Objective To explore the pharmacological effect of Ejiao (Colla Corii Asini, CCA) on delaying D-galactose-induced skin aging and maintaining microvascular homeostasis, and to clarify the molecular mechanism of its regulation of vascular maturity through tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie2)/angiopoietin (Ang)/vascular endothelial cadherin (VE-cadherin) signal axis. Methods The model of premature senility in mice was established by sc D-galactose, and CCA (270.3 mg/kg) was administered ig for eight weeks. The back blood flow was monitored by laser speckle contrast imaging (LSCI), the microvessel density was observed by optical coherence tomography angiography (OCTA), the skin tissue morphology and collagen content were evaluated by hematoxylin-eosin staining (HE) and Masson staining, the expressions of vascular endothelial marker CD31 and pericyte marker platelet-derived growth factor receptor β (PDGFRβ) were detected by immunofluorescence and immunohistochemistry, the Ang1/Ang2 value in serum was detected by ELISA, the expressions of interleukin-1β (IL-1β), C-X-C motif chemokine ligand 1 (CXCL1) and tumor necrosis factor-α (TNF-α) mRNA in skin tissue was detected by qRT-PCR. Human umbilical vein endothelial cells (HUVEC) were induced by hydrogen peroxide (H₂O₂) to construct a stress premature aging model, cells were pretreated with 62.5—250.0 μg/mL CCA for 24 h. Cell viability was detected by CCK-8. Senescence-associated β-galactosidase (SA-β-gal) staining and reactive oxygen species (ROS) level were used to assess the degree of aging. qRT-PCR was used to detect the senescence-associated secretory phenotype (SASP) and inflammation related gene expressions. Western blotting was used to detect tumor protein p53 (p53), cyclin dependent kinase inhibitor 1 A (p21), p-Tie2, Tie2, VE-cadherin and vascular endothelial growth factor A (VEGFA) protein expressions. Ang1/Ang2 value was detected by ELISA. Vascular stability was evaluated through pericyte recruitment and endothelial permeability experiments. Results In the animal experiment, CCA significantly improved the skin fold of aging mice, increased the thickness of epidermis and dermis and collagen volume fraction (P < 0.01, 0.001), restored skin blood flow perfusion and reduced disordered angiogenesis, increased the expression of PDGFRβ in skin tissue and the value of Ang1/Ang2 in serum (P < 0.001), decreased the expressions of inflammatory factors (P < 0.001), and enhanced vascular maturity. In the cell experiment, CCA significantly reduced the positive rate of SA-β-gal and ROS level in HUVEC (P < 0.001), down-regulated the expressions of SASP and inflammation related genes (P < 0.01, 0.001), up-regulated the protein expressions of p-Tie2 and VE-cadherin (P < 0.001), down-regulated the protein expressions of p53, p21, Tie2 and VEGFA (P < 0.05, 0.001), and increased the value of Ang1/Ang2 (P < 0.05, 0.01), significantly enhancing the ability of endothelial cells to recruit pericytes and the integrity of vascular endothelial barrier. Conclusion CCA can improve the aging phenotype of aging skin model induced by D-galactose, improve microvascular maturity and maintain vascular homeostasis, which may be related to the regulation of Tie2/Ang/VE-cadherin signal axis.

Colla Corii Asini  /  skin aging  /  vascular homeostasis  /  vascular maturation  /  Tie2/Ang/VE-cadherin signaling axis  /  inflammatory response