Photopolymerizable gelatin and hyaluronic acid for stereolithographic 3D bioprinting of tissue‐engineered cartilage

Abstract

To create artificial cartilage in vitro, mimicking the function of native extracellular matrix (ECM) and morphological cartilage‐like shape is essential. The interplay of cell patterning and matrix concentration has high impact on the phenotype and viability of the printed cells. To advance the capabilities of cartilage bioprinting, we investigated different ECMs to create an in vitro chondrocyte niche. Therefore, we used methacrylated gelatin (GelMA) and methacrylated hyaluronic acid (HAMA) in a stereolithographic bioprinting approach. Both materials have been shown to support cartilage ECM formation and recovery of chondrocyte phenotype. We used these materials as bioinks to create cartilage models with varying chondrocyte densities. The models maintained shape, viability, and homogenous cell distribution over 14 days in culture. Chondrogenic differentiation was demonstrated by cartilage‐typical proteoglycan and type II collagen deposition and gene expression (COL2A1, ACAN) after 14 days of culture. The differentiation pattern was influenced by cell density. A high cell density print (25 × 106 cells/mL) led to enhanced cartilage‐typical zonal segmentation compared to cultures with lower cell density (5 × 106 cells/mL). Compared to HAMA, GelMA resulted in a higher expression of COL1A1, typical for a more premature chondrocyte phenotype. Both bioinks are feasible for printing in vitro cartilage with varying differentiation patterns and ECM organization depending on starting cell density and chosen bioink. The presented technique could find application in the creation of cartilage models and in the treatment of articular cartilage defects using autologous material and adjusting the bioprinted constructs size and shape to the patient. © 2019 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2649–2657, 2019.

In vitro and in vivo assessment of glucose cross‐linked gelatin/zein nanofibrous scaffolds for cranial bone defects regeneration

“…Even though various biocompatible scaffolds were fabricated for bone tissue engineering, most of them were confined to the in vitro cell tests (Lam et al, ; Sattary et al, ). For the bone injury in vivo, a series of events begin, including recruitment of inflammatory cells and osteogenic cells, which cannot be simulated in vitro.…”

“…Moreover, gelatin nanofibers can be fabricated from environmentally friendly solvents, such as acetic acid. Due to the improved effects of gelatin nanofibers on cell adhesion, proliferation and differentiation, diverse tissue engineering applications for gelatin nanofibers have been reported, such as skin (Dhandayuthapani, Krishnan, & Sethuraman, ), cartilage (Lam et al, ), and bone tissue engineering (Ishiko‐Uzuka et al, ). However, the fast dissolution in body fluid and the weak mechanical properties of gelatin nanofibrous scaffolds have hindered the widespread applications in tissue engineering.…”

Engineered 3D Polymer and Hydrogel Microenvironments for Cell Culture Applications

“…For the addition of 1-3% w/v MeHA, before UV light the storage modulus was 5-200 Pa respectively, while after UV light the storage modulus was 170-2602 Pa respectively, and an overall Young's modulus after UV light of 1.3-10.6 kPa respectively. Such developments has led to photopolymerizable hyaluronic acid-based bioinks mixed with chondrocyte cells for SLA 3D printing at feature sizes of~300 µm [214]. A combined hyaluronic acid/poly-DL-lactic acid/PEG polymer system was printed via projection SLA to achieve structures with compressive modulus of~780 kPa, suitable for cartilage tissue engineering [215].…”

“…Photo-patterned (including the use of TPP) GelMA scaffolds, have been produced down to~50 µm feature size. For SLA, chondrocytes were encapsulated within a GelMA bioink and 3D structures printed with~500 µm feature size [214,327]. The addition of PEGDA with GelMA greatly improved the SLA printing resolution to 300 µm.…”

“…By combining GelMA with different concentrations of methacrylated hyaluronic acid and chondroitin sulphate, encapsulation of chondrocytes, bioprinting the mixture, and in situ UV curing layer-by-layer, a glycosaminoglycan-graded hydrogel was fabricated with good cell viability resulting in its own chondrocyte matrix after 28 days [333]. Chondrocytes encapsulated in a GelMA bioink and 3D printed via SLA showed chondrocyte differentiation after 14 days [214,327]. Finally, a dynamic optical projection SLA system was used to print a vascular network with encapsulated living cells [334].…”