The primary purpose of this study is to evaluate the efficacy of rexlemestrocel-L+HA compared to control in reducing low back pain at 12 months post-treatment and safety of a single injection of rexlemestrocel-L+HA injected into a lumbar intervertebral disc compared to control through 12 months post-treatment.

Inclusion Criteria:

• Participants with moderate to severe low back pain for a duration of at least six months who have failed at least 3 months of conservative care.
• Participants who have moderate radiographic degeneration of an intervertebral disc from L1 to S1, with a single disc suspected of causing chronic lower back pain (CLBP).

Exclusion Criteria:

• Participants who have been a recipient of prior allogeneic stem cell/progenitor cell therapy for any indication or autologous stem cell/progenitor cell therapy or other biological intervention to repair the index intervertebral disc.
• Participants with low back pain duration of less than 6 months or greater than 60 months.
• Participants who have not received at least 3 months of conservative treatment for back pain without adequate pain relief.
• Participants taking systemic immunosuppressants.
• Participants with osteoporosis.
• Participants with alcohol or substance abuse problems.
• Participants with severe depression or anxiety.
• Participants with cauda equina syndrome; fibromyalgia, symptomatic central vertebral canal stenosis, lumbar spondylitis or other undifferentiated spondyloarthropathy affecting the index disc.
• Participants having undergone a surgical procedure affecting the structure/biomechanics of the disc (e.g., discectomy, intradiscal electrothermal therapy, intradiscal radiofrequency, artificial disc replacement, interbody fusion, laminectomy, etc.) at the index or adjacent levels.
• Participants who have received any lumbar intradiscal injection into the index disc or adjacent discs within three months prior to the start of screening, other than injection of contrast medium for discography.
• Participants who received an epidural steroid injection within 6 weeks prior to informed consent.
• Participants with evidence of neurologic deficit on any component of the lumbar neurological exam at baseline.
• Participants with sacroiliac (SI) joint pain, as determined by a targeted physical exam, or SI joint injection.
• Participants with facet joint pain, as determined by a medial branch block.
• Participants with more than a single painful level.
• Participants with a full thickness annular tear observed on magnetic resonance imaging (MRI) or discography.
• Participants with low back pain that is less than moderate in severity.
• Participants with extreme low back pain.
• Participants who lack moderate to extreme functional limitations/disability.

Note: Other exclusion criteria may apply.