Presence of Stem/Progenitor Cells in the Rat Penis

Abstract

Tissue resident stem cells are believed to exist in every organ, and their identification is commonly done using a combination of immunostaining for putative stem cell markers and label-retaining cell (LRC) strategy. In this study, we employed these approaches to identify potential stem cells in the penis. Newborn rats were intraperitoneally injected with thymidine analog, 5-ethynyl-2-deoxyuridine (EdU), and their penis was harvested at 7 h, 3 days, 1 week, and 4 weeks. It was processed for EdU stains and immunofluorescence staining for stem cell markers A2B5, PCNA, and c-kit. EdU-positive cells were counted for each time point and co-localized with each stem cell marker, then isolated and cultured in vitro followed by their characterization using flowcytometry and immunofluorescence. At 7 h post-EdU injection, 410 -105.3 penile corporal cells were labeled in each cross-section (*28%). The number of EdU-positive cells at 3 days increased to 536 -115.6, while their percentage dropped to 25%. Progressively fewer EdU-positive cells were present in the sacrificed rat penis at longer time points (1 and 4 weeks). They were mainly distributed in the subtunic and perisinusoidal spaces, and defined as subtunic penile progenitor cells (STPCs) and perisinusoidal penile progenitor cells (PPCs). These cells expressed c-kit, A2B5, and PCNA. After culturing in vitro, only *0.324% corporal cells were EdUlabeled LRCs and expressed A2B5/PCNA. Therefore, labeling of penis cells by EdU occurred randomly, and label retaining was not associated with expression of c-kit, A2B5, or PCNA. The penile LRCs are mainly distributed within the subtunic and perisinusoidal space.

Kinetics of Label Retaining Cells in the Developing Rat Kidneys

“…At 6 weeks post-EdU injection, only about 5% of renal cells remained labeled. These observations are consistent with most LRC studies and generally reflect the rapid cell cycling in most neonatal animal tissues [ 11 , 22 – 24 ]. Interesting and unreported previously is that, initially (at day 1 post-injection) the cortex had a higher labeling rate than the papilla (28.6% vs. 15.5%), but by week 1 the cortex had fewer EdU+ cells than the papilla, and in the end (at week 6) the latter became the dominant site for LRCs (2.5% vs. 7.7%).…”

The effect of low‐intensity extracorporeal shockwave therapy in an obesity‐associated erectile dysfunction rat model

“…As we previously reported, there are various kinds of cells in the penis including terminally differentiated cells and stem/progenitor cells . Most cavernous smooth muscle cells and fibroblasts are terminally differentiated and cannot be activated to proliferate .…”

“…To track putative endogenous stem cells, each pup received an intraperitoneal (i.p.) injection of 5‐ethynyl‐2’‐deoxyuridine (EdU, 150 mg/kg; Invitrogen, Carlsbad, CA, USA) at birth, as previously described . Body weight was monitored every 2 weeks.…”

Combination of low-energy shock-wave therapy and bone marrow mesenchymal stem cell transplantation to improve the erectile function of diabetic rats

“…On the other hand, LESWT could enhance stem cell proliferation, differentiation and paracrine 44454647. In addition, the types of stem cells detected around the cavernous vasculature, including perisinusoidal and subtunic penile progenitor cells48 and cavernous smooth muscle-derived stem cells,4950 could be induced to activate. Thus, LESWT induced angiogenesis and created a beneficial situation for the establishment of the stem cell niche.…”