The Food and Drug Administration (FDA) has approved Maci (autologous cultured chondrocytes on porcine collagen membrane; Vericel) for the repair of symptomatic, full-thickness cartilage defects of the knee in adults. This is the first approved product that utilizes tissue engineering to grow cells on scaffolds using the patient’s own healthy cartilage tissue from the knee.
Maci consists of autologous cells that are expanded and placed onto a bio-resorbable porcine-derived collagen membrane. This is implanted over the area where the defective or damaged tissue was removed. The Maci implant is made of a small cellular sheet containing 500,000–1,000,000 cells/cm^2 (~0.16in^2). Depending on the size of the cartilage defect, the amount of Maci is trimmed to completely cover the damaged area. More than one implant can be used if there are multiple defects.
The FDA approval was based on safety and efficacy data from a 2-year clinical trial (n=144) that was intended to show reduced pain and improved function with Maci vs. the microfracture procedure. A majority of patients from the trial continued in a 3-year follow-up study. Overall efficacy data supported a long-term benefit from the use of the Maci implant in patients with cartilage defects. The most commonly reported adverse effects among patients who received Maci were joint pain, common cold-like symptoms, headache, and back pain.
The procedure should be performed by a surgeon who is specifically trained in using Maci.