Abstract: Our organs function via repetitive morphological structures like follicles, vertebra, and villi that rival the orderliness achieved by modern manufacturing. In recent decades, the generation of these periodic structures has been primarily ascribed to pre-existing gene expression patterns. In the developing skin, however, recent studies suggest that the concept of a molecular blueprint be shed in order to consider mechanisms where cells self-organize through physical interactions. Self-organization mechanisms are especially uncharted in the collectives of fibroblasts that make up mesenchymal tissues. In our latest work, we find that the self- organization of fibroblasts embedded in extracellular matrix (ECM) is sufficient to robustly generate the ordered structures of the skin: a grid of pre-follicle aggregates. These results highlight the pattern-generating power of the mesenchyme, where the formation of cell-ECM supra-structures may prove to be a broadly-used tool to efficiently and robustly initiate ordered tissue structures. A central gap that remains is dissecting how the biophysical features of individual cells impact the dynamics of cell-cell coordination to enable the structuring of organs. In our proposed studies of such cellular ecology, we aim to understand how cells convert energy injected at the molecular scale to couple motion, organize force, and communicate during tissue morphogenesis. This inquiry is made possible by a novel collective cell behavioral platform that successfully captures the self-organizing process that skin progenitors undergo as they coalesce into an ordered and structurally linked tissue. We will investigate how biophysical features impact self-organization and the cell-cell linkages that emerge as a result. Based on our recent findings, we propose to investigate bioelectrical signaling to determine whether calcium oscillatory behavior can serve as a means to make mechanical coupling of cells more robust. We will also probe the energetic flows occurring across the cell collective as they self-organize in order to discover which metabolic pathways serve to guide the energy flows required for cells to express their mechanical behavior. Understanding how physical entities such as mechanics, electricity, and energy are co-regulated during mesenchymal tissue self-organization formation will offer new pathways for tissue design and reconstitution as well as present new avenues for drug development.

Narrative: It remains unclear how cellular components link across scales to create robust tissue morphology. Given that the function of an organ depends on its correct structure, these gaps in knowledge present a major bottleneck in the mission to engineer or regenerate functional tissues. This proposal will exploit a novel cell behavioral assay to investigate the biomechanical, bioelectric, and bioenergetic regulatory features of the self-organizing progenitor cells of the skin.