Fig. 4. Self-assembly and aggregation of ATDC5s and hMSCs within BTA hydrogels: (A) Cell aggregate formation in cell media in agarose microwell versus cell aggregate formation in BTA viscoelastic hydrogels. (B) ATDC5s formed round and compact aggregates in agarose mould (positive control). ATDC5 chondrocytes tended to aggregate in all BTA formulations; however, cell aggregate were not as compact as compared to agarose mold. Among BTA formulations, 0 : 100 showed more compact aggregates, scale bar 100 μm, n = 2 biological replicates. (C) Self-assembly and aggregation of hMSCs within BTA hydrogels. Cell aggregates size decrease in agarose mold (positive control) showing that aggregate is getting more compact over time. All BTA formulations showed cells aggregation and spheroids formation. However, it can be seen that cells formed smaller aggregates and that there was more spheroid fusion with increasing % of BTA-PG-BTA, scale bar 100 μm. n = 3 biological replicates.