Extra-corporeal in-vitro perfusion of isolated skeletal muscle flaps improves ischaemic survival

[摘要] The field of organ and tissue transplantation has necessitated an improvedunderstanding of their associated pathophysiological pathways. Specificareas of interest involve the changes that follow ischaemia andderangement’s that accompany organ and tissue storage, reperfusion injuryand the 'no-reflow” phenomenon. Strategies have been devised tomanipulate and modify these processes, improving tissue and organ survivaland function. These have involved the use of preservation solutions.Although most research involves organ transplantation, these principles havebeen translated and applied to various tissues, surgical flaps andmicrovascular replantations. These studies have generally used the skin flapas their model with little knowledge regarding muscle flaps, the mostvulnerable to the ischaemic process. This study targets the use of one suchpreservation system and uses skeletal muscle as its tissue model.The vascular anatomy of the rectus femoris muscle in the New Zealandwhite rabbit was studied anatomically and radiologically and thus described.The isolated rectus femoris muscle flap was harvested and perfused in-vitrowith cooled, oxygenated University of Wisconsin solution (UWS) using apulsatile renal perfusion pump. UWS was selected as it contains vitaladditives important in cryopreservation of organs. Monitoring of variousphysiological parameters was performed. The muscle was examined at 0, 4,8, 12, 18 and 24 hours of extra-corporeal perfusion using warm and cold,non-perfused controls. The contralateral muscle served as the control.End-points were the percentage of muscle survival, as determined by a newgrading system of muscle ischaemia, based on 3 light and 7 electronmicroscopic criteria.The overall percentage of muscle survival (combined light and electronmicroscopy scores) resulted in approximately 58% survival at 24 hours forthe perfused muscle versus 31% for the cold stored muscle. The storedmuscle had the same survival rate at 12 hours as did the perfused muscle at24 hours. For all time periods beyond 4 to 8 hours, perfused muscle showedstatistically improved survival rates compared to the stored muscle. Eighthours appears to be a crucial point beyond which survival in muscledeteriorates to a much greater degree without perfusion.Questions remain as to which method of preservation yields the best survivalbenefit and, as yet, there is no 'ideal” perfusate. The future involvesmanipulating perfusion solutions and trying to arrest or reverse establishedwarm ischaemia. Success of free tissue transfers and replantations of musclecontainingbody parts may be enhanced. These techniques may also allow usto effectively store previously harvested flaps and eventually, to enter therealm of 'banked” allograft tissue flaps.

[发布机构] University of the Witwatersrand