Formation of assembloids by DNA-mediated synthetic cell self-assembly.

Area of Science:

• Biomaterials Science
• Synthetic Biology
• Tissue Engineering

Background:

• Current *in vitro* models like organoids and organs-on-chip face challenges in controlling molecular composition and biophysical properties due to reliance on natural cells.
• Variability and limited robustness in natural cell-based models hinder precise control and scalability.

Purpose of the Study:

• To introduce a novel self-assembly strategy for creating millimeter-sized synthetic tissue constructs from individual synthetic cells.
• To overcome limitations in controlling molecular composition and biophysical properties in *in vitro* tissue models.

Main Methods:

• Functionalization of synthetic cell lipid membranes with cholesterol-tagged single-stranded DNA aptamers for programmable intercellular adhesion via sequence-specific hybridization.
• Encoding internal architecture, distinct functional zones, and tuneable mechanical properties by varying aptamer complementarity.
• Demonstration of biological functionality by incorporating T cell-stimulatory antibodies into segregated regions, mimicking lymph node organization.

Main Results:

• Successful formation of millimeter-sized synthetic constructs through DNA-driven self-assembly directly in cell culture medium.
• Demonstrated compatibility with high-throughput microwell formats for scalable screening.
• Reversible assembly achieved through DNA displacement.
• Incorporation of T cells into synthetic tissues, showing infiltration and expansion, mimicking lymph node function.

Conclusions:

• Established a route to tissue-scale matrices built from synthetic cell collectives.
• Represented a critical step toward functionally integrating living and non-living matter.
• Enabled precise control over synthetic tissue architecture and biological function.