Transforming and epidermal growth factors in degenerated intervertebral discs

W e studied the presence of anabolic growth factors in human herniated intervertebral discs (IVD) using a reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. Messenger RNA (mRNA) was isolated from the nucleus pulposus using oligo (dT) 25 superparamagnetic beads and probing with gene-specific primers in RT-PCR.mRNA coding for TGF-␣ (3/10), EGF (0/10), TGF-␤1 (0/10) and TGF-␤3 (2/10) or the EGF receptor (EGF-R; 0/10) and TGF-␤ type-II receptor (0/10) was found only occasionally.Beta-actin was always present and positive sample controls confirmed the validity of the RT-PCR assay.These RT-PCR findings were confirmed using immunohistochemical staining of EGF and TFG-␤, whereas TGF-␣ protein was always found associated with discocytes.We conclude that the nucleus pulposus of the herniated IVD is vulnerable to proteolytic degradation and depletion of proteoglycans due to the lack and/or low production of anabolic growth factors/receptors which could increase the local synthesis of the extracellular matrix.