Purpose: Damaged cartilage has very limited potential for self-repair. Tissue bioengineering offers an interesting alternative for repair of cartilage injury caused by joint trauma or osteochondritis dessicans. The purpose of this work was to use primary chondrocytes cultivated in vitro on collagen gel to produce a neocartilage which can be reimplanted.

Material and methods: Chondrocytes were extracted by enzymatic digestion from calf feet harvested from animals aged less than six months. Two million cells were seeded on collagen gels in multiple-well plates and covered with culture medium (1 ml). Type I collagen was acquired from ground calf skin used at a concentration of 1.25 mg/ml. The culture medium was a v/v mixture of RPMI 1640 and NCTC 109. This mixture was supplemented with 10% foetal calf serum, 100 U/ml penicillin, and 250 ng/ml amphotericin B. Cell proliferation was assess fluorometrically and synthesis of glycosaminoglycans (sGAG) by colorimetric assay. Histological study (safranine O) and immunohistochemistry tests (type I and II collagen) were performed to monitor synthesis of matrix components. Expression of genes coding for certain matrix proteins (collagen Ia 2 and 1, II, X, agrecan and MMP13) was studied using RT-PCR.

Results: The chondrocyte phenotype was preserved. Type II collagen as well as agrecan was expressed and expression of type I collagen did not increase during the culture. Progressive synthesis of sGAG was observed as was moderate cell proliferation. Cell distribution within the gel was apparently homogeneous. The chondrocytes retained their round shape throughout the study. Type II collagen deposits were visible on day 9 in peripheral cells in areas of high-cell density, then progressed with time.

Discussion: Our in vitro results show that three-dimensional cultures of chondrocytes using a collagen gel can produce construction of an extracellular matrix with preservation of chondrocyte phenotype during the culture period.

Conclusion: The collagen matrix offers an environment favouring the formation of a functional artificial cartilage by chondrocytes and opens promising perspectives for repairing damaged cartilage.

Purpose: Associating autologous chondrocytes with a biomaterial has the advantage of facilitating fixation of graft cells and simplifies reimplantation. To evaluate the feasibility, tolerance, and efficacy of the Cartipatch(r) product, we are conducting a phase IIb study.

Material and methods: Cartilage (200–500 mg) was harvested arthroscopically from the lateral borders of the trochlea in the intercondylar space of damaged knees. After enzymatic digestion, the freed chondrocytes were cultured in monolayer in presence of autologous serum. The number of cells needed to achieve a concentration of 107/ml were suspended in an aragose and alginate solution. Before gelification, the suspension was poured into pits to obtain grafts measuring 10, 14 or 18 mm depending on the configuration of the lesion identified by MRI and arthroscopy. A specific instrument set was used to prepare one or two cavities for press fit insertion of the grafts. The grafts were justapositioned in order to best cover the damaged area.

Nineteen patients aged 16–50 years with a single osteochondral lesion or osteochondritis dessicans involving the femoral condyle but who had no other knee anomaly were included in this trial. The graft was inserted via an arthrotomy. Patients were examined preoperatively then at 3, 6, 12 and 24 months after grafting. The main evaluation criteria was improvement in the IDCD score (ICRS item) at 24 months. Secondary evaluation criteria were MRI and arthroscopic aspect associated with biopsy of the repaired tissue performed at 24 months.

Results: The first interventions required less than one hour. Patients followed the rehabilitation protocol with passive mobilisation and progressive weight bearing with no particular problem. Tolerance was good (no inflammation, adherence).

Discussion: The operative time needed to implant the graft was greatly reduced compared with classical chondrocyte grafts. Furthermore, this technique eliminates the need for periosteum suture guaranteeing a more homogeneous cell graft.

Conclusion: This short-term evaluation of the first patients is very encouraging. The first results concerning the effectiveness of this product, Cartipatch(r) are expected in the upcoming months.