A Cross-Sectional Study of Gender-Specific Influences of Orthopedic Subspecialty Selection.

Background: Per the American Academy of Orthopaedic Surgeons, 6.5% of practicing orthopedic surgeons are female and a majority subspecialize in pediatrics, hand, and foot and ankle surgery. The study purpose is to evaluate influences of orthopedic subspecialty selection, specifically factors such as perceived strength, lifestyle, and mentorship influence on subspecialty decisions and to identify if gender plays a role in these perceptions. Methods: An IRB approved cross-sectional study was conducted via email distribution of a REDCapTM survey to U.S. licensed orthopedic surgeons. Data regarding demographics, professional degree, training and current practice location, and perceptions regarding orthopedic surgery was obtained using Likert rating scales. Data was analyzed using descriptive statistics with two-tailed student's t-tests (α=0.05). Results: The survey yielded 282 responses (182 females and 100 males). Overall, the distribution of residents (28%), fellows (6%), and attendings (66%) correlates well with the prevalence of each respective physician category in the field of orthopedic surgery. The study demonstrated no difference in subspecialty choice based on mentorship, work-life-balance, career advancement, subspecialty culture, salary potential, family planning, or schedule. However, a statistically significant difference exists regarding stereotypes, perceived strength required, and perception of discrimination from pursuing a specific orthopedic subspecialty. 27% of females and 10% of males reported discouragement from any subspecialty (p<0.05). Adult reconstructive and oncology were most frequently discouraged. Women reported not choosing a subspecialty because of perceived physical demands more often than men (p<0.001). Women reported an increased use of adaptive strategies in the operating room (p<0.001). Women were also more likely to report feeling discouraged from pursuing a subspecialty due to their gender (p<0.001). Both men and women reported mentorship as the most influential factor in subspecialty selection. Conclusion: Women and men reported different factors were important in their decision of subspecialty. Women were more likely to be discouraged from a subspecialty and experience discrimination based on their perceived strength compared to male peers. Residents, fellows, and attending surgeons valued mentorship as the most influential in their subspeciality choice. This study suggests intrinsic and extrinsic influences that may differentially affect male and female orthopedic surgeons when they choose a subspecialty. Level of Evidence: III.

Fibroblasts from Patients with Melorheostosis Promote Angiogenesis in Healthy Endothelial Cells through Secreted Factors.

Melorheostosis is a rare sclerosing bone disease with associated vascular abnormalities in skin and bone, which is caused by somatic mosaic single nucleotide variations in the MAP2K1 gene, which encodes MAPK/extracellular signal‒regulated kinase (ERK) kinase 1. However, disease pathogenesis is poorly understood. Using patient-derived cells, we found that affected skin fibroblasts carrying the single nucleotide variations have increased activation of ERK1/2, which results in increased expression and secretion of proangiogenic factors, including VEGF. VEGF secretion was strongly reduced in affected cells after treatment with MAPK/ERK kinase 1 inhibitor trametinib. Treatment of healthy endothelial cells on matrigel with conditioned medium from affected fibroblasts induces the adoption of a proangiogenic phenotype. Direct coculture of fibroblasts and endothelial cells further shows that both secreted factors and extracellular matrix are capable of inducing a proangiogenic phenotype in healthy endothelial cells. Blocking VEGF with bevacizumab reduces the proangiogenic effect of affected fibroblasts in both the matrigel and direct coculture angiogenesis models, indicating that elevated VEGF secretion is a key mediator of increased angiogenesis in melorheostosis tissue. In conclusion, this work identifies the role of several important molecular mediators in the pathogenesis of melorheostosis, including MAPK/ERK kinase 1, phosphorylated ERK1/2, and VEGF, all of which have clinically available pharmacologic inhibitors, which could be further explored as therapeutic targets.

Endothelial/Mesenchymal Stem Cell Crosstalk Within Bioprinted Cocultures.

The development of viable tissue surrogates requires a vascular network that sustains cell metabolism and tissue development. The coculture of endothelial cells (ECs) and mesenchymal stem cells (MSCs), the two key players involved in blood vessel formation, has been heralded in tissue engineering (TE) as one of the most promising approaches for scaffold vascularization. However, MSCs may exert both proangiogenic and antiangiogenic role. Furthermore, it is unclear which cell type is responsible for the upregulation of angiogenic pathways observed in EC:MSC cocultures. There is disagreement on the proangiogenic action of MSCs, as they have also been shown to negatively affect the formation of capillary networks. To address these issues, we investigated the regulation of key angiogenic pathways in scaffolds hosting different EC:MSC ratios fabricated through extrusion-based bioprinting. Human ECs were cocultured with either rat or human MSCs, and the regulation of fundamental angiogenic and arteriogenic pathways was analyzed through DNA, gene, and protein expression. The use of a hybrid human/rat coculture system facilitated pinpointing each cell type role in the regulation of specific genes and showed that MSCs exert a dose-dependent inhibitory effect on the EC expression of angiogenic factors within the first 24 h. Within a week of coculture, MSCs exert a proangiogenic effect, as corroborated in human/human bioprinted cocultures. Interestingly, juxtacrine signaling promoted secretion of the angiogenic factor vascular endothelial growth factor in direct cocultures (EC and MSC co-encapsulated), while paracrine signaling encouraged secretion of the arteriogenic factor platelet-derived growth factor in indirect cocultures (adjacent bioprinting of EC-laden and MSC-laden scaffolds). Overall, the use of a bioprinted system to elucidate EC:MSC interplay allows rapid leveraging of the data for novel vascular TE applications. Despite the transitory negative effect early in the culture, MSC presence is necessary for the regulation of pathways involved in arteriogenesis. With further validation in vivo, this study provides a possible explanation to the controversial findings present in literature and shows how MSC effect on angiogenic pathway regulation mimics the dynamics of blood vessel formation reported in literature and normally occurring in vivo. Impact Statement The coculturing of endothelial cells (ECs) and mesenchymal stem cells (MSCs) holds great promise in tissue engineering for the development of prevascularized tissue constructs. Yet, different studies report conflicting results on the role of MSCs, which can either support or inhibit vasculature formation. Furthermore, it is unclear how each cell type modulates distinct pathways involved in angiogenesis when cocultured. Using bioprinted hybrid coculture systems, we show that MSCs have both a time- and dose-dependent effect on the gene and protein expression of key angiogenic and arteriogenic factors by ECs. These findings, obtained in translationally relevant setup, can readily inform the design of vascularized scaffolds.