Stem cell injections improve pain, function in knee osteoarthritis
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Key takeaways:
- Patients receiving injections of autologous adipose-derived stem cells or adipose-derived stromal vascular fraction had improved pain.
- Additional studies are needed to determine optimal number and timing of doses.
Intra-articular injections of autologous adipose-derived stem cells or adipose-derived stromal vascular fraction significantly improve pain and function in knee osteoarthritis, according to data published in Arthritis Research & Therapy.
“In recent years, there has been a growing fascination with the potential use of stem cells as a therapeutic approach for treating knee osteoarthritis,” Yang Yang, MD, of Ningxia Medical University, in China, and colleagues wrote. “Among the various types of stem cells, mesenchymal stem cells (MSCs) have shown great promise in restoring damaged articular cartilage and slowing the progression of knee OA.
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“Since autologous adipose tissue is easily available and abundantly sourced, as a type of mesenchymal stem cells, adipose-derived mesenchymal stem cells (ASCs) and adipose-derived stromal vascular fraction (ADSVF) have been receiving increasing attention,” they added. “ASCs, as a type of pluripotent stem cells, have the ability to self-renew and differentiate into multiple cell types. ADSVF refers to a cell population in adipose tissue, consisting of various cell types and extracellular matrix components, with the ability to promote angiogenesis and tissue repair.”
To investigate the impact of single or multiple intra-articular injections of ASCs or ADSVF on knee OA, Yang and colleagues conducted a systematic literature search of PubMed, Embase, Web of Science, Cochrane Library and Clinicaltrials.gov for papers published through April 20. Included studies were English-language randomized controlled trials of single or multiple intra-articular injections of autologous ASCs or ADSVF in patients with knee OA, without additional treatment, vs. either placebo or hyaluronic acid. Duplicate studies were excluded.
The researchers collected and analyzed basic publication details, patient demographic information, the type and number of injections used, the scale used to determine outcomes, whole-organ MRI scores and the magnetic resonance observation of cartilage repair tissue. The primary outcomes were patient pain and function scores.
The analysis included seven randomized controlled trials. According to the researchers, patients who received one or more injections of ASCs or ADSVF demonstrated improved short-term pain (Z = 3.1; P < .0001 and Z = 4.66; P < .00001, respectively) and function (Z = 2.61; P < .009 and Z = 2.80; P = .005, respectively) scores. In addition, MRI results showed that patients receiving injections had improved cartilage conditions compared with the patients in the control groups (Z = 8.14; P < .000001 and Z = 5.58; P < .00001, respectively).
“In osteoarthritis of the knee, single or multiple intra-articular injections of autologous ASCs or ADSVF have shown significant pain improvement and safety in the short term in the absence of adjuvant therapy,” Yang and colleagues wrote. “Significant improvements in cartilage status were also shown on MRI. A larger sample size of randomized controlled trials is needed for direct comparison of the difference in effect between single and multiple injections.”
Perspective
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Interest in stem cell therapy for knee osteoarthritis has been increasing over recent years, particularly considering the unmet needs of many patients who remain symptomatic despite standard therapy and are either not eligible for, or desirous of, knee replacement. The public finds stem cell therapy an attractive concept. However, physicians require robust data to relay information on symptomatic and disease modifying benefit of therapy, particularly if out of pocket cost is high.
Yang and colleagues report their meta-analysis of 7 RCTs for efficacy of single and multiple intra-articular injections with abdominal-sourced autologous adipose derived stem cells (ASCs) or adipose derived stromal vascular fraction (ADSVF), representing the most commonly used sources of mesenchymal stem cells (MSCs). ADSVF is a combination of extra cellular matrix components with varying cell types capable of tissue repair and angiogenesis. ASCs are pluripotent to differentiate into multiple cell types and self-renew.
VAS and WOMAC scores significantly improved in treatment arms compared with controls at both 6 and 12 months. However, subgroup analysis indicated the VAS improvement was greater only at 6 months for the ADSVF than the ASC group. WOMAC scores were significantly improved compared with controls for only the single injection group at 6 months. At 12 months, only the ADSVF — for both single and multiple injections — proved efficacious.
MRI assessment revealed significant improvement in cartilage status in four of six studies at both 6 and 12 months with none in the long term 5-year study.
Injections of MSCs in general improved pain and function in knee osteoarthritis at 6 and 12 months. Subgroup analyses indicate single and multiple injections are effective for pain but are variable in functional efficacy. MRI functional status improved in some studies.
MSC therapy represents a promising therapy for knee osteoarthritis but requires more robust study to standardize treatment protocol in order to predict symptomatic and cartilage benefit.
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