The Food and Drug Administration approved Maci (autologous cultured chondrocytes on porcine collagen membrane) for the repair of symptomatic, full-thickness cartilage defects of the knee in adult patients. Maci is the first FDA-approved product that applies the process of tissue engineering to grow cells on scaffolds using healthy cartilage tissue from the patient’s own knee.

Knee problems are common, and occur in people of all ages. Cartilage defects in the knee can result from an injury, straining the knee beyond its normal motion, or can be caused by overuse, muscle weakness, and general wear and tear.  

“Different cartilage defects require different treatments, so therapy must be tailored to the patient,” said Celia Witten, Ph.D., M.D., deputy director of the FDA’s Center for Biologics Evaluation and Research. “The introduction of Maci provides surgeons with an additional option for treatment.”

Maci is composed of a patient’s own (autologous) cells that are expanded and placed onto a bio-resorbable (can be broken down by the body) porcine-derived collagen membrane that is implanted over the area where the defective or damaged tissue was removed. Administration should be performed by a surgeon specifically trained in the use of Maci.

Each Maci implant consists of a small cellular sheet containing 500,000 to 1,000,000 cells per cm2 (about 0.16 square inches). The amount of Maci administered depends on the size of the cartilage defect, and is trimmed to ensure that the damaged area is completely covered. Multiple implants may be used if there is more than one defect. During a mini-open technique, damaged and / or diseased cartilage tissue is debrided from the defect area and the MACI implant is cut and shaped to fit and adhered in place using an off-the-shelf sealant.

The safety and efficacy of Maci were shown in a two-year clinical trial designed to demonstrate reduced pain and improved function in comparison to microfracture, an alternative surgical procedure for cartilage repair. The trial included 144 patients (72 in each treatment group). A majority of the patients who completed the two-year clinical trial also participated in a three year follow-up study. Overall efficacy data support a long-term clinical benefit from the use of the Maci implant in patients with cartilage defects.  

The most common side effect reported by people who received Maci were: joint pain, common cold-like symptoms, headache and back pain.

Maci is manufactured by Vericel Corporation, headquartered in Cambridge, Massachusetts. Vericel focuses on autologous cell therapies, which its website calls “For Me, By Me” treatments. The company is currently developing a heart failure treatment called ixmyelocel-T that involves extracting bone marrow from a patient’s hip, expanding the population of cells and administering them through a catheter. The treatment recently met its primary goal in a Phase 2 study.

Nonetheless, it has been a down year for FDA approvals, with just 20 new drugs approved thus far. That’s compared to more than 40 in each of the past two years. Maci is only the fourth biotech treatment to get FDA approval this year developed by a Massachusetts-based company.