Adaptive fabrication of biofunctional decellularized extracellular matrix niche towards complex engineered tissues
Recreating organ-specific microenvironments of the extracellular matrix (ECM) in vitro has been an ongoing challenge in biofabrication. In this study, I present a biofunctional ECM-mimicking protein scaffold with tunable biochemical, mechanical and topographical properties. This scaffold, formed by microfibres, displays three favorable characteristics as a cell culture platform: high-loading of key ECM proteins, single-layered mesh membrane with controllable mesh size, and flexibility for supporting a range of cell culture configurations. Decellularized extracellular matrix (dECM) powder was used to fabricate this protein scaffold, as a close replicate of the chemical composition of physiological ECM. The highest dECM concentration in the solidified protein scaffold was 50 wt%, with gelatin consisting the rest. In practice, a high density of dECM-laden nano- to microfibres was directly patterned on a variety of substrates to form a single layer of mesh membrane, using the low-voltage electrospinning patterning (LEP) method. The smallest fibre diameter was measured at 450 nm, the smallest mesh size of the membrane was below 1 μm, and the thickness of the membrane was estimated to be less than 2 μm. This fabrication method demonstrated a good preservation of the key ECM proteins and growth factors, including collagen IV, laminin, fibronectin, VEGF and b-FGF. The integrated fibrous mesh exhibited robust mechanical properties, with tunable fibril Young’s modulus for over two orders of magnitude in the physiological range (depending on the dECM concentration). Combining this mesh membrane with 3D printing, a cell culture device was constructed. Co-culture of human glomerulus endothelial cells and podocytes was performed on this device, to simulate the blood-to-urine interface in vitro. Good cell attachment and viability were demonstrated, and specific cell differentiation and fibronectin secretion were observed. This dECM-laden protein scaffold sees the potential to be incorporated into a glomerulus-on-chip model, to further improve the physiological relevance of in vitro pathological models.