Several years ago, The U.S. Food and Drug Administration (FDA) approved a product called MACI® for the repair of knee cartilage defects in adult patients. MACI, an acronym for matrix-induced autologous chondrocyte implantation, is an advanced cell therapy developed and marketed by American biopharmaceutical company Vericel Corporation; it utilizes the groundbreaking technique of cartilage tissue engineering to address knee damage resulting from injury, overuse and surrounding muscle weakness. With more widespread adaptation and usage, this technique may eventually replace microfracture as the standard of care for adult knee cartilage injuries. (Microfracture is the process of creating tiny fractures in the bone underlying damaged cartilage to spur new cartilage growth and repair.)

What is Cartilage Tissue Engineering?

Cartilage tissue engineering is a multi-step process. First, a surgeon conducts a biopsy of the patient’s knee to determine the extent of the cartilage damage, followed by removal of damaged or defective tissue. The surgeon then extracts a small sample of healthy cells from the patient’s knee (autologous cells), and seeds them onto a three-dimensional membrane made from porcine-derived collagen. In Vericel’s MACI technique, the process of cell expansion takes roughly a month; afterward, the autologous cellularized scaffold is implanted into the area of the patient’s knee where the damaged or defective cartilage has been removed. (The size of the MACI implant is dependent on the amount of cartilage damage in the patient, and is tailored accordingly by the surgeon.) The collagen membrane on which the cells have been seeded is biodegradable and eventually dissolves, leaving the expanded cells to regenerate and strengthen in vivo.

How Successful is Cartilage Tissue Engineering?

Results have been very promising for this procedure. According to a press release from Vericel, a multi-center two-year group study called SUMMIT (Superiority of MACI Versus Microfracture Treatment in Patients With Symptomatic Articular Cartilage Defects in the Knee) demonstrated a significant improvement in knee pain and function of MACI patients as compared with those undergoing microfracture procedures for similar injuries. Specifically, response rates for MACI patients were 88%, versus a 68% response rate for microfracture patients. An extension study highlighted the efficacy and durability of the procedure for up to five years as well.

An Emerging MACI Alternative

While Vericel’s MACI is the first tissue engineering therapy to earn FDA approval, another pharmaceutical company is looking to achieve the same goal with their product. The FDA has just approved Phase III trial design for NeoCart®, a regenerative cell therapy developed by Ocugen, Inc. NeoCart, like MACI, utilizes autologous chondrocytes that have been cultured on a 3-D scaffold and are then implanted into the patient’s knee. Ocugen expects to begin their Phase III clinical trial in late 2023.

Given the success of Vericel’s MACI product, the prospective emergence of a similar treatment is a positive development - not only for patients and medical professionals, but for those in the scientific community who are dedicated to the advancement of cell regenerative therapeutics.

Located in San Antonio, TX, StemBioSys develops cell culture technologies licensed from The University of Texas Health Science Center, San Antonio. Our work represents the next evolution in stem cell research. For more information about StemBioSys and our patented technology, please contact us.