By: Jack Farr, MD
In the recent past, the popular press excitedly reported the promise of stem cells for all tissues of the body. Today, there remains a public perception that stem cells can “grow into anything” from a new pancreas to a new meniscus; however, in reality stem cell research still has much to learn.
The perception that stem cells can form any tissue is based on the fact, that indeed, they have the potential to form a variety of more specialized cells. The tissues that form joints (bone and cartilage) originate from mesenchymal stem cells most commonly isolated from the bone marrow. These rare cells can be used in a diluted state, concentrated or commonly multiplied through culturing. The uses for knee problems may be broadly categorized: injected or applied directly to a cartilage lesion.
Injected cells may be thought of either as small molecular factories, which influence the local environment of the knee (paracrine effect) or as directly influencing a “repair” (see Saw study below). In a recently published study in the Journal of Bone and Joint, adult donor mesenchymal stem cells were injected into knee joints of patients who had undergoing partial excision of torn meniscal cartilage tissue in an effort to regrow the meniscus. OrthoIndy surgeon, Jack Farr, MD participated in the multicenter study in which neither the physicians nor the patients knew if the pateinets received stems cells or not (Adult Human Mesenchymal Stem Cells Delivered via Intra-Articular Injection to the Knee Following Partial Medial Meniscectomy: A Randomized, Double-Blind, Controlled Study Thomas Vangsness, Jr., MD; Jack Farr II, MD; Joel Boyd, MD; David T. Dellaero, MD; C. Randal Mills, PhD; Michelle LeRoux-Williams, PhD JBJS Am, 2014 Jan 15;96(2); 90 90-98). While definite meniscal regrowth was demonstrated statistically significant, the regrowth was not felt to probably be clinically significant. However, the patients who received the stem cells had diminishment of symptoms—with persistence over several months. (Also, see the blog on amniotic membrane and amniotic fluid cells injection study).
Links to comments on our study:
A second approach to injections was reported at a recent arthroscopy meeting (AANS, San Antonio 2013 by Dr. Adam Anz who presented Dr. Saw’s study) and published in Arthroscopy 2013 April (http://www.ncbi.nlm.nih.gov/pubmed/23380230). While the technique is not available in the US, Malaysian surgeons led by Dr. Saw reported improved patient outcomes comparing microfracture alone to patients who had stem cells serially injected in the knee after microfracture. Confirmatory, randomized controls will be important.
Alternatively, stem cells may be localized within a cartilage lesion either using an absorbable patch or fibrin glue. The bone marrow aspirate concentrate (BMAC) appears promising in the horse (Fortier et al JBJS 2010 (http://www.ncbi.nlm.nih.gov/pubmed/20720135). Gobi reported similar positive results in the human (AJSM 2014 http://www.ncbi.nlm.nih.gov/pubmed/20720135) and confirmatory controlled studies in the human will be interesting to review.
Placing the cells directly into a cartilage defect with or without a patch after culturing has been expanded from the work by Wakatani and others in Japan published in 2010 (Wakitani et al Safety of autologous bone marrow-derived mesenchymal stem cell transplantation for cartilage repair in 41 patients with 45 joints followed for up to 11 years and 5 months. J TissueEng Regen Med 5(2):146–150). The case series outcomes appear promising and suggest the merit of a randomized comparative study. As in all areas of the knee, it is important to continue to apply the rigors of scientific investigation before adopting new technologies clinically.
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