Effects of pentosan polysulfate on human mesenchymal precursor stem cell differentiation: adipocyte formation. Bar graph showing the concentration effects of pentosan polysulfate (PPS) on human mesenchymal precursor stem cell (MPC) adipogenic differentiation when cultured for 28 days in an adipogenic inductive medium. Primary MPCs were cultured in nonadipogenic growth media (media control) or under adipogenic conditions in the presence of PPS at the indicated concentrations. n = 3 for each PPS concentration studied. On day 28: (a) levels of lipid determined relative to the total amount of DNA per well, and (b) phase-contrast photomicrography of Oil Red O-labelled adipocytes (× 20). Data expressed as mean ± standard error of the mean. A statistically significant increase (P < 0.01) in adipocyte number was observed at PPS concentrations > 1.0 μg/ml. *P < 0.01.