The detection, isolation and sorting of cells holds an important role in cell therapy
and regenerative medicine. Also, injectable systems have been explored for tissue
regeneration in vivo, because it allows repairing complex shaped tissue defects
through minimally invasive procedures.
Here, we report the use of polymeric microspheres to simultaneously isolate and
enrich specific cell types that can be also used as an injectable cell carrier system to
form small tissue constructs in situ. The rationale was to functionalize the particles
with antibodies to target specific cell types and release growth factors (GFs), first to
increase the number of cells growing over the particle surface and then induce the
differentiation of these cells by a sustained release from the particle core.
GFs loaded microspheres of photocrosslinkable chitosan were fabricated using a
flow focusing microfluidic chip. The droplets produced were crosslinked by UV while
flowing inside a Tygon tube before being collected into an eppendorf. Monoclonal
antibodies against cell surface antigens specific to endothelial cells and stem cells
were immobilized on the surface of the microspheres. Experimental results showed
that the microfabricated spheres provide suitable surfaces to capture a target cell
type and subsequent expansion of the captured cells. The aggregation of the
functionalized microspheres has been also shown to successfully form 3D robust
structures upon injection into a mold.