Surface modified PLGA/carbon nanofiber composite enhances articular chondrocyte functions

Grace Eunseung Park, Purdue University

Abstract

Since articular cartilage has a limited self regeneration capability, alternative methods are needed for repairing cartilage defects. The purpose of the present in vitro study was to explore the effects of material surface properties and external stimulation on chondrocyte (cartilage-synthesizing cell) functions. Based on this information, a goal of this research was to propose a scaffold composite material for enhancing articular chondrocyte function. To improve functions of chondrocytes, material (namely, poly(lactic-co-glycolic acid); PLGA) surfaces were modified via chemical (NaOH) etching techniques. Chondrocytes were cultured on surface-modified 2-D PLGA films and 3-D PLGA tissue engineering scaffolds, which were created by a salt-leaching method. Carbon nanofibers were imprinted on PLGA matrices in an aligned pattern for controlled electrically-active surface features. Electrical stimulation was applied to expedite and enhance chondrocyte functions. Results demonstrated that both NaOH-treated 2-D and 3-D substrates enhanced chondrocyte functions (cell numbers as well as extracellular matrix production) compared to non-treated PLGA substrates. Furthermore, chondrocytes preferred to attach along the carbon nanofiber patterns imprinted on PLGA. Electrical stimulation also enhanced chondrocyte functions on carbon nanofiber/PLGA composites. Underlying material properties that may have enhanced chondrocyte functions include a more hydrophilic surface, surface energy differences due to the presence of carbon nanofibers, increased surface area, altered porosity, and a greater degree of nanometer roughness. Moreover, these altered surface properties positively influenced select protein adsorption that controlled subsequent chondrocyte adhesion. Collectively, this study provided a scaffold model for osteochondral defects that can be synthesized using the above techniques and a layer by layer approach to accommodate the property differences in each layer of natural cartilage. Specifically, these results suggest that the superficial zone, middle zone, and deep zone of cartilage should be composed of carbon nanofibers aligned parallel to the surface in PLGA, randomly oriented carbon nanofibers in PLGA, and carbon nanofibers aligned perpendicular to the surface in PLGA, respectively. Clearly, such scaffolds may ultimately enhance the efficacy of scaffolds used for articular cartilage repair.

Degree

Ph.D.

Advisors

Webster, Purdue University.

Subject Area

Biomedical research|Materials science

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