3D Bioprinting of Low-Concentration Cell-Laden Gelatin Methacrylate (GelMA) Bioinks with a Two-Step Cross-linking Strategy

Abstract

Methacrylated gelatin (GelMA) has been widely used as a tissue-engineered scaffold material, but only low-concentration GelMA hydrogels were found to be promising cell-laden bioinks with excellent cell viability. In this work, we reported a strategy for precise deposition of 5% (w/v) cell-laden GelMA bioinks into controlled microarchitectures with high cell viability using extrusion-based three-dimensional (3D) bioprinting. By adding gelatin into GelMA bioinks, a two-step cross-linking combining the rapid and reversible thermo-cross-linking of gelatin with irreversible photo-cross-linking of GelMA was achieved. The GelMA/gelatin bioinks showed significant advantages in processability because the tunable rheology and the rapid thermo-cross-linking of bioinks improved the shape fidelity after bioprinting. Here, the rheology, mechanical properties, and swelling of GelMA/gelatin bioinks with different concentration ratios were carefully characterized to obtain the optimized bioprinting setup. We successfully printed the 5% (w/v) GelMA with 8% (w/v) gelatin into 3D structures, which had the similar geometrical resolution as that of the structures printed by 30% (w/v) GelMA bioinks. Moreover, the cell viability of 5/8% (w/v) GelMA/gelatin bioinks was demonstrated by in vitro culture and cell printing of bone marrow stem cells (BMSCs). Larger BMSC spreading area was found on 5/8% (w/v) GelMA/gelatin scaffolds, and the BMSC viability after the printing of 5/8% (w/v) GelMA/gelatin cell-laden bioinks was more than 90%, which was very close to the viability of printing pure 5% (w/v) GelMA cell-laden bioinks. Therefore, this printing strategy of GelMA/gelatin bioinks may extensively extend the applications of GelMA hydrogels for tissue engineering, organ printing, or drug delivery.

Glucosamine‐grafted methacrylated gelatin hydrogels as potential biomaterials for cartilage repair

“…As shown in Figure a, the compressive strength of GelMA–AGA hydrogels improved with GelMA concentration; while the compressive modulus of GelMA–AGA hydrogels varied from 4.4 to 94.7 kPa (Figure b). Compared with our previous results (Yin, Yan, Wang, Fu, & Suo, ), the GelMA–AGA hydrogels were mechanically stronger than pure GelMA hydrogels. Also, it should be noticed that the compressive modulus of 15% GelMA–AGA hydrogels almost reaches the value of immature articular cartilage (100–300 kPa) (Nguyen, Hwang, Chen, Varghese, & Sah, ; Williamson, Chen, & Sah, ).…”

“…Recently, efforts also have been made to improve the processability of GelMA hydrogels using additive manufacturing (Billiet, Gevaert, Schryver, Cornelissen, & Dubruel, 2014;Yin, Yan, Wang, Fu, & Suo, 2018;Zhang et al, 2018). The 3D printing of GelMA-AGA hydrogels would more precisely control the porosity and structure of scaffolds, leading to promising results for osteoarthritis treatment in the future.…”

Composite Biomaterials as Long‐Lasting Scaffolds for 3D Bioprinting of Highly Aligned Muscle Tissue

“…The percentage of living cells in the hydrogels was determined using the live/dead staining kit at 1 and 7 d. The viability obtained in the GelMA hydrogels was about 80% at 1 d, in agreement with previous studies, [61] and about 60% for GelMA-CMCMA and GelMA-AlgMA hydrogels. These composite hydrogels showed a similar slight decrease in the cell viability at day 7 (Figure 6a,b).…”

3D Bioprinting of Architected Hydrogels from Entangled Microstrands

“…Increasing the polymer content of bioinks enhances printability ( 4 ), but the resulting densely crosslinked networked can reduce cell viability and spreading. Methods to print low content bioinks include 1) the addition of flow modifying fillers or additives ( 5 ) 2) printing within a sacrificial support material ( 6 ) 3) partially crosslinking the bioink before or during extrusion to increase yield stress amongst others ( 7 ), 4) templating using a rapidly crosslinkable material, often alginate ( 8 ) and 5) sequential crosslinking of individual layers directly after deposition ( 9 ). In general, stability of structures during printing is challenging given the high water content of most bioinks and tendency of heavy and tall structures to sag under their weight.…”