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International Journal of Bioprinting 3D-bioprinting of osteochondral plugs

scanner (Axio Scan.Z1; Carl Zeiss Microscopy, USA) at 24 h. PicoGreen (ThermoFisher, USA), 1,9-dimethylene
20× magnification. blue (BlyScan; Biocolor, United Kingdom), and
hydroxyproline (Abcam, USA) assays were performed on
2.10. Biochemical assays the digestate to quantify DNA, sulfated GAG, and collagen
Immediately after culture, hydrogel disks were massed and contents, respectively.
stored frozen (−80°C) prior to conducting biochemical
analyses. The hydrogels were digested with hyaluronidase 3. Results
in PBS (10,000 U/mL; 1 mL per gel) at 37°C for 72 h and
further digested with a papain solution (1.8 U/mL in a 0.2 3.1. Osteochondral plug design
M sodium phosphate buffer solution containing 0.1 M We designed a biphasic OC plug (Figure 2) with a thin
sodium acetate, 14 mM ethylenediaminetetraacetic acid, solid chondral section made from a single cell-laden
and 5 mM cysteine HCl; pH 6.4; 1 mL per gel) at 65°C for bioink, and a thicker bone section consisting of a

Figure 2. Osteochondral (OC) plug design. (A) The cylindrical plug, measuring 12 mm in diameter, consists of a 2-mm-thick chondral section and a
5-mm-thick bone portion. The chondral section consists of a bioprinted cell-laden bioink, and the bone section consists of a reinforcing lattice 3D printed
from a bioresorbable thermoplastic and ceramic composite and a bioprinted cell-laden ink. (B) Schematic representation of replacing damaged OC tissue
with 3D-bioprinted tissue. Damaged tissue is surgically resected similarly to OC autograft and allograft transplants (left). Subsequently, a 3D-bioprinted
OC plug with dimensions matching the resected tissue is implanted (right). Abbreviations: GelMA, methacrylated gelatin; HAMA, methacrylate-modified
hyaluronic acid; HMWHA, high-molecular weight hyaluronic acid; PCL, polycaprolactone. Figure 2A was created using Autodesk Inventor. Figure 2B was
created using BioRender.

Volume 10 Issue 4 (2024) 536 doi: 10.36922/ijb.4053