Embedded Bioprinting of Tissue-like Structures Using κ-Carrageenan Sub-Microgel Medium

Summary

This study introduces a novel κ-carrageenan sub-microgel suspension bath, displaying remarkable reversible jamming-unjamming transition properties. These attributes contribute to the construction of biomimetic tissues and organs in embedded 3D bioprinting. The successful printing of heart/esophageal-like tissues with high resolution and cell growth demonstrates high-quality bioprinting and tissue engineering applications.

Abstract

Embedded three-dimensional (3D) bioprinting utilizing a granular hydrogel supporting bath has emerged as a critical technique for creating biomimetic scaffolds. However, engineering a suitable gel suspension medium that balances precise bioink deposition with cell viability and function presents multiple challenges, particularly in achieving the desired viscoelastic properties. Here, a novel κ-carrageenan gel supporting bath is fabricated through an easy-to-operate mechanical grinding process, producing homogeneous sub-microscale particles. These sub-microgels exhibit typical Bingham flow behavior with small yield stress and rapid shear-thinning properties, which facilitate the smooth deposition of bioinks. Moreover, the reversible gel-sol transition and self-healing capabilities of the κ-carrageenan microgel network ensure the structural integrity of printed constructs, enabling the creation of complex, multi-layered tissue structures with defined architectural features. Post-printing, the κ-carrageenan sub-microgels can be easily removed by a simple phosphate-buffered saline wash. Further bioprinting with cell-laden bioinks demonstrates that cells within the biomimetic constructs have a high viability of 92% and quickly extend pseudopodia, as well as maintain robust proliferation, indicating the potential of this bioprinting strategy for tissue and organ fabrication. In summary, this novel κ-carrageenan sub-microgel medium emerges as a promising avenue for embedded bioprinting of exceptional quality, bearing profound implications for the in vitro development of engineered tissues and organs.

Introduction

Tissue engineering scaffolds, including electro-spun fibers, porous sponges, and polymer hydrogels, play a pivotal role in the repair and reconstruction of damaged tissues and organs by providing a structural framework supporting cell growth, tissue regeneration, and the restoration of organ function^1,2,3. However, traditional scaffolds encounter challenges in accurately replicating native tissue structures, leading to a mismatch between the engineered and natural tissues. This limitation hinders the efficient healing of defective tissues, emphasizing the urgent need for scaf....

Protocol

1. Preparation of the κ -carrageenan sub-microgel suspension bath

1. Prepare 500 mL of κ-carrageenan suspension bath (0.35% wt/vol) by adding 1.75 g of κ -carrageenan powder into 500 mL of phosphate-buffered saline (PBS, pH 7.4) solution within a 1,000 mL glass bottle.
2. Introduce a 70 mm magnetic stirrer bar into the glass bottle to stir the aqueous mixture. Tighten the glass bottle cap and then loosen it by half a turn.
3. Place the glas.......

Discussion

The preparation of κ-carrageenan sub-microgel suspension baths for use in bioprinting is a carefully orchestrated process that involves several critical steps to ensure the resulting medium exhibits the desired properties for supporting bioinks. Initially, a κ-carrageenan solution is prepared by dissolving the κ-carrageenan powder in deionized water at elevated temperatures, creating a homogeneous mixture. The concentration of th.......

Materials

Name	Company	Catalog Number	Comments
3D bioprinter	Custom-designed
4’,6-Diamidino-2-Phenylindole	Solarbio Life Science	C0065	Ready-to-use
405 nm UV light	EFL	XY-WJ01
Cell Counter	Corning	Cyto smart 6749
Confocal laser scanning microscope	Leica	STELLARIS 5
DMEM high glucose	VivaCell	C3113-0500	High Glucose, with Sodium Pyruvate and L-Glutamine
Dynamic rotational rheometer	TA Instrument	Discovery HR-20
Esophageal smooth muscle cells	Supplied by the Department of Cell Biology and Regenerative Medicine, Health Science Center, Ningbo University		Primary cells from the rabbit esophagus
Fetal bovine serum	UE	F9070L
Fluorescein isothiocyanate labeled phalloidin	Solarbio Life Science	CA1610	300T
Gelatin methacrylate	EFL	EFL-GM-60	60% substitution
k-carrageenan	Aladdin	C121013-100g	Reagent grade
Lithium Phenyl (2,4,6-trimethylbenzoyl) phosphinate	Aladdin	L157759-1g	365~405 nm
Live-Dead kit	beyotime	C2015M
Microplate reader	Potenov	PT-3502B
Paraformaldehyde	Solarbio Life Science	P1110	4%
Penicillin/streptomycin	Solarbio Life Science	MA0110	100 ´
Phosphate buffered saline	VivaCell	C3580-0500	pH 7.2-7.4
Silk fibroin methacrylate	EFL	EFL-SilMA-001	39% substitution
Triton X-100	Solarbio Life Science	T8200
Trypsin-EDTA	VivaCell	C100C1	0.25%, without phenol red