Tissue Engineering Technologies AG

To compare substantial clinical benefit (SCB) of a hydrogel-based, matrix-associated autologous chondrocyte implantation (M-ACI) method versus microfracture (MFx) in the treatment of knee cartilage defects.

Propensity score matched-pair analysis, using the MFx control group of a phase III study as comparator for M-ACI treatment in a single-arm phase III study, resulting in 144 patients in the matched-pair set.

Groups were comparable regarding baseline Knee Injury and Osteoarthritis Outcome Score (KOOS), sex, age, body mass index, symptom duration, smoking status, and previous knee surgeries. Defect sizes in the M-ACI group were significantly larger than in the MFx group (6.4 cm 2 vs. 3.7 cm 2 ). Other differences concerned location, number, and etiology of defects that were not considered to influence the interpretation of results. At 24 months, significantly more patients in the M-ACI group achieved SCB in KOOS pain (72.2% vs. 48.6%; P = 0.0108), symptoms (84.7% vs. 61.1%, P = 0.0039), sports/recreation (84.7% vs. 56.9%, P = 0.0008), and quality of life (QoL; 72.2% vs. 44.4%, P = 0.0014). The SCBs for KOOS activities in daily living and International Knee Documentation Committee score were higher for M-ACI but not significantly different from MFx. The SCB rates consistently favored M-ACI from 3 months onward. The highest improvements from baseline at 24 months in patients with SCB were observed for KOOS sports/rec. (M-ACI: 60.8 points, MFx: 55.9 points) and QoL (M-ACI: 58.1, MFx: 57.4).

Hydrogel-based M-ACI demonstrated superior SCB in KOOS pain, symptoms, sports/rec., and QoL compared with MFx in patients with knee cartilage defects through 2 years follow-up.

Few studies exist for large defects comparing matrix-associated autologous chondrocyte implantation (M-ACI) with other cartilage repair methods due to the limited availability of suitable comparator treatments.

To compare the clinical efficacy of a novel hydrogel-based M-ACI method (NOVOCART Inject plus) versus microfracture (MFx) in patients with knee cartilage defects.

Cohort study; Level of evidence, 3.

Propensity score matched-pair analysis was used to compare the 24-month outcomes between the M-ACI treatment group from a previous single-arm phase 3 study and the MFx control group from another phase 3 study. Patients were matched based on preoperative Knee injury and Osteoarthritis Outcomes Score (KOOS), symptom duration, previous knee surgeries, age, and sex, resulting in 144 patients in the matched-pair set (72 patients per group). The primary endpoint was the change in least-squares means (ΔLSmeans) for the KOOS from baseline to the 24-month assessment.

Defect sizes in the M-ACI group were significantly larger than in the MFx group (6.4 versus 3.7 cm2). Other differences included defect location (no patellar or tibial defects in the MFx group), number of defects (33.3% with 2 defects in the M-ACI group versus 9.7% in the MFx group), and defect cause (more patients with degenerative lesions in the M-ACI group). The M-ACI group had higher posttreatment KOOS (M-ACI versus MFX: 81.8 ± 16.8 versus 73.0 ± 20.6 points) and KOOS ΔLSmeans from baseline to 24 months posttreatment (M-ACI versus MFX: 36.9 versus 26.9 points). Treatment contrasts in KOOS ΔLSmeans from baseline indicated statistical significance in favor of M-ACI from 3 to 24 months posttreatment ( P = .0026). Significant and clinically meaningful differences in favor of M-ACI at 24 months were also found regarding International Knee Documentation Committee (IKDC) score ΔLSmeans from baseline (37.8 versus 30.4 points; P = .0334), KOOS responder rates at 24 months (≥10-point improvement from baseline; 94.4% versus 65.3%; P < .0001), IKDC responder rates at 24 months (>20.5-point improvement from baseline; 83.3% versus 61.1%, P = .0126) and MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score in a subgroup of patients (LS means, 86.9 versus 69.1; P = .0096).

In this exploratory analysis, M-ACI using an in situ crosslinked hydrogel demonstrated superior clinical and structural (MOCART) 24-month outcomes compared with MFx in patients with knee cartilage defects.

In autologous chondrocyte implantation (ACI), there is no consensus about used bioscaffolds. The aim of this study was to perform an in vitro comparative analysis of 2 clinically applied biomaterials for cartilage lesion treatment.

Monolayer expanded human chondrocytes ( n = 6) were embedded in a collagen scaffold (CS) and a hyaluronic acid–based hydrogel (HA). Cells were cultured in chondropermissive medium supplemented with and without interleukin-10 (IL-10) and bone morphogenetic protein–2 (BMP-2). Gene expression of chondrogenic markers (COL1A1, COL2A1, COL10A1, ACAN, SOX9) was detected via quantitative real-time–polymerase chain reaction (RT-qPCR). Biosynthesis of matrix compounds, cell viability, morphology as well as migration from surrounding native bovine cartilage into cell-free scaffolds were analyzed histologically. Adhesion of the material to adjacent cartilage was investigated by a custom-made push-out test.

The shift of COL1/2 ratio toward COL2A1 was more pronounced in HA, and cells displayed a more spherical morphology compared with CS. BMP-2 and IL-10 significantly increased COL2A1, SOX9, and ACAN expression, which was paralleled by enhanced staining of glycosaminoglycans (GAGs) and type 2 collagen in histological sections of CS and HA. COL10A1 was not significantly expressed in HA and CS. Better interfacial integration and enhanced cell invasion was observed in CS. Push-out tests using CS showed higher bonding strength to native cartilage.

HA-based hydrogel revealed a more chondrocyte-like phenotype but only allowed limited cell invasion, whereas CS were advantageous in terms of cellular invasion and interfacial adhesion. These differences may be clinically relevant when treating cartilaginous or osteochondral defects.