Characterization of age‐related penile microvascular hemodynamic impairment using laser speckle contrast imaging: possible role of increased fibrogenesis

Abstract

Current technology for penile hemodynamic evaluations in small animals is invasive and has limitations. We evaluated a novel laser speckle contrast imaging (LSCI) technique to determine age‐related changes in penile microvascular perfusion (PMP) and tested the role of cavernosal muscle (CC) fibrosis mediated by Wnt‐TGF β1 signaling pathways in a mouse model. Ten young (2–3 months) and old (24–28 months) wild‐type C57BL6 male mice were subjected to PMP measured using a LSCI system. Penile blood flow (PBF, peak systolic velocity, PSV) was also measured using a color Doppler ultrasound for comparison. Measurements were made before and after injection of vasoactive drugs: prostaglandin E1 (PGE 1) and acetylcholine (ACh). CC was processed for immunohistochemical studies for markers of endothelium and fibrosis. Protein levels were quantified by Western blot.PMP and PBF increased significantly from baseline after injection of vasoactive drugs. Peak PMP after PGE 1 and ACh was higher in young mice (225.0 ± 12.0 and 211.3 ± 12.1 AU) compared to old (155.9 ± 7.1 and 162.6 ± 5.1 AU, respectively). PSV after PGE 1 was higher in young than old mice (112.7 ± 8.5 vs. 78.2 ± 4.6 mm/sec). PSV after ACh was also higher in young (112.7 ± 5.6 mm/sec) than older mice (69.2 ± 7.1 mm/sec). PMP positively correlated with PSV (r = 0.867, P = 0.001). Immunostaining and Western blot showed increased protein expression of all fibrosis markers with aging. LSCI is a viable technique for evaluating penile hemodynamics. Increased cavernosal fibrosis may cause impaired penile hemodynamics and increased incidence of erectile dysfunction in older men.

Transpelvic Magnetic Stimulation Enhances Penile Microvascular Perfusion in a Rat Model: A Novel Interventional Strategy to Prevent Penile Fibrosis after Cavernosal Nerve Injury

“…Penile MVP was assessed by the PeriCam PSI system (Perimed AB, Järfälla, Sweden). This laser speckle Doppler imaging technique quantifies penile MVP and displays a real-time image using arbitrary perfusion units (AU) [ 9 ]. The rats were prepared by using Nair hair remover in the pelvic region and were placed on a custom-made rat-restrainer lying supine, with their pelvis/penis positioned under the PeriCam ( Fig.…”

“…Microcirculation refers to the smallest arteries (less than ~150 µm in diameter), arterioles, capillaries, and venules. Reports suggest that penile microvascular dysfunction is an important contributor to ED severity and an underlying mechanism linking ED to cardiovascular disease [ 9 10 ]. In addition, a pre-clinical study from Department of Urology, VA San Diego Health Care System has revealed that increased penile fibrosis has been shown to impair penile microvascular perfusion (MVP) [ 9 ] measured using a novel laser speckle contrast imaging (LSCI) system.…”

“…Reports suggest that penile microvascular dysfunction is an important contributor to ED severity and an underlying mechanism linking ED to cardiovascular disease [ 9 10 ]. In addition, a pre-clinical study from Department of Urology, VA San Diego Health Care System has revealed that increased penile fibrosis has been shown to impair penile microvascular perfusion (MVP) [ 9 ] measured using a novel laser speckle contrast imaging (LSCI) system. Our studies also showed a positive correlation between penile MVP (using LSCI) and macrovascular function (measured by clinically used Doppler blood flow).…”