. 2017

“…Since the first use of synthetic biodegradable sutures in the latter half of the 1960s, 1 biodegradable polymers prepared from poly(lactic acid) (PLA), poly(glycolic acid) (PGA), and other degradable poly(a-hydroxy acids) have been widely used in biomedical applications approved by the FDA. Poly (lactide-co-glycolide) acid (PLGA) based on PLA and PGA has been used for fabricating temporary prostheses, 2-5 threedimensional porous scaffolds and films, [6][7][8][9][10][11][12][13][14][15][16][17] controlled/sustained release drug delivery vehicles, [18][19][20][21][22][23][24][25][26] wound closure (surgical sutures and staples), [27][28][29] and implantable thera-peutic devices (orthopedic fixation devices and cardiovascular stents and grafts), [30][31][32][33][34][35][36] all of which have made many significant achievements in tissue engineering, regenerative medicine, gene therapy, controlled drug delivery, and bionanotechnology. 37 PLGA has its hydrolytically labile chemical bonds in its backbone and has been shown to primarily undergo bulk degradation in vivo via chemical hydrolysis of the hydrolytically unstable ester bonds into lactic acid and glycolic acid.…”

Section: Introductionmentioning

confidence: 99%

The effect of fluid shear stress on the in vitro degradation of poly(lactide‐co‐glycolide) acid membranes

Chu

Zheng

Yao

et al. 2016

Self Cite

Poly(lactide-co-glycolide) acid (PLGA) has been widely used as a biodegradable polymer material for coating stents or fabricating biodegradable stents. Its mechanism of degradation has been extensively investigated, especially with regard to how tensile and compressive loadings may affect the in vitro degradation of PLGA. Fluid shear stress is also one of the most important factors in the development of atherosclerosis and restenosis. But the effect of fluid shear stress on the degradation process is still unclear. The purpose of this study was to characterize the in vitro degradation of PLGA membranes that experienced different fluid shear stresses in 150 mL of deionized water at 37°C for 20 days. Particular emphasis was given to changes in the viscosity of the degradation solution, as well as the mechanical and morphological properties of the samples. The viscosity of the degradation solution with the mechanical loaded specimens was more severely affected than that of the control group. Increasing the fluid shear stress could accelerate the loss of the ultimate strength of PLGA membranes while it slowed down the change of the tensile elastic modulus in the early period. With regard to morphology, the surface roughness was more obviously reduced in the loaded groups. This indicated that the fluid shear stress could affect the in vitro degradation of PLGA membranes. Therefore, this study could help improve the design of PLGA membranes for biomedical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2016.

“…This process leads to generate poly(lactic acid) (PLA) and poly(glycolic acid) (PGA), and the final degradation products are CO 2 and H 2 O which can be excreted from the body by the tricarboxylic acid cycle safely . Regard to its great biocompatibility and good processability, PLGA was approved by the FDA and widely used in biomedical applications such as degradable and absorbable sutures, implants, artificial skin graft and scaffolds, and drug release systems . Especially, as cardiovascular incidents are dramatically increasing, the applications of PLGA in heart patches and polymeric biodegradable stents (BDSs) have been drawn more and more attention.…”

Section: Introductionmentioning

confidence: 99%

Effects of different fluid shear stress patterns on the in vitro degradation of poly(lactide‐co‐glycolide) acid membranes

Chu

et al. 2016

Self Cite

The applications of poly (lactide-co-glycolide) acid (PLGA) for coating or fabricating polymeric biodegradable stents (BDSs) have drawn more attention. The fluid shear stress has been proved to affect the in vitro degradation process of PLGA membranes. During the maintenance, BDSs could be suffered different patterns of fluid shear stress, but the effect of these different patterns on the whole degradation process is unclear. In this study, in vitro degradation of PLGA membranes was examined with steady, sinusoid, and squarewave fluid shear stress patterns in 150 mL deionized water at 37°C for 20 days, emphasizing on the changes in the viscosity of the degradation solution, mechanical, and morphological properties of the samples. The unsteady fluid shear stress with the same average magnitude as the steady one accelerate the in vitro degradation process of PLGA membranes in terms of maximum fluid shear stress and "window" of effectiveness. Maximum fluid shear stress accelerates the in vitro degradation of molecular fragments that diffused out in the solution while the "window" of effectiveness affects too in the early stage. Besides, maximum fluid shear stress and "window" of effectiveness accelerates the in vitro loss of tensile modulus and ultimate strength of the PLGA membranes while the maximum fluid shear stress plays the leading role in the decrease of tensile modulus at the early degradation stage. This study could help advance the degradation design of PLGA membranes under different fluid shear stress patterns for biomedical applications like stents and drug release systems. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 23-30, 2017.