Distefano, M. | Search bioRxiv

bioRxiv2022

Macro-Chemical Biology: Engineering Biomimetic Trogocytosis with Farnesylated Chemically Self-Assembled Nanorings

With the recent success of cell-based therapies, there has been a rapidly emerging interest in the engineering of cell-cell interactions and communications. Inspired by the natural intercellular material transfer process of trans-endocytosis or trogocytosis, we proposed that targeted farnesylated chemically self-assembled nanorings (farnesyl-CSANs) could serve as a biomimetic trogocytosis vehicle for engineering directional cargo transfer between cells; thus, allowing cell-cell interactions to be monitored, as well as facilitating communication between the cells by delivery of bioactive species. The membranes of sender cells were stably modified by hydrophobic insertion with the targeted farnesyl-CSANs and to be efficiently transferred to receiver cells expressing the appropriate receptor by endocytosis. CSAN-assisted cell-cell cargo transfer (C4T) was demonstrated to be receptor-specific and dependent on direct cell-cell interactions, the rate of receptor internalization and the amount of receptor expression. In addition, C4T was shown to facilitate cell-to-cell delivery of an apoptosis inducing drug, as wells as antisense oligonucleotides (ASO). Taken together, the C4T approach is a potentially versatile biomimetic trogocytosis platform that can be used to monitor cell-cell interactions, as well as the engineering of cell-cell communications, such as cell-based drug delivery.

bioengineering↗

bioRxiv2020

Negative durotaxis: cell movement toward softer environments

Durotaxis - the ability of cells to sense and migrate along stiffness gradients - is important for embryonic development and has been implicated in pathologies including fibrosis and cancer. Although cellular processes can sometimes turn toward softer environments, durotaxis at the level of cells has thus far been observed exclusively as migration from soft to stiff regions. The molecular basis of durotaxis, especially the factors that contribute to different durotactic behaviors in various cell types, are still inadequately understood. With the recent discovery of optimal stiffness, where cells generate maximal traction forces on substrates in an intermediate stiffness range, we hypothesized that some migratory cells may be capable of moving away from stiff environments and toward matrix on which they can generate more traction. Combining hydrogel-based stiffness gradients, live-cell imaging, genetic manipulations, and computational modeling, we found that cells move preferentially toward their stiffness optimum for maximal force transmission. Importantly, we directly observed biased migration toward softer environments, i.e. negative durotaxis, in human glioblastoma cells. This directional migration did not coincide with changes in FAK, ERK or YAP signaling, or with altered actomyosin contractility. Instead, integrin-mediated adhesion and motor-clutch dynamics alone are sufficient to generate asymmetric traction to drive both positive and negative durotaxis. We verified this mechanistically by applying a motor-clutch-based model to explain negative durotaxis in the glioblastoma cells and in neurites, and experimentally by switching breast cancer cells from positive to negative durotaxis via talin downregulation. Our results identify the likely molecular mechanisms of durotaxis, with a cells contractile and adhesive machinery dictating its capacity to exert traction on mechanically distinct substrates, directing cell migration.

biophysics↗