I first learned the technique of autologous chondrocyte implantation (ACI) from a course sponsored by Genzyme, Inc in Cambridge Mass., sometime in 1997. Genzyme recently has been acquired by Sanofi, and it remains to be seen how this cell based program will be affected in the future.
ACI is now performed all over the world with combinations of cells alone,or cells plus scaffolds. Due to its high cost (In the US), and the requirement for two separate procedures, the volume of cases has remained low- something like 1500 cases/year in the US. A biopsy of normal tissue is sent to the lab in Cambridge where it is broken down into cells and then tissue cultured to achieve a volume of about 12 million cells. It is then sent back on a specific date and must be implanted into the joint within 24 hours. In other words, there is no shelf life. The costs for this procedure in the US begin at about 30K just for the cells, which then can be marked up to 48K by the time the procedure is billed; plus the doctor’s fee, the surgicenter, the original surgery to get the biopsy, physical therapy…75K? higher?
Nevertheless, the results of ACI can be quite good and durable. This in spite of evidence that the cultured cells do not make normal cartilage, but a type of fibrous cartilage, as opposed to the hyaline cartilage that is found in nature. I now have many patients between 5-10 years out from ACI who are quite satisfied, pain free or nearly so, active, and who show no signs of progressive arthritis. Depending upon the location of the cartilage problem, the literature would support a success rate somewhere in the 85% range. Nitpicking about the histology may be quite beside the point for most of these patients.
Of course there is an Achilles heel to ACI, and that is the source material of the cartilage. In some patients the biopsy is probably abnormal to begin with, and the cultured cells even more so. In terms of quality control, only one
marker protein is currently used to evaluate the cells before they are shipped- and this is a recent development (2010). The other stumbling block is technical; the technique requires use of a “patch” over the cells, and often this patch can overgrow. If that occurs, a third procedure can be needed to trim the patch. Be that as it may, ACI was a major advance in the development of cartilage repair technologies and one reason the field is thriving at the moment is proof of concept- that patients do not need to be resigned to continued deterioration of their cartilage,
that imaging studies will discover problems earlier, and that scientists should continue to develop new repair technologies based upon the experience we now have.