Electrospun poly(caprolactone) (PCL) microfibers with controlled release of ascorbic acid for bone tissue engineering

Abstract

The concept of bone tissue engineering holds great promise for the future treatment of large bone defects through the utility of implanting degradable polymeric scaffolds, to which mesenchymal stem cells (MSCs) can attach, allowing the ingrowths of new tissue.

Current methods of osteoinduction of cultured stem cells require osteogenic supplements to be replenished every 2 to 3 days. Although it is convenient to do so for in vitro, it will cause unnecessary pain and inconvenience for in vivo testing. Thus, the purpose of this project is to realize a sustained release of ascorbic acid (one of the osteogenic supplements), which was loaded into the scaffold directly, up to 14 days to induce early osteogenic differentiation in vitro.

Poly(caprolactone) (PCL) scaffold of micro-sized fibers with embedded ascorbic acid was being fabricated through electrospinning method. By manipulating processing factors, such as electrospinning conditions and polymer solution parameters, drug delivery profiles of ascorbic acid, fiber morphology and mechanical properties of scaffolds can be optimized. Drug release profiles were studied by UV-Vis spectroscopy, while fiber morphology and mechanical properties of scaffolds were studied using FESEM and instron tester respectively.

Different solvents systems (DCM + DMF or DCM + Methanol), spinning methods (core-sheath, single and emulsion) and the addition of polymer or copolymers were tested to find the best ascorbic acid (ASB) release profile for scaffolds. It was observed that the emulsion spinning method gave the best result of obtaining micro-sized fibers with drug release profile of 40% initial burst release and up to 70% of sustained release of ASB over 14 days. However, its young‟s modulus was found to be the lowest as compared to other experimented scaffolds. Thus, more work needs to be done to find a more appropriate scaffold for bone tissue engineering.