Microarrays as a preliminary screen for useful surface epitopes. (A) Schematic of 2 protocols used to prepare human MSCs. (B) Phase-contrast photomicrographs of viable MSCs from passage 1/donor 1 plated at 100 cells/cm² and incubated for 5 or 9 days to generate passage 2 MSCs. (C) Assay by forward and side scatter of light of MSCs from panel B. Vertical and horizontal lines were generated with microbeads to standardize the assay.¹⁰  (D) Microarray assays of mRNAs from viable MSCs from passage 1/donor 6 plated at 100 cells/cm² and incubated for 5 days to approximately 50% confluency, 10 days to 100% confluency, and 15 days to overconfluency. The values were normalized to mRNA signals on day 15 (left) or on day 5 (right).