Researcher(s)
- Kaitlyn Dohn, Mechanical Engineering, University of Delaware
Faculty Mentor(s)
- X. Lucas Lu, Mechanical Engineering, University of Delaware
Abstract
Calcium ions (Ca2+) are fundamental second messengers in cell signaling, which impacts nearly every aspect of cellular life. The oscillation of the intracellular calcium concentration is known as calcium signaling. Spontaneous calcium signaling in bovine (cow) chondrocytes (the sole cell type in cartilage) has been shown to occur in the absence of external stimuli but in relation to cellular pathways. However, little is known for the mechanisms of intracellular calcium signaling in human osteoarthritis (OA) cartilage. The goal of this study is to determine how different chemicals, each targeting different pathways in the cell, affect spontaneous calcium signaling in human OA chondrocytes. Cartilage explants were harvested from patients who underwent total knee joint replacement surgery. Fluorescent dye was used to label intracellular calcium ions in the samples. Confocal microscopy was then utilized to record spontaneous activity of intracellular calcium ions of in situ chondrocytes. The calcium curve of each individual cell was analyzed based on the formation of peaks to determine responsive rate, number of peaks, time to reach the first peak, time to reach 50% relaxation, magnitude of the first peak, magnitude of all peaks, and time between peaks. With the treatment of antagonists for 10 calcium pathways, we have found that the presence of extracellular Ca2+, intracellular Ca2+ storage in endoplasmic reticulum, Phospholipase-inositol 1,4,5-trisphosphate pathway, purinoceptors, transient receptor potential vanilloid 4 channel, and gap junction affect the initiation and intracellular propagation of spontaneous calcium signaling. This study gives us insight into the mechanism of calcium signaling initiation and intracellular propagation, which are important for chondrocyte mechanobiology and the study of OA.