A new method for fabricating cell-embedded ECM capsules and ECM-loaded spheroids

A typical three-dimensional culture of hepatocytes is to embed cells in extracellular matrix (ECM) capsule by using an emulsion method. However, usage of oil causes cellular damage. In this study, we aimed to establish a new method for forming cell-embedded ECM capsules without using oil. We also report “ECM-loaded spheroids” which is a different type of cell-embedded ECM capsules having less amount of ECM. To form ECM capsule, we utilized the methylcellulose (MC) medium [1]. We injected 1 μl of undiluted ECM (Matrigel or collagen) suspending 2000 Hep G2 cells into the MC medium. The cellular damage was obviously reduced when we made capsules by the MC medium. However, the albumin secretion activity of the Hep G2 cells in ECM capsule was half level compared with normal multicellular spheroids because too much gels inhibited cell-to-cell interaction. When we used 30-times diluted Matrigel, the thickness of gel between cells was significantly reduced. In this study, we called this kind of spheroid with ECM as “ECM-loaded spheroid”. The albumin secretion activity of ECM-loaded spheroids was higher than that of normal spheroids. In conclusion, we established a new method to fabricate ECM capsules and ECM-loaded spheroids, and ECM-loaded spheroids demonstrated higher hepatic function than conventional spheroids.