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Transforming and epidermal growth factors in degenerated intervertebral discs
Y T Konttinen1, P Kemppinen, T F Li
1Department of Anatomy, University of Helsinki and Helsinki University Central Hospital, Finland.
Abstract:
We 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-alpha (3/10), EGF (0/10), TGF-beta1 (0/10) and TGF-beta3 (2/10) or the EGF receptor (EGF-R; 0/10) and TGF-beta 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-beta, whereas TGF-alpha 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.
Insights
Herniated intervertebral discs (IVD) show low levels of anabolic growth factors, increasing vulnerability to degradation. This lack of growth factors hinders extracellular matrix synthesis in the nucleus pulposus.
Area of Science:
- Biochemistry
- Molecular Biology
- Orthopedics
Background:
- Intervertebral disc (IVD) degeneration is a significant health issue.
- Anabolic growth factors are crucial for maintaining extracellular matrix (ECM) in the nucleus pulposus.
- Understanding growth factor presence in herniated IVDs is key to understanding degeneration.
Purpose of the Study:
- To investigate the presence and expression of key anabolic growth factors and their receptors in human herniated intervertebral discs (IVDs).
- To correlate growth factor levels with the structural integrity of the nucleus pulposus.
Main Methods:
- Utilized reverse transcriptase-polymerase chain reaction (RT-PCR) to detect messenger RNA (mRNA) for specific growth factors (TGF-alpha, EGF, TGF-beta1, TGF-beta3) and receptors (EGF-R, TGF-beta type-II receptor).
- Employed immunohistochemical staining to confirm the protein expression of identified growth factors.
- Isolated mRNA from nucleus pulposus using oligo (dT)25 superparamagnetic beads.
Main Results:
- Messenger RNA for TGF-alpha and TGF-beta3 was detected only occasionally in herniated IVDs.
- Epidermal Growth Factor (EGF), TGF-beta1, EGF receptor (EGF-R), and TGF-beta type-II receptor mRNA were notably absent.
- Immunohistochemistry confirmed the presence of TGF-alpha protein in discocytes, but overall low levels of key anabolic factors were observed.
- Beta-actin served as a consistent positive control, validating the RT-PCR assay.
Conclusions:
- Herniated IVDs exhibit a deficiency in essential anabolic growth factors and their receptors.
- This deficiency likely contributes to the observed proteolytic degradation and proteoglycan depletion in the nucleus pulposus.
- Low anabolic factor production impairs the local synthesis of the extracellular matrix, exacerbating disc degeneration.