Today’s life science research realizes that understanding complex and fast cellular dynamics within and among cells as they grow and differentiate is key to gaining insight into biological processes. Although technically more challenging, live cell imaging enables researchers to explore the complex mechanisms of cellular biology which normally can not be visualized in fixed specimens. Instead of viewing a snapshot of a cell’s current state, live cell imaging (time lapse) turns snapshots into movies providing additional opportunities of discovery. Live cell imaging has now become an essential technique for addressing physiological questions in cell biology, neuroscience, cancer research, and developmental biology. “The aggregation of multiple cells, such as mesenchymal condensation, is an important biological process in skeletal muscle development, osteogenesis, and adipogenesis.

Due to limited in vivo study model systems, a simple and effective in vitro three-dimensional (3D) aggregation system is required to study the mechanisms of multicellular aggregation and its applications. We first generated controlled mesenchymal stem cell (MSC) aggregates using a bioprinting technique to monitor their aggregation and sprouting. We induced the angiogenic potential of the MSCs through chemical inhibition of the Rho/Rho-associated protein kinase (ROCK) pathway, which led to hairy sprouting in the aggregates.

The angiogenic potential of this 3D construct was then tested by subcutaneously implanting the Matrigel with 3D MSC aggregates in a rat. Treatment of 3D MSCs with the ROCK inhibitor, Y27632, increased their angiogenic activity in vivo. The gene expressions and histological staining indicated that angiogenesis and neovascularization were mainly regulated by the paracrine factors secreted from human 3D MSC constructs. Our results demonstrate the enhancement of the angiogenic potential of the MSC constructs through the secretion of vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) by the inhibition of the Rho/ROCK pathway” (NIST).