Unveiling how mitotic spindle orientation in 3D human colon organoids affects matrix displacements through a 4D study...

Cell division is a major event in tissue homeostasis, enabling renewal and regeneration. In human colon, vertical division is mainly observed in the stem cell compartment while horizontal division is more frequent in the progenitor transit amplifying zone. To study cell division, the human colon epithelium represents a relevant model due to its rapid renewal and high number of mitoses. Studying live mechanical interactions between the epithelium and its matrix in vivo is challenging due to the lack of suitable methods. Colon organoids seeded in Matrigel are good models because they recapitulate the organization and properties of tissue architecture. This culture set-up allows to study the displacements of the matrix around the organoid. We studied the impact of cell division within the human colonic epithelium on the extracellular matrix. We validated an original experimental and analytical process with 3D time-lapse confocal microscopy to follow cell division and matrix displacements, on which we performed a 4D Digital Volume Correlation. Depending on the orientation of the mitotic spindle, cell division affects the matrix differently. Vertical division causes a predominantly uniaxial displacement of the matrix, while horizontal division involves a multiaxial and wider displacement.