Vascularisation is the physiological process through which

blood vessels Blood vessels are the tubular structures of a circulatory system that transport blood throughout many animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the tissues of a body. They also take waste an ...

form in tissues or

organs In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to a ...

. Vascularisation is crucial to supply the organs and tissues with an adequate supply of

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

and

nutrients A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

and for removing waste products. Blood vessels transport blood, water, and nutrients needed to support body systems. When blood vessels lose efficiency, it may lead to serious diseases such as

cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

heart disease Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina pectoris, angina, myocardial infarction, heart attack), heart failure, ...

, and

diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...

. Scientists are currently working on ways to grow new blood vessels to help with tissue engineering and healing injuries. This is why vascularisation is important in medicine.

Mechanisms

These are processes in which vascularisation happens and should not be confused with vascularisation itself:

Angiogenesis

It is the process where new blood vessels form from pre-existing ones. This happens naturally when the body needs to repair tissue or when a wound needs to heal. It is driven by signals from growth factors, such as Vascular Endothelial Growth Factor (VEGF), which prompts the formation of new vessels. However, this process can occasionally go wrong in tumour formation where it allows the tumours to create their own blood supply and grow larger, which can contribute to diseases like cancer.

Vasculogenesis

This is the creation of blood vessels during early development particularly in embryos. Blood vessels start to form from special cells known as endothelial progenitor cells. While this process mostly happens during embryonic development, it can also occur in adults when the body needs to repair damaged blood vessels or grow new ones after an injury occurs.

Arteriogenesis

This is a process where smaller and less efficient blood vessels become enlarged into fully functioning arteries. This usually happens in response to increased demand in the body such as during exercise or when blood vessels are blocked. This aids in ensuring that tissues are supplied with enough blood and oxygen.

Lymphangiogenesis

This process is similar to angiogenesis but involves the creation of lymphatic vessels which are essential for draining excess fluid and fighting infections. This process is also key to conditions like inflammation and the spreading of cancer.

Applications in medicine

Cancer

In cancer, tumours take over the body’s vascularisation processes to supply themselves with blood, helping them grow and spread. Scientists are now developing therapies that block angiogenesis, cutting off the tumour blood supply. This has become a strategy in

cancer treatments Cancer treatments are a wide range of treatments available for the many different types of cancer, with each cancer type needing its own specific treatment. Treatments can include surgery, chemotherapy, radiation therapy, hormonal therapy, targe ...

, with medications like

bevacizumab Bevacizumab, sold under the brand name Avastin among others, is a monoclonal antibody medication used to treat a number of types of cancers and a specific eye disease. For cancer, it is given by slow injection into a vein (intravenous) and use ...

that are being used to shrink tumours by preventing blood vessel growth.

Cardiovascular diseases

*In

atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...

, new blood vessels form within plaques, contributing to their growth and instability. These vessels are often fragile, allowing inflammatory cells and fats to enter, which can cause bleeding inside the plaque and increase the risk of rupture. Some studies in animal models suggest that blocking this vessel growth can reduce atherosclerotic progression. *In a

myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...

, blocked blood flow deprives heart tissue of oxygen, leading to cell damage.

Neovascularization Neovascularization is the natural formation of new blood vessels ('' neo-'' + ''vascular'' + '' -ization''), usually in the form of functional microvascular networks, capable of perfusion by red blood cells, that form to serve as collateral circu ...

in the surrounding area can help restore oxygen supply and limit further injury. Therapeutic angiogenesis, which encourages new blood vessel growth, is being explored as a potential treatment. Growth factors such as basic fibroblast growth factor (bFGF) and brain natriuretic peptide (BNP) have shown promise in promoting this process after a heart attack. *Following a

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

, post-stroke angiogenesis occurs in the ischemic penumbra (the region surrounding the infarct core) which disrupts

cerebral blood flow Cerebral circulation is the movement of blood through a network of cerebral arteries and veins supplying the brain. The rate of cerebral blood flow in an adult human is typically 750 milliliters per minute, or about 15% of cardiac output. ...

. This process helps restore

perfusion Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ (anatomy), organ or a tissue (biology), tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion may also refer t ...

and supports neurological recovery. Additionally, arteriogenesis, the enlargement of pre-existing collateral vessels, contributes to post-stroke blood flow restoration. Various

immune cells White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are genera ...

and

cytokines Cytokines () are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are produced by a broad range of cells, including immune cells like macrophages, B cell, B lymphocytes, T cell, T lymphocytes ...

play a role in regulating angiogenesis after ischemic injury.

Wound healing

Vascularization is crucial for wound healing, as it provides oxygen and nutrients necessary for tissue repair. Angiogenesis temporarily increases vascular density around the wound, aiding the healing process.

Vascular endothelial growth factor Vascular endothelial growth factor (VEGF, ), originally known as vascular permeability factor (VPF), is a signal protein produced by many cells that stimulates the formation of blood vessels. To be specific, VEGF is a sub-family of growth factors ...

(VEGF) is a key pro-angiogenic factor in this process, stimulating both vasculogenesis and angiogenesis in the skin. Impaired angiogenesis can result in delayed wound healing, as seen in conditions such as

, where chronic wounds often exhibit reduced levels of active VEGF. Scientists are exploring ways to stimulate angiogenesis to help speed up healing, especially in persistent wounds.

Diabetic retinopathy

Diabetic retinopathy Diabetic retinopathy (also known as diabetic eye disease) is a medical condition in which damage occurs to the retina due to diabetes. It is a leading cause of blindness in developed countries and one of the lead causes of sight loss in the wor ...

is a complication of diabetes in which there is abnormal proliferation of

microvessels The microcirculation is the circulatory system, circulation of the blood in the smallest blood vessels, the microvessels of the microvasculature present within organ (anatomy), organ Tissue (biology), tissues. The microvessels include terminal ar ...

in the

retina The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...

, which can lead to vision loss{{Cite journal , last=Suh , first=D. Y. , date=2000-07-01 , title=Understanding angiogenesis and its clinical applications , url=https://pubmed.ncbi.nlm.nih.gov/10945562 , journal=Annals of Clinical and Laboratory Science , volume=30 , issue=3 , pages=227–238 , issn=0091-7370 , pmid=10945562

References

Cardiovascular physiology