Blood vessels are composed of two main cell types, endothelial cells (ECs) and smooth muscle cells (SMCs). All blood vessels share the same basic structure with a single concentric layer of ECs separated from the surrounding secondary layer of SMCs, by an elastic membrane – the internal elastic lamina. Depending on the type of vessel, (elastic artery, muscular artery or arteriole), the secondary compartment can contain different numbers of SMC layers.

Here, we hypothesise that ECs not only communicate via EVs over intermediate and long distances but also signal to neighbouring SMCs in the myoendothelial junction (MEJ) using the same paracrine mechanism. The overall goal of this work was to use the nanofibrillar cellulose hydrogel (NFC) – GrowDex^®-T, to create a physiological model of the EC and SMC layers, whilst studying EV-mediated communication between these ECs and SMCs. We have successfully transduced A10 cells (SMCs) with a red fluorescent protein (RFP) lentivirus construct and along with a green fluorescent protein (GFP) expressing HMEC-1 cell line (ECs), we have been able to determine the optimal 3D cultivation and co-culture conditions within and on the surface of GrowDex-T. Additionally, we have tested and confirmed the viability of the cells using XTT viability assays. Finally, we have used GrowDex-T to form long tube-like constructs, coated the outer layer of the constructs with a thick layer of ECs and cultured them for up to 4 weeks.

In summary, we have been able to develop a novel co-culture model of GFP-ECs and RFP-SMCs to study the cell-cell interactions on an NFC based scaffold.