Long-term stability, high strength, and 3D printable alginate hydrogel for cartilage tissue engineering application

Abstract

Cartilage damage is one of the main causes of disability, and 3D bioprinting technology can produce complex structures that are particularly suitable for constructing a customized and irregular tissue engineering scaffold for cartilage repair. Alginate is an attractive biomaterial for bioinks because of its good biological safety profile and fast ionic gelation. However, ionically crosslinked alginate hydrogels are recognized as lacking enough mechanical property and long-term stability due to ion exchange. Here, we developed a double crosslinked alginate (DC-Alg) hydrogel for 3D bioprinting, and human umbilical cord mesenchymal stem cells (huMSCs) could differentiate into chondrocytes on its printed 3D scaffold after 4 weeks’ culture. We performed sequential modification of alginate with L-cysteine and 5-norbornene-2-methylamine, and the DC-Alg hydrogels were obtained in the presence of CaCl2 and ultraviolet light with stronger mechanical properties than those of the single ionic crosslinked alginate hydrogels, which was similar to natural cartilage. They also had better stability and could be maintained in DMEM medium for over 1 month, as well good viability for huMSCs. Moreover, the DC-Alg as 3D printing inks demonstrated a better printing accuracy (∼200 µm). After 4 weeks culture of huMSCs in the 3D printed DC-Alg scaffolds, the expressions of chondrogenic genes such as aggrecan (agg), collagen II (col II), and SRY-box transcription factor 9 (sox-9) were obviously observed, indicating the differentiation of huMSCs into cartilage. Immumohistochemical staining analysis further exhibited cartilage tissue developed well in the 3D printed scaffolds. Our study is the first demonstration of DC-Alg in 3D printing for MSC differentiation into cartilage, which shows a potential application in cartilage defect repair.

Stem Cell-Laden Hydrogel-Based 3D Bioprinting for Bone and Cartilage Tissue Engineering

“…Stem cell-laden alginate-based 3D bioprinting structures have been used in different tissues including bones, cartilage, cardiac, and blood vessels ( Choe et al, 2019 ; Chu et al, 2021 ; De Santis et al, 2021 ). However, two main disadvantages challenge the development: one is the loss of the shape fidelity and integrity after being printed due to the weak mechanical property and the other is the impairment to the adhesion and proliferation of the stem cell.…”

Application of Alginate Hydrogels for Next-Generation Articular Cartilage Regeneration

“…With this goal, alginate was either chemically modified or engineered (sulfhydrylation, alkylation, dopamine modification) [349,354,359,361,376] or combined with other materials or compounds in order to generate mechanically stronger composite systems adapted for cartilage engineering [116,326,346,[350][351][352][353][355][356][357][358]360,[362][363][364][365][369][370][371][372]379].…”

Three-Dimensional Bioprinting for Cartilage Tissue Engineering: Insights into Naturally-Derived Bioinks from Land and Marine Sources

“…In the literature, there is evidence that ionically crosslinked ALG features low mechanical properties and long-term stability due to ion exchange. For these reasons, Chu et al [ 60 ] developed a double crosslinked ALG (DC-ALG) bioink for 3D bioprinting. The study demonstrated that human umbilical cord MSCs could differentiate into chondrocytes after 4 weeks of culture.…”

“…In particular, the authors sequentially modified ALG with L-cysteine and 5-norbornene-2-methylamine and crosslinked scaffolds were obtained using CaCl 2 and ultraviolet (UV) light. The structures showed stronger mechanical properties, similar to native cartilage, good cell viability and chondrogenic potential, indicating cartilage tissue development [ 60 ]. DC-ALG showed a prolonged stability (4 weeks), preserving 60% of its original weight after 30 days.…”