Cell laden hydrogel microspheres using 3D printed microfluidics

Cell laden hydrogel microspheres using 3D printed microfluidics Abstract By Sanika Suvarnapathaki Current tissue engineering therapies use macro-scale three dimensional (3D) scaffolds to treat tissue defects surgically. Uneven cell seeding and oxygen and media perfusion cause low cell viability in these macro-scale scaffolds. Microencapsulation, a technique of encapsulating cells in biocompatible polymers or hydrogels, has the potential to address these key issues, and therefore this technology has been used for numerous healthcare applications over the last two decades. Cell microencapsulation in hydrogels that mimic the tissue physiology and biochemistry has made it possible to use natural hydrogels like gelatin methacrylate (GelMA) to encapsulate cells in microspheres inside an oil emulsion, to serve as micron scale scaffolds to encapsulate cells for tissue engineering applications. Cell microencapsulation, however, has challenges with respect to the number of cell laden microspheres that can be achieved repeatedly with a consistent cell density per microsphere and their ability to achieve and maintain a high cell viability. This is the major impediment to the clinical translation of cell microencapsulation to treat tissue defects without surgery. In this work, cells were encapsulated within GelMA microspheres, ranging 30-250 micrometers in diameter using a 3D printing and replica casting-molding approach. It is a non-clean room fabrication approach and hence a relatively inexpensive universal platform to encapsulate cells. Rheological properties of varying GelMA concentration were used to identify optimal concentration, flow rates of the GelMA and oil phases and the pressures required to achieve the desired size of microspheres with high repeatability. The success of this approach is demonstrated by high cell viability observed in the in vitro results. The use of 3D printing makes the fabrication of this microfluidic chip easy, inexpensive and accessible to biological researchers, and as a result, help lower the barrier of entry to the field of microencapsulation