Mapping cellular interactions from spatially resolved transcriptomics data.

Cell-cell communication (CCC) is essential to how life forms and functions. However, accurate, high-throughput mapping of how expression of all genes in one cell affects expression of all genes in another cell is made possible only recently through the introduction of spatially resolved transcriptomics (SRT) technologies, especially those that achieve single-cell resolution. Nevertheless, substantial challenges remain to analyze such highly complex data properly. Here, we introduce a multiple-instance learning framework, Spacia, to detect CCCs from data generated by SRTs, by uniquely exploiting their spatial modality. We highlight Spacia's power to overcome fundamental limitations of popular analytical tools for inference of CCCs, including losing single-cell resolution, limited to ligand-receptor relationships and prior interaction databases, high false positive rates and, most importantly, the lack of consideration of the multiple-sender-to-one-receiver paradigm. We evaluated the fitness of Spacia for three commercialized single-cell resolution SRT technologies: MERSCOPE/Vizgen, CosMx/NanoString and Xenium/10x. Overall, Spacia represents a notable step in advancing quantitative theories of cellular communications.

Initial Experience with an Absorbable Urologic Scaffold to Mitigate Early Urinary Incontinence following Radical Prostatectomy: A Report of 2 Cases.

INTRODUCTION: Stress urinary incontinence (SUI) is a frequent, known complication following robot-assisted radical prostatectomy (RARP) for prostate cancer. Urethral shortening and reduced urethral support following RARP are contributing factors. CASE PRESENTATIONS: Herein, we describe a surgical approach using a novel absorbable urologic scaffold to mitigate SUI in 2 patients enrolled in an ongoing single-arm prospective study. The scaffold is designed to relieve the burden on the urinary sphincter by lengthening the effective urethra following RARP. The scaffold is placed at the anastomotic site, overlying the bladder neck and urethral stump following prostate removal and prior to the creation of the anastomosis. Both patients successfully underwent the prostatectomy and urologic scaffold placement with no reported perioperative complications. Neither patient suffered from early SUI following RARP as measured by pad weight and usage at 1 and 3 months following the procedure. CONCLUSION: Early experience with the absorbable urologic scaffold suggests it could safely and effectively prevent SUI following RARP. Early and long-term results derived from the ongoing prospective study with this device will better define its potential role in the prevention of SUI.

5-Alpha reductase inhibitors induce a prostate luminal to club cell transition in human benign prostatic hyperplasia.

Benign prostatic hyperplasia (BPH) is a progressive expansion of peri-urethral prostate tissue common in aging men. Patients with enlarged prostates are treated with 5-alpha reductase inhibitors (5ARIs) to shrink prostate volume by blocking the conversion of testosterone to dihydrotestosterone (DHT). A reduction in DHT levels can elicit atrophy and apoptosis of prostate secretory luminal cells, which results in a favorable clinical response characterized by improved lower urinary tract symptoms. However, the histologic response to 5ARI treatment is often heterogeneous across prostate acini and lower urinary tract symptoms can persist to require surgical intervention. We used two spatial profiling approaches to characterize gene expression changes across histologically normal and atrophied regions in prostates from 5ARI-treated men. Objective transcriptomic profiling using the Visium spatial gene expression platform showed that 5ARI-induced atrophy of prostate luminal cells correlated with reduced androgen receptor signaling and increased expression of urethral club cell genes including LTF, PIGR, OLFM4, SCGB1A1, and SCGB3A1. Prostate luminal cells within atrophied acini adapted to decreased DHT conditions by increasing NF-κB signaling and anti-apoptotic BCL2 expression, which may explain their survival. Using GeoMx digital spatial profiling with a probe set to assess ~18 000 RNA targets, we confirmed that atrophied acini expressing SCGB3A1 displayed higher levels of club cell markers compared with histologically normal acini with NKX3-1 expression. In addition, club-like cells within regions of 5ARI-induced atrophy closely resembled true club cells from the prostatic urethra. A comparison of histologically normal regions from 5ARI-treated men and histologically normal regions from untreated men revealed few transcriptional differences. Taken together, our results describe a heterogeneous response to 5ARI treatment where cells in atrophied acini undergo an adaptation from a prostate secretory luminal to a club cell-like state in response to 5ARI treatment. © 2021 The Pathological Society of Great Britain and Ireland.

PSA density is associated with BPH cellular composition.

BACKGROUND: Current AUA guidelines recommend 5 alpha reductase inhibitor (5ARI) treatment for patients with obstructive benign prostatic hyperplasia (BPH) that display prostate volume ≥30 cc and total prostate specific antigen (PSA) ≥1.5 ng/ml. However, BPH is highly pleomorphic and response to 5ARIs is highly variable. An understanding of cellular composition based on a noninvasive PSA density test could lead to improved clinical decision making. METHODS: The histological composition of 307 BPH specimens was scored by a pathologist for stromo-glandular content and associated with total PSA, prostate volume, PSA density and other clinical variables using univariate and multivariate linear regression. RESULTS: The percentage of glandular composition in prostates of 5ARI-naïve men was positively and independently associated with PSA and PSA density. It was determined through statistical modeling that a PSA density ≤0.05 ng/ml2 associated with a glandular composition of ≤30% with 76% sensitivity. CONCLUSIONS: PSA density could provide a decisive variable for estimating BPH cellular content and may eventually improve selection of patients for 5ARI treatment. Further work is needed to demonstrate that patients with higher glandular content are more responsive to 5ARI treatment.

Single-cell analysis of mouse and human prostate reveals novel fibroblasts with specialized distribution and microenvironment interactions.

Stromal-epithelial interactions are critical to the morphogenesis, differentiation, and homeostasis of the prostate, but the molecular identity and anatomy of discrete stromal cell types is poorly understood. Using single-cell RNA sequencing, we identified and validated the in situ localization of three smooth muscle subtypes (prostate smooth muscle, pericytes, and vascular smooth muscle) and two novel fibroblast subtypes in human prostate. Peri-epithelial fibroblasts (APOD+) wrap around epithelial structures, whereas interstitial fibroblasts (C7+) are interspersed in extracellular matrix. In contrast, the mouse displayed three fibroblast subtypes with distinct proximal-distal and lobe-specific distribution patterns. Statistical analysis of mouse and human fibroblasts showed transcriptional correlation between mouse prostate (C3+) and urethral (Lgr5+) fibroblasts and the human interstitial fibroblast subtype. Both urethral fibroblasts (Lgr5+) and ductal fibroblasts (Wnt2+) in the mouse contribute to a proximal Wnt/Tgfb signaling niche that is absent in human prostate. Instead, human peri-epithelial fibroblasts express secreted WNT inhibitors SFRPs and DKK1, which could serve as a buffer against stromal WNT ligands by creating a localized signaling niche around individual prostate glands. We also identified proximal-distal fibroblast density differences in human prostate that could amplify stromal signaling around proximal prostate ducts. In human benign prostatic hyperplasia, fibroblast subtypes upregulate critical immunoregulatory pathways and show distinct distributions in stromal and glandular phenotypes. A detailed taxonomy of leukocytes in benign prostatic hyperplasia reveals an influx of myeloid dendritic cells, T cells and B cells, resembling a mucosal inflammatory disorder. A receptor-ligand interaction analysis of all cell types revealed a central role for fibroblasts in growth factor, morphogen, and chemokine signaling to endothelia, epithelia, and leukocytes. These data are foundational to the development of new therapeutic targets in benign prostatic hyperplasia. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Identifying predictors of antispasmodic use following robotic assisted simple prostatectomy.

INTRODUCTION: Anticholinergic or ß-3 agonist use following robotic simple prostatectomy (RASP) is not well described. We describe rates of antispasmodic use following RASP and identify potential predictors of medication use. MATERIALS AND METHODS: A retrospective review of all RASP patients from 2/2016 - 1/2020 was conducted. Patients with no preoperative International Prostate Symptom Score (IPSS) were excluded. Demographics, clinical data, and postoperative medication use were collected by electronic medical record review. Multivariable logistic regression analysis using a priori variables was performed to identify independent factors associated with antispasmodic use. RESULTS: A total of 255 patients underwent RASP at a mean age of 70.0 years ± 7.3 and mean body mass index (BMI) of 28.6 kg/m2 ± 5.0. Median preoperative prostate volume was 132.3 cc ± 45.0. Rates of preoperative diabetes, obstructive sleep apnea (OSA), smoking and alcohol use were 19.6%, 6.3%, 3.1%, and 11.8% respectively; 8.6% of patients (n = 22) initiated antispasmodics at a median of 2.5 months (IQR 1.3-4.2) postoperatively. Median duration of antispasmodic use was 6.5 months (IQR 1.7-14.7). Mirabegron was most commonly prescribed (31.8%). On multivariable logistic regression analysis, OSA was independently associated with postoperative antispasmodic use (OR 8.13, 95% CI 2.02-32.67, p = 0.003); 68.8% of OSA patients were treated with continuous positive airway pressure (CPAP). Treatment was not significantly associated with postoperative antispasmodic use (p = 0.61). CONCLUSION: Patients with OSA are over 8 times more likely to require antispasmodic medications following RASP in the short term. These patients may benefit from more tailored preoperative counseling.

Clinical and radiographic outcomes following salvage intervention for ureteropelvic junction obstruction.

PURPOSE: We aimed to assess failure rates of salvage interventions and changes in split kidney function (SKF) following failed primary repair of ureteropelvic junction obstruction (UPJO). MATERIALS AND METHODS: A retrospective review of adult patients at an academic medical center who underwent salvage intervention following primary treatment for UPJO was performed. Symptomatic failure was defined as significant flank pain. Radiographic failure was defined as no improvement in drainage or a decrease in SKF by ≥7%. Overall failure, the primary outcome, was defined as symptomatic failure, radiographic failure, or both. RESULTS: Between 2008-2017, 34 patients (median age 38 years, 50% men) met study criteria. UPJO management was primary pyeloplasty/secondary endopyelotomy for 21/34 (62%), primary pyeloplasty/secondary pyeloplasty for 6/34 (18%), and primary endopyelotomy/secondary pyeloplasty for 7/34 (21%). Median follow-up was 3.3 years following secondary intervention. Patients undergoing primary pyeloplasty/secondary endopyelotomy had significantly higher overall failure than those undergoing primary pyeloplasty/secondary pyeloplasty (16/21 [76%] vs. 1/6 [17%], p=0.015). Among patients undergoing secondary endopyelotomy, presence of a stricture on retrograde pyelogram, stricture length, and SKF were not associated with symptomatic, radiographic, or overall failure. Serial renography was performed for 28/34 (82%) patients and 2/28 (7%) had a significant decline in SKF. CONCLUSIONS: Following failed primary pyeloplasty, secondary endopyelotomy had a greater overall failure rate than secondary pyeloplasty. No radiographic features assessed were associated with secondary endopyelotomy failure. Secondary intervention overall failure rates were higher than reported in the literature. Unique to this study, serial renography demonstrated that significant functional loss was overall infrequent.

Urethral luminal epithelia are castration-insensitive cells of the proximal prostate.

BACKGROUND: Castration-insensitive epithelial progenitors capable of regenerating the prostate have been proposed to be concentrated in the proximal region based on facultative assays. Functional characterization of prostate epithelial populations isolated with individual cell surface markers has failed to provide a consensus on the anatomical and transcriptional identity of proximal prostate progenitors. METHODS: Here, we use single-cell RNA sequencing to obtain a complete transcriptomic profile of all epithelial cells in the mouse prostate and urethra to objectively identify cellular subtypes. Pan-transcriptomic comparison to human prostate cell types identified a mouse equivalent of human urethral luminal cells, which highly expressed putative prostate progenitor markers. Validation of the urethral luminal cell cluster was performed using immunostaining and flow cytometry. RESULTS: Our data reveal that previously identified facultative progenitors marked by Trop2, Sca-1, KRT4, and PSCA are actually luminal epithelial cells of the urethra that extend into the proximal region of the prostate, and are resistant to castration-induced androgen deprivation. Mouse urethral luminal cells were identified to be the equivalent of previously identified human club and hillock cells that similarly extend into proximal prostate ducts. Benign prostatic hyperplasia (BPH) has long been considered an "embryonic reawakening," but the cellular origin of the hyperplastic growth concentrated in the periurethral region is unclear. We demonstrate an increase in urethral luminal cells within glandular nodules from BPH patients. Urethral luminal cells are further increased in patients treated with a 5-α reductase inhibitor. CONCLUSIONS: Our data demonstrate that cells of the proximal prostate that express putative progenitor markers, and are enriched by castration in the proximal prostate, are urethral luminal cells and that these cells may play an important role in the etiology of human BPH.

Natural history of 'second' biochemical failure after salvage radiation therapy for prostate cancer: a multi-institution study.

OBJECTIVES: To describe the natural history of prostate cancer in men who experience a second biochemical recurrence (BCR) after salvage radiotherapy (SRT) after prostatectomy. PATIENTS AND METHODS: After undergoing SRT at one of two institutions between 1986 and 2013, 286 patients experienced a second BCR, defined as two rises in prostate-specific antigen (PSA) of ≥0.2 ng/mL above nadir. Event rates for distant metastasis (DM) or freedom from DM (FFDM), castration-resistant prostate cancer (CRPC), prostate cancer-specific survival (PCSS), and overall survival (OS) were estimated using the Kaplan-Meier method. Cox regression was used for comparative analyses. RESULTS: At a median of 6.1 years after second BCR, DM, CRPC, PCSS and OS rates were 41%, 27%, 83% and 73%, respectively. On multivariable analysis, interval to second BCR <1 year (hazard ratio [HR] 2.66, 95% confidence interval [CI] 1.71-4.14; P < 0.001], Gleason score 8-10 (HR 1.65, 95% CI 1.07-2.54; P = 0.022), and concurrent ADT during SRT (HR 1.76, 95% CI 1.08-2.88; P = 0.024) were associated with FFDM, while PCSS was associated with interval to second BCR <1 year (HR 3.00, 95% CI 1.69-5.32; P < 0.001) and concurrent ADT during SRT (HR 2.15, CI 1.13-4.08; P = 0.019). These risk factors were used to stratify patients into three groups, with 6-year FFDM rates of 71%, 59% and 33%, and PCSS rates of 89%, 79%, and 65%, respectively. CONCLUSION: Following second BCR after SRT, clinical progression is enriched in a subgroup of patients with prostate cancer, while others remain without DM for long intervals. Stratifying patients into risk groups using prognostic factors may aid counselling and future trial design.

Comparison of Robot-Assisted Versus Open Simple Prostatectomy for Benign Prostatic Hyperplasia.

PURPOSE OF REVIEW: Recent advancements in minimally invasive approaches for prostate surgery have provided numerous options for surgical management of benign prostatic hyperplasia (BPH). In the setting of a large prostate, an open simple prostatectomy was previously considered the gold standard surgical treatment. However, the recently updated American Urological Association (AUA) guidelines on surgical management of BPH now consider both open and minimally invasive approaches to simple prostatectomy viable alternatives for treating large glands, depending on expertise with the techniques. The purpose of our review is to discuss the minimally invasive robot-assisted approach and compare it to the classic open approach to simple prostatectomy. RECENT FINDINGS: Despite longer operative times, the robotic approach is associated with shorter hospital stay and lower morbidity profile. The morbidity of an open approach remains significant. Blood transfusions are 3-4 times as likely compared to a robotic approach and major complications are twice as likely. Consistent with previous literature, our review shows functional outcome improvements like flow rate and symptom score to be comparable between the robotic and open approach. The amount of adenoma resected and PSA decline is also similar among robotic and open cases. Robot-assisted simple prostatectomy is a safe and effective procedure for BPH secondary to a large prostate gland. Appropriately, it is no longer deemed "investigational" by the latest AUA guidelines on BPH and recommended as an alternative to the open approach.