Stem cells: Implantation and regeneration
There is a lot of ongoing research into this area. Hyaline cartilage thickening has been observed and reported after stem cell therapy. Hyaline cartilage tissue provides smooth surfaces, enabling tissues to move easily over each other, it also provides flexibility and support. Stem cell treatment has also been observed and reported to decrease pain and increase function of a joint. These patients become more active and are able to enjoy the activities of life more as a result of having a joint that can move more normally and have less pain. If that is satisfactory information, then you can stop here before we get into the scientific weeds.
It is unclear to what degree cartilage depth and/or function is caused by implantation of chondrocytes (cartilage cells) and to what degree cell-to-cell signaling is simply improving the biochemical environment of the inside of a joint, leading to increased function and decreased pain. The following article showed that cartilage cultured from stem cells did both. For example, lubrication in the joint was improved, and even under heavy biomechanical loads (like walking) that there was integration and implantation of stem-cell derived cartilage. This is a culture model, not an in-vivo model for many reasons, but at least some of the basic principles apply.
The Role of Unhealthy Joint Tissues in Osteoarthritis, and the Role of Stem Cells in the Cure
We now know that osteoarthritis (OA) is much more than just “wear and tear.” There are numerous maladaptive changes to a joint with OA. An osteoarthritic joint is besieged with substances that eat away at healthy hyaline (joint) cartilage. These are certain matrix metalloproteinases (MMPs) and interleukins secreted from the synovium (joint lining) of an arthritic joint. In addition, the native long chain hyaluronic acid molecules that help normalize and lubricate healthy joints is chopped into smaller, less effective pieces. In addition, the bone under the hyaline cartilage (subchondral bone) is inflammatory and structurally
The link will take you to the full article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5745427/
If you don’t have time for the entire article, here is the abstract:
World J Orthop. 2017 Dec 18;8(12):853-860.
Update on mesenchymal stem cell therapies for cartilage disorders.
Cartilage disorders, including focal cartilage lesions, are among the most common clinical problems in orthopedic practice. Left untreated, large focal lesions may result in progression to osteoarthritis, with tremendous impact on the quality of life of affected individuals. Current management strategies have shown only a modest degree of success, while several upcoming interventions signify better outcomes in the future. Among these, stem cell therapies have been suggested as a promising new era for cartilage disorders. Certain characteristics of the stem cells, such as their potential to differentiate but also to support healing made them a fruitful candidate for lesions in cartilage, a tissue with poor healing capacity. The aim of this editorial is to provide an update on the recent advancements in the field of stem cell therapy for the management of focal cartilage defects. Our goal is to present recent basic science advances and to present the potential of the use of stem cells in novel clinical interventions towards the enhancement of the treatment armamentarium for cartilage lesions. Furthermore, we highlight some thoughts for the future of cartilage regeneration and repair and to explore future perspectives for the next steps in the field.
Here is a specific article about inflammation in the subchondral bone of OA.:
J Orthop Res. 2016 Feb;34(2):262-9. doi: 10.1002/jor.23009. Epub 2015 Aug 14.
Elevated marrow inflammatory cells and osteoclasts in subchondral osteosclerosis in human knee osteoarthritis
Subchondral osteosclerosis, characterized by an increase of hypomineralized bone material, is a pathological hallmark of osteoarthritis. The cellular components in the subchondral marrow compartment that participate in this aberrant bone remodeling process remain to be elucidated. This study assessed the presence of marrow inflammatory cells and their relative abundance between nonsclerotic and sclerotic tissues in knee osteoarthritis. Bone samples from osteoarthritic knee tibial plateaus were stratified for histological analyses using computed tomography osteoabsorptiometry. Immunohistological analysis revealed the presence of CD20 (B-lymphocyte) and CD68 (macrophage), but not CD3 (T-lymphocyte) immunoreactive mononuclear cells in subchondral marrow tissues and their relative abundance was significantly increased in sclerotic compared with nonsclerotic bone samples. Multinucleated osteoclasts that stained positive for CD68 and tartrate-resistant acid phosphatase, predominantly associated with CD34-positive blood vessels and their abundance was strongly increased in sclerotic samples. Bone-specific alkaline phosphatase activity in outgrowth osteoblasts was induced by conditioned medium from nonsclerotic, but not sclerotic, bone pieces. These results suggest that an interaction between bone-resident cells and marrow inflammatory cells might play a role in aberrant bone remodeling leading to subchondral osteosclerosis. Elevated osteoclast activity in sclerotic bone suggests that bone formation and resorption activities are increased, yet uncoupled, in human knee osteoarthritis.
Stem cell therapy has the potential to address each of the problems created by osteoarthritis and the unhealthy things OA does to a joint. Research on the exact mechanisms is ongoing. We don’t know all of the many reasons people have less pain and improved functioning after stem cell treatment. Here are a few of the potential reasons that we get good results from stem cell therapy:
- Stem cells, monocytes and other cells and biochemical mediators in the transplanted marrow is anti-inflammatory. This can have numerous positive effects and does not have the negative “bone softening” effects of repeated steroid injections.
- Stem cells do communicate biochemical signals back and forth with the entire surrounding area. This can result in migration of beneficial cells to the joint, potentially making it heal better and behave as though it were a younger joint.
- Some of the stem cells may implant and become normal hyaline cartilage. They also may recruit stem cells from surrounding marrow to migrate into defects. In either case, a superior result would occur as compared with microfracture surgery because microfracture surgery results in articular cartilage defects becoming Type I cartilage, which is not hyaline cartilage at all. It is just scar tissue.