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Perivascular myofibroblasts and microvascular occlusion in hypertrophic scars and keloids
Abstract:
Microvessels in normal skin, granulation tissue, hypertrophic scar, keloid, and mature scar from human subjects were studied by transmission electron microscopy. Comparative observations suggested that most microvessels in hypertrophic scar and keloid are occluded or partially occluded, apparently owing to an excess of endothelial cells. Endothelial cell contraction was also supported by the observations, and perivascular satellite cells (pericytes), some of which were identified as myofibroblasts, were observed in hypertrophic scars and keloids. Among findings from statistical analyses were that 1) the patency of microvessels in hypertrophic scar and granulation tissue is similar, as is that of microvessels in keloid and mature scar, but the patency of all these microvessels is significantly less than that of microvessels in normal skin, and 2) endothelial cell density is greater in nonpatent vessels than in patent vessels. The observed extent of microvascular occlusion supports a previously published theory that hypoxia is involved in the generation of hypertrophic scar.
Insights
Microvessels in hypertrophic scars and keloids are often blocked due to excess endothelial cells. This microvascular occlusion supports the theory that hypoxia contributes to scar formation.
Area of Science:
- Dermatology
- Pathology
- Microcirculation Research
Background:
- Hypertrophic scars and keloids represent abnormal wound healing.
- The role of microvascular changes in scar development is not fully understood.
Purpose of the Study:
- To investigate the microvessel structure and patency in various scar types and normal skin.
- To explore the cellular basis of microvascular occlusion in hypertrophic scars and keloids.
Main Methods:
- Transmission electron microscopy was used to examine microvessels from human skin samples.
- Comparative analysis of microvessel patency and endothelial cell density was performed.
- Statistical analyses were conducted to compare different tissue types.
Main Results:
- Microvessels in hypertrophic scars and keloids showed significant occlusion, attributed to excess endothelial cells and potential endothelial cell contraction.
- Perivascular satellite cells, including myofibroblasts, were identified in hypertrophic scars and keloids.
- Microvessel patency was significantly reduced in all scar types compared to normal skin, with similar patency levels between hypertrophic scar/granulation tissue and keloid/mature scar.
- Endothelial cell density was higher in nonpatent vessels.
Conclusions:
- Microvascular occlusion, driven by endothelial cell proliferation and contraction, is a key feature of hypertrophic scars and keloids.
- Reduced microvessel patency in scars supports the hypothesis that hypoxia plays a role in their pathogenesis.
- Findings provide insights into the cellular mechanisms underlying abnormal scar formation.