An Innovative Collagen-Based Cell-Printing Method for Obtaining Human Adipose Stem Cell-Laden Structures Consisting of Core–Sheath Structures for Tissue Engineering

Abstract

Three-dimensional (3D) cell printing processes have been used widely in various tissue engineering applications due to the efficient embedding of living cells in appropriately designed micro- or macro-structures. However, there are several issues to overcome, such as the limited choice of bioinks and tailor-made fabricating strategies. Here, we suggest a new, innovative cell-printing process, supplemented with a core-sheath nozzle and an aerosol cross-linking method, to obtain multilayered cell-laden mesh structure and a newly considered collagen-based cell-laden bioink. To obtain a mechanically and biologically enhanced cell-laden structure, we used collagen-bioink in the core region, and also used pure alginate in the sheath region to protect the cells in the collagen during the printing and cross-linking process and support the 3D cell-laden mesh structure. To achieve the most appropriate conditions for fabricating cell-embedded cylindrical core-sheath struts, various processing conditions, including weight fractions of the cross-linking agent and pneumatic pressure in the core region, were tested. The fabricated 3D MG63-laden mesh structure showed significantly higher cell viability (92 ± 3%) compared with that (83 ± 4%) of the control, obtained using a general alginate-based cell-printing process. To expand the feasibility to stem cell-embedded structures, we fabricated a cell-laden mesh structure consisting of core (cell-laden collagen)/sheath (pure alginate) using human adipose stem cells (hASCs). Using the selected processing conditions, we could achieve a stable 3D hASC-laden mesh structure. The fabricated cell-laden 3D core-sheath structure exhibited outstanding cell viability (91%) compared to that (83%) of an alginate-based hASC-laden mesh structure (control), and more efficient hepatogenic differentiations (albumin: ∼ 1.7-fold, TDO-2: ∼ 7.6-fold) were observed versus the control. The selection of collagen-bioink and the new printing strategy could lead to an efficient way to achieve 3D cell-laden mesh structures that mimic the anatomical architecture of a patient's defective region.

3D bioprinting of liver-mimetic construct with alginate/cellulose nanocrystal hybrid bioink

“…18 Alginate is a natural polymer that has been extensively studied as a hydrogel material for tissue engineering applications due to its favorable properties, such as biocompatibility and easy processability. [19][20][21] Upon exposure to divalent cations such as Ca 2+ , alginate undergoes a rapid and robust gelation process where the polymer chains form an "egg-box structure" with the divalent ions. 22,23 However, the rheological properties of pure alginate result in poor printability and pattern fidelity, which greatly limits its use in 3D bioprinting.…”

An innovative cell-laden α-TCP/collagen scaffold fabricated using a two-step printing process for potential application in regenerating hard tissues

“…Cell printing can directly print any cells, using a cell-laden hydrogel (bioink), on the required region of the scaffold, resulting in successful 3D tissue architecture with homogeneous cell proliferation and even differentiation. Various methods, such as dispensing with a micro-sized nozzle using pneumatic/mechanical pressure, ink-jet printing with heat, acoustic waves, piezoelectric transducers (PZT), and laser printing, have been used to fabricate cell-laden structures 5–10 . Using the crosslinking properties of bioinks has improved the process of cell printing.…”

Spatially and temporally controlled hydrogels for tissue engineering

“…A cell-laden collagen-based bioink was delivered in the core region, while an alginate bioink was delivered in the sheath region, which created a mechanically robust and biologically functional structure (Fig. 12a) [178]. Fibrinogen is converted into insoluble fibrin catalyzed by thrombin in presence of Ca 2+ during the blood clot formation process.…”

“…(iii) Cell viability of 3D bioprinted structures. Reproduced with permission from: (a) [178] (b) [181] (c) [182]. …”