3D printed porous sulfonated polyetheretherketone scaffold for cartilage repair: Potential and limitation

The treatment of cartilage lesions has always been a difficult problem. Although cartilage tissue engineering provides alternative treatment options for cartilage lesions, biodegradable tissue engineering scaffolds have limitations.

In this study, we constructed a porous PEEK scaffold via 3D printing, surface-engineered with concentrated sulfuric acid for 15 s (SPK-15), 30 s (SPK-30), and 60 s (SPK-60). We systematically evaluated the physical and chemical characteristics and biofunctionalities of the scaffolds, and then evaluated the macrophage polarization modulating ability and anti-inflammatory effects of the sulfonated PEEK, and observed the cartilage-protective effect of SPK using a co-culture study. We further evaluated the repair effect of PEEK and SPK by implanting the prosthetic scaffold into a cartilage defect in a rabbit model.

Compared to the PEEK, SPK-15 and SPK-60 scaffolds, SPK-30 has a good micro/nanostructure, appropriate biomechanical properties (compressive modulus, 43 ± 5 MPa; Shaw hardness, 20.6 ± 1.3 HD; close to native cartilage, 30 ± 8 MPa, 17.8 ± 0.8 HD), and superior biofunctionalities. Compared to PEEK, sulfonated PEEK can favor macrophage polarization to the M2 phenotype, which increases anti-inflammatory cytokine secretion. Furthermore, SPK can also prevent macrophage-induced cartilage degeneration. The in-vivo animal experiment demonstrates that SPK can favor new tissue ingrowth and integration, prevent peri-scaffold cartilage degeneration and patellar cartilage degeneration, inhibit inflammatory cytokine secretion, and promote cartilage function restoration.

The present study confirmed that the 3D printed porous sulfonated PEEK scaffold could promote cartilage functional repair, and suggests a new promising strategy for treating cartilage defects with a functional prosthesis that spontaneously inhibits nearby cartilage degeneration.

In the present study, we propose a new cartilage repair strategy based on a porous, non-biodegradable polyetheretherketone (PEEK) scaffold, which may bring up a new treatment route for elderly patients with cartilage lesions in the future.