Gene-Expressing Liposomes as Synthetic Cells for Molecular Communication Studies

Abstract

The bottom-up branch of synthetic biology includes—among others—innovative studies that combine cell-free protein synthesis with liposome technology to generate cell-like systems of minimal complexity, often referred to as synthetic cells. The functions of this type of synthetic cell derive from gene expression, hence they can be programmed in a modular, progressive and customizable manner by means of ad hoc designed genetic circuits. This experimental scenario is rapidly expanding and synthetic cell research already counts numerous successes. Here, we present a review focused on the exchange of chemical signals between liposome-based synthetic cells (operating by gene expression) and biological cells, as well as between two populations of synthetic cells. The review includes a short presentation of the “molecular communication technologies,” briefly discussing their promises and challenges.

Intercellular communication between artificial cells by allosteric amplification of a molecular signal

“…Although communication by diffusing chemical signals is widely used in nature to regulate multicellular behaviour, the engineering of synthetic, analogous systems remains challenging and is little explored 45,46 . The handful of designs that explore communication between artificial cells mostly rely on signalling molecules that (i) can induce protein expression in cell lysates 32,36,38 (ii) are small, uncharged substrates in model enzymatic cascades (most notably hydrogen peroxide) [28][29][30][31] , (iii) or use DNA oligonucleotides or entire proteins to program a highly selective signal 13,25,38 .…”

Cell‐free protein synthesis: The transition from batch reactions to minimal cells and microfluidic devices

“…A merit of the former approach is the accommodation of the essential constituents by the existing microorganism, without the necessity to hold substantial knowledge of the component parts (Lee & Kim, 2013). On the other hand, however, cell construction from minimal components, though assiduous, would lead to a facilitated, sufficiently understood cell‐like system which, as a consequence, would allow indulgent engineering of the system (Rampioni, D'Angelo, Leoni, & Stano, 2019).…”

Membrane functionalization in artificial cell engineering

“…The biomimetic nature of such lipid systems facilitates active protein reconstitution [108] as well as a high degree of biocompatibility [109], enabling membranes to be interfaced with (and generated by) biochemical machinery such as cell-free transcription-translation systems obtained from the lysates of living cells [110]. This allows the creation of ACs with the ability to express proteins in the cell lumen [11,[111][112][113], and has been exploited in a variety of contexts as detailed by a recent review [114]. Unlike living systems which rely on proteins for almost all functions, ACs are readily compatible with the wide range of molecules generated by synthetic chemistry and nanotechnology.…”