Liver Regeneration: The Hepatostat Model

Surgery

Resection extent 70%

Regeneration Signaling

Growth-factor (HGF/EGF) strength 1.0×

Simulation speed 1.5 days/s

Liver at 100% — steady state.

Live Readouts

Liver mass (of original)100.0%

Time since resection0.0 d

Growth rate0.0 %/d

How it works

Remove up to ~70% of a mammalian liver and the remnant does not "heal a wound" — the remaining hepatocytes re-enter the cell cycle and proliferate until the organ's total mass is restored to almost exactly its original fraction of body weight, then stop. This is compensatory hyperplasia, and the classic 2/3-partial-hepatectomy rat model is one of the best-characterized regeneration systems in biology.

dM/dt = k · H(t) · M · (1 − M / M_target)
H(t) = H0 · e^(−t/τ) + 1      (HGF/EGF pulse, decays over days)
M_target = 1.0                 (the "hepatostat" set point)

Growth is logistic: proliferation is fastest right after resection, driven by a spike in hepatocyte growth factor (HGF) and EGF released within hours, then slows as mass M approaches the target set by the hepatostat — a still only partly understood size-sensing feedback that halts mitosis once the liver-to-body-weight ratio is restored, typically within 1–2 weeks in rodents.

Resection extent — how much mass is surgically removed before regrowth begins.
Growth-factor strength — scales the HGF/EGF signal driving the proliferation rate k·H(t).
Hepatostat feedback — toggling it off removes the (1 − M/M_target) brake, so growth keeps accelerating past 100% instead of stopping — a simplified stand-in for what happens when size-sensing control fails.
Bright, pulsing cells mark the active proliferative front; the pale wireframe shell marks the 100% hepatostat target.

This isn't just curiosity — the hepatostat is central to living-donor liver transplantation (both the donor remnant and the graft regrow to their own target size) and to understanding how loss of growth control contributes to hepatocellular carcinoma.

Quiescent hepatocyte tissue Actively dividing front Hepatostat target (100%)

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