(M1530-04-19) Bioengineering Models to Study Cell-Specific Durotaxis in Pulmonary Arterial Hypertension

Purpose: Pathological recruitment of stromal cells to sites of vascular remodeling and subsequent activation or dedifferentiation are critical steps in the progression of many lung diseases. We have recently identified a novel mechanism in which diseased pulmonary cells, such as diseased smooth muscle cells (SMCs), are recruited to the distal arteries via “durotaxis,” a form of directed cell migration driven by spatial gradients of matrix stiffness. Here, we explore the molecular mechanisms driving SMC-specific durotaxis in the pathogenesis of pulmonary arterial hypertension (PAH), which is characterized by the presence of steep stiffness gradients, and develop tools to address the lack of suitable models to study durotaxis in vitro and in vivo comprehensively.

Methods: We characterized the durotaxis process in vivo in the preclinical models of Sugen/Hypoxia-induced PAH using a Biological Atomic Force Microscopy (Bio-AFM) nanoindentation technique. We studied the mechanobiology of durotaxis in the complex environment of PAH tissue. We used a photolithographic technique to develop dedicated functional in vitro durotaxis assays based on mechanically patterned hydrogels incorporating stiffness gradients and screen drugs to inhibit durotaxis. Additionally, we utilized phenotypic mapping analysis in an in vivo PAH model to assess how durotaxis affected the spatial mobility of SMCs in the pulmonary arteries using a bioimage analysis tool.

Results: Using in situ Bio-AFM-nanoindentation, we identified steep stiffness gradients from proximal-to-distal arteries of Sugen/Hypoxia-induced PAH lung tissues. Employing our functional durotaxis assays, we demonstrated the potent durotactic capacity of PAH-SMCs in vitro, suggesting that durotaxis may promote the recruitment of those cells. PAH-SMCs durotaxis by sensing proximal-to-distal arterial stiffness gradient that contributes to the muscularization process (presence of SMCs in the distal arterioles). We identified the JAK/STAT pathway as a potent kinase that is highly active in the process of proximal-to-distal migration of SMCs, and the novel inhibitors of JAK-3 reverse the durotaxis process in PAH.

Conclusion: Our work provides novel and innovative mechanistic insights into the role of SMC-specific durotaxis in the development of PAH disease, where mechanotransduction plays an important role. Anti-durotactic therapies may emerge as first-in-class drugs that can target durotaxis pathways in PAH disease.