Editing the functional layer

The argument starts from a contrast. Gene editing, the solicitation says, acts as a permanent, binary switch. The proposed alternative intervention point is the mature protein, the “functional execution layer”: a non-permanent, non-heritable control knob that lets a physiological response scale up or down for long enough to limit an acute injury, after which the protein turns over. Three obstacles have blocked a general “CRISPR for proteins”: folded domains are thermodynamically hard to reach, chemistry has been bespoke to each target, and editing several sites at once tends to misfold the protein.

PENG asks teams to integrate three capabilities in one pipeline.

Pillar	What it must do
Programmable targeting	Use generative design to make de novo binders that dock the editing machinery to virtually any epitope on a mature, native protein.
Generalizable chemistry	Replace single-use chemistry with universal mechanisms: for example a generalized intein chassis with logic-gated chemistry, or co-translational editing that intercepts the nascent chain before it folds.
Multiplexing	Run several orthogonal, non-interfering editing modules together, without destabilizing the protein or making the cell toxic.

Schedule and metrics

The programme runs 42 months: Phase 1A (platform foundations) 18 months, Phase 1B (capability demonstration) 6 months, Phase 2 (system integration) 18 months. In Phase 1A teams must edit targets from at least three distinct structural protein families, and the solicitation names globular, transmembrane and fibrous as examples. In Phase 1B teams are evaluated head to head on previously unannounced targets, edited under short-notice constraints in complex tissue systems.

Pillar	Phase 1	Phase 2
Targeting	at least 50% of nascent proteins in a cell edited over 8 weeks	at least 75% across diverse proteins over 4 weeks
Chemistry	at least 3 edit sites (not simultaneous), on proteins with more than 5 edits per machine	at least 5 edit sites, on proteins with more than 20 edits per machine
Multiplexing and complexity	a functioning protein with more than 2 edits, in more than 2 cell types	more than 3 edits, in more than 3 cell types or an organoid system
Future-capabilities readiness	edited protein stable for hours to days	stable for more than 3 weeks

The limits the solicitation sets on itself

Three limits matter for the rest of this chapter. Proposed research must edit existing proteins in their native cellular environments, not isolated in vitro protein preparations. It must not include human subjects research, and animal work is expected only in Phase 2. The programme is bench-top and in vitro tissue models such as organoids.

What the script confirms

book7/ch-peng-verify.py does three things and no more. It searches the text of the solicitation, and of the Muir 2025 paper it builds on, for the statements used above. It checks the schedule and metric arithmetic: 18 + 6 + 18 = 42 months, and every Phase 2 threshold at least as demanding as its Phase 1 counterpart. And it checks what the corpus's own Polylaminin page says, so that Part III quotes that page and nothing more. Every check is paired with a control that must fail; a swapped metric table is reported as wrong, and the search that shows a word is absent is first shown to find it where it exists.

The nearest published mechanism

The solicitation cites three 2025 papers as the breakthroughs it builds on. One of them, Kofoed, Erkalo, Tay, Ye, Lin and Muir, Programmable protein ligation on cell surfaces (Nature, 2025), describes a device driven by proximity-gated protein trans-splicing: two inactive polypeptide fragments are brought together by cell-surface features and an active protein is generated locally. That is the closest published example of the “logic-gated chemistry triggered by specific cellular environments” the solicitation asks for. It works on cell surfaces; it is not an editing platform for arbitrary endogenous proteins, and this chapter does not suggest that it is.

Five statements, each with a status

The corpus's Polylaminin chapter (Book 3, chapter B) describes laminin polymerised at acidic pH into a scaffold, a 2024 pilot (a preprint when the page was written; published in Spinal Cord on 4 August 2026, see the update box on that page), and a Phase I safety trial authorised in January 2026. The table sets that against the solicitation. Status uses the corpus's own scale: established, model, analogy, open.

Statement	Status
Scope. Polylaminin as the corpus page describes it is purified laminin polymerised in vitro and given to patients. PENG excludes isolated in vitro preparations and human subjects research. As described, that work is outside the programme.	established, from the two documents
Shared goal. Both change what an existing protein does without changing its gene. Polylaminin does it by changing laminin’s assembly state with pH. PENG wants programmable edits to the protein itself. The goal is shared; the mechanism is not.	analogy
Fibrous family. PENG requires edits across three structural families, with fibrous named as one. Laminin is an extracellular matrix protein. Whether the solicitation would count it as a fibrous target is not something the solicitation says.	open, unchecked
Gated ligation on laminin. Whether proximity-gated trans-splicing could be used to control a matrix protein’s assembly is a question this chapter raises and does not answer. Nothing here is a proposal, and no evidence for it is offered.	open
The fold reading. The Polylaminin chapter reads axon regrowth as a Whitney A1 fold. PENG neither tests nor supports that reading. The chapter’s own caveats stand: its Lean file is not held in the repository, and the figure’s fold marker is a display threshold, not a computed transition.	model, unchanged by this chapter

One further point, from the author’s own question of whether DARPA is a place Polylaminin-type work could be done. DARPA is a funder with many programmes, and PENG is only one. Search results indicate that its Biological Technologies Office runs other work on spinal cord injury; one headline names a programme, BG+, for implantable adaptive devices, which is a different technology from a laminin scaffold. This desk read only those headlines, not the programme pages, and has not checked whether any of it is open, current or suited to a biologic scaffold. That is a separate question from PENG and is left open.

Where a DoD route for this kind of work does exist

PENG is not the vehicle, and the table above says why. The question that remains is which Department of Defense mechanisms are, if any. This desk looked at one candidate and one that is not.

Programme	What this desk found	Fit
CDMRP Spinal Cord Injury Research Program, FY26	Four award mechanisms are listed, including a Clinical Trial Award and a Clinical Translation Research Award. The pre-application date was 3 August 2026, which has passed. The full-application date is 12 November 2026.	The nearest fit by subject and by mechanism. Open: whether a biologic scaffold is eligible, and whether a full application can be made without a pre-application. The programme announcement was not read.
DARPA BG+ (Bridging the Gap Plus)	A headline describes implantable adaptive devices for spinal cord injury. The programme page was not read.	Different technology from a laminin scaffold. Not assessed.
DARPA PENG	Excludes isolated in vitro preparations and human subjects research (Part I).	Outside its stated scope as the corpus page describes Polylaminin.

That is the gap this chapter exists to record. The programme built around editing proteins in cells does not take a scaffold made in vitro, and the programme built around spinal cord injury is a different office with its own calendar. Whether anyone in the United States is doing Polylaminin-type work is not established here. A short web search turned up the published pilot and the corpus page, and no US trial; failing to find one in a short search is not evidence that none exists. For scale, a systematic review of local hypothermia in acute spinal cord injury, published in Spinal Cord on the same day as the Polylaminin pilot, pooled five mostly retrospective single-arm studies, 48 patients in all, only two of which reported baseline injury grades, and its authors call the result hypothesis-generating; its introduction lists biomaterial scaffolds among the localised interventions now attracting attention; the Polylaminin pilot is eight patients in one uncontrolled study, and the two use different outcome definitions, so their figures should not be set side by side.