[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Blood vessels](https://durgical.com/en/general-pathology/areas/vessels/) › Vessel wall response to injury # Vessel wall response to injury - Mechanism Whatever hurts an artery, its lining reacts the same way: the endothelium misbehaves and smooth-muscle cells move in and thicken the inner layer. Updated Nov 12, 2026 ## Key points - Healthy endothelium is anti-thrombotic, anti-adhesive and vasodilating (nitric oxide, prostacyclin). - Endothelial activation: new adhesion molecules, cytokines and tissue factor; triggered by cytokines, disturbed flow, hypertension, lipids, smoking, toxins. - Endothelial dysfunction = loss of nitric oxide-dependent relaxation plus a pro-inflammatory, pro-coagulant surface. - Smooth-muscle cells change from a contractile to a synthetic phenotype: they migrate, proliferate and make collagen and proteoglycans. - The resulting neointima narrows the lumen; it is the common end point of many different injuries. ## What it is Two cells decide how a vessel reacts to injury. Endothelial cells normally keep blood fluid, keep leukocytes moving and keep the wall relaxed; when they are activated or dysfunctional they turn sticky, leaky and pro-thrombotic. Medial smooth-muscle cells then migrate into the intima, divide and lay down matrix. This stereotyped healing response, called intimal thickening or neointima, underlies atherosclerosis, hypertensive arteriolar disease, restenosis after stents and transplant vasculopathy. ## Structure - Gross: a pale, firm thickening of the inner wall that narrows the lumen. - H&E: spindle-shaped smooth-muscle cells in a loose to dense collagen-proteoglycan matrix between the endothelium and the internal elastic lamina. - Elastic stain: the internal elastic lamina marks the old intimal border; neointima lies inside it. ## Function - Normal endothelium: barrier, anticoagulant surface (thrombomodulin, heparan sulfate), tone control and regulation of leukocyte traffic. - Normal smooth muscle: contraction and relaxation, and maintenance of the elastic and collagen matrix of the media. ## Step by step - Injury reaches the endothelium: mechanical (shear, pressure), chemical (lipids, smoke), immune or infectious. - Activated endothelial cells express adhesion molecules and release chemokines and growth factors. - Leukocytes and platelets adhere; nitric oxide falls and the wall constricts more easily. - Platelet-derived growth factor and other signals call smooth-muscle cells and their precursors into the intima. - Synthetic smooth-muscle cells proliferate and deposit extracellular matrix. - The intima thickens; if the stimulus stops the endothelium recovers, if it persists the thickening grows. ## Clinical notes - Explains restenosis after angioplasty, vein-graft failure and chronic allograft vasculopathy. - Endothelial dysfunction is measurable before any plaque exists and is reversible with control of risk factors. ## Memory aid Injury always gets the same answer: the lining turns sticky, the muscle moves in, and the inner wall gets thicker. ## Test yourself Think of the answer, then tap the question to see it. ## Which endothelial product is the main vasodilator lost in endothelial dysfunction? Nitric oxide. ## Where do the smooth-muscle cells of a neointima come from? Mainly from the media (and circulating precursors); they migrate across the internal elastic lamina and become synthetic. ## In which two clinical situations does intimal thickening narrow a vessel after treatment? Restenosis after angioplasty or stenting, and vein-graft or transplant (allograft) vasculopathy. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/general-pathology/vessel-wall-response-to-injury/) [More Pathology questions →](https://durgical.com/en/practice/?f=pathology) ## Elsewhere in DurgiPedia - [Blood vessels: artery, vein and capillary layers](https://durgical.com/en/histology/blood-vessels-artery-vein-and-capillary-layers/) - [Nitric oxide (NO)](https://durgical.com/en/biochemistry/molecules/nitric-oxide/) - [Local and humoral control of blood flow](https://durgical.com/en/physiology/local-and-humoral-control-of-blood-flow/) ## Connections ## Related 6 - [How an atheroma forms: the response-to-injury model step by step](https://durgical.com/en/general-pathology/how-an-atheroma-forms-the-response-to-injury-model-step-by-step/) - [Pathology after angioplasty, stents and grafts](https://durgical.com/en/general-pathology/pathology-after-angioplasty-stents-and-grafts/) - [Arteriosclerosis: the three patterns](https://durgical.com/en/general-pathology/arteriosclerosis-the-three-patterns/) - [Vascular changes in acute inflammation: vasodilation, leakage, exudate vs transudate](https://durgical.com/en/general-pathology/vascular-changes-in-acute-inflammation-vasodilation-leakage-exudate-vs-transudat/) - [Granulation tissue and scar formation](https://durgical.com/en/general-pathology/granulation-tissue-and-scar-formation/) - [Thrombosis and Virchow's triad](https://durgical.com/en/general-pathology/thrombosis-and-virchow-s-triad/) ## Related conditions 4 - [Atherosclerosis and dyslipidaemia](https://durgical.com/en/conditions/atherosclerosis-and-dyslipidaemia/) - [Arterial hypertension](https://durgical.com/en/conditions/arterial-hypertension/) - [Type 2 diabetes mellitus](https://durgical.com/en/conditions/type-2-diabetes-mellitus/) - [Peripheral artery disease](https://durgical.com/en/conditions/peripheral-artery-disease/) [← All of general pathology](https://durgical.com/en/general-pathology/) Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given. Sources: [Atherosclerosis: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000171.htm) (MedlinePlus, US National Library of Medicine, 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/general-pathology/vessel-wall-response-to-injury/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/vessel-wall-response-to-injury/