Platelet-derived growth factor (PDGF) is a signaling protein, released by activated platelets and several other cell types, that tells connective tissue cells to divide, move, and build new tissue. In healthy vessels it drives wound repair and helps stabilize newly formed blood vessels. When its signaling is overactive, PDGF contributes to atherosclerosis, vessel re-narrowing after stenting, organ fibrosis, and several cancers, which is why drugs that block its receptors are used in clinical practice.
Platelets are best known for stopping bleeding, but their role goes well beyond that. In haematology we increasingly see them as messengers that coordinate healing, and PDGF is one of their most important messages.
What Is Platelet-Derived Growth Factor?
PDGF was first identified in the 1970s as the factor in serum that made cultured cells grow. Serum, the fluid left after blood clots, contains it because platelets release it during clotting. That origin gave it its name.
Inside platelets, PDGF is stored in alpha granules, small packets that are emptied when a platelet is activated at a site of injury. Macrophages, endothelial cells (the vessel lining), smooth muscle cells, and fibroblasts can also produce it, so PDGF signaling occurs in many tissues, not just where platelets gather.
PDGF Isoforms and Receptors
PDGF is built from four related chains, labeled A, B, C, and D, which pair up as dimers. They act on two receptors, PDGFR-alpha and PDGFR-beta, which are receptor tyrosine kinases: enzymes in the cell membrane that switch on internal signals when their partner binds.
| Isoform | Main receptor(s) activated | Notable roles |
|---|---|---|
| PDGF-AA | Alpha | Development of lung, intestine, and certain glial cells |
| PDGF-AB | Alpha; alpha-beta | Major form released from human platelets |
| PDGF-BB | Alpha, beta, and alpha-beta | Recruits pericytes and smooth muscle cells to vessels; wound healing |
| PDGF-CC | Alpha | Tissue repair and fibrosis |
| PDGF-DD | Beta | Vascular and fibrotic processes |
Once activated, the receptors switch on several signaling pathways, including PI3K/AKT, which supports cell survival, Ras/MAPK, which drives division, and phospholipase C, which influences movement. Together these make target cells grow, migrate toward the PDGF source, and produce extracellular matrix.
PDGF in Normal Vascular Biology
Wound Healing
When a vessel is injured, platelets stick to the damaged area and release PDGF along with other growth factors. PDGF attracts fibroblasts, smooth muscle cells, and immune cells into the wound, and it stimulates them to lay down new matrix. This is the transition from a simple clot to repaired tissue.
Building Stable Blood Vessels
New capillaries are initially fragile tubes of endothelial cells. PDGF-BB released by these cells recruits pericytes and smooth muscle cells that wrap around the tube and stabilize it. Without this signal, vessels are leaky and prone to bleeding, a principle seen clearly in experimental models where PDGF-B signaling is absent.
Development
PDGF signaling is essential during embryonic life for forming blood vessels, kidneys, lungs, and parts of the nervous system. In adults it mostly returns to the background until tissue is damaged.
When PDGF Signaling Goes Wrong
The same actions that heal tissue can cause disease when they are prolonged or excessive.
- Atherosclerosis: PDGF from platelets and macrophages encourages smooth muscle cells to migrate into the vessel wall and multiply, contributing to plaque growth.
- Restenosis: after angioplasty or stenting, PDGF-driven smooth muscle proliferation can thicken the inner wall (intimal hyperplasia) and re-narrow the artery.
- Pulmonary arterial hypertension: overgrowth of cells in small lung arteries is linked in part to PDGF signaling.
- Fibrosis: sustained PDGF activity drives scarring in the lungs, liver, kidneys, and skin.
- Cancer: mutations or rearrangements that switch on PDGF receptors drive some gastrointestinal stromal tumors, some gliomas, dermatofibrosarcoma protuberans, and certain blood cancers.
The Hematology Connection
A small group of myeloid neoplasms with eosinophilia is caused by gene rearrangements involving PDGFRA or PDGFRB, the best known being FIP1L1-PDGFRA. These patients often have very high eosinophil counts and organ damage. Identifying the rearrangement matters because these diseases typically respond well to the tyrosine kinase inhibitor imatinib.
Testing and Clinical Relevance
PDGF is not measured in routine clinical blood tests. Levels in blood samples vary with how the sample is handled, because platelets release PDGF when blood clots in the tube. In practice, what doctors test for is PDGF receptor involvement in disease:
- Molecular testing of blood or marrow for PDGFRA and PDGFRB rearrangements in unexplained eosinophilia
- Mutation testing of tumor tissue, such as PDGFRA mutations in gastrointestinal stromal tumors
- Immunohistochemistry to show receptor expression in tumor samples
Treatments That Target PDGF
Several established drugs act on the PDGF pathway, either blocking it or supplying it:
- Imatinib: blocks PDGF receptors (as well as BCR-ABL1 and KIT) and is used in PDGFR-driven myeloid neoplasms, some gastrointestinal stromal tumors, and dermatofibrosarcoma protuberans.
- Sunitinib and other multi-target kinase inhibitors: block PDGF and VEGF receptors in certain cancers.
- Nintedanib: an antifibrotic kinase inhibitor that targets PDGF, FGF, and VEGF receptors and is used in idiopathic pulmonary fibrosis.
- Becaplermin: a topical gel of recombinant PDGF-BB used for selected chronic diabetic foot ulcers, where extra PDGF helps healing.
Lifestyle measures that reduce vascular injury, such as not smoking and controlling blood pressure, cholesterol, and diabetes, lower the repeated triggers that keep PDGF-driven repair switched on in artery walls. For more on how platelets work beyond clotting, see our platelets guide.
Key Takeaways
- PDGF is a growth factor stored in platelet alpha granules and made by several other cell types.
- It acts through the PDGFR-alpha and PDGFR-beta receptor tyrosine kinases.
- Normal roles include wound healing, vessel stabilization, and embryonic development.
- Excess signaling contributes to atherosclerosis, restenosis, fibrosis, and several cancers.
- Kinase inhibitors such as imatinib and nintedanib target the pathway in clinical practice.
Frequently Asked Questions
Is PDGF only made by platelets?
No. Platelets are a major and rapid source, but macrophages, endothelial cells, smooth muscle cells, and fibroblasts also produce PDGF. That is why PDGF signaling can persist long after the platelet clot has gone.
Does platelet-rich plasma work because of PDGF?
Platelet-rich plasma contains PDGF along with many other growth factors, and that is the rationale behind it. How well it works depends on the condition treated, and the evidence varies between uses.
Can a blood test measure my PDGF level?
Not in routine care. PDGF can be measured in research laboratories, but results depend heavily on sample handling. Clinical testing focuses on PDGF receptor mutations or rearrangements in specific diseases.
Why does imatinib treat both leukemia and PDGF-driven diseases?
Imatinib blocks several related tyrosine kinases, including BCR-ABL1 in chronic myeloid leukemia and the PDGF receptors. Diseases driven by any of these targets can respond to it.
