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.
See more of this Group/Topical: Student Poster Sessions