Smooth Muscle Differentiation Research Articles

10-year Observation of A Rare Presentation of Pure Fibromyxoid Nephrogenic Adenoma in the Renal Pelvis

Abstract Introduction/Objective Pure fibromyxoid NA is an unusual rare variant that typically presents with a well circumscribed bulbous, or tumefacient architecture composed of mitotically inactive bland spindled cells and rare tubular structures within a myxoid or collagenized stroma. Here we report a rare case of pure fibromyxoid NA involving the renal pelvis with over 10-year clinical observation and comparison and correlation of biopsy and resection findings. To the best of our knowledge, this is the first reported case of pure fibromyxoid NA in renal pelvis with close comparison and correlation of biopsy and resection findings with over 10-year clinical manifestation, hoping that knowledge of this long-term rare spindle cell lesion will enhance awareness of pathologists to carefully consider this unusual entity, especially in the biopsy specimen in which typical histologic features of fibromyxoid NA are usually absent, as well as prevent misdiagnosis and overtreatment of a typically benign process. Methods/Case Report A retrospective case study of a 37-year-old female with multiple previous biopsy of the nodule in the renal pelvis, and final resection specimen. Biopsies of the mass showed predominantly bland spindle cell lesion with smooth muscle differentiation and scant urothelial epithelial cells, but no tubular structure identified at the biopsy specimen. On the final resection specimen, a urothelium-lining polypoid nodule composing of abundant bland spindle- shaped cells and scattered conventional tubules lined by a single layer of cuboidal epithelial cells in hobnail arrangement that are positive for PAX8 and GATA3 was identified. These morphological and immunohistochemical findings were consistent with the diagnosis of pure fibromyxoid NA. Results (if a Case Study enter NA) NA Conclusion To the best of our knowledge, this is the first description of a pure fibromyxoid NA of the renal pelvis with more than 10-year clinical observation, as well as comparison and correlation of biopsy and resection findings.Close observation and comparison of the findinigs between biopsy and resection specimen will enhance awareness of pathologists to carefully consider this unusual entity, especially in the biopsy specimen in which typical histologic features of fibromyxoid NA are usually absent, as well as prevent misdiagnosis and overtreatment of a typically benign process.

Adenomatoid tumor with extensive reactive smooth muscle: a diagnostic dilemma

Abstract Introduction/Objective Adenomatoid tumors are slow-growing benign tumors of mesothelial origin. They comprise 30% of all tumors of the paratesticular area. In this location, they commonly involve the epididymis, spermatic cord, ejaculatory duct and rarely testicular parenchyma. Histologically, a spectrum of growth patterns can be seen, such as adenoid, tubular, glandular, solid, or cystic. In some cases, a smooth muscle component can also be present. The purpose of this report is to describe a case of adenomatoid tumor with exuberant smooth muscle component, mimicking leiomyoma. Methods/Case Report A 28-year-old male presented with painless left inguinal bulge. He noticed it five years prior, and it had been slowly growing since then. Examination revealed a paratesticular mass which was subsequently excised. Grossly, the tumor was firm with smooth, white-tan cut surfaces. Microscopically, the tumor was well- circumscribed, showing predominance of smooth muscle bundles and rare cuboidal to ovoid cells in tubular growth pattern. In the background there was little intervening stroma. Immunohistochemical stains showed the cuboidal cells to be positive for WT1 and calretinin, confirming the mesothelial origin. Diagnosis of adenomatoid tumor was rendered. In contrast to adenomatoid tumors, leiomyomas are whiter and firmer on gross examination and lack the characteristic tubules or cystic spaces lined by mesothelial cells. Results (if a Case Study enter NA) N/A Conclusion Exuberant smooth muscle differentiation in adenomatoid tumor can mislead to diagnosis of leiomyoma. Careful inspection for tubules of mesothelial origin and appropriate immunohistochemical stains are key to accurate diagnosis. Pathologists need to be aware of this potential pitfall.

Sclerosing Perivascular epithelioid cell neoplasms (PEComa), a rare variant in a unique family of tumors

Abstract Introduction/Objective Perivascular epithelioid cell neoplasms (PEComas) are a rare group of neoplasms that characteristically show both smooth muscle and melanocytic differentiation. The most common tumor in this family is renal angiomyolipoma but may occur in various sites. Sclerosing PEComa (S-PEComa) is an extremely rare variant. its only reported in females and it is usually an incidental finding in the retroperitoneum, in close proximity to the kidney. Methods/Case Report . We present a 52-year-old female, who had a chest CT scan for worsening cough. An - 4 cm exophytic renal mass in the left renal upper pole was found. Patient underwent left partial nephrectomy. Grossly the specimen consisted of 2.5 cm well-circumscribed, white tan mass, abutting the renal capsule, and extending into perinephric adipose tissue. Histology revealed uniform bland epithelioid cells with palely eosinophilic cytoplasm and round nuclei embedded in abundant densely sclerotic stroma. No fat was identified. Immunohistochemistry showed the tumor to be positive for desmin, HMB-45 and SMA with focal staining for AE1/AE3 and negative staining for EMA, cam 5.2, CD 117, calretinin, CD 34, S-100, PAX 8, and Melan A, which confirming the diagnosis of S-PEComa. Results (if a Case Study enter NA) NA Conclusion PEComas, excluding the epithelioid variant, usually has a benign course. In the 13 cases previously reported S-PEComa, 2 patients had metastasis. Our patient, 3-month post-op, has no evidence of disease, but close follow up still warranted.

Mitochondrial influences on smooth muscle phenotype.

Smooth muscle cells transition reversibly between contractile and noncontractile phenotypes in response to diverse influences, including many from mitochondria. Numerous molecules including myocardin, procontractile miRNAs, and the mitochondrial protein prohibitin-2 promote contractile differentiation; this is opposed by mitochondrial reactive oxygen species (mtROS), high lactate concentrations, and metabolic reprogramming induced by mitophagy and/or mitochondrial fission. A major pathway through which vascular pathologies such as oncogenic transformation, pulmonary hypertension, and atherosclerosis cause loss of vascular contractility is by enhancing mitophagy and mitochondrial fission with secondary effects on smooth muscle phenotype. Proproliferative miRNAs and the mitochondrial translocase TOMM40 also attenuate contractile differentiation. Hypoxia can initiate loss of contractility by enhancing mtROS and lactate production while simultaneously depressing mitochondrial respiration. Mitochondria can reduce cytosolic calcium by moving it across the inner mitochondrial membrane via the mitochondrial calcium uniporter, and then through mitochondria-associated membranes to and from calcium stores in the sarcoplasmic/endoplasmic reticulum. Through these effects on calcium, mitochondria can influence multiple calcium-sensitive nuclear transcription factors and genes, some of which govern smooth muscle phenotype, and possibly also the production of genomically encoded mitochondrial proteins and miRNAs (mitoMirs) that target the mitochondria. In turn, mitochondria also can influence nuclear transcription and mRNA processing through mitochondrial retrograde signaling, which is currently a topic of intensive investigation. Mitochondria also can signal to adjacent cells by contributing to the content of exosomes. Considering these and other mechanisms, it is becoming increasingly clear that mitochondria contribute significantly to the regulation of smooth muscle phenotype and differentiation.

Pathological features of primary cardiac myxoid tumour in dogs: a review of 11 cases (2002–2022)

This report documents the pathological features of primary cardiac myxoid tumour (MT) in 11 dogs. Macroscopically, all the tumours were located in the tricuspid valve (TV), its septal leaflet being predominantly affected. Therefore, it appears that the TV is the most common site of occurrence for cardiac MT in dogs. Two gross anatomical types of canine valvular MT were evident. Seven of the 11 tumours were round or oval with a smooth or gently lobulated and glistening surface, while the other four were gelatinous, multilobulated and polypoid, with an irregular surface. Microscopically, in nine cases the tumours had an abundant myxoid matrix within which elongated spindle-shaped cells with no remarkable cytological atypia were sparsely embedded, suggesting a benign character (ie, myxoma). In the other two cases the tumours consisted of variably dense, haphazardly arranged, interlacing streams of anaplastic spindle-shaped or polygonal cells containing many mitotic figures, indicative of a malignant form of myxoma (ie, myxosarcoma). Isolated or clustered collections of myxoma cells (eg, cords, rings, syncytia) characteristic of human atrial myxoma were only rarely evident or lacking in all 11 cases, indicating that rarity or absence of such structural features may be specific to valvular MTs. Immunohistochemical findings were indicative of smooth muscle differentiation of the neoplastic cells. Tumour embolization to the intrapulmonary arteries and/or tumour implantation on the endocardium of the right heart chambers was evident only in the four cases of irregular-surfaced MT.

Melanotic PEComa: A Rare But Distinctive Subtype Analyzed in a Series of 7 Cases.

Perivascular epithelioid cell neoplasms (PEComas) are tumors of uncertain cell lineage that show a strong female predominance. Their hallmark is the presence of combined smooth muscle and melanocytic differentiation. In most cases, melanocytic differentiation is detectable only by immunohistochemistry, but there are rare reports of PEComa with extensive melanin accumulation (so-called "melanotic PEComa"). Here we report a clinicopathologic series of 7 melanotic PEComas that occurred across a wide patient age range of 21 to 82 years (median: 41y) and with a wide anatomic distribution, including 2 cases in the pelvis and 1 case each in the gallbladder, cervix, eyelid, epidural space, and femur. All tumors were heavily pigmented and, like conventional PEComas, were composed of variably sized neoplastic cells with voluminous granular, or less commonly clear, cytoplasm with prominent nucleoli. All tumors expressed HMB45 by immunohistochemistry, and 6 of 7 showed nuclear TFE3 expression. Where tested, tumors were uniformly negative for Mart-1/Melan-A, S100, desmin, and smooth muscle actin. Molecular analysis identified TFE3 gene rearrangement in 5 of 7 cases, 4 of which were demonstrated by fluorescence in situ hybridization and one by whole-exome RNA sequencing which revealed a SFPQ::TFE3 fusion. The one tumor negative for TFE3 by immunohistochemistry was found instead to harbor a SFPQ::TFEB fusion, the first reported example to our knowledge of TFEB fusion in a PEComa. Clinical follow-up was available for 6 of 7 patients (median: 2.5y: range: 0.75 to 7y). The patient whose tumor harbored SFPQ::TFEB died of metastatic disease 9 months after diagnosis. The other tumors behaved in an indolent fashion: 4 patients were alive without evidence of disease at the most recent follow-up and 1 patient died of an unrelated cancer 4 years after diagnosis of the melanotic PEComa. Our results expand the morphologic and molecular spectrum of melanotic PEComa, and awareness of this rare but distinctive subtype is important to ensure accurate diagnosis within the broader family of heavily pigmented neoplasms.

Myoid hamartoma of breast: a rare case report with review of literature

Myoid hamartomas of breast are extremely rare lesions with poorly defined pathogenesis. They are composed of differentiated mammary glandular and stromal structures with areas of smooth muscle differentiation. They are postulated to arise from walls of the blood vessels and/or muscularis mammillae of the areolae. They usual present as a well demarcated lump and it is difficult to diagnose them on clinical and radiological basis. Diagnosis requires demonstration of smooth muscle phenotype using immunohistochemistry by smooth muscle actin and desmin. Surgical resection is the curative treatment. We reported a case of myoid hamartoma in a 50-year-old postmenopausal lady with its clinical, radiological and histopathological discussion. The lesion presented as a painless lump and was initially reported as BIRADS 4a on mammography. Apart from the stroma showing spindle cell component with smooth muscle differentiation, the histopathology also showed epithelial changes including epithelial hyperplasia and columnar cell change.

Pulmonary inflammatory leiomyosarcoma represents a potential diagnostic pitfall of DNA methylation-based classification of sarcomas: a case report

BackgroundPulmonary inflammatory leiomyosarcoma (PILMS) is a rare type of myogenic tumor with prominent lymphohistiocytic infiltration. Despite their histological similarities, PILMS is immunohistochemically and genetically distinct from soft tissue inflammatory leiomyosarcoma, and its clinicopathological picture including DNA methylome data remains still unknown.Case presentationHere we present a case of PILMS in an 18-year-old male who underwent lobectomy. As reported previously, the current case demonstrated spindle myoid cell proliferation with smooth muscle differentiation within a prominent lymphohistiocytic infiltration and a diploid genome with a MUC3A gene alteration. DNA methylation analysis predicted this case to be an “inflammatory myofibroblastic tumor” (IMT) according to the Deutsches Krebsforschungszentrum (DKFZ) classifier. The data was analyzed by t-distributed stochastic neighbor embedding, which plotted the case tumor in the vicinity of IMT, however, there were no IMT histological features. These discordant results could be due to background non-neoplastic inflammatory cells.ConclusionsAs the DNA methylation classification of PILMS might be a potential diagnostic pitfall, an integrative histological and genetic approach is required for its accurate diagnosis.

P4HA2-induced prolyl hydroxylation of YAP1 restricts vascular smooth muscle cell proliferation and neointima formation

Vascular smooth muscle cell (VSMC) proliferation and neointima formation play significant roles in atherosclerosis development and restenosis following percutaneous coronary intervention. Our team previously discovered that TEA domain transcription factor 1 (TEAD1) promotes vascular smooth muscle differentiation, which is necessary for vascular development. Conversely, aberrant YAP1 activation upregulates the platelet-derived growth factor receptor beta to encourage VSMC proliferation and neointima formation. In this study, we aimed to investigate the molecular mechanisms of YAP1/TEAD signaling during neointima formation. Our research focused on the prolyl 4-hydroxylase alpha 2 (P4HA2) and its downstream target, Yes-associated protein 1 (YAP1), in regulating VSMC differentiation and neointima formation. Our results indicated that P4HA2 reduction leads to VSMC dedifferentiation and promotes neointima formation after injury. Furthermore, we found that P4HA2-induced prolyl hydroxylation of YAP1 restricts its transcriptional activity, which is essential to maintaining VSMC differentiation. These findings suggest that targeting P4HA2-mediated prolyl hydroxylation of YAP1 may be a promising therapeutic approach to prevent injury-induced neointima formation in cardiovascular disease.

Mammary stromal-epithelial lesions with myofibroblastic stroma and HMGA2 overexpression linked smooth muscle differentiation, a case series from single institution

Fibroadenoma and phyllodes tumor are the prototypical mammary fibroepithelial lesions (FELs). Recently, a subset of FELs, identified as stromal-epithelial lesion (SEL) with myofibroblastic stroma have been labelled as myofibroepithelial nodule (MFN). The MFN stromal cells are diffusely positive for SMA immunostaining and frequently show unusual histological features including irregular borders. There is limited literature on FELs with myofibroblastic or smooth muscle stroma. The etiology of the variation in the FEL stromal histology and its clinical significance is unknown. In this short report we describe clinicopathologic features of six FELs with myofibroblastic and/or smooth muscle stroma. We also report immunohistochemical overexpression of HMGA2 in 2 FELs that contained stromal smooth muscle differentiation suggesting a link to mammary myoid hamartoma. On limited follow up all the 6 FELs with myofibroblastic or smooth muscle stroma had benign outcome. The HMGA2 overexpressing FEL with smooth muscle stroma and myoid hamartoma of the breast show overlapping etiology, and histological features.

40-OR: Insulin Stabilized Arterial Plaque by Regulating Vascular Smooth Muscle Cell Metabolism and Differentiation

The main pathology of cardiovascular diseases (CVD) in insulin resistance and diabetes is an acceleration of atherosclerosis and increased risk for the development of unstable plaques. Insulin’s effect on vascular smooth muscle cell (VSMC) has been attributed to be pro-atherogenic due to its actions to increase migration and proliferation. We reported that insulin receptors (IR) are responsible for increasing arterial intimal hyperplasia after wire injury. Surprisingly, mice with VSMC specific deletion of IR (Myh11IRKO/ApoE-/-), atherosclerosis was increased with plaques exhibited unstable pathologies of less VSMC and ECM, but more macrophages and necrosis than ApoE-/- mice. To characterize these unexpected findings in the arterial plaques of Myh11IRKO/ApoE-/- mice, we performed single cell RNA sequencing study of VSMC comparing 4 groups of mice including ApoE-/- and MyH11IRKO/ApoE-/- on normal chow or high fat diet (HFD). Bioinformatics analysis demonstrated that VSMC can be separated into 21 distinctive clusters with those expression enriched for contractile and mitochondrial genes separated from clusters which expressed heat shock protein (HSP) or inflammatory genes. Aorta of HFD insulin resistant WT ApoE-/- mice exhibited significantly increases of multiple clusters of inflammatory VSMCs and, surprisingly, also those clusters enriched for mitochondrial metabolism. However, in Myh11IRKO/ApoE-/- mice on HFD, aortic VMSC clusters with contractile and mitochondrial genes were significantly reduced, but distinct VMSC clusters with expressions of HSP or inflammatory genes were greatly increased. These novel findings, along with metabolic studies in cultured VSMC, indicated that insulin’s actions on VSMC metabolism to reduce the transition of VSMCs subsets from mitochondria enriched VSMCs to stressed and inflammatory VSMCs, which is critical to increase plaque stability and decrease CVD risks in people with insulin resistance and diabetes. Disclosure Q.Li: None. J.Fu: None. K.Park: None. I.Wu: None. G.L.King: Research Support; Janssen Research & Development, LLC.

Beyond Limits: A Case of Progressive Leiomyosarcoma of the Mandible

Leiomyosarcoma (LMS) is a rare malignancy which develops from the smooth muscles. It constitutes about 3 to 10% of all sarcomas in the head and neck area. Furthermore, it is extremely rare in the area of the mouth and jaws due to the rarity of smooth muscle in these areas. Spindle cells with visible smooth muscle differentiation, distinct features of atypia and presence of actin and desmin in Immunohistochemical (IHC) stains are characteristic of LMS. The common pattern of spread is similar with other sarcomas, involving the lung and rarely the lymphatics. Surgery, Radiotherapy and Chemotherapy have been described as standard forms of management. The prognosis is usually poor as rate of local, regional and distant metastasis is high. In this paper, we present a case of a 23 year-old female who presented with Leiomyosarcoma of the mandible. She remained to have good performance status and was able to undergo multiple lines of treatment for progressive disease prior to her demise.

LOW-GRADE MYOFIBROBLASTIC SARCOMA OF THE ORAL CAVITY

Low-grade myofibroblastic sarcoma (LGMS) represents a distinct atypical myofibroblastic tumor of deep soft tissues, with a head and neck predilection. It has a variety of appearances, from fasciitis-like or fibromatosis-like to fibrosarcoma-like. Here, a series of four cases from two different institutions is shown, represented by 2 men and 2 women presenting a nodular lesion, with equal distribution in maxilla and mandibula. Microscopically, all cases showed neoplasms formed by oval to spindle cells in a fibrous stroma with myxoid and dense areas, some atypical mitoses, and prominent nucleoli. These findings suggested a mesenchymal tumor. An immunohistochemical panel was performed, which showed positivity for smooth muscle actin (3 of 4 cases), HHF35 (2 of 4 cases), β-catenin (3 of 3 cases), calponin (2 of 4 cases), and Ki-67 (range 5-40%). H-Caldesmon was negative for all cases, demonstrating myofibroblastic and smooth muscle differentiation. The diagnosis of LGMS was confirmed in all cases. Low-grade myofibroblastic sarcoma (LGMS) represents a distinct atypical myofibroblastic tumor of deep soft tissues, with a head and neck predilection. It has a variety of appearances, from fasciitis-like or fibromatosis-like to fibrosarcoma-like. Here, a series of four cases from two different institutions is shown, represented by 2 men and 2 women presenting a nodular lesion, with equal distribution in maxilla and mandibula. Microscopically, all cases showed neoplasms formed by oval to spindle cells in a fibrous stroma with myxoid and dense areas, some atypical mitoses, and prominent nucleoli. These findings suggested a mesenchymal tumor. An immunohistochemical panel was performed, which showed positivity for smooth muscle actin (3 of 4 cases), HHF35 (2 of 4 cases), β-catenin (3 of 3 cases), calponin (2 of 4 cases), and Ki-67 (range 5-40%). H-Caldesmon was negative for all cases, demonstrating myofibroblastic and smooth muscle differentiation. The diagnosis of LGMS was confirmed in all cases.

Smooth muscle differentiation of coronary intima in autopsy tissues after sirolimus-eluting stent implantation

BackgroundIn coronary atherosclerotic disease, the proliferation of intimal smooth muscle cells (SMCs) is regarded as beneficial with respect to stable and unstable plaques, but is thought detrimental in discussions on coronary stent restenosis. To resolve this discrepancy, we focused on the quality, not quantity, of intimal SMCs in coronary atherosclerotic disease. MethodsAutopsied coronary artery specimens from seven patients implanted with bare metal stents (BMS), three with paclitaxel-eluting stents (PES), and 10 with sirolimus (rapamycin)-eluting stents (SES) were immunostained for SMC markers. Cultured human coronary artery SMCs were also treated with sirolimus and paclitaxel. ResultsIntimal SMC differentiation, estimated by the ratio of h-caldesmon+ cells to α-smooth muscle actin+ (α-SMA+) cells, was significantly increased whereas dedifferentiation, estimated from the ratio of fibroblast activation protein alpha (FAPα)+ cells to α-SMA+ cells, was significantly decreased, in tissues of SES compared with BMS cases. No difference in the degree of differentiation was found between PES and BMS cases or between the three groups in nonstented arteries used as controls. Correlation analyses for each field of view revealed a significant positive correlation between h-caldesmon and calponin staining but significant negative correlations with FAPα staining in α-SMA+ cells. Cultured SMCs were shorter (dedifferentiated) and showed an increased FAPα/α-SMA protein when treated with paclitaxel, whereas they became elongated (differentiated) and showed increased calponin/α-SMA proteins with sirolimus. ConclusionsThe SMCs of the coronary intima may differentiate after SES implantation. SMC differentiation may explain both the plaque stabilization and reduced risk of reintervention associated with SES.

In vitro biocompatibility of polylactide and polybutylene succinate blends for urethral tissue engineering.

Surgical treatment of urothelial defects with autologous genital or extragenital tissue grafts is susceptible to complications. Tissue engineering utilizing novel biomaterials and cells such as human urothelial cells (hUC) for epithelial regeneration and adipose stromal cells (hASC) for smooth muscle restoration might offer new treatment options for urothelial defects. Previously, polylactide (PLA) has been studied for urethral tissue engineering, however, as such, it is too stiff and rigid for the application. Blending it with ductile polybutylene succinate (PBSu) could provide suitable mechanical properties for the application. Our aim was to study the morphology, viability and proliferation of hUC and hASC when cultured on 100/0 PLA/PBSu, 75/25 PLA/PBSu blend, 50/50 PLA/PBSu blend, and 0/100 PLA/PBSu discs. The results showed that the hUCs were viable and proliferated on all the studied materials. The hUCs stained pancytokeratin at 7 and 14 days, suggesting maintenance of the urothelial phenotype. The hASCs retained their viability and morphology and proliferated on all the other discs, except on PLA. On the PLA, the hASCs formed large aggregates with each other rather than attached to the material. The early smooth muscle cell markers SM22α and α-SMA were stained in hASC at 7 and 14 day time points on all PBSu-containing materials, indicating that hASCs maintain their smooth muscle differentiation potential also on PBSu. As a conclusion, PBSu is a highly potential biomaterial for urothelial tissue engineering since it supports growth and phenotypic maintenance of hUC and smooth muscle differentiation of hASC.

Abstract 158: The Histone Demethylase JMJD3 Regulates Smooth Muscle Differentiation And Is Associated With Blood Pressure

Hypertension is associated with significant morbidity and mortality in the United States, and despite its prevalence an unmet need exists for more personalized targeted therapies. Blood pressure is regulated by environmental and genetic factors, and genome wide association studies (GWAS) have identified numerous genes in the human population associated with hypertension. Recently, one GWAS identified the single nucleotide polymorphism rs62059712 that is associated with systolic blood pressure in humans. rs62059712 is located upstream of the gene JMJD3, a histone demethylase that our lab has studied in a variety of disease contexts, and the rs62059712 major C allele (MAF 0.92) is associated with increased blood pressure in humans. Based on our analysis of data from the UCSC genome browser, we found that rs62059712 is located in a DNase Hypersensitive Site marked by H3K27Ac, suggesting it may regulate JMJD3 transcription. In luciferase assays, the fragment containing rs62059712 displayed transcription activity in smooth muscle cells (SMC), and the major C allele exhibited increased luciferase activity compared to the minor T allele in mouse aortic SMC (p<0.05). Notably, rs62059712 is in linkage disequilibrium with rs74480102, which did not display allele-specific transcription activity in SMC. siRNA knockdown of JMJD3 in mouse aortic SMC significantly decreased SMC-specific gene expression (p<0.05), and SMC marker gene expression was also reduced by treatment of SMC with the JMJD3 selective inhibitor GSK4J (p<0.05). Likewise, SMC contractile gene expression was reduced in aortas from SM22Cre;JMJD3 flox/flox mice harboring SMC-specific deletion of JMJD3. Further, angiotensin II increased JMJD3 expression in human aortic SMC. Finally, in chromatin immunoprecipitation assays in mouse aortic SMC, JMJD3 was significantly enriched at smooth muscle gene promoters (p<0.05). Our results identify the blood pressure-associated gene JMJD3 as a key epigenetic regulator of smooth muscle differentiation. Additionally, we show that the rs62059712 major C allele, which is associated with increased blood pressure, increases JMJD3 transcription activity, and likely expression, to drive increased downstream contractile smooth muscle gene expression.

Targeting the Molecular and Immunologic Features of Leiomyosarcoma.

Leiomyosarcoma (LMS) is a rare, aggressive mesenchymal tumor with smooth muscle differentiation. LMS is one of the most common histologic subtypes of soft tissue sarcoma; it most frequently occurs in the extremities, retroperitoneum, or uterus. LMS often demonstrates aggressive tumor biology, with a higher risk of developing distant metastatic disease than most sarcoma histologic types. The prognosis is poor, particularly in patients with uterine disease, and there is a need for the development of more effective therapies. Genetically, LMS is karyotypically complex and characterized by a low tumor mutational burden, with frequent alterations in TP53, RB1, PTEN, and DNA damage response pathways that may contribute to resistance against immune-checkpoint blockade monotherapy. The LMS immune microenvironment is highly infiltrated with tumor-associated macrophages and tumor-infiltrating lymphocytes, which may represent promising biomarkers. This review provides an overview of the clinical and pathologic behavior of both soft tissue and uterine LMS and summarizes the genomic and immune characteristics of these tumors and how they may provide opportunities for the development of biomarker-based immune therapies.

Single-cell transcriptomics uncovers a non-autonomous Tbx1-dependent genetic program controlling cardiac neural crest cell development

Disruption of cardiac neural crest cells (CNCCs) results in congenital heart disease, yet we do not understand the cell fate dynamics as these cells differentiate to vascular smooth muscle cells. Here we performed single-cell RNA-sequencing of NCCs from the pharyngeal apparatus with the heart in control mouse embryos and when Tbx1, the gene for 22q11.2 deletion syndrome, is inactivated. We uncover three dynamic transitions of pharyngeal NCCs expressing Tbx2 and Tbx3 through differentiated CNCCs expressing cardiac transcription factors with smooth muscle genes. These transitions are altered non-autonomously by loss of Tbx1. Further, inactivation of Tbx2 and Tbx3 in early CNCCs results in aortic arch branching defects due to failed smooth muscle differentiation. Loss of Tbx1 interrupts mesoderm to CNCC cell-cell communication with upregulation and premature activation of BMP signaling and reduced MAPK signaling, as well as alteration of other signaling, and failed dynamic transitions of CNCCs leading to disruption of aortic arch artery formation and cardiac outflow tract septation.

Extracellular vesicle microRNA and protein cargo profiling in three clinical-grade stem cell products reveals key functional pathways

The cell origin-specific payloads within extracellular vesicles (EVs) mediate therapeutic bioactivity for a wide variety of stem cell types. In this study, we profiled the microRNA (miRNA) and protein cargos found within EVs produced by three clinical-grade stem cell products of different ontogenies being considered for clinical application, namely bone marrow-derived mesenchymal stromal cells (BM-MSCs), heart-derived cells (HDCs), and umbilical cord-derived MSCs (UC-MSCs). Although several miRNAs (757) and proteins (420) were found in common, each producer cell type expressed unique miRNA profiles when the most highly expressed transcripts were compared. Differential expression analysis revealed that BM-MSCs and HDCs were quite similar, while UC-MSCs had the greatest number of unique miRNAs and proteins. Despite these differences, all three EVs promoted cell adhesion/migration, immune response, platelet aggregation, protein translation/stabilization, and RNA processing. EVs from BM-MSCs were implicated in apoptosis, cell-cycle progression, collagen formation, heme pigment synthesis, and smooth muscle differentiation, while HDC and UC-MSC EVs were found to regulate complement activation, endopeptidase activity, and matrix metallopeptidases. Overall, miRNA and protein profiling reveal functional differences between three leading stem cell products. These findings provide a framework for mechanistic exploration of candidate therapeutic molecules driving the salutary effects of EVs.

Plasticity in airway smooth muscle differentiation during mouse lung development.

It has been proposed that smooth muscle differentiation may physically sculpt airway epithelial branches in mammalian lungs. Serum response factor (SRF) acts with its co-factor myocardin to activate the expression of contractile smooth muscle markers. In the adult, however, smooth muscle exhibits a variety of phenotypes beyond contractile, and these are independent of SRF/myocardin-induced transcription. To determine whether a similar phenotypic plasticity is exhibited during development, we deleted Srf from the mouse embryonic pulmonary mesenchyme. Srf-mutant lungs branch normally, and the mesenchyme displays mechanical properties indistinguishable from controls. scRNA-seq identified an Srf-null smooth muscle cluster, wrapping the airways of mutant lungs, which lacks contractile smooth muscle markers but retains many features of control smooth muscle. Srf-null embryonic airway smooth muscle exhibits a synthetic phenotype, compared with the contractile phenotype of mature wild-type airway smooth muscle. Our findings identify plasticity in embryonic airway smooth muscle and demonstrate that a synthetic smooth muscle layer promotes airway branching morphogenesis.