Microfluidically Spun Microfibers for Cell-Therapy and Tissue Engineering Applications
Microfluidically Spun Microfibers for Cell-Therapy and Tissue Engineering Applications
Soheyl Mirzababaei,1Mona Navaei-Nigjeh,2,*
1. Pharmaceutical Sciences Research Center, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences (TUMS), Tehran, Iran 2. Pharmaceutical Sciences Research Center, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences (TUMS), Tehran, Iran
Introduction: Tissue engineering (TE) is a multidisciplinary approach that combines cell biology and engineering. TE aims to develop functional scaffolds outside of the human body that could replace damaged or dysfunctional tissues or organs. To fulfill this purpose, different bottom-up construction methods have been used to develop cell-laden structures in the form of fibers, droplets, and sheets with the functionality of the target tissue. Among these structures, fibers have gained attraction in the field of biofabrication and biomaterials since they can resemble the connective tissue and guide cell growth and network.
Methods: Several methods including wet spinning, rotary spinning, phase separation, and electrospinning have been used to develop microfibers. Among these, electrospinning is the most common method for fiber fabrication due to scalability and its capability to control the physicochemical properties of the fibers by changing the operational parameters. In this method, a high electric field will be subjected to a polymer solution that is fed to a needle in order to draw a fiber from the solution. This method yields in nonwoven or oriented mats. Meanwhile, due to the advances in microfabrication methods, microfluidic devices have been used for the fabrication of biomaterials. The microfluidic spinning approach consists of a sample flow which is a polymerizable solution, a sheath flow which acts as a lubricant to facilitate fiber extrusion and/or fiber formation, and a microfluidic device that provides a platform, in the channels of which the two fluids flow and come into contact to form the fiber. In this method, fibers form based on ion cross-linking, photopolymerization, solvent exchange, and chemical crosslinking.
Results: Although electrospinning is a simple method to fabricate fibers from a variety of polymers, it is not a suitable technique for generating cell-laden fibers. This is because the stress that is imposed on the cells could dramatically reduce their viability and functionality. In contrast, microfluidic spinning provides a more cell-friendly approach for the fabrication of meter-long cell-laden microfibers. By changing the properties of the sample flow, sheat flow, and the design of the microfluidic device, fibers with desirable physicochemical properties could be generated. Besides, fibers with different cross-sections could be tailored by changing the cross-section of microchannels. Accordingly, cell-laden microfibers of desirable functionality could be produced. For instance, pancreatic islets could be encapsulated in microfibers for the treatment of type 1 diabetes mellitus. Grooved microfibers could be generated to guide the alignment of neural cells in order to generate neural conduits. Also by fabricating hollow fibers and encapsulating endothelial cells in them, microvessels could be generated to mimic vasculature in the human body.
Conclusion: Microfluidic spinning is a versatile approach that could fabricate microfibers with appropriate properties suiting a specific purpose. In this manner, not only could cells be seeded on the surface of the fibers, but also they could be encapsulated in the fibers to form functional hydrogel-based microfibers. The generated cell-laden microfibers could be used as artificial tissues to replace dysfunctional tissue in the human body. Besides, since they could provide a 3D structure that mimics the extracellular matrix, they could improve cell viability and functionality, therefore, be used as 3D in vitro models.