Evaluation of a synthetic peptide-based bioink (PeptiInk Alpha 1) for in vitro 3D bioprinting of cartilage tissue models

Cartilage pathology in human disease is poorly understood and requires further research. Various attempts have been made to study cartilage pathologies using in vitro human cartilage models as an alternative for preclinical research. Three-dimensional (3D) bioprinting is a technique that has been used to 3D-bioprint cartilage tissue models in vitro using animal-derived materials such as gelatine or hyaluronan, which present challenges in terms of scalability, reproducibility, and ethical concerns. We present an assessment of synthetic self-assembling peptides as bioinks for bioprinted human in vitro cartilage models. Primary human chondrocytes were mixed with PeptiInk Alpha 1, 3D-bioprinted and cultured for 14 days, and compared with 3D chondrocyte pellet controls. Cell viability was assessed through LIVE/DEAD assays and DNA quantification. High cell viability was observed in the PeptiInk culture, while a fast decrease in DNA levels was observed in the 3D pellet control. Histological evaluation using hematoxylin and eosin staining and immunofluorescence labeling for SOX-9, collagen type II, and aggrecan showed a homogeneous cell distribution in the 3D-bioprinted PeptiInks as well as high expression of chondrogenic markers in both control and PeptiInk cultures. mRNA expression levels assessed by - qRT-PCR (quantitative real time-polymerase chain reaction) confirmed chondrogenic cell behavior. These data showed promise in the potential use of PeptiInk Alpha 1 as a bioprintable manufacturing material for human cartilage in vitro models.