Sound-based assembly of three-dimensional cellularized and acellularized constructs.

Herein we show an accessible technique based on Faraday waves that assist the rapid assembly of osteoinductive ß-Tricalcium phosphate (ß-TCP) particles as well as human osteoblast pre-assembled in spheroids. The hydrodynamic forces originating at 'seabed' of the assembly chamber can be used to tightly aggregate inorganic and biological entities at packing densities that resemble those of native tissues. Additionally, following a layer-by-layer assembly procedure, centimeter scaled osteoinductive three-dimensional and cellularized constructs have been fabricated. We showed that the intimate connection between biological building blocks is essential in engineering living system able of localized mineral deposition. Our results demonstrate, for the first time, the possibility to obtain three-dimensional cellularized and acellularized anisotropic constructs using Faraday waves.

Ray Optics Model for Optical Trapping of Biconcave Red Blood Cells.

Red blood cells (RBCs) or erythrocytes are essential for oxygenating the peripherical tissue in the human body. Impairment of their physical properties may lead to severe diseases. Optical tweezers have in experiments been shown to be a powerful tool for assessing the biochemical and biophysical properties of RBCs. Despite this success there has been little theoretical work investigating of the stability of erythrocytes in optical tweezers. In this paper we report a numerical study of the trapping of RBCs in the healthy, native biconcave disk conformation in optical tweezers using the ray optics approximation. We study trapping using both single- and dual-beam optical tweezers and show that the complex biconcave shape of the RBC is a significant factor in determining the optical forces and torques on the cell, and ultimately the equilibrium configuration of the RBC within the trap. We also numerically demonstrate how the addition of a third or even fourth trapping laser beam can be used to control the cell orientation in the optical trap. The present investigation sheds light on the trapping mechanism of healthy erythrocytes and can be exploited by experimentalist to envisage new experiments.

Sound-induced morphogenesis of multicellular systems for rapid orchestration of vascular networks.

Morphogenesis, a complex process, ubiquitous in developmental biology and many pathologies, is based on self-patterning of cells. Spatial patterns of cells, organoids, or inorganic particles can be forced on demand using acoustic surface standing waves, such as the Faraday waves. This technology allows tuning of parameters (sound frequency, amplitude, chamber shape) under contactless, fast and mild culture conditions, for morphologically relevant tissue generation. We call this method Sound Induced Morphogenesis (SIM). In this work, we use SIM to achieve tight control over patterning of endothelial cells and mesenchymal stem cells densities within a hydrogel, with the endpoint formation of vascular structures. Here, we first parameterize our system to produce enhanced cell density gradients. Second, we allow for vasculogenesis after SIM patterning control and compare our controlled technology against state-of-the-art microfluidic culture systems, the latter characteristic of pure self-organized patterning and uniform initial density. Our sound-induced cell density patterning and subsequent vasculogenesis requires less cells than the microfluidic chamber. We advocate for the use of SIM for rapid, mild, and reproducible morphogenesis induction and further explorations in the regenerative medicine and cell therapy fields.