ECM from decellularised tissues as an additive for polysaccharidic hybrid gels

The use of decellularised tissues represents a valid and emerging alternative over traditional synthetic scaffolds, which have limited ability to mimic the sophisticated tissue specificity1. Within the tissue engineering context, gels composed by decellularised tissues have been produced through enzymatic digestion followed by basic pH treatment2. Nevertheless, low viscosity, stability and reproducibility often limit their applicative potential. Herein, ECM, obtained from porcine blood vessels, was imbedded within alginate gels and compared to both alginate and alginate/gelatin gels aiming to process decellularised tissues in diverse physical forms and therefore broaden their application. Porcine blood vessels were decellularised1 and gels were further obtained adapting the procedure previously described2. Gels containing ECM or gelatin (8 mg/ml) and different concentrations of alginate (2-20 mg/ml) were produced by internal gelation (CaCO3 2,8% w/v, D- (+)-gluconic acid δ-lactone 0,5% w/v). The alginate samples were obtained preserving the final polymer concentration (10,13,18, 28 mg/ml). Rheological characterization was performed by time, frequency and temperature sweep analyses3. Stability tests were conducted using cell culture medium (complete DMEM medium) from 3 hours up to 7 days. Additionally, preliminary biological characterization was assessed through DNA content after seeding EA.hy 926 for 1 day. ECM-loaded alginate gels (AlgECM) samples were successfully obtained for all the concentration tested. All the samples could be removed from a mould while retaining the shape. The storage and loss moduli of all the tested alginate concentrations were frequency-independent, with the storage modulus higher than the loss modulus, therefore exhibiting gel behaviour. Higher final polymer concentration resulted in gels with higher complex viscosity. Overall, AlgECM samples showed higher values of both storage and loss moduli and higher stability in the medium comparing with unloaded alginate gels. Samples obtained with gelatin could not be produced at polymer concentrations lower than 18 mg/ml. The AlgECM samples remained stable in cell culture medium; samples with the lowest concentration of alginate (2 mg/ml of alginate and 8 mg/ml w/v of ECM) degraded after 7 days. A first biological characterization indicated an increased number of cells for AlgECM gels compared to alginate and alginate/gelatin samples. A novel gel composed of alginate and native vascular decellularised ECM is here proposed. AlgECM gels able to combine the properties of its components. Alginate improved ECM gels reproducibility and allowed the tailoring of gels rheological properties through the variation of alginate concentration. The use of ECM should promote the creation of a tissue-specific material, able to enhance cell growth and proliferation. However, a wider biological characterization should be conducted to test the ECM influence. References 1. Cells Tissues Organs 200:363–373, 2015. 2. Biomaterials 29:1630-1637, 2008. 3. Carbohyd. Polym. 103:339–347, 2014.