442768 Using Microfluidics to Mimic the Bone Marrow Microenvironment

Monday, November 9, 2015
Exhibit Hall 1 (Salt Palace Convention Center)
Steven Tau, Chemical Engineering, University of Rochester, Rochester, NY and Jungwoo Lee, Chemical Engineering, University of Massachusetts Amherst, Amherst, MA

Bone marrow stromal cells (BMSCs) are a key cellular component that regulates many key physiological processes in the bone marrow ranging from bone tissue regeneration to blood cell production. Thus, harnessing BMSC function effectively is a critical step to recapitulate functional bone marrow microenvironments outside of the body. Notably BMSCs are known to sensitively respond to their surrounding biophysical environments. We hypothesized that a rational design of material system can direct BMSCs function and in turn create a defined and functional marrow-mimicking microenvironment. In this study, as a first step we aim to develop a simple materials-engineering strategy that can systematically emulate a heterogeneous mechanical environment in the bone marrow.

We prepared size-controlled and varying rigidity microparticles using a glass capillary-based microfluidic droplet technology. Microfluidic devices were constructed using coaxial glass capillaries with one inserted into the other and both affixed to a glass slide. The tip size of the inner glass capillary was modulated using a Flaming/Brown micropipette puller. Liquids were introduced into the microfluidic device via syringe tips connected to the glass capillaries.  For emulating a soft mechanical environment, we prepared polyacrylamide hydrogel (10wt%) via water-oil emulsion droplets.  For mimicking hard mechanical environment, we synthesized polycaprolactone (2wt%) via oil-water emulsion droplets.

We demonstrated mono-dispersed microparticle preparation with sizes ranging from 100-300 mm. Collagen was introduced into polyacrylamide microparticles to induce cell adhesion of BMSCs.  Polycaprolactone microspheres were treated with 0.5 M NaOH and 70% ethanol for 15 minutes each to entail nano-scale surface roughness that in turn promoted BMSCs adhesion.  Primary human BMSCs were seeded onto microparticles for 5 hours, dyed via CellTracker Red dye and then imaged under a confocal microscope. In future studies, we will determine the role of mechanical stiffness and microbead size in regulating BMSC differentiation and secretion. We envision that our microbead-based BMSC culture system would create defined and functional in vitro bone marrow mimicking microenvironments that can be used for basic and translational research related to the bone marrow microenvironment.

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