The dream of every kid who ever read a comic book — and quite a few of us in limb preservation — is that one day a person will regrow what they have lost. Salamanders do it. Zebrafish do it. We… fibrose.
In a paper just out in Nature Communications, Yu L and colleagues from Ken Muneoka’s long-running regeneration lab (Texas A&M and Tulane) add a striking new wrinkle to that story. They took adult mice — not neonates, not embryos, but adult mice — performed proximal digit amputations at a level that ordinarily heals with scar and nothing else, and asked a beautifully simple question: what if we just gave the wound the two signals it would have gotten in utero, in the right order?
The recipe: FGF2 first, then BMP2
FGF2 first. Then BMP2. That is the entire intervention.
FGF2 coaxes wound cells into forming a blastema — the regenerative cap that amphibians use to rebuild an entire limb. BMP2 then tells the blastema what to differentiate into. The result is regeneration of the distal phalanx, complete with a phalangeal growth plate — strongly suggesting the tissue is genuinely recapitulating embryonic development rather than papering over the defect with scar.
Two regenerative engines, running side by side
The wilder part: in parallel with the blastema-dependent response, the FGF2 → BMP2 cocktail also triggers a blastema-independent response that rebuilds a synovial joint complex — tendon, ligament, articular cartilage, and a sesamoid-like bone — from cells in the stump itself. Together the two responses replace essentially all of the skeletal architecture removed by amputation.
Cell lineage tracing nailed down something philosophically important. The wound cells that populated the blastema were positionally re-specified — meaning they appear to forget where they came from and behave like embryonic progenitors at the appropriate site. The regeneration-competent cells were already there. The mammalian wound bed is not barren. It is just waiting for an invitation that adult mammals rarely send.
A few thoughts from the limb preservation chair
This is a mouse digit, not a transmetatarsal amputation in a 68-year-old with diabetes, CKD, PAD, and a healed contralateral TMA. The scale, the vascular environment, the neuropathy, the infection biology — none of it is the same problem. The decades-long body of work coming out of the Muneoka lab — Yu L, Han M, Dawson LA, Dolan CP, and colleagues — has been moving stepwise from neonatal to adult mouse, and from distal to more proximal amputation levels, one signal at a time. Sequential FGF2 → BMP2 is the latest, and arguably tidiest, demonstration that the right cue at the right time can flip fibrosis to regeneration.
For us, the conceptual takeaway is what matters now. Wound healing is not a destiny written in tissue type. It is a decision the local cells are making based on the signals around them. The right question for diabetic foot wounds is not only “how do we close this?” — it is also “how do we recruit the regeneration-competent cells we already know are sitting in the periosteum, the dermis, and the plantar fat pad?”
Plenty of unanswered questions, of course. Will the same sequence work in older, diabetic, vasculopathic tissue? Can the joint-rebuilding response be induced without amputation — say, in a chronic non-healing wound bed? What is the right delivery vehicle, the right dose, the right interval between FGF2 and BMP2? And what is the downside risk when you tell adult cells to behave like embryos? (Ask any oncologist.)
Still — what a fun direction. Sequential growth factors. Positional re-specification. A regenerated joint with tendon and ligament. The fact that the cells are already there is the whole point. We just have to learn what to say to them.
Open access. Worth a careful read.
Yu L, Yan M, Scaturro KZ, Qureshi O, Lin YL, Bartelle BB, Smith CA, Hurtado DO, Cai JJ, Dawson LA, Brunauer R, Suva LJ, Han M, Dolan CP, Muneoka K. Digit regeneration in mice is stimulated by sequential treatment with FGF2 and BMP2. Nature Communications. 2026 Apr 17. doi: 10.1038/s41467-026-72066-8
#regeneration #amputation #limbpreservation #woundhealing #growthfactor #FGF2 #BMP2 #blastema #fibrosis #repairregenerationreplacement #SALSAdoc #ALPSdoc
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