BME Seminar Series: Dr. Jill Middendorf, University of Minnesota

Jill Middendorf, PhD
Postdoctoral Researcher
University of Minnesota

Abstract:

"Heterogeneity in Soft Musculoskeletal Tissues from Tissue Engineered Cartilage to Lumbar Spine Degeneration"

Understanding the repair process of musculoskeletal engineered tissues and the degeneration process of musculoskeletal soft tissues remains a challenge. Full understanding requires advanced analysis techniques to assess and predict the heterogeneous structure and mechanics throughout the growth process.  In this talk, I will focus on advancing our understanding of human tissue engineered cartilage constructs and lumbar spine degeneration. The engineered cartilage discussed was based on a construct in advanced clinical trials and made by seeding chondrocytes into a collagen scaffold. The scaffold is prone to buckling under compressive loads, which may cause cell death and tissue damage. By experimentally measuring buckling and quantifying local proteoglycan content, I show that local deposition of proteoglycans can increase resistance to buckling. This increased resistance to buckling may be critical to assessing repeatability during the manufacturing process of engineered cartilage. In the second half of the talk, I focus on understanding degeneration of the lumbar spine and low back pain. Using a discrete fiber network model, I show increased axon strain occurs due to heterogeneous collagen networks. This increased strain has previously been correlated with increased expression of pain signaling molecules. Additionally, heterogeneous mechanical properties of the facet capsular ligament are presented based on MRI scores of lumbar spine degeneration. Together these two models advanced understanding of lumbar spine degeneration and low back pain. At the end of this talk, I will briefly discuss my future research goals that use experiments and computational models designed to optimize the long term success of engineered constructs.

Bio:

Jill is currently a postdoctoral researcher at the University of Minnesota-Twin Cities. Her research uses mechanics-based experiments and computational models to understand the mechanisms and the effectiveness of tissue engineering strategies for orthopedic diseases. Specifically, she has used a discrete fiber network model and an inverse mechanics approach to understand how changes to the facet capsular ligament in the spine could cause increased pain signaling. Jill has also investigated buckling in tissue engineered cartilage and the effects of buckling on the repair capabilities of articular cartilage. Jill received her Ph.D. in 2019 from Cornell University. She has received multiple conference awards including 2^nd place in ASME’s student paper competition at the World Congress of Biomechanics and the force and motion foundation travel award at the Orthopedic Research Society (ORS) conference. Additionally, she was awarded an NSF graduate research fellowship (GRFP).