Mesenchymal stem cells (MSCs) are one of the most thoroughly studied and understood stem cell types. They are used in a wide range of therapies, and the many studies using MSCs have enjoyed varied levels of success, depending on delivery methods, patients, co-therapies and other factors.
Today, we will be taking a look at MSCs and a new human clinical trial focused on treating osteoarthritis, an age-related inflammatory condition that leads to the breakdown of bone and cartilage.
What are mesenchymal stem cells?
Mesenchymal stem cells are multipotent cells, which means that they can differentiate (transform) into a variety of cell types, including osteoblasts (bone cells), chondrocytes (cartilage cells), myocytes (muscle cells) and adipocytes (fat cells). Sources of MSCs are varied and include bone marrow, which is the original source of MSCs and still the most frequently used; umbilical cord tissue; adipose tissue; amniotic fluid; and molar cells.
MSCs have been used to treat multiple joint and musculoskeletal problems with the goals of reducing inflammation and promoting tissue regeneration. In general, the transplanted MSCs do not tend to survive long in the body; however, they last long enough in most cases to generate anti-inflammatory signals and promote tissue regeneration.
MSCs to treat osteoarthritis in human trials
Today, we wanted to bring your attention to a small open access study that used MSCs to treat age-related osteoarthritis, a common complaint for many older people. This condition is caused by localized inflammation in the joints, leading to the breakdown of bone and cartilage and painful and potentially crippling outcomes for the patient.
The presence of proinflammatory senescent cells are very likely a major factor in how this condition develops, and it will be important to see how senolytic therapies that remove these cells might ameliorate osteoarthritis. It would potentially be even more interesting to see how MSCs and senolytics used as a co-therapy might ameliorate osteoarthritis, given that reducing inflammation enhances tissue regeneration in stem cell therapies.
The study here is also different from the majority of previous studies, as it tracked patient outcomes for two years following MSC therapy, a considerably longer period than other studies. This is important because we need to know more about the long-term effects of these therapies in order to refine and optimize the approaches used. This study was a phase 1 and 2 human clinical trial; you can learn more about clinical phases here, but essentially, it means that this approach is both safe and effective at combating osteoarthritis.
Mesenchymal stem cell therapies do not address the root cause of osteoarthritis, which is chronic inflammation from senescent cells, cell debris, microbial burden and other sources, but they do locally suppress inflammation long enough to promote tissue repair.
The study results here show that there was a significant improvement in patients with osteoarthritis. Despite the limited number of patients in the study, the therapy was shown to safely increase knee cartilage thickness; this demonstrates its ability to improve the function and structure of joints and shows that it could be an effective therapy for osteoarthritis patients.
 Nardi, N. B., & da Silva Meirelles, L. (2008). Mesenchymal stem cells: isolation, in vitro expansion and characterization. In Stem cells (pp. 249-282). Springer Berlin Heidelberg.
 Al-Najar, M., Khalil, H., Al-Ajlouni, J., Al-Antary, E., Hamdan, M., Rahmeh, R., … & Al-jabbari, E. (2017). Intra-articular injection of expanded autologous bone marrow mesenchymal cells in moderate and severe knee osteoarthritis is safe: a phase I/II study. Journal of orthopaedic surgery and research, 12(1), 190.