Fabrication and characterization of PLGA/HAp composite scaffolds for delivery of BMP-2 plasmid DNA

The objective of this study is to construct complex of DNA and PLGA/HAp composite scaffold for bone tissue engineering. Naked DNA has low transfection efficiency so DNA loaded chitosan particles are used nowadays in gene delivery due to their high transfection efficiency, but unfortunately this is accompanied by strong immunological reaction of cells. In order to preserve the advantage of polymeric particles and reduce immunological effect at the same time, a new DNA release system is developed which makes possible sustained DNA release with negligible immunological effects. Poly (lactide-co-glycolide) (PLGA)/Hydroxylapatite (HAp) composite scaffolds with different HAp contents (0%, 5% and 10%) are fabricated by an electrospinning method and DNA is incorporated into the scaffolds in 3 ways (i.e. naked DNA, encapsulation of DNA/chitosan nanoparticles into scaffolds after fiber fabrication by dripping, and encapsulation of DNA/chitosan nanoparticles into scaffold by mixing with PLGA/HAp solution before fiber fabrication). All the scaffolds are characterized by SEM, XRD, DSC and GC-MS and the results show that the scaffolds are non-woven, nano- to micro-fibered membrane structures composed predominantly of PLGA with amorphous dispersion of HAp nanoparticles inside polymeric matrix. In vitro release tests were carried out on 9 different scaffolds to check the effects of HAp contents and the encapsulation ways of DNA on the release properties. These effects are also tested by human marrow stem cells (hMSCs) by comparing their cell attachment ability, cell viability and DNA transfection efficiency. It is demonstrated that the addition of HAp nanoparticles increased the release rate of DNA for both naked and encapsulated DNA. Cell culture experiments show that the scaffolds with encapsulated DNA/chitosan nanoparticles have higher cell attachment, higher cell viablility and desirable transfection efficiency of DNA. The observations show that DNA/chitosan nanoparticles encapsulated PLGA/HAp composite scaffold is promising for use in bone regeneration.