🩸 Tumor Angiogenesis

Hypoxic tumor cells secrete VEGF; capillary sprout tips perform a biased random walk up the gradient, branch and fuse with the network — the Anderson-Chaplain model of tumor-induced blood-vessel growth.

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P pause · R reset · watch sprouts chase the VEGF gradient toward the tumor

How it Works

A tumor mass sits on the right side of the canvas and continuously secretes VEGF (vascular endothelial growth factor) into a diffusing, decaying chemical field. On the left, a fixed parent vessel periodically sprouts new capillary tip cells. Each tip samples the VEGF field at three points projected ahead of it — front-left, straight ahead, and front-right — and steers toward whichever reading is highest, with the strength of that steering set by the chemotactic sensitivity slider. As a tip moves it leaves behind a permanent vessel trail, so the sprout's path becomes a new blood-vessel segment.

Every active tip has a small per-frame chance, set by the branching probability slider, of splitting into two tips heading in slightly different directions, mimicking real endothelial tip-cell branching. When a growing tip passes within a short distance of another vessel segment it undergoes anastomosis: the two vessels fuse and the tip stops growing, forming a loop the blood could flow through. When a tip instead reaches the tumor mass itself, that connection is marked in glowing red and counted separately, since it represents a vessel now capable of directly feeding the tumor with oxygen and nutrients — the outcome tumors exploit to keep growing past the diffusion limit of a few millimetres.

VEGF secretion: field(tumor cells) += secretionRate each frame
Diffusion+decay: field = blur3x3(field)·diffuseRate + field·(1-diffuseRate); field *= 0.995
Tip steering: turn toward argmax(V(front-left), V(front), V(front-right)) · chemoSensitivity
Anastomosis: fuse tip with vessel segment if distance(tip, segment) < 6px

Frequently Asked Questions

What is tumor angiogenesis?

Tumor angiogenesis is the process by which a growing tumor recruits new blood vessels from nearby existing vasculature to secure the oxygen and nutrients it needs to keep growing beyond a few millimetres in size.

What is VEGF and why does the tumor release it?

VEGF (vascular endothelial growth factor) is a signalling protein released by oxygen-starved (hypoxic) tumor cells. It diffuses outward and forms a concentration gradient that nearby blood vessels can sense and grow toward.

How do capillary sprout tips find their way to the tumor?

Each sprout tip samples VEGF concentration slightly ahead, to its left, and to its right, then biases its next step toward the highest reading — a biased random walk up the chemical gradient, with the bias strength set by chemotactic sensitivity.

What is anastomosis?

Anastomosis is the fusion of a growing sprout tip with another vessel segment when they come close enough together. It converts a dead-end sprout into a looped, perfusable channel that blood can actually flow through.

What is the Anderson-Chaplain model?

The Anderson-Chaplain model is a classic mathematical model of tumor-induced angiogenesis that combines a diffusing, decaying VEGF field with discrete endothelial tip cells whose movement is biased by the local VEGF gradient, plus rules for branching and anastomosis.

About this simulation

Written by MySimulator Team · Reviewed by MySimulator Editorial Review

Last updated: 11 July 2026

Every orange sprout tip on screen is chasing an invisible chemical scent it can only feel a few pixels away. Watching a handful of dead-end capillaries eventually stumble onto a route that glows red as it plugs directly into the tumor shows exactly why cutting off VEGF signalling — the strategy behind anti-angiogenic cancer drugs — can starve a tumor of the blood supply it depends on.

🔬 What it shows

A diffusing VEGF field secreted by a tumor mass guiding chemotactic capillary sprout tips that branch, wander, and either fuse with the existing vessel network or connect directly to the tumor.

🎮 How to use

Raise VEGF Secretion Rate and Chemotactic Sensitivity to speed up vascularisation, or lower them to see sprouts wander aimlessly; tune Branching Probability and Tumor Size to compare sparse versus dense vessel networks.

💡 Did you know?

The first anti-angiogenic cancer drug, bevacizumab, works by binding and neutralising VEGF itself, directly targeting the gradient this simulation visualises to try to starve tumors of new blood supply.

Frequently asked questions

What is tumor angiogenesis?

Tumor angiogenesis is the process by which a growing tumor recruits new blood vessels from nearby existing vasculature to secure the oxygen and nutrients it needs to keep growing beyond a few millimetres in size.

What is VEGF and why does the tumor release it?

VEGF (vascular endothelial growth factor) is a signalling protein released by oxygen-starved (hypoxic) tumor cells. It diffuses outward and forms a concentration gradient that nearby blood vessels can sense and grow toward.

How do capillary sprout tips find their way to the tumor?

Each sprout tip samples VEGF concentration slightly ahead, to its left, and to its right, then biases its next step toward the highest reading — a biased random walk up the chemical gradient, with the bias strength set by chemotactic sensitivity.

What is anastomosis?

Anastomosis is the fusion of a growing sprout tip with another vessel segment when they come close enough together. It converts a dead-end sprout into a looped, perfusable channel that blood can actually flow through.

What is the Anderson-Chaplain model?

The Anderson-Chaplain model is a classic mathematical model of tumor-induced angiogenesis that combines a diffusing, decaying VEGF field with discrete endothelial tip cells whose movement is biased by the local VEGF gradient, plus rules for branching and anastomosis.