Mechanics of intact bone marrow

Abstract

The current knowledge of bone marrow mechanics is limited to its viscous properties, neglecting the elastic contribution of the extracellular matrix. To get a more complete view of the mechanics of marrow, we characterized intact yellow porcine bone marrow using three different, but complementary techniques: rheology, indentation, and cavitation. Our analysis shows that bone marrow is elastic, and has a large amount of intra- and inter-sample heterogeneity, with an effective Young’s modulus ranging from 0.25–24.7 kPa at physiological temperature. Each testing method was consistent across matched tissue samples, and each provided unique benefits depending on user needs. We recommend bulk rheology to capture the effects of temperature on tissue elasticity and moduli, indentation for quantifying local tissue heterogeneity, and cavitation rheology for mitigating destructive sample preparation. We anticipate the knowledge of bone marrow elastic properties for building in vitro models will elucidate mechanisms involved in disease progression and regenerative medicine.

Complementary, Semiautomated Methods for Creating Multidimensional PEG-Based Biomaterials

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Mesenchymal stromal cell remodeling of a gelatin hydrogel microenvironment defines an artificial hematopoietic stem cell niche

“…Therefore, we developed a culture system that takes advantage of paracrine signaling from niche-associated mesenchymal stromal cells (MSCs). Our application of a library of GelMA hydrogels that span the range of elastic moduli found within the native HSC niche [17], as well as advanced poroelastic characterization methods [50,52], allows us to examine dynamic relationships between MSCs, the local matrix architecture, and autocrine versus paracrine domains. HSCPs were co-cultured with MSCs at varying ratios (1:0, 1:1, 1:10…”

“…For example, the native bone marrow niche presents complex patterns of ligands such as laminins and fibronectin [15,16] as well as an effective Young's modulus ranging from 0.25 to 24.7 kPa [17]. Matrix biophysical cues such as elasticity and substrate stiffness can significantly influence HSC expansion and migration, with elastic substrates functionalized with fibronectin shown to induce ex vivo expansion of HSC progenitor populations [1-3, 18, 19].…”

A biomaterial screening approach reveals microenvironmental mechanisms of drug resistance

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