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.

An Overview of PRP-Delivering Scaffolds for Bone and Cartilage Tissue Engineering

Tissue engineering is nowadays an emerging approach that aims to replace or regenerate diseased or damaged organs with engineered constructs. Considering the key role of growth factors (GFs) in the tissue regeneration process, these biomolecules are considered an important part of the tissue engineering process, so the presence of growth factors in engineered scaffolds can accelerate tissue regeneration by influencing the behavior of cells. Platelet-rich plasma (PRP), as an autologous source of a variety of growth factors, is considered a therapeutic agent for the treatment of degenerative diseases. Regarding its ability to promote the healing process and tissue regeneration, PRP therapy has attracted great attention in bone and cartilage tissue engineering. Incorporating PRP and its derivatives into engineered scaffolds not only bioactivates the scaffold, but the scaffold matrix also acts as a sustained and localized growth factor release system. In addition, the presence of a scaffold can promote the bioactivity of GFs by providing an environment that facilitates their interaction, leading to enhanced effects compared to their free form. This review presents a brief overview of PRP's role in bone and cartilage tissue regeneration with the main focus on scaffold-mediated PRP delivery. In addition, the classification of platelet-rich products, current extraction techniques, terminology, and scaffold bioactivation methods are presented to provide a better understanding of the basics and the key aspects that may affect the effectiveness of therapy in bone and cartilage tissue engineering.