Table 2.

Synthetic 3D printed conditioned scaffolds.

Authors and references	Printing method/parameters	Printing material	Additives or bioink	Shape and/or dimensions — Pore size µm/porosity%	Cells	Scaffold characterization studies	In vitro cells/scaffold interactions	In vivo studies
Bahcecioglu et al. 27	3D CAD (SketchUp, Google). 3D Bioprinter (Bioscaffolder, SYS + ENG). Parameters. Strand orientation: 0/90°; strand distance: 1 mm; w/wo shifting (offset: 0.5 mm) and w/wo circumferential strands. Pig knee MRI scanned on a 3T scanner; lateral meniscus CAD (Mimics, Materialize); 3D Bioprinter (Bioscaffolder, SYS + ENG).	PCL Mw 50,000 Da	- GelMA + cells suspension (impregnation) - GelMA- Agarose + cells suspension (impregnation)	- Square prism, 10 × 10 × 3 mm; - Rectangular prism, 30 × 10 × 3 mm; - Coliseum, 26 × 8 × 5 mm 810 ± 40 μm MESH: Scaffolds w/wo circumferential strands + non-shifted designs + shifted design	- Human fibrochondrocytes (Passage: 3)	- SEM - Mechanical behavior, compressive/tensile load	Static culture - Cell viability - COL I/II deposition, immunostaining	—
Ghodbane et al. 38	3D Bioprinter (Bioplotter, EnvisionTEC). Pneumatic extrusion. Parameters. Needle inner Ø: 400 µm; print T: 160°C; speed: 1.2 mm/s; P: 8.9 bar.	p(DTD DD)	Collagen-hyaluronate sponge infusion	Anterior-posterior length: 32 mm; medial-lateral length: 24 mm 69.9% ± 8.0% MESH: successive layers of circumferential and radial filaments	—	- Determination of percent polymer and COL-hyaluronan - Porosity - Mechanical behavior, confined compressive creep, circumferential tensile testing - Suture retention test - In situ contact stress test	—	—
Li et al. 140	3D CAM/CAD of rabbit medial meniscus (SolidWorks, Autodesk), 3D-Bioprinter (Bioplotter, EnvisionTEC). Parameters. Nozzle Ø: 300 µm; T: 130°C; speed: 7.0 mm/s; P: 0.8 MPa.	PCL Mw 80,000 Da	SF crosslinking + synovial MSCs specific affinity peptide	- Medial meniscus model of a wedged shaped arc disk 300 µm MESH: PCL bundles alternately oriented along the circumferential and perpendicular direction in a bionic manner	- Rat synovial derived MSCs (Passage: 3)	- SEM - Degradation in vitro - Frictional force of interface - Mechanical behavior, compression - FTIR	Static culture - Cell viability - Cell morphology - Biochemical assays (GAG, COL I/II) - Gene expression (COL I/II, SOX9, aggrecan) - Synovial derived MSCs recruitment in vivo	Orthotopic implant (rat) [− cells] Synovial MSCs recruitment (rabbit) [− cells] End point: 12, 24 weeks - Gross evaluation (meniscus) - Cartilage evaluation - SEM (cartilage) - Inflammatory response (histology, IL-1, TNF-α synovia, and synovial fluid) - Biomechanical behavior, compressive/tensile load
Bahcecioglu et al. 141	3D CAD (SketchUp, Google) 3D Bioprinter (Bioscaffolder system, SYS + ENG). Parameters. Strand orientation: 0/90°; strand distance: 1 mm.	PCL Mw 70,000–90,000 Da	- Agarose (impregnation) - GelMA (impregnation) - Agarose + cells suspension (impregnation of inner region) and GelMA + cells suspension (impregnation of outer region)	- Prism, 4 × 4 × 3 mm - Meniscus-like, outer Ø: 30 mm, height at periphery: 5 mm, inner Ø: 10 mm 751 ± 43 μm (PCL) in xy-direction and 97 ± 40 μm in z-direction, filled with hydrogel MESH: strand distance, 1 mm; strand orientation, 0/90°; average strand Ø, 211 ± 18 μm	- Pig MFCs (Passage: 2)	- Mechanical behavior, compressive/tensile load	Static and dynamic culture (compression) - Cell viability - Biochemical assays (DNA, sGAGs, hydroxyproline, and COL content) - IF (COL I/II)	—
Cengiz et al. 142	3D Bioprinter (Bioplotter, EnvisionTEC) Parameters. Needle Ø: 22G metallic; print T: 110°C; P: 5.5 bar.	PCL Mw 45,000 Da	Entrapped SF (8 or 16 wt%) in PCL	5 mm3 697.1 µm, 61.1% (PCL); 278.7 µm, 54.6% (PCL + 8%SF); 287.2 µm; 50.0% (PCL + 16%SF) MESH: parallel strands 1.2 mm apart from each other (layers); layer-wise alternating strand directions of 90° and 0° (3D cubic cage)	- Human meniscocytes (Passage: 5) - Human IFPSCs (Passage: 4)	- Micro-CT - SEM - Water uptake - Mechanical behavior, compression	Static culture - Cell adhesion/migration (SEM) - Cell viability - Proliferation - Staining for filamentous actin	Subcutaneous implant (nude mice) [+cells] 7 d static culture before implant End point: 4 weeks - Micro-CT - Histological analyses for tissue infiltration, COL matrix, vessels, inflammation
Nakagawa et al. 145	MRI of ovine meniscus CAD reconstruction of sheep medial meniscus 3D Bioprinter (Bioplotter, Envision TEC), Parameters. T: 120°C; microstrands: 300 µm; microchannels: 100 µm.	PCL Mw 65,000 Da	Recombinant human CTGF (outer/middle zones) and recombinant human TGF-β3 (inner/middle zones) incorporation in PLGA	Meniscus-like 100/200 μm MESH: layer path, 300 μm microstrands, 100 μm microchannels	—	—	—	Orthotopic implant (sheep) End-point: 6, 12 months - MRI and MRI score - Macroscopic analysis - Histological analysis of meniscal, articular cartilage, and synovial tissues - Meniscal histological score (size, morphology, integrity, integration to the capsule, cellularity, cell morphology, COL organization, matrix staining)
Cengiz et al. 146	3D Bioprinter (Bioplotter, EnvisionTEC). Parameters. Print T: 110°C; P: 5.5 bar.	PCL Mw 45,000 Da	SF reinforced in the middle on the transverse plane with PCL	5 m3 242.1 ± 7.6μm 76.9% ± 0.5% MESH: layer-wise alternating strand directions of 45° and 135°; 2 mm inter-strands distance	- Human meniscocytes (Passage: 5) - Human ADSCs from IFP (Passage: 4)	- SEM - Micro-CT - Water uptake - Suture retention test - X-ray diffraction - Mechanical behavior, compression - In vitro enzymatic degradation	—	Subcutaneous implant (nude mice) [± cells] 7 d static culture before implant End point: 4 weeks - Histological analyses for biocompatibility, tissue infiltration, new vessels
Chen et al. 147	Micro-CT of rabbit menisci 3D CAD of scaffolds FFF 3D printing. Parameters. N.R.	PCL Mw 45,000 Da	- Pig meniscal dECM injection and crossliking - Pig meniscal dECM injection and crossliking + cells	- Wedge-shaped porous scaffold, 10 × 4 × 1 mm 1000 μm MESH: circumferential fibers spacing of 1000 μm, adjacent radial fibers angle of 18°, fiber diameters of 250 μm	- Rabbit MFCs (Passage: 3)	- Water contact angle, - FTIR - SEM - Mechanical behavior, compressive/tensile load	—	Subcutaneous implant (rats) [− cells] End point: 1 week, 1 month - Histology for inflammatory and immune responses Orthotopic implant (rabbit) [± cells] 24 h static culture before implant End point: 3, 6 months - Morphologic observation - Histology (cartilage) - IHC (COL I/II) - Ishida Score menisci - COL and GAG content - Mechanical behavior, compressive/tensile load - Image assessment (X-ray, MRI) - Kellgren−Lawrence and WORMS grading
Lee et al. 149	Laser Scan of human/sheep Meniscus 3D CAD 3D Bioprinter (Bioplotter, EnvisionTEC). Parameters.print T: 120°C.	PCL Mw 65,000 Da	Tethering of CTGF and TGF-β3 incorporated in PLGA microstrands	Meniscus-like 100 µm MESH: (a) interlaid strands and interconnecting microchannels with 100 µm Ø + circumferentially aligned fibers added (human meniscus scaffold); (b) 300 µm microstrands and 100 mm microchannels (sheep meniscus scaffold)	- Human BM or synovium MSCs (Passage: 2–3)	—	Static culture - Cell recruitment - Fibrocartilage matrix formation	Orthotopic implant (sheep) [− cells] End point: 12 weeks - Mechanical behavior (dynamic compression, pull-out strength, friction coefficient, stress relaxation, tensile test)
Abar et al. 150	3D CAM/CAD (Fusion 360), FFF 3D printer (Taz 5, Lulzbot). Parameters. Nozzle Ø: 400 µm; print T: 212°C–220°C; bed T: 40°C; speed: 360 mm/min.	PCU	Collagen hydrogel infill	Prism, 105 × 55 × 1.66 mm 0/100/200/400/600/800 µm MESH: first layer, a solid printed in diagonal pattern; next four layers, rectilinear infill pattern	- NIH/3T3, fibroblasts in aqueous or COL solution (Passage: N.R.)	- Light microscopy - Micro-CT - Mechanical behavior, tensile testing	Static culture - Cell proliferation and distribution	—
Ghodbane et al. 153	3D Bioprinter (Bioplotter, EnvisionTEC). Pneumatic extrusion. Parameters. Nozzle inner Ø: 500 µm; T: 160 °C; P: 9 bar; speed: 2 and 4.5 mm/s.	p(DTD DD)	Collagen infusion	Anterior-posterior length: 32 mm, medial-lateral length: 24 mm 69.9% ± 8.0% MESH: successive layers of circumferential and radial filaments	—	- Orientation characterization (XRD) - Mechanical behavior, circumferential tensile stiffness and ultimate tensile load	—	—
Ghodbane et al. 154	3D Bioprinter (Bioplotter, EnvisionTEC). Pneumatic extrusion. Parameters. Needle inner Ø: 400 µm; print T: 160°C; speed: 1.2 mm/s; P: 8.9 bar.	p(DTD DD)	Collagen hyaluronate sponge infusion	Anterior-posterior length: 32 mm, medial-lateral length: 24 mm 69.9% ± 8.0% MESH: successive layers of circumferential and radial filaments	—	—	—	Orthotopic implant (sheep) End point: 12, 24 weeks Histology for magnitude and type of tissue ingrowth, tissue thickness and integrity, surface features, cell density, vascularization, inflammatory response; IF for COL I/II; quantification of COL and sGAGs; cartilage histological analysis
Gupta et al. 156	3D CAM/CAD of scaffolds (Fusion 360, Autodesk), FFF 3D printer (Tarantula 3D printer). Parameters. print T: 200°C; speed: 20 mm/s.	PLA	- COL crosslinking - alginate - oxidized alginate Self-healing interpenetrating network hydrogel	Square prism, 10 × 10 × 3 mm 400 µm MESH: layer by layer with orthogonal orientation of fibers between successive layers. Fiber diameter, 200 μm; fiber spacing in each layer, 400 μm	- Human UC-MSCs (Passage: N.R.)	- Cytotoxicity - Degree of carboxylation - Mechanical behavior, compression - Contact angle - Characterization of hydrogel impregnated scaffolds (in vitro degradation, swelling ratio)	Static culture - Cell viability/ proliferation/ morphology - Differentiation	Subcutaneous implant (rats) [− cells] 28 d of static differentiation before implant End point: 14, 28 days - Biocompatibility - Micro-CT - Histology (tissue architecture, COL content, GAG)
Yang et al. 224	3D printer (Regenovo 3D Bio-Architect Sparrow). Parameters. Print T: 17°C–22°C; needle inner Ø 260 µm; print bed T: 0°C	N-acryloylsemicarbazide/gelatin	Polydopamine coated-ZIF-8	- Printed grid, 66 × 56 × 0.87 mm - Printed porous cuboid, 40 × 20 × 2.1 mm _______________________ MESH: 6 layers grid	- L929 mouse fibroblasts - Rabbit MFCs (Passage: 3)	- Mechanical characterization, tensile/compressive wear, resistance against femur, tearing tests, suture strength - Swelling behavior - Biocompatibility	- In vitro antibacterial activity (Staphylococcus aureus and Escherichia coli)	—

ADSCs: adipose-derived stem cells; BM: bone marrow; CAD: computer aided design; CAM: computer aided manufacturing; CO: collagen; CTGF: connective tissue growth factor; Da: Dalton; dECM: decellularized extracellular matrix; FFF: fusion filament fabrication; FTIR: Fourier-transform infrared spectroscopy; G: gauge; GAG: glycosaminoglycans; GelMA: gelatin methacrylate; IF: immunofluorescence; IFP: infrapatellar fat pad; IL: interleukin; IFPSCs: infrapatellar fat pad stem cells; IHC: immunohistochemistry; MFCs: meniscal fibrochondrocytes; Micro-CT: micro computed tomography; mm: millimiters; mm/min: millimeters/minute; mm/s: millimeters/second; MPa: megapascal; MRI: magnetic resonance imaging; MSC: mesenchymal stem cells; Mw: molecular weight; N.R.: not reported; p(DTD DD): poly(desaminotyrosyl-tyrosine dodecyl ester dodecanoate); P: pressure; PCL: ε-polycaprolactone; PCU: polycarbonate urethane; PLGA: poly lactic-co-glycolic acid; PU: polyurethane; SEM: scanning electron microscopy; SF: silk fibroin; sGAG: sulfated glycosaminoglycans; SOX9: SRY-Box transcription factor 9; T: temperature; TGFβ3: transforming growth factor, beta 3; UC: umbilical cord; w/wo: with/without; wt: weight; XRD: X-ray diffraction analysis; µm: micrometers; °C: centigrades; Ø: diameter.