# Bidirectionally validated in silico and in vitro formation of specific depth zone-derived chondrocyte spheroids and clusters

## TL;DR

Researchers combined computer simulations and lab experiments to understand how cartilage cells form clusters, which could help develop better disease models and therapies.

## Contribution

A bidirectional validation of in silico and in vitro formation of depth zone-specific chondrocyte clusters using a computational model.

## Key findings

- Primary chondrocytes from distinct cartilage zones form zone-specific spherical clusters in vitro.
- Computational simulations using the Cellular Potts Model accurately mirrored in vitro cluster formation.
- The in silico model can predict and support the development of 3D multicellular models for therapeutic applications.

## Abstract

3D multicellular self-organized cluster models, e.g., organoids are promising tools for developing new therapeutic modalities including gene and cell therapies, pharmacological mechanistic and screening assays. Various applications of these models have been used extensively for decades, however, the mechanisms of cluster formation, maintenance, and degradation of these models are not even known over in-vitro-life-time. To explore such advantageous models mimicking native tissues or organs, it is necessary to understand aforementioned mechanisms. Herein, we intend to clarify the mechanisms of the formation of cell clusters. We previously demonstrated that primary chondrocytes isolated from distinct longitudinal depth zones in articular cartilage formed zone-specific spherical multicellular clusters in vitro. To elucidate the mechanisms of such cluster formation, we simulated it using the computational Cellular Potts Model with parameters were translated from gene expression levels and histological characteristics corresponding to interactions between cell and extracellular matrix. This simulation in silico was validated morphologically with cluster formation in vitro and vice versa. Since zone specific chondrocyte cluster models in silico showed similarity with corresponding in vitro model, the in silico has a potential to be used for prediction of the 3D multicellular in vitro models used for development, disease, and therapeutic models.