Figure 5: IDO enzyme activity and PGE2 and HGF concentrations in supernatants of encapsulated hASC. One week after encapsulation in alginate and Si-HPMC, hASC were stimulated (or not) with TNF-α and IFN-γ (20 ng/mL each) for 72 h. For each condition, twenty alginate or Si-HPMC particles were then disrupted and encapsulated hASC were counted. IDO enzyme activity (a) was measured by tryptophan-to-kynurenine conversion with photometric determination of kynurenine concentration in the supernatant. PGE2 (b) and HGF (c) were measured in cell supernatant using ELISA kits according to the manufacturer’s recommendations. The secretion of these biofactors was normalized to the number of encapsulated hASC in both alginate and Si-HPMC particles. Alginate and Si-HPMC particles of 1 mm diameter were selected for this study. , , and .