Graft cells survive bone cement curing
medwireNews: Tissue-engineered constructs are feasible in orthopedic surgery procedures that require polymerizing bone cement, UK scientists say.
The team from the University of Southampton demonstrates that human skeletal stem cells can survive in implants, despite concerns regarding the high temperatures, of 70 °C or more, that occur during cement curing.
The in vivo study used a milled allograft and a polymer graft substitute that were seeded with skeletal stem cells and impacted into a graduated chamber before exposure to curing bone cement.
When the researchers removed 5-mm sections from the allograft-cement interface and measured skeletal stem cell viability using a quantitative proliferation assay, they found that cell viability fell with increasing proximity to the cement, and this effect was more prominent in the allograft samples.
However, only the 5-mm allograft section closest to the cement had a significant 84% decrease in viability measured by mean optical density compared with controls, with a 48% decrease at 0.5-1.0 cm, but this did not reach significance. The corresponding decrease for the polymer graft were 32% and 16% but these were not significant.
The researchers attempted to protect the grafts from heat using several different strategies, including cooling the grafts before exposure to the cement or dipping the allograft or polymer in 1% laponite, a bioactive clay, before exposure to cement.
However, these strategies did not achieve a significant increase in cell viability compared with controls.
"The heat produced by polymerizing bone cement has the potential to denature proteins and kill or attenuate cells. In this model, exothermic effects were significant only within 0.5 cm of the cement-graft interface and were not sufficient to kill all cells in this region, leaving the potential for cell recolonization," write Edward Tayton and co-authors.
"This initial study indicates that the use of tissue-engineered constructs is not necessarily contraindicated in orthopaedic procedures (such as impaction bone-grafting) involving cement, although additional research is required to assess whether the continued viability and differentiation potential of the cells are affected."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Lynda Williams, Senior medwireNews Reporter