Engineering biomimetic culture systems: impact on human bone marrow-derived stem cells

Abstract 3628 Poster Board III-564 The bone marrow (BM) harbours haematopoietic stem/progenitor cells (HSCs) in anatomically distinct sites (niches) where HSCs are subjected to regulatory cues such as cytokines, cell-cell contacts and extra-cellular matrix (ECM) all of which control stem cell fate. In particular mesenchymal stromal cells (MSCs) are an integral part of the bone marrow and are known to be key regulators of the HSC niche. We have previously shown that bio-artificial scaffolds can have a significant impact on the in vitro behaviour of MSCs. Here, we are therefore focussing on the role of (native) ECM within the MSC-HSC microenvironment by building on our previous findings and published data (Seib et al.,Tissue Eng Part A., 2009 in press). Thus the aim of the current study is (a) to identify niche-specific ECM components and (b) the use of such ECMs for in vitro culture of BM-derived stem cells. To mimic the natural ECM composition of the BM, different ECM types were generated from BM-derived cells using (a) Dexter cultures, (b) standard MSC cultures, (c) MSCs subjected to osteogenic differentiation. After 10 days of culture those MSC-derived ECMs were decellularised using 0.5% Triton-X and 20mM NH 4 OH leaving only the ECM behind (verified by scanning electron microscopy). Those ECMs were used as a substrate for a second culture of MSCs, which were analysed for their proliferation and differentiation potential. Cell-free ECM from standard MSC cultures improved MSC proliferation compared to cells grown on regular tissue culture plastic (TCP) over the period of 8 days. Most notably, all cell-free ECM preparations lead to a significant difference in the cytoskeletal arrangement of MSCs during the first 2 days of culture compared to TCP controls. Cultivation of MSCs on native ECM provided a guiding structure for those cells to grow into, and helped to maintain an elongated cell shape compared to substantial cell spreading on TCP (roundness 0.2 versus 0.5 and cell area of 2.2 versus 8.2mm 2 , respectively, p in vitro. Disclosures: No relevant conflicts of interest to declare.