Optimization and comparison of two different 3D culture methods to prepare cell aggregates as a bioink for organ printing

The ultimate goal of tissue engineering is to design and fabricate functional human tissues that are similar to natural cells and are capable of regeneration.Preparation of cell aggregates is one of the important steps in 3D tissue engineering technology,particularly in organ printing.Two simple methods,hanging drop(HD)and conical tube(CT)were utilized to prepare cell aggregates.The size and viability of the aggregates obtained at different initial cell densities and pre-culture duration were compared.The proliferative ability of the cell aggregates and their ability to spread in culture plates were also investigated.In both methods,the optimum average size of the aggregates was less than 500μm.CT aggregates were smaller than HD aggregates.5,000 cells per drop HD aggregates showed a marked ability to attach and spread on the culture surface.The proliferative ability reduced when the initial cell density was increased.Comparing these methods,we found that the HD method having better size controlling ability as well as enhanced ability to maintain higher rates of viability,spreading,and proliferation.In conclusion,smaller HD aggregates might be a suitable choice as building blocks for making bioink particles in bioprinting technique.

Bioactive Materials:A Comprehensive Review on Interactions with Biological Microenvironment Based on the Immune Response

Application of“bioactive materials”,as a modified version of biomaterials,can optimize the response of the biological system due to their surface reactivity and formation of strong interactions with the adjacent tissue upon implantation.However,choosing an appropriate bioactive material that suits to the application and provides the desired mechanical,physical,chemical and biological functionality,as well as understanding the aspects of biological reaction to the biomaterial,in particular immune response,it plays a key role in successful integration of the implant.In this review,we will discuss different bioactive materials including bioactive ceramics,polymers and composites and their applications in drug delivery and scaffold preparation in order to provide an adequate introduction to the recent studies.Considering the necessity of regulation of implant fate for higher biocompatibility,the comprehensive overview to the immune response will be reviewed with the focus on representing the cell-biomaterial interactions and more importantly,the inflammatory responses.Ultimately,we will also discuss about different approaches namely as immunomodulation to elicit the desired physiochemical properties and mimicking native cellular response using bioactive compounds,functionalizing the implant surface with active molecules and alteration of the surface morphology.With better understanding of bioactive materials and their interactions with body,more novel biomaterials representing desired properties can be designed.