Regenerative medicine employs the body’s own biological tissues, often referred to as orthobiologics, to improve symptoms and enhance the healing of musculoskeletal tissues. This approach stimulates natural repair processes rather than managing symptoms or replacing damaged parts with artificial materials, making it relevant for conditions like knee osteoarthritis. Osteoarthritis involves the progressive degeneration of joint cartilage, leading to pain and reduced function. Stem cell therapy, using mesenchymal stem cells (MSCs), has attracted considerable interest because of its potential to modulate the joint environment and promote a healing response.
Sources of Mesenchymal Stem Cells for Knee Treatment
The most common sources for obtaining regenerative cells are autologous, meaning they are harvested from the patient’s own body. These typically include Bone Marrow Aspirate Concentrate (BMAC) and Adipose-Derived Stem Cells (ADSCs). BMAC is prepared by extracting bone marrow, usually from the hip bone (iliac crest), and centrifuging it to concentrate the mesenchymal stem cells and other healing factors.
Harvesting ADSCs involves a mini-liposuction to collect fat tissue, often from the abdomen. This tissue is then processed to isolate the ADSCs and the stromal vascular fraction (SVF), a rich mixture of cells containing MSCs. While BMAC generally provides a higher concentration of MSCs, its cell count declines significantly with age. In contrast, fat tissue is an abundant and easily accessible source that maintains a more consistent cell population regardless of age.
A third category includes allogeneic products derived from donor sources, such as umbilical cord or amniotic fluid. These donor-derived products are often marketed as containing live stem cells. Unlike autologous procedures, these allogeneic products involve complex processing and are not considered “minimally manipulated” human cells and tissues. This places them under stricter regulatory oversight by agencies like the FDA.
Biological Actions in Joint Regeneration
Once injected, mesenchymal stem cells exert their therapeutic effect primarily through paracrine signaling, rather than differentiating directly into new cartilage tissue. Paracrine signaling involves MSCs releasing a complex mixture of bioactive molecules into the joint environment. These molecules include growth factors, anti-inflammatory cytokines, and membrane-bound vesicles called exosomes.
This signaling cascade creates a healing microenvironment within the joint space. The anti-inflammatory factors suppress the chronic inflammation driving osteoarthritis progression. Growth factors stimulate native joint cells to reduce cell death and enhance the synthesis of the extracellular matrix. This overall effect is immunomodulatory and trophic, regulating the immune response and providing nourishment to promote tissue repair.
Comparative Clinical Efficacy and Outcomes
Ongoing clinical research focuses on whether BMAC or ADSCs are superior, though current high-quality studies suggest similar clinical benefits for both. Patients treated with either BMAC or ADSC injections for knee osteoarthritis consistently show significant improvement in clinical scores related to pain and function. Both groups report substantial pain reductions and marked functional improvements.
In comparisons of autologous sources, microfragmented adipose tissue (MFAT, a form of ADSC) and BMAC provided significant and statistically similar improvements in pain and function. While ADSCs may offer quicker short-term pain relief, BMAC treatments have shown greater long-term benefits or structural improvements on imaging at two years in some smaller studies. Furthermore, a multicenter study found that MSCs from bone marrow, adipose tissue, and umbilical cord tissue all provided similar pain reduction compared to a standard corticosteroid injection at one year.
The durability of results often favors cell-based therapies over traditional treatments like hyaluronic acid (HA) injections. For instance, one randomized trial demonstrated that BMAC provided superior and more sustained symptom relief over HA at a 24-month follow-up. Although both BMAC and ADSCs show promising and comparable clinical results, the long-term data needed to declare one source definitively best is still accumulating.
Regulatory Oversight and Treatment Safety
The regulatory landscape for stem cell therapies is complex and directly impacts patient safety and the legality of treatments offered. The FDA regulates human cells, tissues, and cellular and tissue-based products (HCT/Ps) in the United States. This framework distinguishes between treatments considered the practice of medicine and those classified as regulated drugs or biologics requiring formal FDA approval.
Autologous procedures using a patient’s own cells are generally exempt from strict premarket review if the tissue is only “minimally manipulated” and used for a “homologous function.” If cells are extensively processed, such as being grown in a lab, or used to treat a condition for which they lack an established function, the product is classified as a drug requiring full FDA approval. Many commercial clinics operate in a regulatory gray area, offering treatments that may not meet the minimal manipulation criteria, which raises safety concerns.
Patients should be cautious of clinics making exaggerated claims or guaranteeing results without supporting peer-reviewed data. Selecting a reputable clinic involves verifying that practitioners follow established medical guidelines and cite data from formal clinical trials. The lack of rigorous oversight in some commercial settings means consumers may be exposed to unproven or potentially unsafe procedures.