Different Expression of Extracellular Matrix Genes : Primary vs. Recurrent Disc Herniation

Area of Science:

• Biochemistry
• Molecular Biology
• Orthopedic Surgery

Background:

• Recurrent lumbar disc herniation affects 5-15% of patients post-surgery.
• Understanding the molecular basis of recurrence is crucial for improving patient outcomes.

Purpose of the Study:

• To investigate the molecular biologic characteristics of primary and recurrent lumbar disc herniation.
• To compare chondrogenic and osteogenic gene expression between primary and recurrent disc cells.

Main Methods:

• Cells from primary and recurrent herniated lumbar discs were isolated via discectomy.
• Monolayer cultures were established for both cell types.
• Chondrogenic and osteogenic mRNA gene expression and protein levels (Western blot) were compared.

Main Results:

• Recurrent disc cells exhibited significantly increased mRNA expression for aggrecan (1.47x), type I collagen (1.38x), type II collagen (2.04x), Sox-9 (1.22x), osteocalcin (1.22x), and alkaline phosphatase (1.31x) compared to primary disc cells (p < 0.05).
• Western blot analysis revealed similar protein expression levels for aggrecan, type I collagen, type II collagen, Sox-9, osteocalcin, and alkaline phosphatase between primary and recurrent disc cells.

Conclusions:

• Recurrent lumbar disc cells demonstrate comparable chondrogenic and osteogenic gene expression to primary herniated disc cells.
• The molecular similarity suggests that regeneration of remaining disc tissue may contribute to disc space filling and potentially recurrence.