Chemical and molecular tools to probe biological sex differences at multiple length scales

Y chromosome linked UTY modulates sex differences in valvular fibroblast methylation in response to nanoscale extracellular matrix cues

Aortic valve stenosis (AVS) is a progressive disease wherein males develop valve calcification relative to females that develop valve fibrosis. Valvular interstitial cells (VICs) aberrantly activate to myofibroblasts during AVS, driving the fibrotic valve phenotype in females. Myofibroblasts further differentiate into osteoblast-like cells and secrete calcium nanoparticles, driving valve calcification in males. We hypothesized the lysine demethylase UTY (ubiquitously transcribed tetratricopeptide repeat containing, Y-linked) decreases methylation uniquely in response to nanoparticle cues in the valve extracellular matrix to promote an osteoblast-like phenotype. Here, we describe a bioinspired hydrogel cell culture platform to interrogate how nanoscale cues modulate sex-specific methylation states in VICs activating to myofibroblasts and osteoblast-like cells. We found UTY (ubiquitously transcribed tetratricopeptide repeat containing, Y-linked) modulates VIC phenotypes in response to nanoscale cues uniquely in males. Overall, we reveal a novel role of UTY in the regulation of calcification processes in males during AVS progression.

Multifunctional silk vinyl sulfone-based hydrogel scaffolds for dynamic material-cell interactions

Biochemical and mechanical interactions between cells and the surrounding extracellular matrix influence cell behavior and fate. Mimicking these features in vitro has prompted the design and development of biomaterials, with continuing efforts to improve tailorable systems that also incorporate dynamic chemical functionalities. The majority of these chemistries have been incorporated into synthetic biomaterials, here we focus on modifications of silk protein with dynamic features achieved via enzymatic, "click", and photo-chemistries. The one-pot synthesis of vinyl sulfone modified silk (SilkVS) can be tuned to manipulate the degree of functionalization. The resultant modified protein-based material undergoes three different gelation mechanisms, enzymatic, "click", and light-induced, to generate hydrogels for in vitro cell culture. Further, the versatility of this chemical functionality is exploited to mimic cell-ECM interactions via the incorporation of bioactive peptides and proteins or by altering the mechanical properties of the material to guide cell behavior. SilkVS is well-suited for use in in vitro culture, providing a natural protein with both tunable biochemistry and mechanics.

Sex as a Biological Variable in Tissue Engineering and Regenerative Medicine

Although sex differences have been noted in cellular function and behavior, therapy efficacy, and disease incidence and outcomes, the adoption of sex as a biological variable in tissue engineering and regenerative medicine remains limited. Furthering the development of personalized, precision medicine requires considering biological sex at the bench and in the clinic. This review provides the basis for considering biological sex when designing tissue-engineered constructs and regenerative therapies by contextualizing sex as a biological variable within the tissue engineering triad of cells, matrices, and signals. To achieve equity in biological sex within medicine requires a cultural shift in science and engineering research, with active engagement by researchers, clinicians, companies, policymakers, and funding agencies.

Inflammatory serum factors from aortic valve stenosis patients modulate sex differences in valvular myofibroblast activation and osteoblast-like differentiation

Aortic valve stenosis (AVS) is a sexually dimorphic cardiovascular disease that is driven by fibrosis and calcification of the aortic valve leaflets. Circulating inflammatory factors present in serum from AVS patients contribute to sex differences in valve fibro-calcification by driving the activation of valvular interstitial cells (VICs) to myofibroblasts and/or osteoblast-like cells. However, the molecular mechanisms by which inflammatory factors contribute to sex-specific valve fibro-calcification remain largely unknown. In this study, we identified inflammatory factors present in serum samples from AVS patients that regulate sex-specific myofibroblast activation and osteoblast-like differentiation. After correlating serum proteomic datasets with clinical and in vitro myofibroblast datasets, we identified annexin A2 and cystatin C as candidate inflammatory factors that correlate with both AVS patient severity and myofibroblast activation measurements in vitro. Validation experiments utilizing hydrogel biomaterials as cell culture platforms that mimic the valve extracellular matrix confirmed that annexin A2 and cystatin C promote sex-specific VIC activation to myofibroblasts via p38 MAPK signaling. Additionally, annexin A2 and cystatin C increase osteoblast-like differentiation primarily in male VICs. Our results implicate serum inflammatory factors as potential AVS biomarkers that also contribute to sexually dimorphic AVS progression by driving VIC myofibroblast activation and/or osteoblast-like differentiation. Collectively, the results herein further our overall understanding as to how biological sex may impact inflammation-driven AVS and may lead to the development of sex-specific drug treatment strategies.