Role of Decorin in the Structure and Mechanical Properties of Articular Cartilage

Thursday, August 22, 2019

1:00 PM-3:00 PM

BIOMED PhD Research Proposal

Title:
Role of Decorin in the Structure and Mechanical Properties of Articular Cartilage

Speaker:
Biao Han, PhD Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University

Advisor:
Lin Han, Associate Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University

Details:
Osteoarthritis (OA) is a joint disease that affects millions of people worldwide, and usually results in severe pain and limited joint motion. It is characterized by compromised mechanical properties of articular cartilage, a result of the irreversible breakdown of its extracellular matrix (ECM). Currently, there is no effective treatment strategy to reverse the cartilage degradation. Aggrecan, the major proteoglycan of articular cartilage ECM, is essential for the load bearing and energy absorption functions.

In early OA, aggrecan becomes fragmented and its loss from the ECM results in irreversible cartilage degradation. Understanding the mechanisms of aggrecan assembly in the ECM has the potential to improve cartilage regeneration and to attenuate OA. The objective of this proposal is to elucidate the role of decorin, a small leucine rich proteoglycan, in regulating the assembly of the aggrecan network in cartilage. In normal cartilage, decorin has molar concentration similar to that of aggrecan. In early OA, decorin is significantly up-regulated, indicating its potential structural and/or biological roles. Indeed, our preliminary results suggested that decorin is critical to the assembly of aggrecan in cartilage ECM.

Upon maturation, in decorin-null cartilage, the ECM exhibits substantial reduction in aggrecan content, resulting in impaired biomechanical properties, including reduced modulus and increased hydraulic permeability. We have shown that this reduction is not due to decreased aggrecan synthesis, increased aggrecan degradation or other secondary factors. Decorin can directly bind to both collagen II fibrils and aggrecan, therefore, we hypothesize that they can serve as “linkers” to adhere aggrecan molecules with the collagen fibril network, as well as with other aggrecan molecules. This hypothesis can also explain our observations in the 3-D culture of primary chondrocytes. In the absence of decorin, despite the similar amount of synthesis, more aggrecan is released to the culture media instead of being retained in the surrounding matrix of the chondrocytes.

Contact Information

Ken Barbee
215-895-1335
barbee@drexel.edu