A Study of MACI in Patients Aged 10 to <17 Years With Symptomatic Chondral or Osteochondral Defects of the Knee

This is a 2-year prospective, multicenter, randomized, open-label, parallel group clinical
trial; a total of 45 patients, ages 10 to <17 years, will be randomized to receive a 1-time
treatment with MACI or microfracture (2:1, 30 MACI:15 microfracture).

After meeting screening criteria at the initial visit, all patients will have a screening
arthroscopy to further assess study eligibility. During the screening arthroscopy, patients
will be further evaluated against entry criteria. Cartilage lesion size will be measured
prior to any cartilage repair procedure and randomization. All patients who meet the
eligibility criteria and are considered suitable for treatment in the study will have a
cartilage biopsy taken prior to randomization to study treatment. Eligible patients will be
randomized during the screening arthroscopy procedure to receive either MACI or microfracture
treatment. Patients randomized to microfracture will undergo the procedure during the
screening arthroscopy.

All biopsied tissue will be sent to the Vericel manufacturing facility in Cambridge,
Massachusetts, where the sample will be processed to isolate the autologous chondrocytes.
Cells from patients randomized to the MACI group will be used in the preparation of the MACI
implant; cells from patients randomized to the microfracture group will be cryopreserved.

Patients randomized to treatment with MACI will return within 12 weeks of the screening
arthroscopy to undergo the chondrocyte implantation procedure via arthrotomy. Patients are to
follow a recommended postoperative rehabilitation program and compliance with the
rehabilitation schedule will be monitored.

Patients will be followed post-study treatment for 2 years (104 Weeks).

Inclusion Criteria:

- Symptomatic cartilage or osteochondral defects as a result of acute trauma or
Osteochondritis Dissecans (OCD)

- One or more International Cartilage Repair Society (ICRS) Grade III or IV chondral or
unsalvageable osteochondral defects located on the femoral condyles and/or trochlea
amenable to treatment with the surgical procedure determined at randomization (MACI or
microfracture).

- At least 1 defect size ≥2.0 cm2 on the femoral condyles and/or the trochlea; defects
include OCD lesions with a bone lesion depth of ≤6 mm and does not require a bone
graft.

- Stable target knee (ie, anterior and posterior cruciate ligaments should be free of
laxity as well as stable and intact). Ligament repair or reconstruction procedures are
allowed prior to screening arthroscopy.

- Intact meniscus or partial meniscus (at least 50% of functional meniscus remaining) in
the target knee.

Exclusion Criteria:

- Any surgery on the target knee joint within 6 months prior to Screening (not including
diagnostic arthroscopy)

- ICRS Grade III or IV chondral or unsalvageable osteochondral defects located on the
patella or tibia or any lesion that is bipolar to the index lesion

- Concomitant inflammatory disease or other conditions that affects the joints
(eg,rheumatoid arthritis, metabolic bone disease, psoriasis, symptomatic
chondrocalcinosis)

- Known history of septic arthritis in the index knee joint

- Known history of hypersensitivity to gentamicin, other aminoglycosides, or products of
porcine or bovine origin

- Females who are pregnant or lactating