Encapsulation of Neural Cells in Nano-Featured Polymer Scaffolds through Coaxial Electrospinning
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Encapsulation of Neural Cells in Nano-Featured Polymer Scaffolds through Coaxial Electrospinning Rajesh A Pareta1, and Thomas J Webster2 1 Division of Engineering, Brown University, 182 Hope Street, Providence, RI, 02912 2 Division of Engineering and Orthopedics, Brown University, 182 Hope Street, Providence, RI, 02912 ABSTRACT Encapsulation of PC12 cells (neural cell model) in alginate hydrogels with a protective coating of poly(lactic-co-glycolic acid) (PLGA) was achieved in the present study using co-axial electrospinning. Co-axial electrospinning consists of two concentric capillaries compared to only one capillary in conventional electrospinning. This allows for the processing of two liquid solutions simultaneously. Neural cells suspended in hydrogels were injected in the inner capillary, while the carbon nanotubes (added for nano-features on surface and conductivity) suspended in PLGA were injected in the outer capillary at controlled flow rates. The outer surfaceof the scaffold was desired to be conductive so that it could be stimulated though external current, which have been reported to favour neural cells growth. On the application of a high voltage, a compound jet formed at the capillary exits and resulted in a co-electrospun fiber of nerve cells encapsulated in PLGA with carbon nanotubes. In this study, the voltage varied from 0 to 15 kV and various flow rates were tested to achieve a stable cone-jet mode in electrospinning. The cell density in the media varied from 0.5 to 5 million cells/ml and the PLGA solution concentration varied from 1 to 10 mg/ml. This resulted in a three dimensional scaffold with nanofeatures (due to carbon nanotubes) on the polymer surface, which were collected on the grounded substrate. PC12 cells were found to be viable inside microspheres after 3 days. The size of the microspheres was quite uniform and less than 200 µm. This technique may be very useful for the development of cell encapsulated scaffolds which mimic natural body tissue organization for tissue engineering applications such as nervous system regeneration. INTRODUCTION Living cells encapsulated in polymeric shells are receiving increasing attention because of their wide range of possible applications in biotechnology, medicine and ecology. Microencapsulation of living genetically engineered cells may be used as drug delivery vehicles, immunotherapies and engineered tissues [1]. People envisage the use of encapsulated cells in clinical treatments, like type I diabetes, central nervous system regeneration, and tumor therapy. Implantation of microencapsulation of recombinant cells has great potential for gene therapy where therapeutic proteins can be sustained and long-term delivered by microencapsulated cells [2]. The technology of cell microencapsulation represents a strategy in which cells that secrete therapeutic products are immobilized and immunoprotected within polymeric and biocompatible devices [3]. Based on this concept, a wide spectrum of cells and tissues may be immobilized, enhancing the po
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