Ionizing Radiation Induces Disc Annulus Fibrosus Senescence and Matrix Catabolism via MMP-Mediated Pathways.

Previous research has identified an association between external radiation and disc degeneration, but the mechanism was poorly understood. This study explores the effects of ionizing radiation (IR) on inducing cellular senescence of annulus fibrosus (AF) in cell culture and in an in vivo mouse model. Exposure of AF cell culture to 10-15 Gy IR for 5 min followed by 5 days of culture incubation resulted in almost complete senescence induction as evidenced by SA-ßgal positive staining of cells and elevated mRNA expression of the p16 and p21 senescent markers. IR-induced senescent AF cells exhibited increased matrix catabolism, including elevated matrix metalloproteinase (MMP)-1 and -3 protein expression and aggrecanolysis. Analogous results were seen with whole body IR-exposed mice, demonstrating that genotoxic stress also drives disc cellular senescence and matrix catabolism in vivo. These results have important clinical implications in the potential adverse effects of ionizing radiation on spinal health.

Percutaneous cement-augmented short-segment pedicle screw fixation plus percutaneous vertebroplasty for stage III Kummell's disease without neurological symptoms: A case report.

INTRODUCTION: The incidence of stage III Kummell's disease without neurological symptoms is increasing in elderly patients with osteoporotic thoracolumbar fractures. However, the surgical method is still controversial in this condition. This report presented a case of Kummell's disease in which percutaneous bone cement-augmented short-segment pedicle screw fixation combined with percutaneous vertebroplasty was performed, providing a reference for the surgical approach. CASE PRESENTATION: The patient was a 72-year-old female who presented unexplained lower back pain accompanied with limited mobility for the past three months. Based on her medical history, physical examinations, and imaging studies, it was confirmed that she had Kummell's disease in stage III without neurological symptoms. We treated her with percutaneous bone cement-augmented short-segment pedicle screw fixation combined with percutaneous vertebroplasty on the symptomatic vertebrae. CLINICAL DISCUSSION: The majority of patients with stage III Kummell's disease have severe osteoporosis, which result in failure of the internal fixation and a series of other complications. Maintaining the stability of the internal fixation system is crucial, especially after screwing and subsequent locking. When augmented with bone cement, the grip and pull-out resistance of the percutaneous pedicle screws enhance greatly. Simultaneously, percutaneous vertebroplasty on the symptomatic vertebrae can immediately support the spine unit's stability mechanically and maintain the shape of the vertebrae after reduction. CONCLUSIONS: The percutaneous bone cement-augmented short-segment pedicle screw fixation combined with percutaneous vertebroplasty on the symptomatic vertebrae is an effective treatment for stage III Kummell's disease without neurological symptoms. It can effectively restore the vertebral height, correct the kyphotic deformities, improve spinal canal stenosis, and achieve satisfactory short-term clinical outcomes.

The hypertrophy of the cervical ligamentum flavum results in incomplete paralysis of both lower limbs: A case report.

INTRODUCTION: The occurrence of cervical spinal stenosis caused by single-segment hypertrophic folds of the non-calcified ligamentum flavum (LF) at a single level is exceedingly rare, with previous surgical interventions predominantly employing posterior approaches and open procedures. This case report presents an exceptional instance wherein a patient achieved satisfactory outcomes following endoscopic surgery, thereby furnishing valuable evidence supporting the feasibility of endoscopic treatment for cervical LF hypertrophy. CASE PRESENTATION: The patient, a 66-year-old male, presented to our hospital with chronic cervical pain, bilateral lower limb weakness, and gait instability. Physical examination revealed significant tenderness in the cervical region, diminished muscle strength in both lower limbs with poor resistance against resistance testing, and unsteady ambulation even with the assistance of a walking aid. CLINICAL DISCUSSION: The primary diagnosis considered was cervical spinal stenosis caused by hypertrophy of the LF at the C4/5 level. The patient underwent treatment using the "key-hole" technique under spinal endoscopy. Postoperative treatment included detumescence of the nerve and improvement of circulation. CONCLUSIONS: LF hypertrophy could be the principal factor of cervical spinal stenosis inducing neurological symptoms. Endoscopic surgery can get satisfactory clinical effects on single-segment cervical LF hypertrophy, including a minimally invasive approach, less bleeding, reduced cervical spine stability, and rapid recovery, especially for elderly patients with diabetes.

Effects of suppressing bioavailability of insulin-like growth factor on age-associated intervertebral disc degeneration.

Suppression of the insulin-like growth factor-1 (IGF-1) signaling pathway reduces age-related disorders and increases lifespan across species, making the IGF-1 pathway a key regulator of aging. Previous in vitro intervertebral disc cell studies have reported the pro-anabolic effect of exogenously adding IGF-1 on matrix production. However, the overall effects of suppressing IGF-1 signaling on age-related intervertebral disc degeneration (IDD) is not known. Here, the effects of suppressing IGF-1 signaling on age-related IDD in vivo were examined using PAPPA -/- mice. These are animals with targeted deletion of pregnancy-associated plasma protein A (PAPPA), the major protease that cleaves inhibitory IGF binding proteins that control bioavailability of IGF-1 for cell signaling. Compared to age-matched wild-type (Wt) littermates, reduced levels of matrix proteoglycan (PG) and aggrecan were seen in discs of 23-month old PAPPA -/- mice. Decreased aggrecanolysis and expression of two key catabolic markers, matrix metalloproteinase-3 and a disintegrin and metalloproteinase with thrombospondin motifs-4, were also observed in discs of old PAPPA -/- mice compared to Wt littermates. Suppressing IGF-1 signaling has been implicated to shift cellular metabolism toward maintenance rather than growth and decreasing cellular senescence. Along this line, discs of old PAPPA -/- mice also exhibited lower cellular senescence, assessed by p53 and lamin B1 markers. Collectively, the data reveal complex regulation of disc matrix homeostasis by PAPPA/IGF-1 signaling during chronologic aging, that is, reduced IGF-1 bioavailability confers the benefit of decreasing disc cellular senescence and matrix catabolism but also the disadvantage of decreasing disc PG matrix anabolism. This pathway requires further mechanistic elucidation before IGF-1 could be considered as a therapeutic growth factor for treating IDD.