Mechanotransductive Activation of PPAR-γ by Low-Intensity Pulsed Ultrasound Induces Contractile Phenotype in Corpus Spongiosum Smooth Muscle Cells

Background: Previously, we found that the pathological changes in the corpus spongiosum (CS) in hypospadias were mainly localized within smooth muscle tissue, presenting as a transformation from the contraction phenotype to synthesis. The role of low-intensity pulsed ultrasound (LIPUS) in regulating smooth muscle cells (SMCs) and angiogenesis has been confirmed. Objectives: To demonstrate the feasibility of regulating the phenotypic transformation of corpus spongiosum smooth muscle cells (CSSMCs) in hypospadias using LIPUS and to explore the potential mechanisms. Materials and Methods: The CSSMCs were extracted from CS in patients with proximal hypospadias. In vitro experiments were conducted to explore the appropriate LIPUS irradiation intensity and duration which could promote the phenotypic transformation of CSSMCs. A total of 71 patients with severe hypospadias were randomly divided into a control group and a LIPUS group to verify the in vivo transition effect of LIPUS. Consequently, the potential mechanisms by which LIPUS regulates the phenotypic transformation of CSSMCs were explored in vitro. Results: In vitro experiments showed that LIPUS with an intensity of 100 mW/cm2 and a duration of 10 min could significantly increase the expression of contraction markers in CSSMCs and decrease the expression of synthesis markers. Moreover, LIPUS stimulation could alter the phenotype of CSSMCs in patients with proximal hypospadias. RNA sequencing results revealed that peroxisome proliferator-activated receptor gamma (PPAR-γ) significantly increased after LIPUS stimulation. Overexpression of PPAR-γ significantly increased the expression of contraction markers in CSSMCs, and the knockdown of PPAR-γ blocked this effect. Conclusions: LIPUS can regulate the transition of CSSMCs from a synthetic to a contractile phenotype in hypospadias. The PPAR-γ-mediated signaling pathway is a possible mechanism involved in this process. Keywords: corpus spongiosum; hypospadias; low-intensity pulsed ultrasound; phenotypic transformation; smooth muscle cells.