MECHANICAL AND BIOMOLECULAR CHARACTERIZATION OF HUMAN BONE MARROW

Abstract

Human bone marrow (BM)-derived stem cells are considered for clinical applications. Typically, large numbers of cells are required to replenish depleted cell populations. However, current in vitro culture expansion environments promote terminal differentiation and/or senescence. Evidence shows that the biophysical and molecular microenvironment of stem cells exert cues for quiescence, expansion and differentiation. An in-depth understanding of these components can enhance understanding of the stem cell microenvironment. We have quantified the mean stiffness via atomic force microscopy-enabled nanoindentation, signature extracellular matrix (ECM) proteins via multiplexed immunoassays, and ECM composition via mass spectrometry analysis. The stiffness of intact hydrated, adult BM was 138 Pa ×/÷ 1.06 (n = 9), and the major ECM constituent was fibronectin (8.53 μg/mL of marrow aspirate). Five interleukins and growth factors (hepatocyte, fibroblast, and plasma-derived) were most abundant at concentrations greater than 170 pg/mL. These properties provide a baseline to recapitulate BM microenvironment in vitro.