B.Eng. Erick Angel Lopez Lopez

Synthetic cells have emerged as a novel biomimetic approach for studying fundamental cellular functions and enabling new therapeutic interventions. However, the potential to program synthetic cells into self-organized 3D collectives to replicate the structure and function of tissues has remained largely untapped. Here, self-assembly properties are engineered into synthetic cells to form millimeter-sized 3D lymphatic bottom-up tissues (lymphBUTs) with mechanical adaptability, metabolic activity, and hierarchical microstructural organization. It is demonstrated that primary human immune cells spontaneously infiltrate and functionally integrate into these synthetic lymph nodes to form living tissue hybrids. Applying lymphBUTs, it is shown that structured 3D organization and mechanical support drives T cell activation and the application of lymphBUTs for ex vivo expansion of regulatory CD8+ T cells is demonstrated. The study highlights the functional integration of living and non-living matter, advancing synthetic cell engineering toward 3D tissue structures.

Approaches in tissue engineering, organoid culture, and organs-on-chip have propelled the development of increasingly sophisticated in vitro models of human tissues. However, as they are formed from natural cells, it is challenging to control their molecular composition and biophysical properties, increasing variability and limiting their robustness. To overcome these limitations, we introduce a self-assembly strategy for synthetic cells that enables the formation of millimeter-sized synthetic constructs based on single synthetic cells. Specifically, we functionalize the lipid membrane of synthetic cells with cholesterol-tagged single-stranded DNA aptamers, which drive programmable intercellular adhesion through sequence-specific hybridization. This allows individual synthetic cells to interconnect into higher order 3D constructs. By varying aptamer complementarity, internal architecture with spatially distinct functional zones and tuneable mechanical properties can be encoded. Most importantly, the DNA-driven self-assembly operates directly in cell culture medium, is compatible with high-throughput microwell formats enabling scalable screening workflows and is reversible by DNA displacement. To demonstrate the biological functionality of these synthetic tissues, we incorporate T cell-stimulatory antibodies into spatially segregated tissue regions. This design mimics lymph node organization and supports infiltration of natural primary human T cells, which subsequently expand within the synthetic tissue. Together, these results establish a route to tissue-scale matrices built from synthetic cell collectives and represent a critical step toward functionally integrating living and non-living matter.