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In Vitro Impact Model to Generate Sublethal Chondrocyte Injury in Bovine Cartilage Explants
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Mechanical impact induces cartilage degradation via mitogen activated protein kinases

L Ding1, E Heying, N Nicholson

  • 1Department of Orthopaedics and Rehabilitation, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242, USA.

Osteoarthritis and Cartilage
|September 4, 2010
PubMed
Abstract

Insights

Mechanical damage activates Mitogen activated protein (MAP) kinases, including p38 and extracellular signal-regulated protein kinase (ERK), in cartilage. Inhibiting these kinases reduces chondrocyte death and cartilage degeneration, suggesting a therapeutic target for post-traumatic osteoarthritis.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Orthopedics

Background:

  • Mechanical damage to cartilage can lead to chondrocyte death and degeneration.
  • Mitogen activated protein (MAP) kinases are signaling molecules implicated in cellular stress responses.

Purpose of the Study:

  • To investigate the activation of MAP kinases (p38 and ERK) in cartilage following mechanical injury.
  • To evaluate the efficacy of MAP kinase inhibitors in preventing chondrocyte death and cartilage degeneration after impaction injury.

Main Methods:

  • Confocal microscopy and immunoblotting were used to assess MAP kinase phosphorylation.
  • Fluorescent microscopy and DMMB assay quantified chondrocyte death and proteoglycan loss.
  • Quantitative real-time PCR analyzed the expression of catabolic genes.

Main Results:

  • p38 and ERK phosphorylation increased significantly in chondrocytes around impact sites within 24 hours.
  • Inhibition of p38 or ERK pathways markedly reduced chondrocyte death and proteoglycan loss.
  • Blunt impaction upregulated the expression of MMP-13, TNF-α, and ADAMTS-5.

Conclusions:

  • p38 and ERK MAPKs play a critical role in the progression of cartilage degeneration post-injury.
  • Targeting p38 and ERK pathways may offer a strategy to mitigate cartilage damage and reduce the risk of post-traumatic osteoarthritis (PTOA).

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