Novel human placenta-based extract for vascularization strategies in tissue engineering.

BACKGROUND: There is critical unmet need for new vascularized tissues to support or replace injured tissues and organs. Various synthetic and natural materials were already established for use of 2D and 3D in vitro neovascularization assays, however, they still cannot mimic the complex functions of the sum of the extracellular matrix (ECM) in native, intact tissue. Currently, this issue is only addressed by artificial products like MatrigelTM, which comprises of a complex mixture of ECM proteins, extracted from animal tumor tissue. Despite its outstanding bioactivity, the isolation from tumor tissue hinders its translation into clinical applications. Since non-human ECM proteins may cause immune reactions, as are frequently observed in clinical trials, human ECM proteins represent the best option when aiming for clinical applications, Experiment: Here, we describe an effective method of isolating a human placenta substrate (hpS) that induces the spontaneous formation of an interconnected network of green fluorescence labeled human umbilical vein endothelial cells (gfpHUVEC) in vitro. The substrate was biochemically characterized by using a combination of bicinchoninic acid assay (BCA), DNA and glycosaminoglycan (GAG) content assays, sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) analysis and Western blot, angiogenesis arrays, chromatographic thrombin detection, HPLC-based amino acid quantification analysis and assessment of antimicrobial properties.

RESULTS: 2D in vitro cell culture experiments have been performed to determine the vasculogenic potential of hpS, which demonstrated that cell networks developed on hpS show a significantly higher degree of complexity (number of tubules/junctions; total/mean tube length) when compared to MatrigelTM. As 3D cell culture techniques represent a more accurate representation of the in vivo condition, the substrate was 3D solidified using various natural polymers. 3D in vitro vasculogenesis assays have been performed by seeding gfpHUVEC in a hpS-fibrinogen clot.

CONCLUSIONS: Concluding, hpS provides a potent human-material-based alternative to xenogenic-material-based biomaterials for vascularization strategies in tissue engineering.