Treatment with the Non-ionic Surfactant Poloxamer P188 Reduces DNA Fragmentation in Cells from Bovine Chondral Explants Exposed to Injurious Unconfined Compression

Abstract

Excessive mechanical loading to a joint has been linked with the development of post-traumatic osteoarthritis (OA). Among the suspected links between impact trauma to a joint and associated degeneration of articular cartilage is an acute reduction in chondrocyte viability. Recently, the non-ionic surfactant poloxamer 188 (P188) has been shown to reduce by approximately 50% the percentage of non-viable chondrocytes 24 h post-injury in chondral explants exposed to 25 MPa of unconfined compression. There is a question whether these acutely 'saved' chondrocytes will continue to degrade over time, as P188 is only thought to act by acute repair of damaged cell membranes. In order to investigate the degradation of traumatized chondrocytes in the longer term, the current study utilized TUNEL staining to document the percentage of cells suffering DNA fragmentation with and without an immediate 24 h period of exposure of the explants to P188 surfactant. In the current study, as in the previous study by this laboratory, chondral explants were excised from bovine metacarpophalangeal joints and subjected to 25 MPa of unconfined compression. TUNEL staining was performed at 1 h, 4 days, and 7 days post-impact. The current study found that P188 was effective in reducing the percentage of cells with DNA fragmentation in impacted explants by approximately 45% at 4 and 7 days post-impact. These data suggest that early P188 intervention was effective in preventing DNA fragmentation of injured chondrocytes. The current hypothesis is that this process was mitigated by the acute repair of damaged plasma membranes by the non-ionic surfactant P188, and that most repaired cells did not continue to degrade as measured by the fragmentation of their DNA.

Acute repair of chondrocytes in the rabbit tibiofemoral joint following blunt impact using P188 surfactant and a preliminary investigation of its long-term efficacy

“…The concentration level was established in previous studies by this laboratory. 21,24,29 The right legs of these animals received a 1.5-mL sham injection of sterile PBS into the joint. The ''4-day no P188'' animals, received sham injections of 1.5-mL sterile PBS into both the impacted left limb and the opposite, right limb.…”

N-Acetylcysteine Inhibits Post-Impact Chondrocyte Death in Osteochondral Explants

“…There, matrix fissuring and chondrocyte death are evident post-impact [1][2][3][4][5] . Several studies have shown that chondrocytes begin to die within moments after impact and continue to die for up to several days [6][7][8][9][10] . Studies involving use of the cell-membrane-stabilizing surfactant poloxamer 188, a necrosis inhibitor, have indicated that up to 15% of chondrocytes at impact sites succumb to necrosis soon after injury 6,7,11 .…”

Chondrocyte Apoptosis: Implications for Osteochondral Allograft Transplantation

“…P188 is thought to modulate cell death by stabilizing damaged cell membranes. In a recent study, P188 was shown to decrease TUNEL positive chondrocytes by 45% following 25 MPa of unconfined compression of bovine cartilage explants [4]. However, no other assays for apoptosis were employed in this study, thus precluding definitive conclusions about the effects of P188 on true apoptosis versus necrosis.…”