〔Abstract〕 Objective To investigate the effect of Semaphorin 3A (Sema3A) on the progression of pathological cardiac hypertrophy. Methods Wild-type C57BL 6J mice, Sema3A global overexpressing (Sema3A/Cre-ERTM) mice, and their littermate controls (Cre-ERTM) were used, with 6 mice per group. A pressure-overload induced cardiac hypertrophy model was established via transverse aortic constriction (TAC), with a sham-operated group (Sham) as the control. Cardiac hypertrophy was assessed by gross morphology, heart weight/body weight ratio (HW/BW), heart weight/tibia length ratio (HW/HL), and heart weight/lung weight ratio (HW/PW). Cardiac function was evaluated by measuring ejection fraction (EF) and fractional shortening (FS) via echocardiography. In heart tissues, the mRNA level of atrial natriuretic peptide (ANP) and Sema3A were detected by RT-qPCR, Sema3A protein level was detected by western blot, morphological structure was detected by hematoxylin and eosin (HE) staining, level of fibrosis was detected by Masson’s trichrome staining, and angiogenesis was detected by immunohistochemical detection of CD31.Forin vitroexperiments, rat H9C2 cardiomyocytes were treated with angiotensin II (Ang II) to induce hypertrophy, with PBS-treated cells as the control. After 48 hours, the mRNA expression of ANP, B-type natriuretic peptide (BNP) and Sema3A were measured by RT-qPCR, and Sema3A protein level was assessed by western blot.Results At the animal level, compared with the sham group, mice subjected to TAC showed significantly increased mRNA levels of ANP in cardiac tissue, as well as markedly elevated mRNA and protein levels of Sema3A (P<0.05). Compared with the Cre-ERTM + TAC group, the Sema3A/Cre-ERTM + TAC group exhibited more pronounced cardiac hypertrophy, greater ventricular wall thickening, higher HW/BW, HW/HL, and HW/PW ratios, more significant reductions in EF and FS, more severe cardiac fibrosis, and a significant decrease in cardiac CD31 expression levels (P<0.05).At the cellular level, compared with the control group, H9C2 cells treated with Ang II displayed significantly increased mRNA levels ofANP and BNP, along with markedly elevated mRNA and protein levels of Sema3A (P<0.05).ConclusionSema3A promotes the progression of pressure overload-induced cardiac hypertrophy by inhibiting angiogenesis.