Regenerative medicine for the treatment of chronic low back pain: a narrative review

The Clinical Efficacy of Platelet-Rich Plasma Injection Therapy versus Different Control Groups for Chronic Low Back Pain: A Network Meta-Analysis of Randomized Controlled Trials

Objective

Low back pain is one of the main causes of disability in the world. Although regenerative medicine may represent breakthroughs in the management of low back pain, its use remains controversial. Therefore, we conducted a meta-analysis to evaluate the clinical efficacy of platelet-rich plasma (PRP) injection therapy versus different control groups for chronic low back pain during 4 weeks, 3 months, and 6 months.

Methods

Different electronic databases were searched for randomized controlled trials up to August 2023. Mean changes from baseline in pain and Oswestry Disability Index (ODI) scores at 4 weeks, 3 months, and 6 months and standard deviations of outcome were recorded.

Results

Four articles with 154 cases were finally included in this meta-analysis. After 4 weeks, corticosteroid (CS) was the optimal treatment option for chronic low back pain in terms of improvement in pain and disability index (surface under the cumulative ranking curve [SUCRA]=71.3%, SUCRA=57.8%, respectively). After 3 months, radiofrequency (RF) emerged as the best therapy in pain (SUCRA=100%) and disability index (SUCRA=98.5%), followed by PRP (SUCRA=62.3%, SUCRA=64.3%, respectively), CS (SUCRA=24.6%, SUCRA=25.9%, respectively) and lidocaine (SUCRA=13.1%, SUCRA=11.3%, respectively). At 6 months, RF was most likely to be the best treatment in pain (SUCRA=94.9%) and disability index (SUCRA=77.3%), followed by PRP (SUCRA=71.2%, SUCRA=79.6%, respectively). However, compared with the last follow-up, there was a slight downward trend in improvement pain and disability index with RF, while PRP was still an upward trend.

Conclusion

This study demonstrated better short-term improvement of chronic low back pain with CS after 4 weeks. PRP and RF improvement effects matched, but follow-up of at least 6 months showed that PRP seemed to be more advantageous in improvement in disability indices. Considering the limitations of this study, these conclusions still need to be verified by more comparative RCTs and a longer follow-up period.

Safety and Feasibility of Intradiscal Administration of Matrilin-3-Primed Adipose-Derived Mesenchymal Stromal Cell Spheroids for Chronic Discogenic Low Back Pain: Phase 1 Clinical Trial

Functionally enhanced mesenchymal stromal cells participate in the repair of intervertebral disc. This study aimed to assess the safety and tolerability of intradiscal administration of matrilin-3-primed adipose-derived stromal cell (ASC) spheroids with hyaluronic acid (HA) in patients with chronic discogenic low back pain (LBP). In this single-arm, open-label phase I clinical trial, eight patients with chronic discogenic LBP were observed over 6 months. Each patient underwent a one-time intradiscal injection of 1 mL of 6.0 × 106 cells/disc combined with HA under real-time fluoroscopic guidance. Safety and feasibility were gauged using Visual Analogue Scale (VAS) pain and Oswestry Disability Index (ODI) scores and magnetic resonance imaging. All participants remained in the trial, with no reported adverse events linked to the procedure or stem cells. A successful outcome-marked by a minimum 2-point improvement in the VAS pain score and a 10-point improvement in ODI score from the start were observed in six participants. Although the modified Pfirrmann grade remained consistent across all participants, radiological improvements were evident in four patients. Specifically, two patients exhibited reduced high-intensity zones while another two demonstrated decreased disc protrusion. In conclusion, the intradiscal application of matrilin-3-primed ASC spheroids with HA is a safe and feasible treatment option for chronic discogenic LBP.

Recombinant Laminin-511 Fragment (iMatrix-511) Coating Supports Maintenance of Human Nucleus Pulposus Progenitor Cells In Vitro

The angiopoietin-1 receptor (Tie2) marks specific nucleus pulposus (NP) progenitor cells, shows a rapid decline during aging and intervertebral disc degeneration, and has thus sparked interest in its utilization as a regenerative agent against disc degeneration. However, the challenge of maintaining and expanding these progenitor cells in vitro has been a significant hurdle. In this study, we investigated the potential of laminin-511 to sustain Tie2+ NP progenitor cells in vitro. We isolated cells from human NP tissue (n = 5) and cultured them for 6 days on either standard (Non-coat) or iMatrix-511 (laminin-511 product)-coated (Lami-coat) dishes. We assessed these cells for their proliferative capacity, activation of Erk1/2 and Akt pathways, as well as the expression of cell surface markers such as Tie2, GD2, and CD24. To gauge their regenerative potential, we examined their extracellular matrix (ECM) production capacity (intracellular type II collagen (Col2) and proteoglycans (PG)) and their ability to form spherical colonies within methylcellulose hydrogels. Lami-coat significantly enhanced cell proliferation rates and increased Tie2 expression, resulting in a 7.9-fold increase in Tie2-expressing cell yields. Moreover, the overall proportion of cells positive for Tie2 also increased 2.7-fold. Notably, the Col2 positivity rate was significantly higher on laminin-coated plates (Non-coat: 10.24% (±1.7%) versus Lami-coat: 26.2% (±7.5%), p = 0.010), and the ability to form spherical colonies also showed a significant improvement (Non-coat: 40.7 (±8.8)/1000 cells versus Lami-coat: 70.53 (±18.0)/1000 cells, p = 0.016). These findings demonstrate that Lami-coat enhances the potential of NP cells, as indicated by improved colony formation and proliferative characteristics. This highlights the potential of laminin-coating in maintaining the NP progenitor cell phenotype in culture, thereby supporting their translation into prospective clinical cell-transplantation products.