Pathogenesis of infantile haemangioma

KRIT1 in vascular biology and beyond

KRIT1 is a 75 kDa scaffolding protein which regulates endothelial cell phenotype by limiting the response to inflammatory stimuli and maintaining a quiescent and stable endothelial barrier. Loss-of-function mutations in KRIT1 lead to the development of cerebral cavernous malformations (CCM), a disease marked by the formation of abnormal blood vessels which exhibit a loss of barrier function, increased endothelial proliferation, and altered gene expression. While many advances have been made in our understanding of how KRIT1, and the functionally related proteins CCM2 and PDCD10, contribute to the regulation of blood vessels and the vascular barrier, some important open questions remain. In addition, KRIT1 is widely expressed and KRIT1 and the other CCM proteins have been shown to play important roles in non-endothelial cell types and tissues, which may or may not be related to their role as pathogenic originators of CCM. In this review, we discuss some of the unsettled questions regarding the role of KRIT1 in vascular physiology and discuss recent advances that suggest this ubiquitously expressed protein may have a role beyond the endothelial cell.

Congenital Vascular and Lymphatic Diseases

Over the past several centuries, the integration of contemporary medical techniques and innovative technologies, like genetic sequencing, have played a pivotal role in enhancing our comprehension of congenital vascular and lymphatic disorders. Nonetheless, the uncommon and complex characteristics of these disorders, especially considering their formation during the intrauterine stage, present significant obstacles in diagnosis and treatment. Here, we review the intricacies of these congenital abnormalities, offering an in-depth examination of key diagnostic approaches, genetic factors, and therapeutic methods.

A Review of the Current State and Future Directions for Management of Scalp and Facial Vascular Malformations

Vascular malformations are structural abnormalities that are thought to result from errors in vasculogenesis and angiogenesis during embryogenesis. Vascular malformations of the scalp present unique management challenges due to aesthetic and functional implications. This review examines the pathophysiology, clinical presentation, and management techniques for six common types of vascular malformations of the face and scalp : infantile hemangioma, capillary malformations, venous malformations, lymphatic malformations, arteriovenous malformations, and arteriovenous fistulas. These lesions range from common to rare, and have very different natural histories and management paradigms. There has been increasing understanding of the molecular pathways that are altered in association with these vascular lesions and these molecular targets may represent novel strategies of treating lesions that have historically been approached from a structural perspective only.

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.

Defining the Functional Influence of Endothelial Cell-Expressed Oncogenic Activating Mutations on Vascular Morphogenesis and Capillary Assembly

This study sought to define key molecules and signals controlling major steps in vascular morphogenesis, and how these signals regulate pericyte recruitment and pericyte-induced basement membrane deposition. The morphogenic impact of endothelial cell (EC) expression of activating mutants of Kirsten rat sarcoma virus (kRas), mitogen-activated protein kinase 1 (Mek1), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), Akt serine/threonine kinase 1 (Akt1), Ras homolog enriched in brain (Rheb) Janus kinase 2 (Jak2), or signal transducer and activator of transcription 3 (Stat3) expression versus controls was evaluated, along with EC signaling events, pharmacologic inhibitor assays, and siRNA suppression experiments. Primary stimulators of EC lumen formation included kRas, Akt1, and Mek1, whereas PIK3CA and Akt1 stimulated a specialized type of cystic lumen formation. In contrast, the key drivers of EC sprouting behavior were Jak2, Stat3, Mek1, PIK3CA, and mammalian target of rapamycin (mTor). These conclusions are further supported by pharmacologic inhibitor and siRNA suppression experiments. EC expression of active Akt1, kRas, and PIK3CA led to markedly dysregulated lumen formation coupled to strongly inhibited pericyte recruitment and basement membrane deposition. For example, activated Akt1 expression in ECs excessively stimulated lumen formation, decreased EC sprouting behavior, and showed minimal pericyte recruitment with reduced mRNA expression of platelet-derived growth factor-BB, platelet-derived growth factor-DD, and endothelin-1, critical EC-derived factors known to stimulate pericyte invasion. The study identified key signals controlling fundamental steps in capillary morphogenesis and maturation and provided mechanistic details on why EC activating mutations induced a capillary deficiency state with abnormal lumens, impaired pericyte recruitment, and basement deposition: predisposing stimuli for the development of vascular malformations.

Evaluation of adipogenesis over time using a novel bioabsorbable implant without the addition of exogenous cells or growth factors

Background

Breast reconstruction is crucial for patients who have undergone mastectomy for breast cancer. Our bioabsorbable implants comprising an outer poly-l-lactic acid mesh and an inner component filled with collagen sponge promote and retain adipogenesis in vivo without the addition of exogenous cells or growth factors. In this study, we evaluated adipogenesis over time histologically and at the gene expression level using this implant in a rodent model.

Methods

The implants were inserted in the inguinal and dorsal regions of the animals. At 1, 3, 6, and 12 months post-operation, the weight, volume, and histological assessment of all newly formed tissue were performed. We analyzed the formation of new adipose tissue using multiphoton microscopy and RNA sequencing.

Results

Both in the inguinal and dorsal regions, adipose tissue began to form 1 month post-operation in the peripheral area. Angiogenesis into implants was observed until 3 months. At 6 months, microvessels matured and the amount of newly generated adipose tissue peaked and was uniformly distributed inside implants. The amount of newly generated adipose tissue decreased from 6 to 12 months but at 12 months, adipose tissue was equivalent to the native tissue histologically and in terms of gene expression.

Conclusions

Our bioabsorbable implants could induce normal adipogenesis into the implants after subcutaneous implantation. Our implants can serve as a novel and safe material for breast reconstruction without requiring exogenous cells or growth factors.

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.

Circulating Mesenchymal Stromal Cells in Patients with Infantile Hemangioma: Evaluation of Their Functional Capacity and Gene Expression Profile

We previously published that in patients with infantile hemangioma (IH) at the onset (T0) colony forming unit-fibroblasts (CFU-Fs) are present in in vitro cultures from PB. Herein, we characterize these CFU-Fs and investigate their potential role in IH pathogenesis, before and after propranolol therapy. The CFU-F phenotype (by flow cytometry), their differentiation capacity and ability to support angiogenesis (by in vitro cultures) and their gene expression (by RT-PCR) were evaluated. We found that CFU-Fs are actual circulating MSCs (cMSCs). In patients at T0, cMSCs had reduced adipogenic potential, supported the formation of tube-like structures in vitro and showed either inflammatory (IL1β and ESM1) or angiogenic (F3) gene expression higher than that of cMSCs from CTRLs. In patients receiving one-year propranolol therapy, the cMSC differentiation in adipocytes improved, while their support in in vitro tube-like formation was lost; no difference was found between patient and CTRL cMSC gene expressions. In conclusion, in patients with IH at T0 the cMSC reduced adipogenic potential, their support in angiogenic activity and the inflammatory/angiogenic gene expression may fuel the tumor growth. One-year propranolol therapy modifies this picture, suggesting cMSCs as one of the drug targets.

Effects of propranolol on glucose metabolism in hemangioma-derived endothelial cells

Infantile hemangioma (IH) is the most common benign tumor in children. Propranolol is the first-line treatment for IH, but the underlying mechanism of propranolol treatment in IH is not completely understood. Integrated transcriptional and metabolic analyses were performed to investigate the metabolic changes in hemangioma-derived endothelial cells (HemECs) after propranolol treatment. The findings were then further validated through independent cell experiments using a Seahorse XFp analyzer, Western blotting, immunohistochemistry and mitochondrial functional assays. Thirty-four differentially expressed metabolites, including the glycolysis metabolites glucose 6-phosphate, fructose 6-phosphate and fructose 1,6-bisphosphate, were identified by targeted metabolomics. A KEGG pathway enrichment analysis showed that the disturbances in these metabolites were highly related to glucose metabolism-related pathways, including the pentose phosphate pathway, the Warburg effect, glycolysis and the citric acid cycle. Transcriptional analysis revealed that metabolism-related pathways, including glycine, serine and threonine metabolism, tyrosine metabolism, and glutathione metabolism, were highly enriched. Moreover, integration of the metabolomic and transcriptomic data revealed that glucose metabolism-related pathways, particularly glycolysis, were altered after propranolol treatment. Cell experiments demonstrated that HemECs exhibited higher levels of glycolysis than human umbilical vein ECs (HUVECs) and that propranolol suppressed glycolysis in HemECs. In conclusion, propranolol inhibited glucose metabolism in HemECs by suppressing glucose metabolic pathways, particularly glycolysis.

A case report and literature review on reactive cutaneous capillary endothelial proliferation induced by camrelizumab in a nasopharyngeal carcinoma patient

Camrelizumab, a monoclonal antibody, blocks programmed cell death protein-1 from binding to T cells and programmed cell death ligand 1 on tumor cells, thereby ensuring sustained T cell activation and blocking immune escape of various types of cancer, including nasopharyngeal carcinoma. Reactive cutaneous capillary endothelial hyperplasia (RCCEP) is the most common immune-related adverse event in patients treated with camrelizumab. We report a case nasopharyngeal carcinoma in a patient with camrelizumab-induced RCCEP. A 68-year-old man diagnosed with nasopharyngeal carcinoma developed RCCEP at multiple locations after 3 months of camrelizumab treatment. RCCEP of the right lower eyelid affected closure of the right eye. In this report, we also reviewed previous literature on camrelizumab-induced RCCEP. In summary, the mechanism underlying camrelizumab-induced RCCEP remains unclear. RCCEP typically gradually subsides after discontinuing camrelizumab treatment. Larger nodules can be treated with lasers, ligation, or surgery. Although surgical excision is effective, RCCEP may recur in patients undergoing camrelizumab treatment. RCCEP management may not be required in the absence of adverse effects on the patient's daily life.

Infantile Hemangioma: A Cross-Sectional Observational Study

(1) Background: With an incidence of 4-10%, infantile hemangiomas (IH) are the most encountered benign tumors in infancy. Low birth weight (LBW), prematurity, female sex, multiple gestations, and family history of IH are some of the statistically proven risk factors for developing IH. The aim of our study was to evaluate the prevalence of IH in our clinic and its connection to maternal and perinatal factors. (2) Methods: We conducted a cross-sectional study, over three years (2020-2022), at the Clinical Hospital of Obstetrics and Gynecology, "Prof. Dr. P. Sârbu", in Bucharest, Romania. (3) Results: During this period, 12,206 newborns were born and we identified 14 infants with infantile hemangioma. In our study, the prevalence of infantile hemangioma was 0.11%. The prevalence of IH in pregnancies obtained through in vitro fertilization was 1%, in twin pregnancies it was 2.27%, and in those with placenta previa, it was 4.16%. (4) Conclusions: Our findings provide a solid image of the prevalence of IH in our country and underline that the development of IH is strongly connected to maternal and perinatal variables, such as: preterm newborns, in vitro fertilization, high blood pressure, anemia, hypothyroidism, placenta previa, and twin pregnancy.

The effects of propranolol on the biology and Notch signaling pathway of human umbilical vein endothelial cells

BACKGROUND

Propranolol is the first choice for treating infantile hemangioma (IH). How propranolol works in IH remains unclear. Infantile hemangioma endothelial cells (HemECs) express Notch1, Jagged, Hey1, and other molecules in the Notch pathway, suggesting that Notch pathway-related molecules play an important role in affecting vascular endothelial cell proliferation. Whether propranolol can affect the Notch signaling pathway in IH treatment is unclear.

METHODS

We performed this study to observe the effect of propranolol on the expression of Notch signaling pathway molecules in human umbilical vein endothelial cells (HUVECs) and to explore the therapeutic mechanism of propranolol on IH. HUVECs cultured in vitro were exposed to 60, 120, 240, 360, or 480 µM propranolol. The morphological changes of the HUVECs were observed under an inverted microscope. HUVECs proliferation was detected with Cell Counting Kit-8 (CCK-8). The effects of propranolol on HUVECs apoptosis were detected by flow cytometry. The role of Notch in propranolol inhibition of HUVEC proliferation was analyzed with real-time polymerase chain reaction (PCR) and western blotting.

RESULTS

Propranolol reduced HUVECs numbers and altered their morphology. The inhibitory effect of propranolol on cell proliferation was dependent on the reaction time and drug concentration. Propranolol upregulated Jagged1, Notch1, and Hey1 expression and downregulated delta-like ligand4 (DLL4) expression.

CONCLUSIONS

Propranolol may play a role in IH treatment by increasing Jagged1 expression in endothelial cells, activating the Notch pathway and inducing the upregulation of the downstream target gene HEY1.

Pathological angiogenesis: mechanisms and therapeutic strategies

In multicellular organisms, angiogenesis, the formation of new blood vessels from pre-existing ones, is an essential process for growth and development. Different mechanisms such as vasculogenesis, sprouting, intussusceptive, and coalescent angiogenesis, as well as vessel co-option, vasculogenic mimicry and lymphangiogenesis, underlie the formation of new vasculature. In many pathological conditions, such as cancer, atherosclerosis, arthritis, psoriasis, endometriosis, obesity and SARS-CoV-2(COVID-19), developmental angiogenic processes are recapitulated, but are often done so without the normal feedback mechanisms that regulate the ordinary spatial and temporal patterns of blood vessel formation. Thus, pathological angiogenesis presents new challenges yet new opportunities for the design of vascular-directed therapies. Here, we provide an overview of recent insights into blood vessel development and highlight novel therapeutic strategies that promote or inhibit the process of angiogenesis to stabilize, reverse, or even halt disease progression. In our review, we will also explore several additional aspects (the angiogenic switch, hypoxia, angiocrine signals, endothelial plasticity, vessel normalization, and endothelial cell anergy) that operate in parallel to canonical angiogenesis mechanisms and speculate how these processes may also be targeted with anti-angiogenic or vascular-directed therapies.

Blockage of glycolysis by targeting PFKFB3 suppresses the development of infantile hemangioma

BACKGROUND

Infantile hemangioma (IH) is the most common tumor among infants, but the exact pathogenesis of IH is largely unknown. Our previous study revealed that glucose metabolism may play an important role in the pathogenesis of IH and that the inhibition of the glycolytic key enzyme phosphofructokinase-1 suppresses angiogenesis in IH. 6-Phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) is a metabolic enzyme that converts fructose-6-bisphosphate to fructose-2,6-bisphosphate (F-2,6-BP), which is the most potent allosteric activator of the rate-limiting enzyme phosphofructokinase-1. This study was performed to explore the role of PFKFB3 in IH.

METHODS

Microarray analysis was performed to screen the differentially expressed genes (DEGs) between proliferating and involuting IH tissues. PFKFB3 expression was examined by western blot and immunohistochemistry analyses. Cell migration, apoptosis and tube formation were analyzed. Metabolic analyses were performed to investigate the effect of PFKFB3 inhibition by PFK15. Mouse models were established to examine the effect of PFKFB3 inhibition in vivo.

RESULTS

PFKFB3 was identified as one of the most significant DEGs and was more highly expressed in proliferating IH tissues and hemangioma-derived endothelial cells (HemECs) than in involuting IH tissues and human umbilical vein endothelial cells, respectively. PFKFB3 inhibition by PFK15 suppressed HemEC glucose metabolism mainly by affecting glycolytic metabolite metabolism and decreasing the glycolytic flux. Moreover, PFK15 inhibited HemEC angiogenesis and migration and induced apoptosis via activation of the apoptosis pathway. Treatment with the combination of PFK15 with propranolol had a synergistic inhibitory effect on HemECs. Moreover, PFKFB3 knockdown markedly suppressed HemEC angiogenesis. Mechanistically, inhibition of PFKFB3 suppressed the PI3K-Akt signaling pathway and induced apoptotic cell death. More importantly, the suppression of PFKFB3 by PFK15 or shPFKFB3 led to markedly reduced tumor growth in vivo.

CONCLUSIONS

Our findings suggest that PFKFB3 inhibition can suppress IH angiogenesis and induce apoptosis. Thus, targeting PFKFB3 may be a novel therapeutic strategy for IH.

Treatment outcomes of oral propranolol in the treatment of periocular infantile capillary hemangioma and factors predictive of recurrence and incomplete resolution: A multi-centric study

AIM

This study aims to evaluate the treatment outcomes of periocular capillary hemangioma with oral propranolol (OP) and list the factors predictive of recurrence and incomplete resolution after treatment.

METHODOLOGY

Data were collected by retrospective review of medical files of patients with infantile hemangioma (IH) treated with OP during January 2014-December 2019 from two tertiary eye institutes from India. Patients presenting with symptoms of IH with/without any history of prior treatment were included. All patients were started on OP with the dose of 2-2.5 mg/Kg body weight and continued till complete resolution or till the lesion reached a plateau response. Details about the ophthalmic examination at each visit and availability of imaging findings were noted down from the records. Primary outcome: Study the treatment outcome of patients treated with OP and discussed our observations regarding factors that may predict nonresponse, poor response, or recurrence. Secondary outcome: complications/side effects of therapy. Response to treatment was judged as fair, good, and excellent depending on resolution <50%, >50%, and complete resolution, respectively. Univariate analysis of factors related to treatment response was judged as fair, good, and excellent depending on resolution <50%, >50%, outcome and recurrence was studied using Mann-Whitney U test and Fisher's exact test.

RESULTS

A total of 28 patients were included in the study, out of which 17 were female and 11 were male. The mean age of onset of the lesion was 1.08 (± 1.484) months, 11 being congenital in origin. The mean age at presentation was 4.15 (± 2.92) months. 46.43% (n = 13) of patients showed complete resolution, while 25% (n = 7) showed more than 50% reduction in lesion size. Fair response was noted in 28.57% (n = 8). The mean duration of follow-up after stopping OP was 17.7 (± 20.774) months. The recurrence rate noted was 14.28%. The factors which were associated with incomplete resolution were age at presentation >3 months, later age of appearance of the lesion, superficial lesions with no orbital involvement. Male gender and congenital lesions responded best to OP therapy. Minor complications were noted with a rate of 25% (n = 7). Younger age at presentation was more commonly associated with complications.

CONCLUSION

OP is a safe and effective treatment for capillary hemangioma except for a smaller subset of patients who show suboptimal response to this drug. However, specific factors responsible for suboptimal response or recurrence after OP therapy remain elusive. Although not statistically significant, there was an increasing trend toward higher age at presentation, low birth weight, and superficial lesions with a poorer response. Furthermore, these factors along with the male gender were commonly associated with recurrence in our series. Larger prospective studies focused on evaluating clinical factors responsible for incomplete resolution and recurrence will help in prognosticating and suggesting alternative treatment regimes.

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.

Novel roles of METTL1/WDR4 in tumor via m7G methylation

As one of the prevalent posttranscriptional modifications of RNA, N⁷-methylguanosine (m⁷G) plays essential roles in RNA processing, metabolism, and function, mainly regulated by the methyltransferase-like 1 (METTL1) and WD repeat domain 4 (WDR4) complex. Emerging evidence suggests that the METTL1/WDR4 complex promoted or inhibited the processes of many tumors, including head and neck, lung, liver, colon, bladder cancer, and teratoma, dependent on close m⁷G methylation modification of tRNA or microRNA (miRNA). Therefore, METTL1 and m⁷G modification can be used as biomarkers or potential intervention targets, providing new possibilities for early diagnosis and treatment of tumors. This review will mainly focus on the mechanisms of METTL1/WDR4 via m⁷G in tumorigenesis and the corresponding detection methods.

Propranolol inhibits the angiogenic capacity of hemangioma endothelia via blocking β-adrenoceptor in mast cell

BACKGROUND

Propranolol, a non-selective blocker of the β-adrenoceptor (AR), is a first-line treatment for infantile hemangioma (IH). Mast cells have been implicated in the pathophysiology of propranolol-treated hemangioma. However, the function of mast cells remains unclear.

METHODS

HMC-1s (Human mast cell line) having been treated with propranolol for 24 h were centrifuged, washed with PBS twice, and maintained in cell culture medium for another 24 h. The supernatants with propranolol which were named as propranolol-treated HMC-1s supernatants were obtained. The expression of cytokines and mediators was examined among HMC-1s dealt with propranolol. HemECs (hemangioma endothelial cells) were co-cultured with propranolol-treated HMC-1s supernatants, and their proliferation and apoptosis were investigated. The autophagic-related protein was examined in HemECs using immunoblot.

RESULTS

In propranolol-treated HMC-1s, the expressions of ADRB1 (β1-AR) and ADRB2 (β2-AR) were reduced by 70% and 60%, respectively, and that of cytokines and mediators were reduced. The proliferation was decreased, but apoptosis and autophagy were induced in HemECs treated with propranolol-treated HMC-1s supernatants. However, propranolol can work well in shRNA-ADRB1 or shRNA-ADRB2 transfected HMC-1s.

CONCLUSIONS

Propranolol inhibit the proliferation of HemECs and promote their apoptosis and autophagy through acting on both β1 and β2 adrenoceptor in mast cell.

IMPACT

Treated with propranolol, β1, and β2 adrenoceptor on human mast cell expression was reduced significantly. After hemangioma endothelial cell treated with the supernatants from propranolol-treated human mast cell, its proliferation was decreased, but apoptosis and autophagy were significantly induced. Propranolol can work well in shRNA-ADRB1 or shRNA-ADRB2 transfected HMC-1s. Mast cells may have a role in the action of propranolol in infantile hemangioma through both β1 and β2 adrenoceptors to inhibit the angiogenic capacity of hemangioma endothelial cells.

Orbital Vascular Anomalies: A Nomenclatorial, Etiological, and Nosologic Conundrum

PURPOSE

Vascular anomalies are a heterogeneous group of disorders that frequently present in the periorbital region. They encompass 2 broad entities: vascular tumors, which possess a proliferative endothelium, and vascular malformations, which are basically localized defects of vascular morphogenesis. The primary goal of this review was to address inaccurate or controversial terminology in the oculoplastic literature concerning orbital and periorbital vascular anomalies and to categorize these lesions in an abridged and simplified hierarchical list that adheres as much as possible to the most recent (2018) iteration for the classification of vascular lesions proposed by the International Society for the Study of Vascular Anomalies (ISSVA). The secondary goal of this review was to review and update information regarding the genetic underpinnings of vascular anomalies and the downstream signaling pathways that are subsequently affected as a result of these genetic errors.

METHODS

A literature review was conducted in PubMed, MEDLINE, PubMed Central, National Center for Biotechnology Information Bookshelf, and Embase for several related keywords including "vascular anomalies, vascular malformations, vascular tumors, and cavernous venous malformation," both with and without adding the keywords "eyelid," "orbital," and "periorbital." In addition, a detailed search was conducted for controversial or obsolete keywords like "cavernous hemangioma," "lymphangioma," and "varices," again in their systemic and orbital/periorbital context.

RESULTS

Crucial issues in the 2018 ISSVA classification regarding the proper categorization of orbital vascular anomalies, particularly venous lesions, were critically evaluated and revised, and a regional, simplified, and abridged modification of the ISSVA 2018 classification was proposed.

CONCLUSIONS

Interdisciplinary and intradisciplinary dialogue concerning orbital vascular anomalies is seriously compromised due to the lack of a unanimous agreement on terminology and the absence of a unified classification concept system. The authors recommend that oculoplastic surgeons adopt ISSVA terminology whenever technically possible and scientifically sound. However, they also propose modifying the ISSVA 2018 classification specifically to adapt to the peculiarities of vascular anomalies in the periorbital region. At present, the simplified classification proposed here is a preliminary first step towards managing patients with orbital vascular anomalies with greater diagnostic and therapeutic precision, until such time in the future when the entire genetic makeup of orbital vascular anomalies is more completely elucidated. Optimistically, this could pave the way for a more robust classification and the ultimate therapeutic cure.

Hemangioma in the lower labial vestibule of an eleven-year-old girl: A case report

BACKGROUND

Hemangioma is a vascular benign tumour of endothelial origin. It appears commonly in the first decade of life with increases incidence in females. Hemangioma is not common to happen in the oral cavity and it is extremely rare to appear in the labial vestibule.

CASE SUMMARY

We present a case of an 11-year-old girl who complained of a painful, slowly growing mass which was consistent with the capillary hemangioma in the left mandibular vestibule. Vascular tumor such as hemangioma in the mandibular vestibule is extremely rare; hence, the clinical definitive diagnosis is very challenging. Therefore, radiographic imaging and histopathologic analysis are crucial to reach to the final diagnosis for proper management.

CONCLUSION

Comprehensive clinical evaluation, proper diagnostic imaging and microscopic analysis of the mass establish a precise diagnosis of the hemangioma for better management.

Endothelial k-RasV12 Expression Induces Capillary Deficiency Attributable to Marked Tube Network Expansion Coupled to Reduced Pericytes and Basement Membranes

OBJECTIVE

We sought to determine how endothelial cell (EC) expression of the activating k-Ras (kirsten rat sarcoma 2 viral oncogene homolog) mutation, k-RasV12, affects their ability to form lumens and tubes and interact with pericytes during capillary assembly Approach and Results: Using defined bioassays where human ECs undergo observable tubulogenesis, sprouting behavior, pericyte recruitment to EC-lined tubes, and pericyte-induced EC basement membrane deposition, we assessed the impact of EC k-RasV12 expression on these critical processes that are necessary for proper capillary network formation. This mutation, which is frequently seen in human ECs within brain arteriovenous malformations, was found to markedly accentuate EC lumen formation mechanisms, with strongly accelerated intracellular vacuole formation, vacuole fusion, and lumen expansion and with reduced sprouting behavior, leading to excessively widened tube networks compared with control ECs. These abnormal tubes demonstrate strong reductions in pericyte recruitment and pericyte-induced EC basement membranes compared with controls, with deficiencies in fibronectin, collagen type IV, and perlecan deposition. Analyses of signaling during tube formation from these k-RasV12 ECs reveals strong enhancement of Src (Src proto-oncogene, non-receptor tyrosine kinase), Pak2 (P21 [RAC1 (Rac family small GTPase 1)] activated kinase 2), b-Raf (v-raf murine sarcoma viral oncogene homolog B1), Erk (extracellular signal-related kinase), and Akt (AK strain transforming) activation and increased expression of PKCε (protein kinase C epsilon), MT1-MMP (membrane-type 1 matrix metalloproteinase), acetylated tubulin and CDCP1 (CUB domain-containing protein 1; most are known EC lumen regulators). Pharmacological blockade of MT1-MMP, Src, Pak, Raf, Mek (mitogen-activated protein kinase) kinases, Cdc42 (cell division cycle 42)/Rac1, and Notch markedly interferes with lumen and tube formation from these ECs.

CONCLUSIONS

Overall, this novel work demonstrates that EC expression of k-RasV12 disrupts capillary assembly due to markedly excessive lumen formation coupled with strongly reduced pericyte recruitment and basement membrane deposition, which are critical pathogenic features predisposing the vasculature to develop arteriovenous malformations.

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.

Burn Hemangioma: A New Variant of Hemangioma

BACKGROUND

Burn hemangioma, also known as scalded pyogenic granuloma, is considered a variant of pyogenic granuloma, but unlike the classic type it presents with rapid progression. Most patients are infants and young children with a history of burns caused by liquids.

OBJECTIVE

The present study aims to present all patients with burn hemangiomas treated at our institutions with a full clinical and histopathological assessment.

PATIENTS AND METHODS

This case series includes 34 cases that were treated during the period from 2016 to 2021.

RESULTS

A total of 34 patients (16 female/18 male, mean age of 17.6 years) were included. Two age groups presented: infants and children (n = 22, age range 0.5-8 years, 10 female/12 male), and adults (n = 11, age range 25-44 years, 6 female/6 male). Lesions appeared 1-2 weeks following predominantly second-degree burns, and multiple lesions predominated in infants and children. The lesions evolved to large lesions within weeks, and these appeared to be either static or involute. The histopathology was compatible with hemangioma, rather than pyogenic granuloma.

CONCLUSION

Burn hemangioma should be considered a new variant of hemangioma rather than a type of pyogenic granuloma that follows second-degree burns. They have many similarities with infantile hemangioma, both clinically and histopathologically.

Update on infantile hemangioma

The International Society for the Study of Vascular Anomalies classifies vascular anomalies into vascular tumors and vascular malformations. Vascular tumors are neoplasms of endothelial cells, among which infantile hemangiomas (IHs) are the most common, occurring in 5%-10% of infants. Glucose transporter-1 protein expression in IHs differs from that of other vascular tumors or vascular malformations. IHs are not present at birth but are usually diagnosed at 1 week to 1 month of age, rapidly proliferate between 1 and 3 months of age, mostly complete proliferation by 5 months of age, and then slowly involute to the adipose or fibrous tissue. Approximately 10% of IH cases require early treatment. The 2019 American Academy of Pediatrics clinical practice guideline for the management of IHs recommends that primary care clinicians frequently monitor infants with IHs, educate the parents about the clinical course, and refer infants with high-risk IH to IH specialists ideally at 1 month of age. High-risk IHs include those with life-threatening complications, functional impairment, ulceration, associated structural anomalies, or disfigurement. In Korea, IHs are usually treated by pediatric hematology-oncologists with the cooperation of pediatric cardiologists, radiologists, dermatologists, and plastic surgeons. Oral propranolol, a nonselective beta-adrenergic antagonist, is the first-line treatment for IHs at a dosage of 2-3 mg/kg/day divided into 2 daily doses maintained for at least 6 months and often continuing until 12 months of age. Topical timolol maleate solution, a topical nonselective beta-blocker, may be used for small superficial type IHs at a dosage of 1-2 drops of 0.5% gel-forming ophthalmic solution applied twice daily. Pulse-dye laser therapy or surgery is useful for the treatment of residual skin changes after IH involution.

Exosome-eluting stents for vascular healing after ischaemic injury

Drug-eluting stents implanted after ischaemic injury reduce the proliferation of endothelial cells and vascular smooth muscle cells and thus neointimal hyperplasia. However, the eluted drug also slows down the re-endothelialization process, delays arterial healing and can increase the risk of late restenosis. Here we show that stents releasing exosomes derived from mesenchymal stem cells in the presence of reactive oxygen species enhance vascular healing in rats with renal ischaemia-reperfusion injury, promoting endothelial cell tube formation and proliferation, and impairing the migration of smooth muscle cells. Compared with drug-eluting stents and bare-metal stents, the exosome-coated stents accelerated re-endothelialization and decreased in-stent restenosis 28 days after implantation. We also show that exosome-eluting stents implanted in the abdominal aorta of rats with unilateral hindlimb ischaemia regulated macrophage polarization, reduced local vascular and systemic inflammation, and promoted muscle tissue repair.

The mechanobiological theory: a unifying hypothesis on the pathogenesis of moyamoya disease based on a systematic review

OBJECTIVE

Moyamoya angiopathy (MMA) affects the distal internal carotid artery and is designated as moyamoya disease (MMD) when predisposing conditions are absent, or moyamoya syndrome (MMS) when it occurs secondary to other causes. The authors aimed to investigate the reason for this anatomical site predilection of MMA. There is compelling evidence to suggest that MMA is a phenomenon that occurs due to stereotyped mechanobiological processes. Literature regarding MMD and MMS was systematically reviewed to decipher a common pattern relating to the development of MMA.

METHODS

A systematic review was conducted to understand the pathogenesis of MMA in accordance with PRISMA guidelines. PubMed MEDLINE and Scopus were searched using "moyamoya" and "pathogenesis" as common keywords and specific keywords related to six identified key factors. Additionally, a literature search was performed for MMS using "moyamoya" and "pathogenesis" combined with reported associations. A progressive search of the literature was also performed using the keywords "matrix metalloprotease," "tissue inhibitor of matrix metalloprotease," "endothelial cell," "smooth muscle cell," "cytokines," "endothelin," and "transforming growth factor" to infer the missing links in molecular pathogenesis of MMA. Studies conforming to the inclusion criteria were reviewed.

RESULTS

The literature search yielded 44 published articles on MMD by using keywords classified under the six key factors, namely arterial tortuosity, vascular angles, wall shear stress, molecular factors, blood rheology/viscosity, and blood vessel wall strength, and 477 published articles on MMS associations. Information obtained from 51 articles that matched the inclusion criteria and additional information derived from the progressive search mentioned above were used to connect the key factors to derive a network pattern of pathogenesis.

CONCLUSIONS

Based on the available literature, the authors have proposed a unifying theory for the pathogenesis of MMA. The moyamoya phenomenon appears to be the culmination of an interplay of vascular anatomy, hemodynamics, rheology, blood vessel wall strength, and a plethora of intricately linked mechanobiological molecular mediators that ultimately results in the mechanical process of occlusion of the blood vessel, stimulating angiogenesis and collateral blood supply in an attempt to perfuse the compromised brain.

Mediastinal and subglottic hemangioma in an infant: a case report and literature review

We performed a retrospective analysis of the clinical manifestations, laboratory and imaging examinations, treatment, and prognosis of a male infant who was diagnosed with mediastinal and subglottic hemangioma in our hospital. The clinical features of this patient were coughing, wheezing, and dyspnea. Enhanced computed tomography of the neck and chest showed a diffuse abnormality in the right-upper mediastinum. He was diagnosed with a hemangioma after a physical examination combined with bronchoscopy. The clinical symptoms were relieved by oral propranolol. We also investigated the clinical characteristics, treatment, and prognosis of mediastinal and subglottic hemangioma in infants in the previous literature, and searched for case reports of this disease in China and in other countries. We only identified three previous cases of mediastinal and subglottic hemangioma in infants, indicating that this condition is rare. In the proliferative stage, surrounding organs and tissues are compressed, which can be life-threatening. Most of these children develop wheezing, shortness of breath, dyspnea, cyanosis, and other symptoms within 2 months. Enhanced computed tomography and magnetic resonance imaging combined with soft bronchoscopy can confirm the diagnosis of this disease, and oral propranolol achieves a favorable effect.

The flavonoid luteolin suppresses infantile hemangioma by targeting FZD6 in the Wnt pathway

Infantile hemangioma is the most common vascular tumor of childhood. It is characterized by clinical expansion of endothelial cells and promoted by angiogenic factors. Luteolin is a flavonoid compound that carries anti-cancer and anti-angiogenesis properties. The study aimed to investigate the effect of luteolin in treating infantile hemangioma. We first tested the effect of luteolin on cell proliferative potential and VEGFA expression in hemangioma-derived stem cells (HemSCs). We then examined the efficacy of systemic application of luteolin in a murine hemangioma model. We then identified the downstream factor regulated by luteolin in HemSCs and validated its causative relationship with knock-down method in both in vitro and in vivo models. We also investigated the protein expression change of this targeting factor in proliferating hemangiomas. Luteolin inhibited HemSC growth and suppressed VEGF-A expression in a dose-dependent manner. Luteolin inhibited microvessel formation and de novo vasculogenesis in the murine model. FZD6 was induced by luteolin and exerted the anti-angiogenesis effect in our tumor models. Lastly, FZD6 level was repressed in the clinical tissues of human proliferating hemangiomas. Luteolin is a promising new agent to treat infantile hemangioma. Targeting the Wnt pathway may represent a potential therapeutic strategic to inhibit angiogenesis in proliferating hemangiomas.

Evaluation of plasma and urinary levels of vascular endothelial growth factor and matrix metalloproteinase-9 in patients with infantile hemangioma

BACKGROUND

The pathogenesis of infantile hemangioma (IH) is not fully understood. It has been suggested that angiogenic factors increase in the proliferative stage, decreasing subsequently in the regression phase.

OBJECTIVES

To evaluate vascular endothelial growth factor (VEGF) and matrix metalloproteinase 9 (MMP-9) levels, according to infantile hemangioma (IH) growth stages and size, and to compare these levels in patients with IH and control subjects.

METHODS

This cross-sectional study included 68 patients with IH and 25 control subjects. Plasma and urinary MMP-9 and VEGF levels were evaluated during proliferative and regression phases. These levels were correlated with tumor size measured by ultrasonography. Nonparametric tests were performed.

RESULTS

Among 68 patients with IH, 55 (81%) were female. Age ranged from 1 to 40 months (median 7.0 months). There was no difference in plasma and urinary levels of VEGF and MMP-9 between patients and control subjects. There were no significant differences in these levels between IH patients younger or older than 12 months of age, as a cutoff between proliferative and involution phases. No significant correlation was observed between tumor size and levels of the markers (R < 0.20 and P > 0.05 for all comparisons).

CONCLUSION

In our large sample, levels of VEGF and MMP-9 did not reflect the characteristic increased angiogenesis in patients with IH when compared to healthy subjects. In addition, these markers were not increased in the proliferative stage of the IH and did not correlate with tumor size.

Propranolol versus nadolol for treatment of pediatric subglottic hemangioma

PURPOSE

The beta-blocker propranolol is the standard medical therapy for subglottic hemangioma (SGH), but side effects and incomplete response rates require close monitoring. Nadolol has been identified as a potential alternative but its use has not been examined for SGH.

METHODS

Single institution retrospective cohort study of pediatric SGH treated with propranolol or nadolol.

RESULTS

Thirteen children (1 male, 12 female) with SGH were included: 6 were treated with propranolol (2.0-3.5 mg/kg/d) and 7 with nadolol (2.0-4.0 mg/kg/d). The most common presenting symptom was stridor (85%) and mean (SD) symptom duration prior to diagnosis was 4.6 (3.8) weeks. Cutaneous vascular lesions were present in 54%. There were 7 right-sided, 5 left-sided and 1 bilateral SGH. The mean (SD) percentage of airway obstruction was 60.6% (27.4). The response rate was 100% (6/6) for propranolol and 85.7% (6/7) for nadolol (p = 0.36). Mean (SD) time to symptomatic improvement was 2.6 (2.2) days with no difference across groups (p = 0.71). There was no hypotension, hypoglycemia, weight loss, or sleep disturbances in either group. One patient in the propranolol group experienced vomiting. Two patients in the nadolol group required dosage reduction due to asymptomatic bradycardia. The mean (SD) duration of admission was 14.4 (12.6) days and duration of treatment was 13.8 (11.2) days with no difference across groups (p = 0.23; p = 0.31, respectively). All patients had treatment initiated as inpatients and completed as outpatients.

CONCLUSION

Children with SGH treated with propranolol or nadolol had similar response rates and side effect profiles.

Postcricoid haemangioma with laryngomalacia in infancy

Infantile haemangioma represents a congenital vascular anomaly commonly observed in the head and neck region. Such an occurrence over the postcricoid region, however, is rather unusual. Herein, the authors report a case of a synchronous postcricoid haemangioma in a 7-week-old newborn diagnosed with severe laryngomalacia. In addition to the floppy redundant arytenoid mucosa, flexible laryngoscopy revealed a lobulated bluish mass at the postcricoid. The lesion was hyperintense on T1-weighted sequence and was enhanced with contrast, supporting the diagnosis of a haemangioma. She underwent surgical excision of the haemangioma with intralesional steroid injection. Surveillance at 6-month postoperation did not show disease recurrence.

Morphological, genetic and clinical correlations in infantile hemangiomas and their mimics

Infantile hemangiomas (IHs) are the most frequent pediatric benign vascular tumors, with a reported incidence of 5% to 10%. They have self-limiting evolution pattern divided into a growth phase in the first 12 months and a regression one, that may take up to 10 years. Occasionally, hemangiomas might lead to local or systemic complications, depending on their morphological characteristics. The first line of treatment is β-blockers, such as Propranolol, Timolol, Nadolol, administered either locally or systemically. Newer therapeutic strategies involving laser therapy and angiotensin-converting enzyme inhibitors are being studied, while older treatment modalities like corticosteroids, Imiquimod, Vincristine, Bleomycin and Interferon-α have become second line therapy options. Before establishing the appropriate treatment, clinical, histological, and imaging investigations are required.

Propranolol Reduces the Development of Lesions and Rescues Barrier Function in Cerebral Cavernous Malformations: A Preclinical Study

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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.

Microarray expression profile of mRNAs and long noncoding RNAs and the potential role of PFK-1 in infantile hemangioma

BACKGROUND

Infantile hemangioma (IH) is the most common benign tumor in children. Long noncoding RNAs (lncRNAs) play a critical role in tumorigenesis. However, the expression levels and biological functions of lncRNAs in IH have not been well-studied. This study aimed to analyze the expression profile of lncRNAs and mRNAs in proliferating and involuting IHs.

METHODS

The expression profiles of lncRNAs and mRNAs in proliferating and involuting IHs were identified by microarray analysis. Subsequently, detailed bioinformatics analyses were performed. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) analyses were conducted to validate the microarray results.

RESULTS

In total, 146 differentially expressed (DE) lncRNAs and 374 DE mRNAs were identified. The DE mRNAs were enriched mostly in angiogenesis-related biological processes (BPs) and pathways by bioinformatics analysis. In addition, metabolism-related BPs (e.g., "glycogen biosynthetic process" and "metabolic process") and pathways (e.g., "oxidative phosphorylation") were identified. A lncRNA-mRNA co-expression network was constructed from 42 DE lncRNAs and 217 DE mRNAs. Twelve lncRNAs were predicted to have cis-regulated target genes. The microarray analysis results were validated by qRT-PCR using 5 randomly selected lncRNAs and 13 mRNAs. The IHC results revealed that both LOXL2 and FPK-1 exhibited higher protein expression levels in proliferating IH than in involuting IH. Moreover, inhibition of PFK-1 could suppress hemangioma-derived endothelial cell proliferation and migration, induce cell arrest, and reduce glucose uptake and lactate and ATP production.

CONCLUSIONS

The findings suggest that the identified DE lncRNAs and mRNAs may be associated with the pathogenesis of IH. The data presented herein can improve our understanding of IH development and provide direction for further studies investigating the mechanism underlying IH.

Proanthocyanidins as a Potential Novel Way for the Treatment of Hemangioma

Hemangioma, the most common benign vascular tumor, not only affects the appearance and psychology but also has a life-threatening potential. It is considered that clonal vascular endothelial cell proliferation and excessive angiogenesis are responsible for hemangioma pathogenesis, in which abnormal cytokines/pathways are closely implicated, primarily including high expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) as well as their downstream pathways, especially phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt). These further stimulate the migration and proliferation of vascular endothelial cells and promote the formation of new vessels, ultimately leading to the occurrence and development of hemangioma. Proanthocyanidins are naturally active substance from plants and fruits. They possess multiple functions like antiproliferation, antiangiogenesis, and antitumor. It has been demonstrated that proanthocyanidins effectively work in various diseases via inhibiting the expression of various factors, e.g., HIF-1α, VEGF, PI3K, and Akt. Considering the pathogenesis of hemangioma and the effect of proanthocyanidins, we hold a hypothesis that proanthocyanidins would be applied in hemangioma via downregulating cytokine/pathway expression, suppressing vascular cell proliferation and arrest abnormal angiogenesis. Taken together, proanthocyanidins may be a potential novel way for the treatment of hemangioma.

Infantile and congenital hemangiomas

Infantile hemangiomas (IHs) are the most common benign tumors of infancy. They typically appear after birth and undergo a period of rapid growth, followed by a gradual period of involution. Although the majority of IHs do not requirement treatment, oral propranolol is the first-line therapy for lesions that are at risk for life-threatening complications, functional impairment, ulceration, or permanent disfigurement. Rarely, IHs can be associated with structural anomalies. Congenital hemangiomas (CHs) are a distinct clinical entity, caused by a point mutation in GNAQ or GNA11. These lesions are typically present at birth and display a wide spectrum of clinical presentations. CHs can be distinguished from IHs by their unique histologic and radiographic features. Given the high-flow vascularity of CHs, surgical excision may be indicated due to the high risk of bleeding.

PropAngio study protocol: a neoadjuvant trial on the efficacy of propranolol monotherapy in cutaneous angiosarcoma-a proof of principle study

INTRODUCTION

Angiosarcoma is a rare and aggressive malignancy with a high metastatic potential and recurrence rate. Despite optimal treatment with surgery, with or without radiation, the prognosis remains poor and, therefore, new treatment strategies are warranted. Recently, propranolol has effectively been repurposed for the treatment of infantile haemangioma. Propranolol is a β3-sparing antagonist of the β-adrenergic receptor. In infantile haemangioma, the β1, β2 and β3 receptors are highly expressed. Angiosarcoma has several similarities with haemangioma, including its high β-adrenergic receptor expression and the supposedly important role of vascular endothelial growth factor in malignant growth. As a result, propranolol has been administered small scale in individual angiosarcoma cases with promising results. The precise effect of propranolol, however, is not yet established.

METHODS AND ANALYSIS

The goal of this neoadjuvant window of opportunity study is to prospectively evaluate the activity of propranolol monotherapy in patients with cutaneous angiosarcoma. The neoadjuvant setting provides a good opportunity to rapidly evaluate both the clinical response and histological response, without a significant delay in standard anticancer treatment. Fourteen patients with primary, recurrent or metastatic cutaneous angiosarcoma will be included. Propranolol will be administered orally in an escalating dose during 3-6 weeks, before the initiation of standard treatment. The primary endpoint is clinical response according to Response Evaluation Criteria in Solid Tumours, as measured on consecutive coloured photographs or CT/MRI. The histological response will be determined as secondary endpoint, comparing the difference in proliferation index before and after propranolol by measuring the change in immunohistochemistry staining of Ki-67. The study will be considered positive when at least three patients have a response to propranolol.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Medical Ethical Committee of the Netherlands Cancer Institute. Independent of the outcome, results of this study will be shared and submitted for publication in an international peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NL8118; registry through the Netherlands Trial Register.

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.

The histopathology of congenital haemangioma and its clinical correlations: a long-term follow-up study of 55 cases

AIMS

Congenital haemangiomas (CHs) can be subdivided into different subtypes [rapidly involuting CHs (RICHs), non-involuting CHs (NICHs), and partially involuting CHs (PICHs)]. During the first few days of life, RICHs may be associated with transient but sometimes marked thrombocytopenia. We sought to assess the histological aspects and clinicopathological correlations of the three subtypes.

METHODS AND RESULTS

We assessed the histopathological features of 10 RICHs, 25 NICHs, and 20 PICHs, described the patients' long-term clinical outcomes, and assessed clinicopathological correlations. All CHs were located in the dermis and hypodermis, and comprised both capillary lobules (with three distinct histopathological patterns) and extralobular large vessels. Most of the extralobular vessels were abnormal veins and abnormal lymphatic vessels. We did not observe significant correlations between the CH subtype, the histopathological pattern, and the time of the histopathological assessment. Interestingly, unexpected intralobular expression of podoplanin was found in neonatal biopsies of five RICHs and PICHs. Four of these five patients had concomitant thrombocytopenia. The podoplanin staining intensity decreased over time as the thrombocytopenia resolved and the tumour shrank.

CONCLUSION

The histopathological features were similar in all three subtypes of CH, and were related to the time since disease onset; we consider that RICH, PICH and NICH form a single entity and differ only in their involuting potential. Along with the transient expression of intralobular podoplanin observed in some specimens from the newborn, the lobular architecture might lead to misdiagnosis of tufted haemangioma or kaposiform haemangioendothelioma.

CircAP2A2 acts as a ceRNA to participate in infantile hemangiomas progression by sponging miR-382-5p via regulating the expression of VEGFA

Background

Increasing evidences reveal that circular RNAs (circRNAs) play crucial functions in cancer development. However, the expression pattern and roles of circRNAs in infantile hemangiomas (IH) remain unclear.

Methods

In this study, qRT‐PCR was performed to determine the expression of circAP2A2, miR‐382‐5p, and VEGFA in IH tissues and cell lines. Moreover, MTT assay, colony formation, transwell assay, and Western blot analysis were conducted to assess the function of circAP2A2 or miR‐382‐5p on cell proliferation, and migration in vitro, respectively. Also, dual luciferase assay was used to confirm the interactions among circAP2A2, miR‐382‐5p, and VEGFA.

Results

CircAP2A2 was confirmed to be highly expressed in IH. CircAP2A2 knockdown or miR‐382‐5p overexpression decreased the proliferation, colony formation, migration, and invasion of HemECs and HUVEC cells.

Conclusion

CircAP2A2 could promote proliferation and invasion of IH by regulating miR‐382‐5p/VEGFA axis.

Cell engraftment, vascularization, and inflammation after treatment of equine distal limb wounds with endothelial colony forming cells encapsulated within hydrogel microspheres

BACKGROUND

Endothelial colony forming cells (ECFCs) may be useful therapeutically in conditions with poor blood supply, such as distal limb wounds in the horse. Encapsulation of ECFCs into injectable hydrogel microspheres may ensure cell survival and cell localization to improve neovascularization and healing. Autologous ECFCs were isolated from 6 horses, labeled with quantum nanodots (QD), and a subset were encapsulated in poly(ethylene) glycol fibrinogen microspheres (PEG-Fb MS). Full-thickness dermal wounds were created on each distal limb and injected with empty PEG-Fb MS, serum, ECFCs, or ECFCs encapsulated into PEG- Fb MS (ECFC/MS). Analysis included wound surface area (WSA), granulation tissue scoring (GS), thermography, collagen density staining, and immunohistochemical staining for endothelial and inflammatory cells. The purpose of this study was to track cell location and evaluate wound vascularization and inflammatory response after injection of ECFC/MS or naked ECFCs in equine distal limb wounds.

RESULTS

ECFCs were found near and within newly formed blood vessels up to 3 weeks after injection. ECFC and ECFC/MS groups had the greatest blood vessel quantity at week 1 in the wound periphery. Wounds treated with ECFCs and ECFC/MS had the lowest density of neutrophils and macrophages at week 4. There were no significant effects of ECFC or ECFC/MS treatment on other measured parameters.

CONCLUSIONS

Injection of microsphere encapsulated ECFCs was practical for clinical use and well-tolerated. The positive ECFC treatment effects on blood vessel density and wound inflammation warrant further investigation.

Calcium Signaling in Endothelial Colony Forming Cells in Health and Disease

Endothelial colony forming cells (ECFCs) represent the only known truly endothelial precursors. ECFCs are released in peripheral circulation to restore the vascular networks dismantled by an ischemic insult or to sustain the early phases of the angiogenic switch in solid tumors. A growing number of studies demonstrated that intracellular Ca²⁺ signaling plays a crucial role in driving ECFC proliferation, migration, homing and neovessel formation. For instance, vascular endothelial growth factor (VEGF) triggers intracellular Ca²⁺ oscillations and stimulates angiogenesis in healthy ECFCs, whereas stromal derived factor-1α promotes ECFC migration through a biphasic Ca²⁺ signal. The Ca²⁺ toolkit endowed to circulating ECFCs is extremely plastic and shows striking differences depending on the physiological background of the donor. For instance, inositol-1,4,5-trisphosphate-induced Ca²⁺ release from the endoplasmic reticulum is downregulated in tumor-derived ECFCs, while agonists-induced store-operated Ca²⁺ entry is up-regulated in renal cellular carcinoma and is unaltered in breast cancer and reduced in infantile hemangioma. This remodeling of the Ca²⁺ toolkit prevents VEGF-induced pro-angiogenic Ca²⁺ oscillations in tumor-derived ECFCs. An emerging theme of research is the dysregulation of the Ca²⁺ toolkit in primary myelofibrosis-derived ECFCs, as this myeloproliferative disorder may depend on a driver mutation in the calreticulin gene. In this chapter, I provide a comprehensive, but succinct, description on the architecture and role of the intracellular Ca²⁺ signaling toolkit in ECFCs derived from umbilical cord blood and from peripheral blood of healthy donors, cancer patients and subjects affected by primary myelofibrosis.

Propranolol inhibits proliferation and induces apoptosis of hemangioma-derived endothelial cells via Akt pathway by down-regulating Ang-2 expression

Hemangioma is one of the commonest benign vascular tumors among children. Propranolol is the first-line therapeutic drug for hemangioma. However, the effects and mechanisms of propranolol in hemangioma have not been thoroughly elaborated. In this study, the effects and mechanisms of propranolol were explored using hemangioma-derived endothelial cells (HemECs). The expression of GLUT1 were determined by immunofluorescence staining. qRT-PCR assay was conducted to detect the mRNA expressions of angiopoietin-2 (Ang-2) and Tie-2. Western blot assay was carried out to measure the protein levels of Ang-2, Tie-2, protein kinase-B (Akt) and phospholyrated-Akt (p-Akt). Cell proliferation was assessed by Cell Counting Kit-8 (CCK-8) assay and Western blot of Ki67 protein level. Cell apoptosis was measured by flow cytometry analysis and Western blot of Bax and Bcl-2 levels. We found that propranolol inhibited proliferation and induced apoptosis in human umbilical vein endothelial cells (HUVECs) and HemECs. Moreover, propranolol inhibited the expressions of Ang-2 and Tie-2 in HUVECs and HemECs. Functional analysis revealed that Ang-2 attenuated the effects of propranolol on HemEC proliferation and apoptosis. Mechanistical analysis showed that propranolol inhibited the Akt pathway by regulating Ang-2 expression in HemECs. Futhermore, inhibition of the Akt pathway attenuated the effects of Ang-2 on proliferation and apoptosis in HemECs. In conclusion, propranolol inhibited proliferation and induced apoptosis of HemECs via Akt pathway by down-regulating Ang-2 expression, which contributes to our understanding on the pathogenesis of hemangioma and promotes the development of therapeutic approaches for hemangioma.

Increased risk of hemangioma after exposure to neonatal phototherapy in infants with predisposing risk factors

AIM

To determine the relationship between neonatal phototherapy and future risk of clinically significant hemangioma.

METHODS

We analysed a cohort of 678 879 infants born after 34 weeks gestation comprising 3 975 242 person-years of follow-up over 11 years (2006-2016). The exposure was phototherapy the first 28 days of life. The outcome was hemangioma that required in-hospital treatment during follow-up. We estimated hazard ratios (HR) and 95% confidence intervals (CI) for the association of phototherapy with risk of hemangioma, accounting for preterm birth, low birthweight and congenital anomalies.

RESULTS

The incidence of hemangioma was greater in neonates who received phototherapy than in untreated infants, but there was no association in adjusted models (HR 1.19, 95% CI 0.89-1.58). Risk of hemangioma was elevated in infants who received phototherapy and were born late preterm (HR 2.35, 95% CI 1.51-3.64), with low birthweight (HR 1.91, 95% CI 1.12-3.24), or with anomalies (HR 5.09, 95% CI 3.42-7.58). Without phototherapy, these three risk factors were more weakly associated with hemangioma.

CONCLUSION

Neonatal phototherapy in infants with predisposing risk factors may increase the chance of hemangioma, but confirmation in further studies is needed.