Recapitulating the mechanical properties of human tissue is key when developing biomimetic models for basic research and drug development. To determine the potential of GelMA-CBP inks to mimic tissue, we measured the mechanical properties of porcine tissues and compared them with those of 1-7% GelMA formulations. Fresh porcine brain, lung, liver, and heart were sliced and cut to form 8 mm puck-like pieces that match the size of our GelMA cast pucks. The storage (G'), loss (G") and compressive (E) modulus were obtained from the naïve tissue samples and after conditioning in cell culture media (Supplementary Information, Figure ). We found statistically significant differences between the naïve and the cell culture media conditioned samples for the softer tissues (brain, lung, and liver), with the conditioned tissues showing higher moduli than fresh naïve ones. In the case of the heart, the stiffest tissue analyzed, there were no differences between naïve and conditioned samples in all cases. These differences may point to interactions between the tissue of interest and the cell culture media components (e.g., proteins, divalent cations) that lead to stiffening of soft tissues, where the extracellular matrix network is not strong enough to overcome these interactions. In addition, we observed that the samples measured without a previous conditioning step showed a larger replicate to replicate variability, suggesting that the tissues could be drying during processing and data acquisition, yielding variable and progressively higher modulus values. These are key observations that, together with the use of different techniques for the determination of the mechanical properties, could explain some of the high variability observed in the moduli reported in the literature for fresh tissues (the interested reader is referred to Reference 51, where the mechanical properties of human tissue as reported by different techniques is discussed). To ameliorate these issues and obtain the most reproducible and comparable data, we elected to do conditioning step in cell culture media for the GelMA-CBP materials prior to performing the mechanical property measurements.