A comparison between the mechanical properties of samples with and without conditioning in cell culture media was also performed (Supplemental Information, Figure ). The comparisons of the storage, loss, and compressive moduli for porcine tissues and the crosslinked GelMA-CBP materials are shown in Figure -H (shaded areas present the minimum and maximum values for the tissues measured). It can be observed that compressive moduli, and largely the storage moduli, of the crosslinked GelMA-CBP constructs closely matched those of the porcine organs, indicating that they could be used for building representative biomimetic models. However, when a deeper analysis is conducted, it is evident that the GelMA-CBP materials do not exactly match the three moduli simultaneously. For example, despite the match of the E values between the heart tissue and 7% GelMA, the range of values for G' and G" of the heart were well above that of any of the crosslinked materials. Furthermore, most of the G" values of the crosslinked materials were lower than those of the tissues, indicating a limitation in capturing the viscous properties of porcine tissues. This mismatch of the viscoelastic properties between the GelMA-CBP materials and the porcine tissues depending on the type of rheological measurement points to the importance of performing a complete analysis of the samples of interest and biomaterial inks when developing biomimetic models. It has been previously reported that tissues, including the brain, 52 lung, liver, and heart, present viscoelastic properties that result in a time-dependent mechanical response and stress-relaxation in response to a deformation. This means that to mimic tissues accurately, it is necessary to use hydrogels with the appropriate viscoelastic characteristics.