Encapsulation of Adipose Stromal Vascular Fraction Cells in Alginate Hydrogel Spheroids Using a Direct-Write Three-Dimensional Printing System

Abstract

The study of tissue function in vitro has been aided by the development of three-dimensional culture systems that more accurately duplicate the complex cell components of tissues and organs. Bioprinting of cells provides a rapid tissue fabrication technique that can be used to evaluate normal and pathologic conditions in vitro as well as to construct complex three-dimensional tissue structures for implantation in regenerative medicine therapies. Studies were performed using a direct write three-dimensional bioprinting system to fabricate adipose-derived stromal vascular fraction cell spheroids. Human fat–derived stromal vascular fraction cells were mixed in 1.5% (w/v) alginate solutions, and fabrication conditions were varied to produce an array of spheroids. The spheroids were placed in spinner culture, and spheroid integrity and encapsulated cell viability were assessed for 16 days. Results establish the ability to tightly control adipose SVF spheroids in the range of 800–1500 μm. Fabrication conditions were used to control spheroid size, and the results illustrate the ability to construct spheroids of precise size and shape. The adipose SVF cell population remains viable and the spheroid integrity was maintained for 16 days in suspension culture. The direct-write printing of adipose stromal vascular fraction cell containing spheroids provides a rapid fabrication technology to support in vitro microphysiologic system studies.

Advances in multicellular spheroids formation

“…Human colon Matrigel -rich in growth factors, signal factors for cell proliferation -expensive and animal derived PC-3M, PrCa, NCI-H600 [74], HepG2 [75], A235, B16F10 [76] agar -damage on cells by forces from gel formation inside the agar -excellent mechanical properties human foreskin dermal fibroblasts [77], cortical cell [78] alginate -rapid formation of hydrogel scaffolds -strong chemicals required to break hydrogel networks to harvest MCSs human fat-derived stromal vascular fraction cells [79], human colon cancer cells (HCT116) [80] fibrin -promoting cell attachment -high cell viability human mesenchymal stem cell [81], B16-F1…”

3D bioprinting technology for regenerative medicine applications

“…Different OBL systems such as "Fabber"(a robotic printer developed by Cornell University, USA), 3D dispensing laboratory printer (LBP) developed by MUSC bioprinting research centre, Charles-ton, SC and 3D-Bioassembly Tool (BAB) developed by Scipero, Orlando USA have been developed to construct 3D tissues/organs. Though BAB is still in its infancy, this method can evolve as a promising solution to create patient-specific tissue constructs for regenerative medicine applications [33,70,71] . However, lack of scalability and problems with precise printing are the major drawbacks of the current robotic bioprinters.…”

Biofabrication of Vascular Networks

“…Interestingly, and immediately relevant to fabricating vasculatures, fusion of hollow spheroids containing vascular cells printed in contact with each other leads to the formation of a contiguous lumen between the spheroids via a fluid forces mechanism [73]. In continuous extrusion printing, or direct-write printing [64,74], vascular bioinks are additively extruded onto a surface using controlled x, y, and z movements of either the print head or stage of a printing robot in a manner analogous to rapid prototyping in mechanical applications [64,75]. It was this type of printing that was used to construct the sacrificial glass channels mentioned previously [63] and has been used to directly pattern ECs in a mixed-cell bone construct [76] and preangiogenic microvessels to form microvascular networks of defined topologies [28].…”