A biomimetic collagen membrane for delivery of mesenchymal stem cells and growth factors for large fracture repair

This study aimed to engineer a collagen membrane scaffold for the delivery of platelet rich plasma (PRP) and bone marrow derived mesenchymal stem cells (BM-MSCs) for complex fracture repair. The design of the guided bone regeneration device was based on the microarchitecture of the induced membrane which was found to be rich in high organised collagen fibres and have less distinct bi-layer organisation than expected. This contributed towards the design, optimisation and manufacturing of a working prototype made of 70% collagen and 30% polycaprolactone (PCL) using novel needleless-electrospinning technology. The scaffolds produced had substantial mechanical properties and were found to be biocompatible. The scaffold was also found to be made up of nano-scale fibres and sub-micron pores which acted as a barrier. The scaffold can be tailored using laser cutting to incorporate pores as well as folding and heat-treating the scaffold to increase the construct’s thickness. PRP was also optimised as a biological signalling product to maximise BM-MSC migration and proliferation at the site of injury. Removal of leukocytes was not found to improve cell migration or proliferation as expected and all platelet products tested induced significantly more cell migration than fetal calf serum (FCS). Most promising was the experiments that combined the platelet products, BM-MSCs and scaffolds, which found that the loaded scaffolds were effectively able to support rare BM-MSC colony formation from bone marrow aspirate. These promising findings indicate that this scaffold could be effectively translated in future treatment of bone reconstruction alongside clinical standard PRP.