A prospective, randomized, parallel, open-label phase-2 trial (ClinicalTrials.gov, NCT02673905) was conducted across five hospitals in four countries, involving 108 patients aged 30 to 46 years with full-thickness knee cartilage defects ranging from 2.7 to 6.0 square centimeters. Patients were equally randomized to receive either N-TEC or N-CAM. The primary outcome, preregistered in the trial, was the overall Knee Injury Osteoarthritis Outcome Score (KOOS) at 24 months post-treatment.

N-TEC, which underwent a longer culture period, exhibited properties more closely resembling hyaline cartilage in terms of phenotype, structure, and function compared to N-CAM. Both treatment groups showed clinically relevant improvements in KOOS compared to preoperative scores. However, at 24 months, the N-TEC group achieved a higher KOOS (85; interquartile range [IQR], 74 to 91) than the N-CAM group (79; IQR, 65 to 85). Notably, N-TEC demonstrated consistent effectiveness in patients with larger defects or those undergoing revision surgery, whereas N-CAM did not show similar efficacy in these more challenging cases.

Radiological assessments revealed that N-TEC resulted in superior repair tissue composition and integration with surrounding cartilage, although structural scores were comparable between the two groups. These findings validate the clinical efficacy of nasal chondrocyte-based grafts for articular cartilage repair and highlight the importance of engineering mature cartilage tissues, particularly for patients with complex or larger cartilage defects. This study supports the therapeutic potential of N-TEC as a promising approach for cartilage regeneration.