In the face and neck, keloid scar distribution is related to skin thickness and stiffness changes associated with movement.

Keloid scars tend to occur in high-tension sites due to mechanical stimuli that are involved in their development. To date, a detailed analysis of keloid distribution focused specifically on facial and neck areas has not been reported, and limited literature exists as to the related mechanical factors. To rectify this deficiency of knowledge, we first quantified the facial and neck keloid distribution observed clinically in 113 patients. Subsequently, we performed a rigorous investigation into the mechanical factors and their associated changes at these anatomic sites in healthy volunteers without a history of pathologic scarring. The association between keloid-predilection sites and sebaceous gland-dense and acne-prone sites was also examined. To assess skin stretch, thickness and stiffness, VECTRA, ultrasound and indentometer were utilised. Baseline skin stiffness and thickness were measured, as well as the magnitude of change in these values associated with facial expression and postural changes. Within the face and neck, keloids were most common near the mandibular angle (41.3%) and lateral submental (20.0%) regions. These areas of increased keloid incidence were not associated with areas more dense in sebaceous glands, nor linked consistently with acne-susceptible regions. Binomial logistic regression revealed that changes in skin stiffness and thickness related to postural changes significantly predicted keloid distribution. Skin stiffness and thickness changes related to prolonged mechanical forces (postural changes) are most pronounced at sites of high keloid predilection. This finding further elucidates the means by which skin stretch and tension are related to keloid development. As a more detailed analysis of mechanical forces on facial and neck skin, this study evaluates the nuances of multiple skin-mechanical properties, and their changes in a three-dimensional framework. Such factors may be critical to better understanding keloid progression and development in the face and neck.

Effectiveness of various methods of manual scar therapy.

BACKGROUND: The skin is a protective barrier of the body against external factors, and its damage leads to a loss of integrity. Normal wound healing results in a correct, flat, bright, and flexible scar. Initial skin damage and patient specific factors in wound healing contribute that many of these scars may progress into widespread or pathologic hypertrophic and keloid scars. The changes in cosmetic appearance, continuing pain, and loss of movement due to contracture or adhesion and persistent pruritis can significantly affect an individual's quality of life and psychological recovery post injury. Many different treatment methods can reduce the trauma and surgical scars. Manual scar treatment includes various techniques of therapy. The most effectiveness is a combined therapy, which has a multidirectional impact. Clinical observations show an effectiveness of manual scar therapy. MATERIAL AND METHODS: The aim of this work was to evaluate effectiveness of the scar manual therapy combined with complementary methods on the postoperative scars. Treatment protocol included two therapies during 30 min per week for 8 weeks. Therapy included manual scar manipulation, massage, cupping, dry needling, and taping. RESULTS: Treatment had a significant positive effect to influence pain, pigmentation, pliability, pruritus, surface area, and scar stiffness. Improvement of skin parameters (scar elasticity, thickness, regularity, color) was also noticed. CONCLUSION: To investigate the most effective manual therapy strategy, further studies are needed, evaluating comparisons of different individual and combined scar therapy modalities.

Exon skip-inducing variants in FLNA in an attenuated form of frontometaphyseal dysplasia.

Pathogenic variation in the X-linked gene FLNA causes a wide range of human developmental phenotypes. Loss-of-function is usually male embryonic-lethal, and most commonly results in a neuronal migration disorder in affected females. Gain-of-function variants cause a spectrum of skeletal dysplasias that present with variable additional, often distinctive, soft-tissue anomalies in males and females. Here we present two, unrelated, male individuals with novel, intronic variants in FLNA that are predicted to be pathogenic. Their phenotypes are reminiscent of the gain-of-function spectrum without the skeletal manifestations. Most strikingly, they manifest urethral anomalies, cardiac malformations, and keloid scarring, all commonly encountered features of frontometaphyseal dysplasia. Both variants prevent inclusion of exon 40 into the FLNA transcript, predicting the in-frame deletion of 42 amino acids, however the abundance of FLNA protein was equivalent to that observed in healthy individuals. Loss of these 42 amino acids removes sites that mediate key FLNA functions, including binding of some ligands and phosphorylation. This phenotype further expands the spectrum of the FLNA filaminopathies.

Laser Speckle Contrast Imaging for the Objective Assessment of Blood Perfusion in Keloids Treated With Dual-Wavelength Laser Therapy.

BACKGROUND: Most of the widely used methods for the assessment of keloid treatment are subjective grading scales based on the opinion of an individual clinician or patient. There is a growing need for objective methods to evaluate keloid treatment. OBJECTIVE: This study aimed to evaluate the value of laser speckle contrast imaging (LSCI) as an objective method for the assessment of dual-wavelength laser therapy for keloids. METHODS: This prospective study included 21 patients with 54 keloids. All patients were treated with a combined 585-nm pulsed dye laser and 1,064 nm neodymium-doped yttrium aluminum garnet dual-wavelength laser at 4 weeks to 6 weeks intervals. Keloids were assessed using the Vancouver Scar Scale (VSS) and LSCI. RESULTS: The total VSS score significantly decreased after 4 sessions of treatment (p < .05). Blood perfusion in keloids as measured by LSCI was significantly reduced after treatment (p < .05). The improvement of chest keloids in terms of the total VSS score and blood perfusion was significantly greater than that of scapular keloids (p < .05). There was a positive correlation between decreased perfusion and reduced total VSS score (R2 = 0.84). CONCLUSION: Blood perfusion in keloids significantly decreased after dual-wavelength laser therapy. Laser speckle contrast imaging is a promising objective method for assessing the improvement of keloids treated with laser therapy.

Long-term outcomes and recurrence-free interval after the treatment of keloids with a standardized protocol.

BACKGROUND: Recurrence rates of keloids have generally been reported at one time point. However, the longer the duration after treatment, the greater the likelihood that such lesions will recur. In this study, we analysed the time to recurrence during long-term follow-up. MATERIAL AND METHODS: We retrospectively reviewed recurrence-free interval in 52 patients with keloid (age 8-79 years) who had been treated between June 2006 and January 2011 using a standardised protocol developed by our group. RESULTS: Mean duration of follow-up was 37.5 (range, 7-120) months in patients with keloid. Kaplan-Meier survival curves revealed a statistically significant difference in recurrence-free interval between ear keloids and keloids excluding ear keloids. Recurrence rate for keloids was high in the first 2 years after treatment. CONCLUSIONS: Kaplan-Meier analysis was useful for understanding the tendency of recurrence of keloids after treatment using a standardised protocol.

Tumor suppressive role of miR-1224-5p in keloid proliferation, apoptosis and invasion via the TGF-ß1/Smad3 signaling pathway.

The molecular mechanism of the pathogenesis of keloids is still not known and the clinical management of keloids remains challenging. MiRNA (microRNA) is a novel class of small regulatory RNAs that has emerged as key post-transcriptional regulators of gene expression. MiRNAs participate in diverse biological processes of various skin diseases and function as key regulators in the occurrence and development of tumors. The purpose of this study was to investigate the involvement of miRNAs in keloid pathogenesis. We performed miRNA microarray analysis to compare miRNA expression between keloid and normal skin samples. We found that 46 miRNAs were upregulated and 28 miRNAs were downregulated in keloid compared with normal skin samples. We focused on miR-1224-5p, which has been reported to function in cancers, although the expression and mechanism of miR-1224-5p in keloids remain to be explored. Overexpression of miR-1224-5p led to inhibition of keloid fibroblast proliferation, promotion of apoptosis and decrease of migration and invasion. Our results suggest that downregulation of miR-1224-5p may be one of the mechanisms involved in the occurrence and development of keloids.

Insights into the Pathophysiology of Hypertrophic Scars and Keloids: How Do They Differ?

GENERAL PURPOSE: To provide information about the clinical presentation of hypertrophic scars and keloids based on their varied structural components. TARGET AUDIENCE: This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care. LEARNING OBJECTIVES/OUTCOMES: After completing this continuing education activity, you should be able to: ABSTRACT: Hypertrophic scars and keloids are firm, raised, erythematous plaques or nodules that manifest when the cicatrix fails to properly heal. They result from pathologic wound healing and often cause pain and decreased quality of life. The appearance of such cosmetically unappealing scars affects the confidence and self-esteem of many patients. These scars can also cause dysfunction by interfering with flexion and extension across joints. Both possess some unique and distinct histochemical and physiologic characteristics that set them apart morphologically and at the molecular level. While these entities have been the focus of research for many years, differentiating between them remains challenging for clinicians.This article reviews the clinical presentation of aberrant scars and illustrates how they can be differentiated. It outlines their pathophysiology and emphasizes the unique molecular mechanisms underlying each disorder. It also examines how altered expression levels and the distribution of several factors may contribute to their unique clinical characteristics and presentation. Further research is needed to elucidate optimal treatments and preventive measures for these types of aberrant scarring.

A novel model of humanised keloid scarring in mice.

Treatments for keloid scarring are a major challenge to scientists and physicians for their unknown aetiology. Although several models, including monolayer cell culture to tissue-engineered models, were developed, further research on keloid has more or less been hindered by the lack of appropriate animal models. Because these aberrant scars are specific to humans, we obtained human normal and keloid skin tissues and isolated dermal fibroblasts from them. Cell morphology, growth and immunohistochemical staining of myofibroblastmarker α-SMA were examined, and the cell medium of 2-hour culture and 24-hour culture was implanted on the back of nude mice. The cell medium of 2-hour culture and 24-hour culture was also analysed by a protein array for the detection of distinction in inflammatory factors. We showed that keloid fibroblasts had similar morphology and growth compared to normal skin fibroblasts, but the α-SMA expression was obviously up-regulated. After 6 weeks, mice of the 2-hour keloid-derived culture medium group exhibited keloid-like hypertrophic nodules macroscopically, while mice of 24-hour keloid-derived culture medium group were similar to normal skin. Histological findings confirmed that the reconstituted skin tissues had the typical features of human keloids. The protein array data revealed that RANTES were involved in humanised fibrotic occurrence in mice, also suggesting they were important modulators of this inflammatory event. This novel model might help to understand the key events that result in the formation of these abnormal scars and provide new therapeutic options.

Endothelial dysfunction may promote keloid growth.

Keloid is a cutaneous fibroproliferative disorder. It results from impaired wound healing that generates persistent inflammation and extensive deposition of collagen fibers in the wound/scar. Keloids tend to be worse in hypertensive patients. The present prospective cross-sectional study assessed whether endothelial dysfunction, which occurs in hypertension, associates with keloid formation and progression. This study included randomly selected patients with keloids who were assessed for surgical keloid treatment in 2013-2014. A series of nonkeloid patients admitted to the hospital was also recruited during this period. To measure endothelial function, all patients underwent digital reactive hyperemia peripheral arterial tonometry. Test results were expressed as reactive hyperemia index (RHI) and augmentation index (AI). In total, 57 patients with keloids and 19 nonkeloid controls were recruited. Keloid patients did not differ from the controls in terms of demographic or clinical variables, but had significantly worse RHI and AI values. Moreover, poor RHI and AI values associated with keloid development on binomial logistic regression. The keloid patients were then divided into four groups depending on whether their keloids started at age 0-12, 13-18, 19-29, or ≥30 years. Patients whose keloids arose before and well after puberty tended to have lower RHI than the controls, but these differences did not achieve statistical significance. However, these two groups did have significantly poorer AI values than the controls. Thus, endothelial dysfunction could cause keloid formation and/or aggravation. This indicates that vascular endothelial cells are important for wound healing.

Keloids and Hypertrophic Scars: Pathophysiology, Classification, and Treatment.

BACKGROUND: Keloid and hypertrophic scars represent an aberrant response to the wound healing process. These scars are characterized by dysregulated growth with excessive collagen formation, and can be cosmetically and functionally disruptive to patients. OBJECTIVE: Objectives are to describe the pathophysiology of keloid and hypertrophic scar, and to compare differences with the normal wound healing process. The classification of keloids and hypertrophic scars are then discussed. Finally, various treatment options including prevention, conventional therapies, surgical therapies, and adjuvant therapies are described in detail. MATERIALS AND METHODS: Literature review was performed identifying relevant publications pertaining to the pathophysiology, classification, and treatment of keloid and hypertrophic scars. RESULTS: Though the pathophysiology of keloid and hypertrophic scars is not completely known, various cytokines have been implicated, including interleukin (IL)-6, IL-8, and IL-10, as well as various growth factors including transforming growth factor-beta and platelet-derived growth factor. Numerous treatments have been studied for keloid and hypertrophic scars,which include conventional therapies such as occlusive dressings, compression therapy, and steroids; surgical therapies such as excision and cryosurgery; and adjuvant and emerging therapies including radiation therapy, interferon, 5-fluorouracil, imiquimod, tacrolimus, sirolimus, bleomycin, doxorubicin, transforming growth factor-beta, epidermal growth factor, verapamil, retinoic acid, tamoxifen, botulinum toxin A, onion extract, silicone-based camouflage, hydrogel scaffold, and skin tension offloading device. CONCLUSION: Keloid and hypertrophic scars remain a challenging condition, with potential cosmetic and functional consequences to patients. Several therapies exist which function through different mechanisms. Better understanding into the pathogenesis will allow for development of newer and more targeted therapies in the future.

Role of Homeodomain-Interacting Protein Kinase 2 in the Pathogenesis of Tissue Fibrosis in Keloid-Derived Keratinocytes.

Epithelial-mesenchymal transition (EMT) plays a critical role in fibrotic keloid formation, which is characterized by excessive collagen and extracellular matrix synthesis and deposition. Growing evidence suggests that the serine/threonine kinase homeodomain-interacting protein kinase 2 (HIPK2) acts upstream of several major fibrosis signaling pathways; however, the role of HIPK2 in the keloid fibrogenesis remains unknown. In the current study, we investigated the roles of HIPK2 in the pathogenesis of keloids. Primary normal skin and keloid keratinocytes were cultured and pretreated with transforming growth factor (TGF)-ß1. Next, keratinocytes were transfected with scrambled small interfering RNA (siRNA) and anti-HIPK2 siRNA. The TGF-ß1-associated HIPK2 alterations were investigated by quantitative real-time polymerase chain reaction. Protein levels were analyzed by western blotting. The HIPK2 was markedly increased in the keloid-derived keratinocytes compared with normal skin keratinocytes. In addition, HIPK2 induced the expression of EMT markers in normal skin keratinocytes by TGF-ß1-SMAD family member 3 (SMAD3). The effect of TGF-ß1-related EMT markers and SMAD3 phosphorylation in response to added TGF-ß1 was significantly abrogated when the cells were transfected with HIPK2 siRNA. We conclude that HIPK2 is a crucial factor in the pathogenesis of keloids, suggesting that HIPK2 might be a novel potential drug target for antikeloid therapy.

Keloid progression: a stiffness gap hypothesis.

Keloids are fibroproliferative skin disorders characterised clinically by continuous horizontal progression and post-surgical recurrence and histologically by the accumulation of collagen and fibroblast ingredients. Till now, their aetiology remains clear, which may cover genetic, environmental and metabolic factors. Evidence in the involvement of local mechanics (e.g. predilection site and typical shape) and the progress in mechanobiology have incubated our stiffness gap hypotheses in illustrating the chronic but constant development in keloid. We put forward that the enlarged gap between extracellular matrix (ECM) stiffness and cellular stiffness potentiates keloid progression. Matrix stiffness itself provides organisational guidance cues to regulate the mechanosensitive resident cells (e.g. proliferation, migration and apoptosis). During this dynamic process, the ECM stiffness and cell stiffness are not well balanced, and the continuously enlarged stiffness gap between them potentiates keloid progression. The cushion factors, such as prestress for cell stiffness and topology for ECM stiffness, serve as compensations, the decompensation of which aggravates keloid development. It can well explain the typical shape of keloids, their progression in a horizontal but not vertical direction and the post-surgical recurrence, which were evidenced by our clinical cases. Such a stiffness gap hypothesis might be bridged to mechanotherapeutic approaches for keloid progression.

Increased blood flow in keloids and adjacent skin revealed by laser speckle contrast imaging.

BACKGROUND AND OBJECTIVES: Keloids are fibroproliferative lesions of unknown origin that are characterized by increased collagen deposition. Vascularization may play a role in the pathogenesis of keloids, but existing reports are contradictory. Thus, we assessed perfusion within keloids and surrounding skin using laser speckle contrast imaging (LSCI). STUDY DESIGN/MATERIALS AND METHODS: Twenty-one patients with 61 untreated keloids were enrolled into this study. LSCI was used to evaluate blood flow in the keloids and surrounding skin. Three regions of interest were manually defined: keloids (K), skin adjacent to keloids (A), and nonadjacent skin separated by at least 0.3 cm from the edge of the keloids (N). Mean perfusion in each of these regions was determined and ratios (K/N, A/N) were calculated. RESULTS: Significantly higher perfusion was noted in keloids and adjacent skin compared with nonadjacent skin (P < 0.05). The mean values (95% confidence intervals) of the ratios were: K/N = 2.41 (2.28-2.54) and A/N = 1.33 (1.28-1.37). A heterogeneous perfusion map was frequently observed. Mean perfusion in keloids and nonadjacent skin in the chest region was significantly higher than that on the back (P < 0.05). There was no statistical signficant difference in K/N at different locations (P > 0.05). CONCLUSIONS: Perfusion values in keloids and adjacent skin were significantly higher than those in nonadjacent skin. LSCI may be a suitable and useful way of assessing perfusion in keloids.

[How to optimize scarring in dermatologic surgery?] / Optimisation de la cicatrisation en chirurgie dermatologique et gestions des aléas.

Scarring is the response elicited by the skin surface to injury and loss of tissue material. Wound healing takes place through a complex natural repair system consisting of vascular, inflammatory and proliferative phenomena, followed by a remodelling and cell apoptosis phase. This incredible repair system is inevitable, but sometimes unpredictable due to individual differences based on multiple factors. The scar is the objective criterion of a skin surgery, both for the patient and the dermsurgeon. It is therefore crucial to establish with the patient during the preoperative consultation, the size and positioning of the expected scar, taking into account the oncologic, anatomic and surgical constraints. Scars can ideally blend into normal skin, but may also give rise to various abnormalities. We can manage and prevent these abnormalities by mastering initial inflammation, that may induce hyperpigmentation and hypertrophy. Early massage using cortocosteroid topic or anti-inflammatory moisturizers may be effective. Random individual scarring may be minimized by a dynamic personalized accompanying scarring.

Where we stand with human hypertrophic and keloid scar models.

We have yet to create a human scar model that demonstrates the complex nature of hypertrophic scar and keloid formation as well as ways to prevent them despite emerging advances in our understanding of the immune system, the inflammatory response, and proteomic and genomic changes after injury. Despite more complex in vitro models, we fail to explain the fundamental principles to scar formation, and the timeline of their development. The solution to developing the ideal in vitro scar model is one that mimics the heterogeneous cellular and molecular interactions, as well as the evolving structure and function of human skin.

Human hypertrophic and keloid scar models: principles, limitations and future challenges from a tissue engineering perspective.

Most cutaneous wounds heal with scar formation. Ideally, an inconspicuous normotrophic scar is formed, but an abnormal scar (hypertrophic scar or keloid) can also develop. A major challenge to scientists and physicians is to prevent adverse scar formation after severe trauma (e.g. burn injury) and understand why some individuals will form adverse scars even after relatively minor injury. Currently, many different models exist to study scar formation, ranging from simple monolayer cell culture to 3D tissue-engineered models even to humanized mouse models. Currently, these high-/medium-throughput test models avoid the main questions referring to why an adverse scar forms instead of a normotrophic scar and what causes a hypertrophic scar to form rather than a keloid scar and also, how is the genetic predisposition of the individual and the immune system involved. This information is essential if we are to identify new drug targets and develop optimal strategies in the future to prevent adverse scar formation. This viewpoint review summarizes the progress on in vitro and animal scar models, stresses the limitations in the current models and identifies the future challenges if scar-free healing is to be achieved in the future.

Altered expression of hyaluronan synthase and hyaluronidase mRNA may affect hyaluronic acid distribution in keloid disease compared with normal skin.

Keloid disease (KD) is a fibroproliferative disorder characterised partly by an altered extracellular matrix (ECM) profile. In fetal scarring, hyaluronic acid (HA) expression is increased, but is reduced in KD tissue compared with normal skin (NS). The expression of Hyaluronan Synthase (HAS) and hyaluronidase (HYAL) in KD and NS tissue were investigated for the first time using a range of techniques. Hyaluronan synthase and HYAL mRNA expression were significantly increased in NS tissue compared with KD tissue (P < 0.05). Immunohistological analysis of tissue indicated an accumulation of HAS and HYAL protein expression in KD compared with NS due to the thicker epidermis. No differences were observed in mRNA or protein expression in KD and NS fibroblasts. Reduced expression of HAS and HYAL may alter HA synthesis, degradation and accumulation in KD. Better understanding of the role of HA in KD may lead to novel therapeutic approaches to address the resulting ECM imbalance.

Roles of lipid metabolism in keloid development.

Keloids are common cutaneous pathological scars that are characterised by the histological accumulation of fibroblasts, collagen fibres, and clinically significant invasive growth. Although increasing lines of research on keloids have revealed genetic and environmental factors that contribute to their formation, the etiology of these scars remains unclear. Several studies have suggested the involvement of lipid metabolism, from a nutritional point of view. However, the role that lipid metabolism plays in the pathogenesis and progression of keloids has not previously been reviewed. The progress that has been made in understanding the roles of the pro- and anti-inflammatory lipid mediators in inflammation, and how they relate to the formation and progression of keloids, is also outlined. In particular, the possible relationships between mechanotransduction and lipid metabolites in keloids are explored. Mechanotransduction is the process by which physical forces are converted into biochemical signals that are then integrated into cellular responses. It is possible that lipid rafts and caveolae provide the location of lipid signaling and interactions between these signaling pathways and mechanotransduction. Moreover, interactions between lipid signaling pathway molecules and mechanotransduction molecules have been observed. A better understanding of the lipid profile changes and the functional roles lipid metabolism plays in keloids will help to identify target molecules for the development of novel interventions that can prevent, reduce, or even reverse pathological scar formation and/or progression.

The relationship between skin stretching/contraction and pathologic scarring: the important role of mechanical forces in keloid generation.

Keloids tend to occur on highly mobile sites with high tension. This study was designed to determine whether body surface areas exposed to large strain during normal activities correlate with areas that show high rates of keloid generation after wounding. Eight adult Japanese volunteers were enrolled to study the skin stretching/contraction rates of nine different body sites. Skin stretching/contraction was measured by marking eight points on each region and measuring the change in location of the marked points after typical movements. The distribution of 1,500 keloids on 483 Japanese patients was mapped. The parietal region and anterior lower leg were associated with the least stretching/contraction, while the suprapubic region had the highest stretching/contraction rate. With regard to keloid distribution, there were 733 on the anterior chest region (48.9%) and 403 on the scapular regions (26.9%). No keloids were reported on the scalp or anterior lower leg. Because these sites are rarely subjected to skin stretching/contraction, it appears that mechanical force is an important trigger that drives keloid generation even in patients who are genetically predisposed to keloids. Thus, mechanotransduction studies are useful for developing clinical approaches that reduce the skin tension around wounds or scars for the prevention and treatment of not only keloids but also hypertrophic scars.

Notch signaling pathway in keloid disease: enhanced fibroblast activity in a Jagged-1 peptide-dependent manner in lesional vs. extralesional fibroblasts.

Keloid disease (KD) is a fibroproliferative disorder of unknown etiopathogenesis with ill-defined treatment. There is increasing evidence to suggest that aberrant Notch signaling may contribute directly to skin pathogenesis and altered expression of Notch receptors identified in KD. Therefore, the aim of this study was to investigate the Notch signaling pathway in KD compared to normal skin (NS). In this study, we employed in vitro primary cell culture models to elucidate the role of Notch signaling in 44 tissue samples from patients with KD split into keloid and extralesional (EL) samples (internal control) from the same patients, and six NS tissue samples (external control). We show the presence of a significant (p < 0.05) up-regulation of Notch receptors and ligand Jagged-1 (JAG-1) in KD compared to EL and NS tissue samples. Cell spreading, attachment, and proliferation were significantly (p < 0.05) reduced in JAG-1 antisense-treated primary dermal fibroblasts isolated from KD and treated with γ-secretase inhibitor (blocks proteolytic cleavage and activation of Notch), evaluated by real-time cell analyzer (RTCA) on a microelectronic sensory array. In contrast, extralesional skin fibroblasts (ELF) treated with recombinant human JAG-1 (rh-JAG-1) peptide showed significant (p < 0.05) enhancement of cell spreading, attachment, and proliferation in RTCA. Activation/inhibition of JAG-1 and Notch signaling significantly (p < 0.05) altered the behavior of primary keloid fibroblasts and ELF, in cell migration (using a scratch wound assay), invasion (using a 3D invasion assay), and angiogenesis (in vitro coculture tube formation assay). In conclusion, this is the first study to demonstrate a potential role for the Notch signaling pathway in KD progression and that targeting this pathway may provide a novel strategy for treatment of KD.