Fig 1: In vitro hematopoietic recovery: HSPC and MSC co-culture. Hematopoietic stem and progenitors (HSPCs) were grown in direct contact co-culture with MSCs grown on 1, 10, 100 kPa PDMS and TCPS. Proliferation of HSPCs in these co-culture conditions relative to monoculture were determined at (a) 4–5 days and (b) 1 week after co-culture. Individual lines represent replicate experiments. c HSPC surface marker expression of CD123 and CD34 assayed using flow cytometry. d % expression of CD34+ and CD123- cells as mean ± standard deviations. e % expression of CD34- and CD123+ cells as mean ± standard deviations. d-e Co-culture on PDMS of increasing stiffness (1, 10, 100 kPa) indicated in darkening shades of orange, respectively. Co-culture and monoculture of HSPCs on tissue culture polystyrene are shown as with black- and white-striped bars as distinct current standard protocols for comparison. Significant differences were calculated with one-tailed Student’s t tests with unequal variance, (*p < 0.01, **p < 0.005). Data are plotted as mean ± standard deviation, N = 3 across replicate wells