Map and correlate intracellular calcium response and matrix deposition in cartilage under physiological oxygen...

Face to the limited repair capability of cartilage, we intended to find out signaling responsible for its matrix synthesis. Since spontaneous calcium response likes a label of cell status, here it was mapped in fresh and 24 hr cultured in situ chondrocytes under oxygen tensions of 20%, 5%, and 1% as well as mimic hypoxia conditions. The calcium source was traced using ethylene glycol-bis (β-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) and thapsigargin (TG) to treat cartilage. Their relative matrix of type II collagen (COLL-II) and glycosaminoglycan (GAG) were quantified after cultured for 3 and 7 days. We disclosed the specific fingerprint of calcium response and matrix deposition along the histological zones under various oxygen tensions, from which the effects of hyperoxia, normoxia, and hypoxia conditions on as well as the optimal oxygen tensions for maintenance of various zones of cartilage or chondrocytes were derived and obtained. Our results revealed that cytoplasm calcium was conducive to synthesize COLL-II but detrimental to synthesize GAG. These results provide correlation in addition to details of intracellular calcium response and matrix deposition in in situ cartilage along its histological zones under physiological oxygen tensions.