Cell-free systems & cell-free bioproduction

01Overview and value chain

Markers: [EC: Industrial Biotechnology & Synthetic Biology Roadmap | OECD: Industrial Biotechnology | Regulator: FDA (USA), EMA (EU), NMPA (China)]

Cell-free systems (Cell-Free Protein Synthesis, CFPS) are a paradigm that dispenses with the living host cell in industrial synthesis: only the molecular translation machines (ribosomes, tRNAs, initiation/elongation/termination factors) are extracted from organisms and assembled in a reaction tube with a DNA template, amino acids and an ATP-regeneration system. A living cell spends up to 80% of its resources on its own metabolism; a cell-free system directs all activity to the product, cutting synthesis from weeks to hours and enabling proteins toxic to cells as well as non-canonical amino-acid incorporation.

Key platforms of cell-free production:

1. Cell-lysate CFPS (Cell Lysate CFPS): E. coli, CHO, wheat-germ extracts — a ready translation complex.
2. Reconstituted PURE (PURE): 36 purified E. coli enzymes, no endogenous proteases — absolute purity.
3. Enzymatic cascades (Cell-Free Cascades): 10–20 thermostable enzymes turn sugars into chemicals without a cell.
4. Paper sensors (Paper TX-TL): lyophilised TX-TL + riboswitches for field diagnostics.

Sectoral value chain

[producer culture] ──> [lysis & centrifugation] ──> [lysate]
                                                       │
                                              (DNA + ATP cascade)
                                                       │
                                                       ▼
[target protein] <─── [affinity purification] <─── [in-vitro synthesis, hours]

Value chain levels

Cross-cutting technologies of the sector:

• Cheap-substrate ATP regeneration: 10–12-enzyme cascades on glucose/starch cut energy cost 100×.
• Non-canonical amino acids (nSAA): re-assigning tRNA/synthetases to incorporate artificial amino acids (ADC, click chemistry).
• Continuous-flow microfluidic reactors: continuous substrate feed and inhibitor removal — day-long synthesis.

02US

The US leads CFPS commercialisation for therapeutic proteins and RNA pesticides (DARPA, VC).

Sutro, GreenLight, Jewett Lab, DARPA on-demand pharmacy

• Sutro Biopharma: XpressCF® platform on E. coli/CHO lysate — antibodies and ADCs, reactors to thousands of litres.
• GreenLight Biosciences: cell-free dsRNA and mRNA synthesis (agro-pesticides, vaccines) by the tonne.
• DARPA On-Demand Pharmacy + Jewett Lab (Northwestern): portable synthesis suitcases from lyophilised cartridges.

03CN

China bets on large-scale cell-free enzymatic cascades (CAS, TIB).

TIB CAS, cell-free starch from CO2, cascade biocatalysis

• TIB CAS (ASAP): an 11-enzyme cascade synthesises starch from CO2/H2 — 8.5× maize photosynthesis.
• Multi-step biocatalysis: rare sugars (allulose, tagatose), inositol, amino acids without live GMOs.
• National key R&D program: immobilised enzymes for continuous industrial reactors.

04EU

The EU leads in high-purity PURE systems and safety standards for cell-free output.

PUREfrex (GeneFrontier), Horizon Europe, Max Planck/CNRS

• PUREfrex (GeneFrontier): reconstituted system of 36 enzymes — protein screening free of bacterial LPS.
• Horizon Europe: microfluidic/membrane reactors for food and textile enzymes.
• Max Planck/CNRS: artificial cells — cell-free systems in lipid vesicles.

05Leading companies and research institutes

06Tech stack and innovations

The stack rests on PURE, cheap ATP regeneration and genetic-code expansion.

1. PURE (reconstituted translation):
   • 36 purified E. coli enzymes + 70S ribosomes; no proteases/nucleases → absolute-purity proteins.
2. Cheap-substrate ATP cascades:
   • maltodextrin phosphorylase + a starch/glucose cascade — ATP regeneration 100× cheaper.
3. Genetic-code expansion:
   • RF1-free lysates (C321.∆A) — amber codon for a non-canonical amino acid (p-azidophenylalanine) for ADC click chemistry.

07Value chains and production pipelines

Industrial pipeline of cell-free ADC synthesis (XpressCF, ISO 9001 / cGMP)

┌───────────────────────────┐      ┌───────────────────────────┐
│ 1. CHO lysate (XpressCF)  │ ───> │ 2. Reaction with DNA + nSAA│
└───────────────────────────┘      └───────────────────────────┘
                                                 │
                                                 ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 4. Affinity Ab purification│ <─── │ 3. In-vitro synthesis, 10 h│
└───────────────────────────┘      └───────────────────────────┘
              │
              ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 5. Click chemistry w/ toxin│ ───> │ 6. Filtration, QC, fill   │
└───────────────────────────┘      └───────────────────────────┘

Stage 1: CHO lysate

CHO are grown in a cGMP reactor, detergent lysis, 30,000 g centrifugation, own-mRNA removal with micrococcal nuclease.

Stage 2: Reaction mix

The reactor is loaded with lysate, antibody DNA template, energy buffer, amino acids and the non-canonical amino acid (pAMF) at the UAG codon.

Stage 3: Cell-free synthesis

At +32°C, continuous substrate feed and inhibitor dialysis; T7 translation yields the modified antibody in 10 h at 2.5 g/L.

Stage 4: Affinity purification

Protein A Sepharose binds the antibody; elution at pH 3.0, neutralisation to pH 7.2.

Stage 5: Click chemistry

DBCO-linker-toxin (MMAE) reacts with the antibody azide groups in 2 h; fixed DAR = 2.0.

Stage 6: Final control

Sterile 0.22 µm filtration, lyophilisation, MALDI-TOF DAR control, sterility and pyrogen testing.