A normothermic perfusion bioreactor to preserve viability of rat groin flaps extracorporally.

INTRODUCTION

Various attempts have been made to prolong tissue survival ex vivo. To achieve an adequate ex vivo condition for flap perfusion at normothermic temperatures in a bioreactor model, a suitable perfusion solution is necessary. The main purpose of our setting at 37 degrees C was to produce conditions under which multilineage stem cells from adipose tissue could differentiate. This study was designed to evaluate the effect of permanent perfusion on fat flaps of the rat.

MATERIALS AND METHODS

We elevated an epigastric adipofascial flap based on the inferior superficial epigastric vessels bilaterally in male Lewis rats and connected it to a bioreactor. The system was run by a cable pump and filled either with Hannover or Eurocollin's solution with or without permanent perfusion for 10 days. The lactate dehydrogenase (LDH) level in each solution was analyzed every 48 hours, assuming that injured cells emit this enzyme to the extracellular space and consequently to the perfusion solution. Histological samples were analyzed at the end of each trial.

RESULTS

There was a continuous significantly greater LDH level (P < .001) in bioreactors perfused with Hannover than with Eurocollin's solution. The nonperfused bioreactors showed a similar finding with lower levels compared with their perfused equivalents. Histological examination revealed significantly better preserved (P < .001) fat tissue structures in Hannover solution-perfused specimens.

CONCLUSION

Because LDH has a half life of 24 hours, ongoing production of this enzyme for 10 days is a marker for an injured tissue consisting of viable cells. Bioreactors run with Hannover solution showed significantly higher LDH levels. Histological analyses revealed intact cells preserved in Hannover solution. Thus, Hannover solution seemed to be superior to Eurocollin's solution to keep flaps viable under normothermic conditions. The presented model facilitated fat tissue conservation under normothermic conditions and represented a foundation for further studies on the differentiation of vascularized fat tissue.