Glucose transporter 1-positive endothelial cells in infantile hemangioma exhibit features of facultative stem cells

Mechanosensory entities and functionality of endothelial cells

The endothelial cells of the blood circulation are exposed to hemodynamic forces, such as cyclic strain, hydrostatic forces, and shear stress caused by the blood fluid's frictional force. Endothelial cells perceive mechanical forces via mechanosensors and thus elicit physiological reactions such as alterations in vessel width. The mechanosensors considered comprise ion channels, structures linked to the plasma membrane, cytoskeletal spectrin scaffold, mechanoreceptors, and junctional proteins. This review focuses on endothelial mechanosensors and how they alter the vascular functions of endothelial cells. The current state of knowledge on the dysregulation of endothelial mechanosensitivity in disease is briefly presented. The interplay in mechanical perception between endothelial cells and vascular smooth muscle cells is briefly outlined. Finally, future research avenues are highlighted, which are necessary to overcome existing limitations.

Cell Fate Regulation During the Development of Infantile Hemangioma

As the most common benign vascular tumor in infants, infantile hemangioma (IH) is characterized by rapid growth and vasculogenesis early in infancy, followed by spontaneous involution into fibrofatty tissues over time. Extensive evidence suggests that IH originates from hemangioma stem cells (HemSCs), a group of stem cells with clonal expansion and multi-directional differentiation capacity. However, the intricate mechanisms governing the cell fate transition of HemSCs during IH development remain elusive. Here we comprehensively examine the cellular composition of IH, emphasizing the nuanced properties of various IH cell types and their correlation with the clinical features of the tumor. We also summarize the current understanding of the regulatory pathways directing HemSC differentiation into endothelial cells (ECs), pericytes, and adipocytes throughout the stages of IH progression and involution. Furthermore, we discuss recent advances in unraveling the transcriptional and epigenetic regulation of EC and adipocyte development under physiological conditions, which offer crucial perspectives for understanding IH pathogenesis.

Infantile Hemangiomas Lose Vascular Endothelial Cadherin During Involution: Potential Role in Cell Death?

Background

Infantile hemangiomas (IHs) are benign endothelial cell (EC) tumors that undergo a predictable natural history, with rapid proliferation, stabilization, and involution. However, mechanisms regulating these transitions are not well understood. We have observed loss of vascular endothelial cadherin (VECAD) in involuting/involuted IHs. VECAD plays a critical role in angiogenesis, cell cycle progression, and EC survival. We hypothesize that loss of VECAD is associated with apoptosis occurring during IH involution.

Methods

Resected IH samples were clinically categorized as proliferating (n = 4), stable (n = 4), or involuting/involuted (n = 5). Neonatal dermal tissues were used as controls (n = 5). Immunohistochemistry was conducted on sectioned specimens using antibodies against EC markers VECAD and CD31. Apoptosis was assessed with terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay.

Results

CD31 signal intensity in proliferating, stable, and involuting/involuted IH ECs was unchanged relative to each other and to control ECs. VECAD signal significantly and progressively diminished as IHs progressed from proliferation to involution. Involuting/involuted IHs had significantly reduced VECAD expression compared with control ECs (P < 0.0001), proliferating IHs (P < 0.0001), and stable IHs (P < 0.001). As expected, the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling-positive ECs was significantly higher in involuting/involuted IHs (P < 0.05) relative to control ECs and proliferating IHs.

Conclusions

Loss of VECAD expression in IH endothelium corresponded to IH involution and increased apoptosis. It is unclear whether loss of VECAD is causative of IH involution; further studies are needed to elucidate the role of VECAD function in EC survival.

Capillary malformations

Capillary malformation (CM), or port wine birthmark, is a cutaneous congenital vascular anomaly that occurs in 0.1%-2% of newborns. Patients with a CM localized on the forehead have an increased risk of developing a neurocutaneous disorder called encephalotrigeminal angiomatosis or Sturge-Weber syndrome (SWS), with complications including seizure, developmental delay, glaucoma, and vision loss. In 2013, a groundbreaking study revealed causative activating somatic mutations in the gene (GNAQ) encoding guanine nucleotide-binding protein Q subunit α (Gαq) in CM and SWS patient tissues. In this Review, we discuss the disease phenotype, the causative GNAQ mutations, and their cellular origin. We also present the endothelial Gαq-related signaling pathways, the current animal models to study CM and its complications, and future options for therapeutic treatment. Further work remains to fully elucidate the cellular and molecular mechanisms underlying the formation and maintenance of the abnormal vessels.

Infantile hemangioma: the common and enigmatic vascular tumor

Infantile hemangioma (IH) is a benign vascular tumor that occurs in 5% of newborns. The tumor follows a life cycle of rapid proliferation in infancy, followed by slow involution in childhood. This unique life cycle has attracted the interest of basic and clinical scientists alike as a paradigm for vasculogenesis, angiogenesis, and vascular regression. Unanswered questions persist about the genetic and molecular drivers of the proliferating and involuting phases. The beta blocker propranolol usually accelerates regression of problematic IHs, yet its mechanism of action on vascular proliferation and differentiation is unclear. Some IHs fail to respond to beta blockers and regrow after discontinuation. Side effects occur and long-term sequelae of propranolol treatment are unknown. This poses clinical challenges and raises novel questions about the mechanisms of vascular overgrowth in IH.

Intramedullary spinal capillary hemangioma with secondary neurulation defect in children

Intramedullary spinal capillary hemangioma is a rare occurrence in pediatric patients, and only limited cases have been reported. This study presents the first two cases of spinal capillary hemangioma co-present with retained medullary cord and one case of spinal capillary hemangioma with lumbosacral lipomatous malformation. Previous literature on ten patients with this pathology was reviewed. We speculated pathogenesis, imaging features, and histopathologic findings of the disease.

Medical Management of Nonmalignant Vascular Tumors of the Head and Neck: Part 1

Vascular anomalies, broadly classified as nonmalignant tumors and malformations, consist of a multitude of disorders that have a wide range of symptoms and complications as well as overlapping clinical, radiologic, and histologic findings. Although usually difficult, distinguishing between nonmalignant vascular tumors and malformations, as well as the precise diagnosis within these distinctions, is critical because prognosis, therapy, and chronicity of care vary greatly. In contrast to normal endothelial turnover in vascular malformations, vascular tumors are characterized by the abnormal proliferation of endothelial cells and aberrant blood vessels.

Discovery and Characterization of Ephrin B2 and EphB4 Dysregulation and Novel Mutations in Cerebral Cavernous Malformations: In Vitro and Patient-Derived Evidence of Ephrin-Mediated Endothelial Cell Pathophysiology

Intracranial vascular malformations manifest on a continuum ranging from predominantly arterial to predominantly venous in pathology. Cerebral cavernous malformations (CCMs) are capillary malformations that exist at the midpoint of this continuum. The axon guidance factor Ephrin B2 and its receptor EphB4 are critical regulators of vasculogenesis in the developing central nervous system. Ephrin B2/EphB4 dysregulation has been implicated in the pathogenesis of arterial-derived arteriovenous malformations and vein-based vein of Galen malformations. Increasing evidence supports the hypothesis that aberrant Ephrin B2/EphB4 signaling may contribute to developing vascular malformations, but their role in CCMs remains largely uncharacterized. Evidence of Ephrin dysregulation in CCMs would be important to establish a common link in the pathogenic spectrum of EphrinB2/Ephb4 dysregulation. By studying patient-derived primary CCM endothelial cells (CCMECs), we established that CCMECs are functionally distinct from healthy endothelial cell controls; CCMECs demonstrated altered patterns of migration, motility, and impaired tube formation. In addition to the altered phenotype, the CCMECs also displayed an increased ratio of EphrinB2/EphB4 compared to the healthy endothelial control cells. Furthermore, whole exome sequencing identified mutations in both EphrinB2 and EphB4 in the CCMECs. These findings identify functional alterations in the EphrinB2/EphB4 ratio as a feature linking pathophysiology across the spectrum of arterial, capillary, and venous structural malformations in the central nervous system while revealing a putative therapeutic target.

Endothelial-to-mesenchymal transition: New insights into vascular calcification

With the continuous progress of atherosclerosis research, the significant pathological change of it--vascular calcification (VC), gains increasing attention. In recent years, numerous studies have demonstrated that it is an independent predictor of death risk of cardiovascular disease, and it has a strong correlation with poor clinical prognosis. As the world's population continues to age, the occurrence of VC is expected to reach its highest point in the near future. Therefore, it is essential to investigate ways to prevent or even reverse this process for clinical purposes. Endothelial-to-mesenchymal transition (EndMT) describes the progressive differentiation of endothelial cells into mesenchymal stem cells (MSCs) under various stimuli and acquisition of pluripotent cell characteristics. More and more studies show that EndMT plays a vital role in various cardiovascular diseases, including atherosclerosis, vascular calcification and heart valvular disease. EndMT is also involved in the formation and progression of VC. This review vividly describes the history, characteristics of EndMT and how it affects the endothelial cell process, then focuses on the relationship between vascular endothelium, EndMT, amino acid metabolism, and vascular calcification. Finally, it overviews the signal pathway of EndMT and drugs targeting EndMT, hoping to provide new ideas and a theoretical basis for studying potential therapeutic targets of VC.

Infantile hemangioma models: is the needle in a haystack?

Infantile hemangioma (IH) is the most prevalent benign vascular tumor in infants, with distinct disease stages and durations. Despite the fact that the majority of IHs can regress spontaneously, a small percentage can cause disfigurement or even be fatal. The mechanisms underlying the development of IH have not been fully elucidated. Establishing stable and reliable IH models provides a standardized experimental platform for elucidating its pathogenesis, thereby facilitating the development of new drugs and the identification of effective treatments. Common IH models include the cell suspension implantation model, the viral gene transfer model, the tissue block transplantation model, and the most recent three-dimensional (3D) microtumor model. This article summarizes the research progress and clinical utility of various IH models, as well as the benefits and drawbacks of each. Researchers should select distinct IH models based on their individual research objectives to achieve their anticipated experimental objectives, thereby increasing the clinical relevance of their findings.

Limited dorsal myeloschisis associated with intramedullary infantile hemangioma in the conus medullaris: illustrative case

BACKGROUND

Limited dorsal myeloschisis (LDM) and intramedullary infantile hemangioma rarely coexist in the spinal cord.

OBSERVATIONS

The authors describe the case of a 3-month-old girl who, despite lacking neurological symptoms or signs, had a cigarette burn-like mark at the lumbosacral area and skin dimpling in the gluteal area. Magnetic resonance imaging showed a low-set conus due to a thickened filum and an abnormal subcutaneous stalk connected to the conus medullaris. In combination with the skin lesions, these findings strongly implied nonsaccular-type LDM. An intramedullary mass in the conus medullaris was also shown on magnetic resonance imaging and was homogenously enhanced with isointensity on T1- and T2-weighted images. We prophylactically untethered the spinal cord and partially removed the intramedullary mass, which had no clear borders, for a safe surgical dissection. Histologically, the intramedullary mass was an infantile hemangioma, and the subcutaneous stalk was a lesion associated with LDM. The patient remained neurologically intact after surgery, and then 2 years later, there was spontaneous regression of the residual tumor.

LESSONS

Although rare, nonsaccular type LDM may appear concurrently with intramedullary infantile hemangioma at the conus medullaris. The authors present a possible mechanism behind this concurrent presentation in the same area.

Endothelial GLUTs and vascular biology

Endothelial metabolism is a promising target for vascular functional regulation and disease therapy. Glucose is the primary fuel for endothelial metabolism, supporting ATP generation and endothelial cell survival. Multiple studies have discussed the role of endothelial glucose catabolism, such as glycolysis and oxidative phosphorylation, in vascular functional remodeling. However, the role of the first gatekeepers of endothelial glucose utilization, glucose transporters, in the vasculature has long been neglected. Here, this review summarizes glucose transporter studies in vascular research. We mainly focus on GLUT1 and GLUT3 because they are the most critical glucose transporters responsible for most endothelial glucose uptake. Some interesting topics are also discussed, intending to provide directions for endothelial glucose transporter research in the future.

CD146+ mural cells from infantile hemangioma display proangiogenic ability and adipogenesis potential in vitro and in xenograft models

Objective

Infantile hemangioma (IH), the most common infantile vascular neoplasm, is uniquely characterized by rapid proliferation followed by slow spontaneous involution lasting for years. In IH lesions, perivascular cells are the most dynamic cell subset during the transition from the proliferation phase to the involution phase, and we aimed to systematically study this kind of cell.

Methods and results

CD146-selective microbeads were used to isolate IH-derived mural-like cells (HemMCs). Mesenchymal markers of HemMCs were detected by flow cytometry, and the multilineage differentiation potential of HemMCs was detected by specific staining after conditioned culture. CD146-selected nonendothelial cells from IH samples showed characteristics of mesenchymal stem cells with distinct angiogenesis-promoting effects detected by transcriptome sequencing. HemMCs spontaneously differentiated into adipocytes 2 weeks after implantation into immunodeficient mice, and almost all HemMCs had differentiated into adipocytes within 4 weeks. HemMCs could not be induced to differentiate into endothelial cells in vitro. However, 2 weeks after implantation in vivo, HemMCs in combination with human umbilical vein endothelial cells (HUVECs) formed GLUT1⁺ IH-like blood vessels, which spontaneously involuted into adipose tissue 4 weeks after implantation.

Conclusions

In conclusion, we identified a specific cell subset that not only showed behavior consistent with the evolution of IH but also recapitulated the unique course of IH. Thus, we speculate that proangiogenic HemMCs may be a potential target for the construction of hemangioma animal models and the study of IH pathogenesis.

KIAA1429 promotes infantile hemangioma regression by facilitating the stemness of hemangioma endothelial cells

Infantile hemangiomas are common vascular tumors with a specific natural history. The proliferation and regression mechanism of infantile hemangiomas may be related to the multilineage differentiation ability of hemangioma stem cells, but the specific mechanism is not well elucidated. KIAA1429 is an N⁶ -methyladenosine methylation-related protein that can also exert its role in a methylation-independent manner. This study aims to explore the function of KIAA1429 in infantile hemangiomas. qRT-PCR, western blotting, and immunostaining were performed to verify the expression of KIAA1429. The endothelial and fibroblast-like phenotypes of hemangioma endothelial cells were detected after KIAA1429 knockdown and overexpression. The stemness properties of hemangioma endothelial cells and the underlying mechanism of KIAA1429 in hemangiomas were also investigated. Nude mouse models of infantile hemangiomas were conducted to ascertain the effects of KIAA1429 in vivo. The results showed that KIAA1429 was highly expressed in infantile hemangiomas, particularly in involuting hemangiomas. In vitro experiments confirmed that KIAA1429 inhibited the endothelial phenotype, enhanced the differentiation ability, and promoted the fibroblast-like phenotype of hemangioma endothelial cells by inducing endothelial cell transition to facultative stem cells. However, the effect of KIAA1429 on the potential target was shown to be independent of N⁶ -methyladenosine methylation modification. Mouse models further revealed that KIAA1429 could inhibit the proliferation and promote the regression of hemangiomas. In conclusion, this study found that KIAA1429 played an important role in the regression of infantile hemangiomas by enhancing the stemness of hemangioma endothelial cells and could be a potential treatment target for infantile hemangiomas.

Management of infantile hemangiomas: Recent advances

Infantile hemangiomas (IHs) are benign vascular tumors commonly observed in children. A small number of cases can manifest as organ or system dysfunction, permanent scarring, or even disfigurement. Currently, diagnosis is mainly based on clinical history, physical examination, and auxiliary inspection. In the treatment of a hemangioma, the functional damage caused by the lesion and complications that may endanger the patient’s life should be given priority. This suggests that identification, diagnosis, and referral to specialists during the early stages of IHs are important factors in preventing related complications and obtaining a better prognosis. During the past few decades, researchers have explored different treatments according to the condition, including oral or topical drugs, topical drug injections, laser surgery, and surgical treatment. However, oral propranolol remains a well-accepted first-line treatment. This article will primarily focus on the recent advances in the clinical diagnosis and treatment of hemangiomas, along with a literature review on the subject.

VEGF Pathway Gene Expression Profile of Proliferating versus Involuting Infantile Hemangiomas: Preliminary Evidence and Review of the Literature

Background. Infantile hemangiomas may have unexpected behavior. Initial regression (spontaneously or drug-induced) may be followed by unexplained recurrences. At this moment, there are no well-established criteria to predict infantile hemangioma reccurrences. Methods. We compared the VEGF pathway gene expression profile for one case of involuting infantile hemangioma versus one case of recurrent proliferative infantile hemangioma using TaqMan Array. Results. We found ten genes upregulated for both involuting and recurrent proliferative hemangiomas: ACTB, KRAS, MAP2K1, HRAS, NOS3, BAD, HSPB1, HPRT1, GUSB, and CASP9. Thirteen genes were downregulated for both involuting and proliferative hemangiomas: FIGF, ACTG1, GRB2, MAPKAPK2, ACTG2, MAP2K2, MAPK3, HSP90AA1, MAP2K6, NRAS, ACTA1, KDR, and MAPK1. Three genes showed divergent expression between proliferating and involuting hemangiomas. Proliferating hemangioma had MAPK14 and AKT1 gene upregulation and ACTA2 downregulation. Involuting infantile hemangioma was characterized by ACTA2 upregulation and AKT1 and MAPK14 downregulation. Conclusions. Three genes, AKT1, p38/MAPK14, and ACTA2, were found to have divergent expression in proliferating and involuting infantile hemangiomas. Excepting AKT1, which was mentioned in the last ISSVA classification (strictly related to Proteus Syndrome), none of the other genes were reported. An accurate gene expression profile mapping of infantile hemangiomas together with a gene expression-based hemangioma classification is stringently needed.

Infantile Hemangioma: A Current Review

Infantile hemangiomas (IHs) are common vascular lesions which are benign but can cause significant functional and cosmetic morbidity. Since the fortuitous discovery of propranolol being effective to treat IH over a decade ago, the therapy and prognosis for children with IH have improved dramatically. Oral propranolol (as well as other oral beta-blockers and topical timolol) are safe and effective treatments, and have now supplanted other therapies. Making the correct diagnosis is crucial, because other vascular lesions can mimic IH. In addition, IH can be the first manifestation of an underlying syndrome. For IH requiring treatment, initiating treatment early is key to optimizing success. Therefore, early recognition and referral, if necessary, are important. Continued research on IH, both basic science and clinical, should result in continued advances.

Hemangioma Endothelial Cells and Hemangioma Stem Cells in Infantile Hemangioma

BACKGROUND

Hemangioma is one of the most common benign tumors in infants and young children. The 2 most important cells in the course of infantile hemangioma (IH) are hemangioma stem cells (HemSCs) and hemangioma endothelial cells (HemECs). Infantile hemangioma is characterized by massive proliferation of HemECs, but current studies indicate that HemSCs play an important role in pathogenesis of IH.

OBJECTIVE

This review aimed to identify molecules that influence HemSC differentiation and HemEC proliferation and apoptosis to help clarify the pathogenesis of IH and provide novel drug targets for the treatment of IH.

METHODS

Relevant basic science studies related to IH were identified by searching Google Scholar, Embase, PubMed, MEDLINE, and peer-reviewed journal articles.

RESULT

Hemangioma stem cells can differentiate into HemECs, pericytes, and adipocytes. In the proliferating phase of IH, HemSCs mainly differentiate into HemECs and pericytes to promote angiogenesis. In the regressive phase, they mainly differentiate into adipocytes. Therefore, increasing the proportion of HemSCs differentiating into adipocytes, inhibiting the proliferation of HemECs, and promoting the apoptosis of HemECs can facilitate the regression of IH.

Kaposiform hemangioendothelioma of the bone in children and adolescents

Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor that mainly occurs during infancy or early childhood. Approximately 70% of cases are complicated by Kasabach-Merritt phenomenon. Although osseous extension of the primary lesion is relatively common, primary bone involvement by KHE is rare. Given the paucity of literature on primary KHE of the bone, we report a case series of primary KHE of the bone treated at our institution and describe the clinical presentation, radiologic and pathologic findings, management and outcomes.

Non-β-blocker enantiomers of propranolol and atenolol inhibit vasculogenesis in infantile hemangioma

Propranolol and atenolol, current therapies for problematic infantile hemangioma (IH), are composed of R(+) and S(–) enantiomers: the R(+) enantiomer is largely devoid of beta blocker activity. We investigated the effect of R(+) enantiomers of propranolol and atenolol on the formation of IH-like blood vessels from hemangioma stem cells (HemSCs) in a murine xenograft model. Both R(+) enantiomers inhibited HemSC vessel formation in vivo. In vitro, similar to R(+) propranolol, both atenolol and its R(+) enantiomer inhibited HemSC to endothelial cell differentiation. As our previous work implicated the transcription factor sex-determining region Y (SRY) box transcription factor 18 (SOX18) in propranolol-mediated inhibition of HemSC to endothelial differentiation, we tested in parallel a known SOX18 small-molecule inhibitor (Sm4) and show that this compound inhibited HemSC vessel formation in vivo with efficacy similar to that seen with the R(+) enantiomers. We next examined how R(+) propranolol alters SOX18 transcriptional activity. Using a suite of biochemical, biophysical, and quantitative molecular imaging assays, we show that R(+) propranolol directly interfered with SOX18 target gene trans-activation, disrupted SOX18-chromatin binding dynamics, and reduced SOX18 dimer formation. We propose that the R(+) enantiomers of widely used beta blockers could be repurposed to increase the efficiency of current IH treatment and lower adverse associated side effects.

Infantile hemangioma. Part 2: Management

The majority of infantile hemangiomas (IH) can be managed conservatively, but for those requiring active treatment, management has been revolutionized in the last decade by the discovery of propranolol. Patients that may require active intervention should receive specialist review, ideally before 5 weeks of age to mitigate the risk of sequelae. Propranolol can commence for most infants in the outpatient setting and the most frequently employed dosing regimen is 1 mg/kg twice daily. In the future, β-blockers with a more-selective mechanism of action, such as atenolol, show some promise. In recalcitrant lesions, systemic corticosteroids or sirolimus may be considered. For small, superficial IHs, topical timolol maleate or pulsed dye laser may be considered. Where the IH involutes with cutaneous sequelae, a range of interventions have been reported, including surgery, laser, and embolization. IHs have a well-described clinical trajectory and are readily diagnosed and managed via telemedicine. Algorithms have been constructed to stratify those patients who can be managed remotely from those who warrant in-person review during the COVID-19 pandemic.

Isolated Focal Infantile Hemangioma of the Alveolar Ridge with Glucose Transporter-1 Reactivity: An Aberrant Presentation

Aim and objective

To give dental practitioners an insight into the unusual presentation of focal infantile hemangioma on the alveolar ridge showing immunoreactivity to glucose transporter-1 (GLT1). We also recommend the importance of using standardized terminologies to describe the type of hemangioma.

Background

One of the most commonly seen and misdiagnosed vascular tumors of the skin and soft tissues of the head and neck region in children are infantile hemangiomas. Infantile hemangiomas developing at extracutaneous locations such as the oral cavity are rare, especially without cutaneous involvement.

Case description

A 9-month-old infant girl presented to the Pediatric Dental Department with a swelling over the maxillary alveolar ridge. The solitary exophytic mass appeared after birth and gradually enlarged in size with episodes of bleeding during feeding. Clinical examination revealed a reddish-pink pedunculated mass that bled profusely on palpation. The lesion was excised by electrocautery and was found to be express glucose transporter-1 confirming the diagnosis of infantile hemangioma. The patient was followed up for 1 year and showed no recurrence.

Conclusion

Hemangiomas are usually misinterpreted to be pyogenic granulomas, vascular malformation, reactive granulation tissue, or congenital granular cell tumor. This report highlights the use of glucose transporter-1 when there is suspicion of hemangioma for immunohistochemical distinction from other histologically similar vascular lesions of the oral cavity.

Clinical significance

Dental surgeons treating vascular lesions of the oral cavity should advocate for surgical management techniques that also produce hemostasis due to the risk of intraoperative bleeding.

How to cite this article

Natarajan D, Muthukali S, Nachiappan N, et al. Isolated Focal Infantile Hemangioma of the Alveolar Ridge with Glucose Transporter-1 Reactivity: An Aberrant Presentation. Int J Clin Pediatr Dent 2021;14(2):319–322.

Evaluation of GLUT1, IGF-2, VEGF, FGF 1, and angiopoietin 2 in infantile hemangioma

INTRODUCTION

Infantile hemangioma (IH) is a common vascular tumor in children. It is reported that IHs are associated with immunochemical markers such as vascular endothelial growth factor (VEGF)-A, glucose transporter isoform 1 (GLUT1), and insulin-like growth factor-2 (IGF-2).

MATERIAL AND METHODS

This cross-sectional study focused on pediatric patients with IH. A total of 46 patients (mean age 14.2±21.9 months) with IH and 45 healthy controls (mean age 21.8±15.08 months) were enrolled. Demographic data, clinical findings, and laboratory parameters were recorded. Blood samples were collected. Serum GLUT1, IGF-2, VEGF-A, fibroblast growth factor 1 (FGF1), and angiopoietin 2 levels were assessed by enzyme-linked immunosorbent assay.

RESULTS

Serum GLUT1, IGF-2, and VEGF-A levels were significantly higher in patients with IH than in healthy controls (8.80±4.07pg/mL vs. 5.66±4.34pg/mL, 281.10±84.12pg/mL vs. 234.19±75.38pg/mL, 1196.99±389.34pg/mL vs. 996.99±349.16pg/mL, respectively, p=0.026, p=0.030, and p=0.036). Serum GLUT1, IGF-2, and VEGF-A levels in patients with complicated hemangioma were significantly higher than in healthy controls (9.69±3.94pg/mL vs. 5.66±4.34pg/mL, 289.94±83.18pg/mL vs. 234.19±75.38pg/mL, 1276.22±388.24pg/mL vs. 996.99±349.16pg/mL, respectively, p=0.017, p=0.022, and p=0.011). Serum GLUT1, IGF-2, and VEGF-A levels in patients with hemangioma receiving propranolol treatment were significantly higher than in healthy controls. Serum FGF1 levels were higher in patients with IH, complicated hemangioma, and hemangioma receiving propranolol treatment than in healthy controls but the difference was not statistically significantly.

CONCLUSION

Serum GLUT1, IGF-2, and VEGF-A levels were positively correlated with disease severity in patients with hemangioma, for example, in complicated hemangioma and hemangioma requiring propranolol treatment. However, further research on larger and different age subgroups is warranted to assess these markers.

Exosome-derived miR-196b-5p facilitates intercellular interaction in infantile hemangioma via down-regulating CDKN1B

Background

Though infantile hemangioma (IH) is a common benign vascular tumor, its pathogenesis remains unclear. This study explored the function of hemangioma-derived stem cells (HemSCs) derived exosomes, which exerted an intercellular effect on hemangioma-derived endothelial cells (HemECs).

Methods

First, HemSCs and HemECs were extracted and cultured. HemSCs derived exosomes (HemSCs-exos) were harvested. miRNA sequencing and target prediction were used to explore differentially expressed miRNAs and potential binding targets. After HemECs were co-cultured with HemSCs-exos, a series of in vitro assays were then performed including cell counting kit-8 (CCK-8) assay, cell apoptosis assay, cell cycle assay and tube formation assay to evaluate proliferation, angiogenesis abilities, etc. qRT-PCR and Western blot were conducted to detect the expression level of target genes and proteins.

Results

After co-culturing with HemSCs-exos, proliferation, and angiogenesis abilities of HemECs were enhanced, while apoptosis and cell cycle arrest rate were decreased. MiR-196b-5p was observed to be significantly highly expressed in HemSCs-exos. CDKN1B was identified as the binding target of miR-196b-5p. HemECs' proliferation and angiogenesis abilities were elevated when co-cultured with exosomes from HemSCs transfected with miR-196b-5p mimic. In addition, apoptosis rate declined, and lower cells were arrested in G0/G1 phases. Cyclin E, bcl-2 were significantly highly expressed, whereas p27, Bax expression were significantly down-regulated. The positive effect of miR-196b-5p in HemSCs-exos was dramatically reversed when HemECs were transfected with oe-CDKN1B.

Conclusions

The current study found a novel intercellular interaction between IH cells. Briefly, exosome-derived miRNA-196b-5p in HemSCs could facilitate proliferation and angiogenesis abilities, and attenuate apoptosis and cell cycle repression rate of HemECs by directly binding with CDKN1B.

NOGOB receptor-mediated RAS signaling pathway is a target for suppressing proliferating hemangioma

Infantile hemangioma is a vascular tumor characterized by the rapid growth of disorganized blood vessels followed by slow spontaneous involution. The underlying molecular mechanisms that regulate hemangioma proliferation and involution still are not well elucidated. Our previous studies reported that NOGOB receptor (NGBR), a transmembrane protein, is required for the translocation of prenylated RAS from the cytosol to the plasma membrane and promotes RAS activation. Here, we show that NGBR was highly expressed in the proliferating phase of infantile hemangioma, but its expression decreased in the involuting phase, suggesting that NGBR may have been involved in regulating the growth of proliferating hemangioma. Moreover, we demonstrate that NGBR knockdown in hemangioma stem cells (HemSCs) attenuated growth factor-stimulated RAS activation and diminished the migration and proliferation of HemSCs, which is consistent with the effects of RAS knockdown in HemSCs. In vivo differentiation assay further shows that NGBR knockdown inhibited blood vessel formation and adipocyte differentiation of HemSCs in immunodeficient mice. Our data suggest that NGBR served as a RAS modulator in controlling the growth and differentiation of HemSCs.

The expression and role of glycolysis-associated molecules in infantile hemangioma

AIMS

Infantile hemangioma (IH) is one of the most common tumors in infancy, which etiology and pathogenesis has not been fully elucidated, hypoxia and abnormal glucose metabolism is regarded as critical pathogenic factors. This study investigated the expression and function of glycolysis-associated molecules (GLUT1, HK2, PFKFB3, PKM2, and LDHA) under normoxic and hypoxic conditions to further understand the pathogenesis of IH.

MAIN METHODS

Hemangioma-derived endothelial cells (HemECs) were isolated from proliferating phase infantile hemangiomas and identified by immunofluorescence. HemECs and human umbilical vein endothelial cells (HUVECs) were cultured under normoxic and hypoxic conditions. RNA and protein expression of glycolysis-associated molecules were analyzed by quantitative real-time RT-PCR, western blotting, and immunohistochemistry. Glucose consumption, ATP production and lactate production were measured. Glycolysis-associated molecules were inhibited by WZB117, 3BP, 3PO, SKN, and GSK 2837808A and the resulting effects on HemECs proliferation, migration, and tube formation were quantified.

KEY FINDINGS

Glycolysis-associated molecules were highly expressed at both mRNA and protein levels in HemECs compared with HUVECs (P < 0.05). Glucose consumption and ATP production were higher in HemECs than in HUVECs, while lactate production in HemECs was lower than in HUVECs (P < 0.05). Inhibition of some glycolysis-associated molecules reduced the proliferation, migration, and tube formation capacity of HemECs (P < 0.05).

SIGNIFICANCE

Our study revealed that glycolysis-associated molecules were highly expressed in IH. Glucose metabolismin HemECs differed from normal endothelial cells. Altering the expression of glycolysis-associated molecules may influence the phenotype of HemECs and provide new therapeutic approaches to the successful treatment of IH.

Endothelial-to-mesenchymal transition in anticancer therapy and normal tissue damage

Endothelial-to-mesenchymal transition (EndMT) involves the phenotypic conversion of endothelial-to-mesenchymal cells, and was first discovered in association with embryonic heart development. EndMT can regulate various processes, such as tissue fibrosis and cancer. Recent findings have shown that EndMT is related to resistance to cancer therapy, such as chemotherapy, antiangiogenic therapy, and radiation therapy. Based on the known effects of EndMT on the cardiac toxicity of anticancer therapy and tissue damage of radiation therapy, we propose that EndMT can be targeted as a strategy for overcoming tumor resistance while reducing complications, such as tissue damage. In this review, we discuss EndMT and its roles in damaging cardiac and lung tissues, as well as EndMT-related effects on tumor vasculature and resistance in anticancer therapy. Modulating EndMT in radioresistant tumors and radiation-induced tissue fibrosis can especially increase the efficacy of radiation therapy. In addition, we review the role of hypoxia and reactive oxygen species as the main stimulating factors of tissue damage due to vascular damage and EndMT. We consider drugs that may be clinically useful for regulating EndMT in various diseases. Finally, we argue the importance of EndMT as a therapeutic target in anticancer therapy for reducing tissue damage.

A process of cellular conversion known as endothelial-to-mesenchymal transition (EndMT) may offer a valuable target for treating cancer and other diseases. In EndMT, the cells lining blood vessels undergo a striking change in shape and physiology, acquiring features of cells called fibroblasts. Fibroblasts form the body’s connective tissue, but also produce scar tissue that impairs organ function. Researchers led by Yoon-Jin Lee of the Korea Institute of Radiological & Medical Sciences in Seoul, South Korea, have reviewed the impact of this transformation on human disease. EndMT is seen as a prelude to heart failure, in lung tissue affected by pulmonary fibrosis, and within tumors, where the process recruits cells that further stimulate cancer progression. The authors highlight the potential of using drugs that target EndMT to bolster the efficacy and safety of tumor therapy.

TGF-β-Induced Endothelial to Mesenchymal Transition in Disease and Tissue Engineering

Endothelial to mesenchymal transition (EndMT) is a complex biological process that gives rise to cells with multipotent potential. EndMT is essential for the formation of the cardiovascular system during embryonic development. Emerging results link EndMT to the postnatal onset and progression of fibrotic diseases and cancer. Moreover, recent reports have emphasized the potential for EndMT in tissue engineering and regenerative applications by regulating the differentiation status of cells. Transforming growth factor β (TGF-β) engages in many important physiological processes and is a potent inducer of EndMT. In this review, we first summarize the mechanisms of the TGF-β signaling pathway as it relates to EndMT. Thereafter, we discuss the pivotal role of TGF-β-induced EndMT in the development of cardiovascular diseases, fibrosis, and cancer, as well as the potential application of TGF-β-induced EndMT in tissue engineering.

Proliferating Infantile Hemangioma Tissues and Primary Cell Lines Express Markers Associated with Endothelial-to-Mesenchymal Transition

Supplemental Digital Content is available in the text.

Background:

We have previously shown that the endothelium of the microvessels of infantile hemangioma (IH) exhibits a hemogenic endothelium phenotype and proposed its potential to give rise to mesenchymal stem cells, similar to the development of hematopoietic cells. This endothelial-to-mesenchymal transition (Endo-MT) process involves the acquisition of a migratory phenotype by the endothelial cells, similar to epithelial-to-mesenchymal transition that occurs during neural crest development. We hypothesized that proliferating IH expresses Endo-MT–associated proteins and investigated their expression at the mRNA, protein, and functional levels.

Methods:

Immunohistochemical staining of paraffin-embedded sections of proliferating IH samples from 10 patients was undertaken to investigate the expression of the Endo-MT proteins Twist1, Twist2, Snail1, and Slug. Transcriptional analysis was performed for the same markers on proliferating IH tissues and CD34⁺ and CD34⁻ cells from proliferating IH-derived primary cell lines. Adipogenic and osteogenic differentiation plasticity was determined on the CD34-sorted fractions.

Results:

The endothelium of the microvessels and the cells within the interstitium of proliferating IH tissues expressed Twist1, Twist2, and Slug proteins. Twist1 was also expressed on the pericyte layer of the microvessels, whereas Snail1 was not expressed. Both CD34⁺ and CD34⁻ populations from the IH-derived primary cell lines underwent adipogenic and osteogenic differentiation.

Conclusions:

The expression of Endo-MT–associated proteins Twist1, Twist2, and Slug by both the endothelium of the microvessels and cells within the interstitium, and Twist1 on the pericyte layer of the microvessels of proliferating IH, suggest the presence of a process similar to Endo-MT. This may enable a tightly controlled primitive endothelium of proliferating IH to acquire a migratory mesenchymal phenotype with the ability to migrate away, providing a plausible explanation for the development of a fibrofatty residuum observed during involution of IH.

Dysregulation of the EphrinB2-EphB4 ratio in pediatric cerebral arteriovenous malformations is associated with endothelial cell dysfunction in vitro and functions as a novel noninvasive biomarker in patients

We investigated (1) EphrinB2 and EphB4 receptor expression in cerebral AVMs, (2) the impact of an altered EphrinB2:EphB4 ratio on brain endothelial cell function and (3) potential translational applications of these data. The following parameters were compared between AVM endothelial cells (AVMECs) and human brain microvascular endothelial cells (HBMVECs): quantified EphrinB2 and EphB4 expression, angiogenic potential, and responses to manipulation of the EphrinB2:EphB4 ratio via pharmacologic stimulation/inhibition. To investigate the clinical relevance of these in vitro data, Ephrin expression was assessed in AVM tissue (by immunohistochemistry) and urine (by ELISA) from pediatric patients with AVM (n = 30), other cerebrovascular disease (n = 14) and control patients (n = 29), and the data were subjected to univariate and multivariate statistical analyses. Compared to HBMVECs, AVMECs demonstrated increased invasion (p = 0.04) and migration (p = 0.08), impaired tube formation (p = 0.06) and increased EphrinB2:EphB4 ratios. Altering the EphrinB2:EphB4 ratio (by increasing EphrinB2 or blocking EphB4) in HBMVECs increased invasion (p = 0.03 and p < 0.05, respectively). EphrinB2 expression was increased in AVM tissue, which correlated with increased urinary EphrinB2 levels in AVM patients. Using the optimal urinary cutoff value (EphrinB2 > 25.7 pg/μg), AVMs were detected with high accuracy (80% vs. controls) and were distinguished from other cerebrovascular disease (75% accuracy). Post-treatment urinary EphrinB2 levels normalized in an index patient. In summary, AVMECs have an EphrinB2:EphB4 ratio that is increased compared to that of normal HBMVECs. Changing this ratio in HBMVECs induces AVMEC-like behavior. EphrinB2 is clinically relevant, and its levels are increased in AVM tissue and patient urine. This work suggests that dysregulation of the EphrinB2:EphB4 signaling cascade and increases in EphrinB2 may play a role in AVM development, with potential utility as a diagnostic and therapeutic target.

Tangled blood vessel growths in the brain, known as arteriovenous malformations (AVMs), can be identified with a urine test, and the test protein may also help in treatment. AVMs often have no symptoms and can go undiagnosed, but when they rupture they can cause deadly brain hemorrhage. Better diagnostic tools and nonsurgical treatments are needed. Katie Fehnel and Edward Smith at Boston Children’s Hospital, USA, and co-workers identified an imbalance in a pair of signal/receptor proteins called ephrins in AVMs. Disturbing the balance of ephrin levels in blood vessel-forming cells disrupted growth, causing disorganized vessel formation with too many sprouts and insufficient junctions. Testing ephrin levels in patients’ urine reliably identified AVMs. These results offer a rapid and noninvasive new diagnostic tool and may help find new treatments for this mostly invisible and potentially fatal condition.

Isolation of Stem Cells, Endothelial Cells and Pericytes from Human Infantile Hemangioma

Infantile hemangioma (IH) is a vascular tumor noted for its excessive blood vessel formation during infancy, glucose-transporter-1 (GLUT1)-positive staining of the blood vessels, and its slow spontaneous involution over several years in early childhood. For most children, IH poses no serious threat because it will eventually involute, but a subset can destroy facial structures and impair vision, breathing and feeding. To unravel the molecular mechanism(s) driving IH-specific vascular overgrowth, which to date remains elusive, investigators have studied IH histopathology, the cellular constituents and mRNA expression. Hemangioma endothelial cells (HemEC) were first isolated from surgically removed IH specimens in 1982 by Mulliken and colleagues ( Mulliken et al., 1982 ). Hemangioma stem cells (HemSC) were isolated in 2008, hemangioma pericytes in 2013 and GLUT1-positive HemEC in 2015. Indeed, as we describe here, it is possible to isolate HemSC, GLUT1-positive HemEC, GLUT1-negative HemEC and HemPericytes from a single proliferating IH tissue specimen. This is accomplished by sequential selection using antibodies against specific cell surface markers: anti-CD133 to select HemSC, anti-GLUT1 and anti-CD31 to select HemECs and anti-PDGFRβ to select HemPericytes. IH-derived cells proliferate well in culture and can be used for in vitro and in vivo vasculogenesis and angiogenesis assays.

Expression of (pro)renin receptor and its effect on endothelial cell proliferation in infantile hemangioma

BACKGROUND

Propranolol is the preferred treatment for problematic proliferating infantile hemangioma (IH) by targeting the renin-angiotensin system (RAS) expressed by IH endothelium. (Pro)renin receptor (PRR) is a major component of the RAS associated with the canonical wnt signaling pathway. We proposed that activation of PRR by renin causes proliferation of IH.

METHODS

The expression of PRR in IH tissue samples was investigated using immunohistochemical (IHC) staining and NanoString analysis. NanoString analysis was also used to confirm transcriptional expression of PRR in CD34-sorted proliferating IH-derived primary cell lines. MTT assay was utilized to determine the effect of exogenous renin on the number of viable IH cells. RT-qPCR was used to determine the effect of renin on the stem cell gene expression.

RESULTS

NanoString analysis and IHC staining confirmed transcriptional and translational expression of PRR, which was localized to the non-endothelial and the endothelial IH cell populations. MTT assay demonstrated an increased number of viable IH cells by administration of renin and the effect was negated by the wnt receptor blocker dickkopf-1.

CONCLUSION

Our results present a model for renin-induced increased proliferation of IH cells through PRR acting via the wnt signaling pathway, which may account for accumulation of cells in IH during the proliferative phase of the tumor.

Divergent roles of Plexin D1 in cancer

Plexin D1 belongs to a family of transmembrane proteins called plexins. It was characterized as a receptor for semaphorins and is known to be essential for axonal guidance and vascular patterning. Mutations in Plexin D1 have been implicated in pathologic conditions such as truncus arteriosus and Möbius syndrome. Emerging data show that expression of Plexin D1 is deregulated in several cancers; it can support tumor development by aiding in tumor metastasis and EMT; and conversely, it can act as a dependence receptor and stimulate cell death in the absence of its canonical ligand, semaphorin 3E. The role of Plexin D1 in tumor development and progression is thereby garnering research interest for its potential as a biomarker and as a therapeutic target. In this review, we describe its discovery, structure, mutations, role(s) in cancer, and therapeutic potential.

Genetic investigation of childhood vascular tumor biology reveals pathways for therapeutic intervention

Vascular tumors are neoplasms of endothelial cells, a significant number of which present in childhood. Recent studies have examined the mutational landscape of many subtypes of vascular tumors, identifying mutations primarily within the Ras–mitogen-activated protein kinase (MAPK) pathway and providing a unique opportunity to consider targeted therapeutics. This review will summarize the current understanding of childhood vascular tumor pathobiology.

Propranolol for the treatment of vascular sarcomas

Vascular sarcomas are abnormal proliferations of endothelial cells. They range from benign hemangioma to aggressive angiosarcoma, and are characterized by dysregulated angiogenic signaling. Propranolol is a β-adrenergic receptor inhibitor that has demonstrated clinical efficacy in benign infantile hemangioma, and is now being used experimentally for more aggressive vascular sarcomas and other cancers. In this review, we discuss the use of propranolol in targeting these receptors in vascular tumors and other cancers.

The therapeutic potential of targeting the endothelial-to-mesenchymal transition

Endothelial cells (ECs) have been found to be capable of acquiring a mesenchymal phenotype through a process known as endothelial-to-mesenchymal transition (EndMT). First seen in the developing embryo, EndMT can be triggered postnatally under certain pathological conditions. During this process, ECs dedifferentiate into mesenchymal stem-like cells (MSCs) and subsequently give rise to cell types belonging to the mesoderm lineage. As EndMT contributes to a multitude of diseases, pharmacological modulation of the signaling pathways underlying EndMT may prove to be effective as a therapeutic treatment. Additionally, EndMT in ECs could also be exploited to acquire multipotent MSCs, which can be readily re-differentiated into various distinct cell types. In this review, we will consider current models of EndMT, how manipulation of this process might improve treatment of clinically important pathologies and how it could be harnessed to advance regenerative medicine and tissue engineering.

Infantile Hemangioma Presenting as Colocolic Intussusception in an Infant Case Report with Review of Pathologic Lead Points

Infantile hemangioma (IH) is one of the most common vascular anomalies of early childhood and is usually recognized in the first few weeks to months of life as a solitary cutaneous lesion. This report documents our experience with a GLUT-1 positive IH presenting as the pathologic lead point in a colocolic intussusception in a 10-week-old infant who had no skin lesions. Literature suggests approximately 2% of all children presenting with an intussusception require surgical intervention; however, an IH as the pathologic lead point is unique.

Modulation of LIN28B/Let-7 Signaling by Propranolol Contributes to Infantile Hemangioma Involution

OBJECTIVE

Infantile hemangiomas (IHs) are the most common benign vascular neoplasms of infancy, characterized by a rapid growth phase followed by a spontaneous involution, or triggered by propranolol treatment by poorly understood mechanisms. LIN28/let-7 axis plays a central role in the regulation of stem cell self-renewal and tumorigenesis. However, the role of LIN28B/let-7 signaling in IH pathogenesis has not yet been elucidated.

APPROACH AND RESULTS

LIN28B is highly expressed in proliferative IH and is less expressed in involuted and in propranolol-treated IH samples as measured by immunofluorescence staining and quantitative RT-PCR. Small RNA sequencing analysis of IH samples revealed a decrease in microRNAs that target LIN28B, including let-7, and an increase in microRNAs in the mir-498(46) cistron. Overexpression of LIN28B in HEK293 cells induced the expression of miR-516b in the mir-498(46) cistron. Propranolol treatment of induced pluripotent stem cells, which express mir-498(46) endogenously, reduced the expression of both LIN28B and mir-498(46) and increased the expression of let-7. Furthermore, propranolol treatment reduced the proliferation of induced pluripotent stem cells and induced epithelial-mesenchymal transition.

CONCLUSIONS

This work uncovers the role of the LIN28B/let-7 switch in IH pathogenesis and provides a novel mechanism by which propranolol induces IH involution. Furthermore, it provides therapeutic implications for cancers in which the LIN28/let-7 pathway is imbalanced.

Phosphorylated Forms of STAT1, STAT3 and STAT5 Are Expressed in Proliferating but Not Involuted Infantile Hemangioma

We have recently demonstrated the expression of embryonic stem cell markers on the endothelium of infantile hemangioma, a functional hemogenic endothelium with the capacity for primitive erythropoiesis in vitro. Despite recent work characterizing stem cells within proliferating infantile hemangioma, the expression of STAT proteins, well documented for their roles in stem cell signaling, has not been investigated. 3,3-Diaminobenzidine and immunofluorescence immunohistochemical staining revealed expression of pSTAT1, pSTAT3 and pSTAT5 in proliferating infantile hemangioma samples with the strongest expression of pSTAT3. There was reduced expression of these pSTAT proteins in the involuted infantile hemangioma samples. Western blotting confirmed the identification of all these three proteins in proliferating infantile hemangioma. It is therefore not surprising that the phosphorylated/activated forms of these proteins are relatively abundantly expressed in proliferating, in comparison to involuted infantile hemangioma samples. We speculate that the reduced STAT activation, as infantile hemangioma involutes, is a reflection of the depletion of the abundant stem cells within proliferating infantile hemangioma, as the lesion involutes.

NOTCH3 regulates stem-to-mural cell differentiation in infantile hemangioma

Infantile hemangioma (IH) is a vascular tumor that begins with rapid vascular proliferation shortly after birth, followed by vascular involution in early childhood. We have found that NOTCH3, a critical regulator of mural cell differentiation and maturation, is expressed in hemangioma stem cells (HemSCs), suggesting that NOTCH3 may function in HemSC-to-mural cell differentiation and pathological vessel stabilization. Here, we demonstrate that NOTCH3 is expressed in NG2+PDGFRβ+ perivascular HemSCs and CD31+GLUT1+ hemangioma endothelial cells (HemECs) in proliferating IHs and becomes mostly restricted to the αSMA+NG2loPDGFRβlo mural cells in involuting IHs. NOTCH3 knockdown in HemSCs inhibited in vitro mural cell differentiation and perturbed αSMA expression. In a mouse model of IH, NOTCH3 knockdown or systemic expression of the NOTCH3 inhibitor, NOTCH3 Decoy, significantly decreased IH blood flow, vessel caliber, and αSMA+ perivascular cell coverage. Thus, NOTCH3 is necessary for HemSC-to-mural cell differentiation, and adequate perivascular cell coverage of IH vessels is required for IH vessel stability.

Somatic PIK3CA mutations are present in multiple tissues of facial infiltrating lipomatosis

BackgroundFacial infiltrating lipomatosis (FIL) is a congenital disorder that causes overgrowth of one side of the face. The purpose of this study was to determine whether PIK3CA mutations are present in tissues outside of the subcutaneous adipose.MethodsFIL tissues from three patients were dissected to enrich for cells from skin, subcutaneous tissue, orbicularis oris muscle, buccal fat, zygomatic bone, and mucosal neuroma. Endothelial cells within the affected tissue also were enriched using CD31 microbeads. Laser capture microdissection on formalin-fixed paraffin-embedded histologic sections was performed to collect specific cell types. DNA was extracted from each tissue and cell type, and measured for the abundance of mutant PIK3CA alleles using droplet digital PCR.ResultsWe detected mutant PIK3CA alleles in every tissue and cell type tested from each overgrown face; frequencies ranged from 1.5 to 53%. There were fewer mutant endothelial cells compared with nonendothelial cells, and the stromal cell compartment had the highest frequency of mutant cells in each tissue.ConclusionsPIK3CA mutations are not restricted to a single tissue or cell type in FIL. Overgrowth in this condition is likely due to the mutation arising in a cell that contributes to several different facial structures during embryogenesis.

Study protocol: safety and efficacy of propranolol 0.2% eye drops in newborns with a precocious stage of retinopathy of prematurity (DROP-ROP-0.2%): a multicenter, open-label, single arm, phase II trial

BACKGROUND

Retinopathy of prematurity (ROP) still represents one of the leading causes of visual impairment in childhood. Systemic propranolol has proven to be effective in reducing ROP progression in preterm newborns, although safety was not sufficiently guaranteed. On the contrary, topical treatment with propranolol eye micro-drops at a concentration of 0.1% had an optimal safety profile in preterm newborns with ROP, but was not sufficiently effective in reducing the disease progression if administered at an advanced stage (during stage 2). The aim of the present protocol is to evaluate the safety and efficacy of propranolol 0.2% eye micro-drops in preterm newborns at a more precocious stage of ROP (stage 1).

METHODS

A multicenter, open-label, phase II, clinical trial, planned according to the Simon optimal two-stage design, will be performed to analyze the safety and efficacy of propranolol 0.2% eye micro-drops in preterm newborns with stage 1 ROP. Preterm newborns with a gestational age of 23-32 weeks, with a stage 1 ROP will receive propranolol 0.2% eye micro-drops treatment until retinal vascularization has been completed, but for no longer than 90 days. Hemodynamic and respiratory parameters will be continuously monitored. Blood samplings checking metabolic, renal and liver functions, as well as electrocardiogram and echocardiogram, will be periodically performed to investigate treatment safety. Additionally, propranolol plasma levels will be measured at the steady state, on the 10th day of treatment. To assess the efficacy of topical treatment, the ROP progression from stage 1 ROP to stage 2 or 3 with plus will be evaluated by serial ophthalmologic examinations.

DISCUSSION

Propranolol eye micro-drops could represent an ideal strategy in counteracting ROP, because it is definitely safer than oral administration, inexpensive and an easily affordable treatment. Establishing the optimal dosage and treatment schedule is to date a crucial issue.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT02504944, registered on July 19, 2015, updated July 12, 2016. EudraCT Number 2014-005472-29.

Sirolimus for the treatment of progressive kaposiform hemangioendothelioma: A multicenter retrospective study

Kaposiform hemangioendothelioma (KHE) is an aggressive disease with high morbidity and mortality. The aim of this study was to retrospectively evaluate the efficacy and safety of sirolimus for the treatment of progressive KHE. A multicenter, retrospective cohort study was conducted in patients with progressive KHE treated with sirolimus. A total of 52 patients were analyzed. Thirty-seven (71%) patients exhibited Kasabach-Merritt phenomenon (KMP) and were significantly younger than the patients without KMP [95% confidence interval (CI), 14.39-41.61; p < 0.001]. Patients without KMP were all treated with sirolimus alone, whereas 21 KMP patients with severe symptoms received short-term combination therapy with prednisolone. Overall, 96% and 98% of patients showed improved relief of notable symptoms and/or improved complications at 6 and 12 months after treatment, respectively. After sirolimus treatment, significant decreases in mean severity scores occurred at 6 months (95% CI, 2.23-2.54, p < 0.001) and 12 months (95% CI, 1.53-1.90, p < 0.001). Compared to KMP patients, patients without KMP showed a response that was similar to but less pronounced during the 12 months of treatment (95% CI, 40.87-53.80; p < 0.001). For subgroup analysis of KMP patients, there were no significant differences in tumor shrinkage between those treated with combination therapy and those receiving sirolimus alone (95% CI, 18.11-25.02; p > 0.05). No patients permanently discontinued treatment due to toxicity-related events, and no drug-related deaths occurred. Sirolimus was effective and safe for the treatment of progressive KHE. Sirolimus may be considered as a first-line therapy or as part of a multidisciplinary approach for the treatment of KHE.

Somatic GNAQ Mutation is Enriched in Brain Endothelial Cells in Sturge-Weber Syndrome

BACKGROUND

Sturge-Weber syndrome (SWS) is a rare congenital neurocutaneous disorder characterized by facial and extracraniofacial capillary malformations and capillary-venule malformations in the leptomeninges. A somatic mosaic mutation in GNAQ (c.548G>A; p.R183Q) was found in SWS brain and skin capillary malformations. Our laboratory showed endothelial cells in skin capillary malformations are enriched for the GNAQ mutation. The purpose of this study is to determine whether the GNAQ mutation is also enriched in endothelial cells in affected SWS brain.

METHODS

Two human SWS brain specimens were fractionated by fluorescence-activated cell sorting into hematopoietic (CD45), endothelial (CD31, VE-Cadherin, and vascular endothelial growth factor receptor 2), and perivascular (platelet-derived growth factor receptor beta) cells and cells negative for all markers. The sorted cell populations were analyzed for GNAQ p.R183Q mutation by droplet digital polymerase chain reaction. SWS patient-derived brain endothelial cells were selected by anti-CD31-coated magnetic beads and cultured in endothelial growth medium in vitro.

RESULTS

The GNAQ p.R183Q mutation was present in brain endothelial cells in two SWS specimens, with mutant allelic frequencies of 34.7% and 24.0%. Cells negative for all markers also harbored the GNAQ mutation. The mutant allelic frequencies in these unidentified cells were 9.2% and 8.4%. SWS patient-derived brain endothelial cells with mutant allelic frequencies of 14.7% and 21% survived and proliferated in vitro.

CONCLUSIONS

Our study provides evidence that GNAQ p.R183Q mutation is enriched in endothelial cells in SWS brain lesions and thereby reveals endothelial cells as a source of aberrant Gαq signaling. This will help to understand the pathophysiology of SWS, to discover biomarkers for predicting cerebral involvement, and to develop therapeutic targets to prevent neurological impairments in SWS.

Rapamycin inhibits the proliferation of endothelial cells in hemangioma by blocking the mTOR-FABP4 pathway

FABP4 is widely expressed in both normal and pathologic tissues. It promotes cell proliferation, survival and migration of endothelial cells, and therefore, angiogenesis. However, the role of FABP4 in hemangioma or hemangioma endothelial cells (HemECs) has not been explored. In this study, we investigated whether FABP4 directly regulates the proliferation of HemECs. The expression of cell cycle checkpoint genes was analyzed with the microarray data of human dermal microvascular endothelial cells (HDVECs) and infantile hemangioma endothelial cells. Real-time RT-PCR and western blotting were used to examine the expression of FABP4 in HemECs. Next, the FABP4 expression was inhibited in HemECs using siRNA or rapamycin and upregulated using retroviral transduction of HemECs to assess its influence on proliferation of HemECs. The microarray data showed that cell cycle checkpoint genes were upregulated in HemECs. Moreover, HemECs showed significantly higher proliferation rates than HDVECs. The expression of FABP4 and mTOR was increased in the HemECs. While FABP4 knockdown reduced the BrdU incorporation and cell number of HemECs as expected, cell proliferation was accelerated by FABP4 over-expression. Moreover, rapamycin (10nM) inhibited mTOR-FABP4 signaling and HemEC proliferation. Taken together, these results indicated that mTOR signaling pathway-activated FABP4 directly regulates the proliferation of endothelial cells in hemangioma. Rapamycin and inhibitors of FABP4 have therapeutic potential for treating infantile hemangiomas.

Long noncoding RNA expression profile of infantile hemangioma identified by microarray analysis

Infantile hemangioma (IH) is one of the most common vascular tumors of childhood. Long noncoding RNAs (lncRNAs) play a critical role in angiogenesis, but their involvement in hemangioma remains unknown. This study aimed to assess the expression profiles of lncRNAs in IH and adjacent normal tissue samples, exploring the biological functions of lncRNAs as well as their involvement in IH pathogenesis. The lncRNA expression profiles were determined by lncRNA microarrays. A total of 1259 and 857 lncRNAs were upregulated and downregulated in IH, respectively, at a fold change cutoff of 2.0 (p < 0.05); in addition, 1469 and 1184 messenger RNAs (mRNAs) were upregulated and downregulated, respectively (fold change cutoff of 2.0; p < 0.05). A total of 292 differentially expressed mRNAs were targeted by the lncRNAs with altered expression in hemangioma, including 228 and 64 upregulated and downregulated, respectively (cutoff of 2.0, p < 0.05). Gene ontology (GO) analyses revealed several angiogenesis-related pathways. An lncRNA-mRNA co-expression network for differentially expressed lncRNAs revealed significant associations of the lncRNAs MEG3, MEG8, FENDRR, and Linc00152 with their related mRNAs. The validation results of nine differentially expressed lncRNAs (MALAT1, MEG3, MEG8, p29066, p33867, FENDRR, Linc00152, p44557_v4, p8683) as well as two mRNAs (FOXF1, EGFL7) indicated that the microarray data correlated well with the QPCR results. Interestingly, MALAT1 knockdown induced apoptosis and S-phase cell cycle arrest in human umbilical vein endothelial cells (HUVECs). Overall, this study revealed the lncRNA expression profile of IH and that lncRNAs likely regulate several genes with important roles in angiogenesis.