In vitro culture mimicking the liver fibrosis is important not only for investigating its mechanisms, but also for reducing experimental animals. Hepatic stellate cells (HSCs) play a major role in liver fibrosis. HSCs are quiescent in a normal liver and differentiate into activated myofibroblasts in a damaged liver. HSCs are rapidly activated on culture plates, making it difficult to evaluate the fibrosis response over time. Spheroids of HSCs cultured on a porous membrane showed in vivo like deactivation. Therefore, this study aimed to develop a culture system for liver fibrosis evaluation that mimics the in vivo fibrosis mechanism using HSC spheroids. Here, we investigated a culture method that demonstrates the transition of HSCs to fibrosis using uniformly formed HSC spheroids. HSC spheroids were cultured on plastic plates, during which the cells changed to a fibrous state and showed increased expression of activation marker genes, indicating a transition to an activated phenotype. During fibrosis transition, fibrosis is induced by transforming growth factor-β and inhibited by a yes-associated protein inhibitor; thus, the in vitro culture method can reproduce the fibrosis mechanism. Finally, the gene expression of integrin β1 increased, which was related to the adhesion and activation mechanisms in spheroids.

Osteoarthritis is a joint disease categorized by the degradation of articular cartilage, affecting more than 20% of individuals aged 65 and older. Murine in vivo models are often used to study osteoarthritis by destabilizing the medial meniscus. However, there are limited studies to study osteoarthritis in vitro, especially with healthy human chondrocytes. In this study, healthy human MSC-like cells, derived from excised polydactylous human finger cartilage, were investigated as a possible model for studying the pathology of osteoarthritis in humans. YUB625 cells were cultured into monolayers for three days, then loaded with 25 MPa of high hydrostatic pressure. PCR gene expression of chondrocytes showed that excessive stress led to a downregulation of chondrocyte marker expression; early osteoarthritis markers were upregulated. The results are consistent with chondrocyte-based cell murine models, suggesting that human cells derived from excised polydactylous human fingers may be used as an alternative to animal models to study the pathology of osteoarthritis in humans.