Figure 2: HSPC expansion and growth factor expression of CD34+ HSPCs cultured on top of microcavity arrays.

(A) HSPCs cultivated for 2 days on top of hydrogel microcavity arrays with cavities of 15 (top) and 40 μm (bottom) diameters. The phase contrast microscopy images prove the 15 μm microcavities to be single-cell cavities, while the 40 μm microcavities contain multiple cells (up to 12) (scale bar: 80 μm). (B) Overall cell number of HSPCs cultured for 1 week on top of TCP and microcavity arrays consisting of FN functionalized PDMS, sPEG-heparin and sPEG hydrogel scaffolds, grown at cytokine background level of 10 ng·mL⁻¹. All data are presented as mean ± SD from one donor with n = 2–3 microcavity samples per donor. Statistical significance is denoted as follows: *P < 0.05, **P < 0.01, ***P < 0.001. (C) Percentage of cells expressing CD34 and CD133 in the total cell population. All data are presented as mean ± SD from one donor with n = 2–3 samples per condition. (D) Plot shows the influence of heparin content of the microcavity arrays on growth factor levels within the cell culture supernatants exemplarily shown for sequestered (HGF) and non-sequestered (IL12) cytokines. Results are presented as mean ± SD from 3 donors with n = 2–3 microcavity arrays per condition and donor. (E) Growth factor levels were measured in the supernatant of day 7 of culture using multiplex analysis. Plot shows measured growth factor levels normalized with the final cell number. Exemplary factors are presented as mean ± SD from either 1 donor (sPEG-sPEG), 2 donors (PDMS-FN), or 4 donors (sPEG-HEP/TCP) with n = 2–3 samples per condition and donor.