MFAP4 Promotes Vascular Smooth Muscle Migration, Proliferation and Accelerates Neointima Formation.

OBJECTIVE: Arterial injury stimulates remodeling responses that, when excessive, lead to stenosis. These responses are influenced by integrin signaling in vascular smooth muscle cells (VSMCs). Microfibrillar-associated protein 4 (MFAP4) is an integrin ligand localized to extracellular matrix fibers in the vascular wall. The role of MFAP4 in vascular biology is unknown. We aimed to test the hypothesis that MFAP4 would enhance integrin-dependent VSMC activation. APPROACH AND RESULTS: We produced Mfap4-deficient (Mfap4(-/-)) mice and performed carotid artery ligation to explore the role of MFAP4 in vascular biology in vivo. Furthermore, we investigated the effects of MFAP4 in neointimal formation ex vivo and in primary VSMC and monocyte cultures in vitro. When challenged with carotid artery ligation, Mfap4(-/-) mice exhibited delayed neointimal formation, accompanied by early reduction in the number of proliferating medial and neointimal cells, as well as infiltrating leukocytes. Delayed neointimal formation was associated with decreased cross-sectional area of ligated Mfap4(-/-) carotid arteries resulting in lumen narrowing 28 days after ligation. MFAP4 blockade prohibited the formation of neointimal hyperplasia ex vivo. Moreover, we demonstrated that MFAP4 is a ligand for integrin αVß3 and mediates VSMC phosphorylation of focal adhesion kinase, migration, and proliferation in vitro. MFAP4-dependent VSMC activation was reversible by treatment with MFAP4-blocking antibodies and inhibitors of focal adhesion kinase and downstream kinases. In addition, we showed that MFAP4 promotes monocyte chemotaxis in integrin αVß3-dependent manner. CONCLUSIONS: MFAP4 regulates integrin αVß3-induced VSMC proliferation and migration, as well as monocyte chemotaxis, and accelerates neointimal hyperplasia after vascular injury.

Biomedical laboratory scientists and technicians in digital pathology - Is there a need for professional development?

Objective: Digital pathology (DP) is moving into Danish pathology departments at high pace. Conventionally, biomedical laboratory scientists (BLS) and technicians have prepared tissue sections for light microscopy, but workflow alterations are required for the new digital era with whole slide imaging (WSI); digitally assisted image analysis (DAIA) and artificial intelligence (AI). We aim to explore the role of BLS in DP and assess a potential need for professional development. Methods: We investigated the roles of BLS in the new digital era through qualitative interviews at Danish Pathology Departments in 2019/2020 before DP implementation (supported by a questionnaire); and in 2022 after DP implementation. Additionally, senior lecturers from three Danish University Colleges reported on how DP was integrated into the 2023 bachelor's degree educational curricula for BLS students. Results: At some Danish pathology departments, BLS were involved in the implementation process of DP and their greatest concerns were lack of physical laboratory requirements (69%) and implementation strategies (63%). BLS were generally positive towards working with DP, however, some expressed concern about extended working hours for scanning. Work-task transfers from pathologists were generally greeted positively from both management and pathologists; however, at follow-up interviews after DP implementation, job transfers had not been effectuated. At Danish university colleges, DP had been integrated systematically in the curricula for BLS students, especially WSI. Conclusion: Involving BLS in DP implementation and development may benefit the process, as BLS have a hands-on workflow perspective with a focus on quality assurance. Several new work opportunities for BLS may occur with DP including WSI, DAIA and AI, and therefore new qualifications are warranted, which must be considered in future undergraduate programmes for BLS students or postgraduate programmes for BLS.