Proteoglycan biosynthesis in relation to differentiation of cord blood monocytes in vitro

Human monocytes were obtained from umbilical cord blood and cultured in vitro. By morphological criteria, the neonatal monocytes developed into macrophage-like cells in the course of 3-5 days in culture. The cells were exposed to (35S) sulphate for 24 h, either from day 0-1 or day 9-10 in vitro. The 35S-labelled macromolecules recovered were mainly associated with medium fraction (approximately 75%) in both day 1 and day 10 cultures. These secretory macromolecules were demonstrated by use of chondroitinase ABC-digestions to contain predominately chondroitin sulphate proteoglycan (CSPG). (35S) galactoseaminoglycan chains from day 10 cultures were more highly sulphated than the corresponding day 1 species due to the appearance of (glucuronosyl-4,6-diS-N-acetylgalactosamine) disulphated disaccharide units. The galactosaminoglycan chains in neonatal CSPG were found to increase in Mr during cultivation in vitro; from mean Mr of 20400 to 30200 (n=5) in day 1 and day 10 medium proteoglycans, respectively. The corresponding Mr values for adult monocyte (35S) galactosaminoglycan chains were 21 300 and 22 800. On the basis of concomitant changes in cellular morphology and glycosaminoglycan structure, it is concluded that neonatal monocytes, like monocytes from adults, differentiate into macrophage-like cells in vitro. (author)