Ex vivo limb perfusion for traumatic amputation in military medicine

Long-Term Survival and Functional Recovery of Cryopreserved Vascularized Groin Flap and Below-the-Knee Rat Limb Transplants

Effective cryopreservation of large tissues, limbs, and organs has the potential to revolutionize medical post-trauma reconstruction options and organ preservation and transplantation procedures. To date, vitrification and directional freezing are the only viable methods for long-term organ or tissue preservation, but are of limited clinical relevance. This work aimed to develop a vitrification-based approach that will enable the long-term survival and functional recovery of large tissues and limbs following transplantation. The presented novel two-stage cooling process involves rapid specimen cooling to subzero temperatures, followed by gradual cooling to the vitrification solution (VS) and tissue glass transition temperature. Flap cooling and storage were only feasible at temperatures equal to or slightly lower than the VS Tg (i.e., -135°C). Vascularized rat groin flaps and below-the-knee (BTK) hind limb transplants cryopreserved using this approach exhibited long-term survival (>30 days) following transplantation to rats. BTK-limb recovery included hair regrowth, normal peripheral blood flow, and normal skin, fat, and muscle histology. Above all, BTK limbs were reinnervated, enabling rats to sense pain in the cryopreserved limb. These findings provide a strong foundation for the development of a long-term large-tissue, limb and organ preservation protocol for clinical use.

The heart-lung machine in major limb replantation: Report of two cases

Replantation of amputated limbs after long ischemic hours almost always comes with reperfusion syndrome and poor outcomes. An ischemic time of greater than 6 h is often considered unsuitable for major limb replantation. However, usage of extracorporeal perfusion has been shown to prolong the viability of major limbs in animal studies. The aim of this report is to show that extracorporeal perfusion with cardiopulmonary bypass machine (CPBM) is a safe and reliable technique in improving limb survival as illustrated by our cases. We report two cases of successful major limb replantation with late presentation. One case involved a 31-year-old man with shoulder disarticulation and the other involved a 30-year-old man sustained proximal transtibial amputation. Both patients, who were generally fit, were involved in major road traffic accidents. The amputated segments were connected to a CPBM to expedite reperfusion and to flush away anaerobic metabolic products. The major vessels were cannulated and connected to a bypass machine that was initially primed with heparinized saline and perfused with packed cells at 100% oxygen concentration. The perfusion was carried out at 35°C with low pressure to prevent edema and low flow to reduce reperfusion injury. Venous blood was drained completely before replantation. Total ischemia times were 7 h 40 min and 9 h, respectively. No evidences of perioperative reperfusion syndrome were seen. Both of the replanted limbs survived and patients had regained better-than-expected limb functional outcomes at 5-year and 2-year follow-up, respectively. CPBM may be safely used in major replantation surgery to enhance limb survival and therefore warrants further research.

Improving the ischemia-reperfusion injury in vascularized composite allotransplantation: Clinical experience and experimental implications

Long-time ischemia worsening transplant outcomes in vascularized composite allotransplantation (VCA) is often neglected. Ischemia-reperfusion injury (IRI) is an inevitable event that follows reperfusion after a period of cold static storage. The pathophysiological mechanism activates local inflammation, which is a barrier to allograft long-term immune tolerance. The previous publications have not clearly described the relationship between the tissue damage and ischemia time, nor the rejection grade. In this review, we found that the rejection episodes and rejection grade are usually related to the ischemia time, both in clinical and experimental aspects. Moreover, we summarized the potential therapeutic measures to mitigate the ischemia-reperfusion injury. Compare to static preservation, machine perfusion is a promising method that can keep VCA tissue viability and extend preservation time, which is especially beneficial for the expansion of the donor pool and better MHC-matching.

Pushing the frontiers of military medical excellence: updates, progress and future needs

Since its establishment in 2014, Military Medical Research has come a long way in becoming a premier journal for scientific articles from various different specialties, with a special emphasis on topics with military relevance. The field of military medicine may be obscure, and may not be readily encountered by the typical clinician on a day-to-day basis. This journal aims not only to pursue excellence in military research, but also keep current with the latest advancements on general medical topics from each and every specialty. This editorial serves to recap and synthesize the existing progress, updates and future needs of military medical excellence, discussing foremostly the unique traits of literature published in this journal, and subsequently presenting the discourse regarding wartime and peacetime medicine, the role of the military in a public health emergency, as well as wound healing and organ regeneration. Special attention have been devoted to military topics to shed light on the effects of Chemical, Biological, Radiological and Explosive (CBRE) warfare, environmental medicine and military psychiatry, topics which rarely have a chance to be discussed elsewhere. The interconnectedness between military combat and soldier physical and mental well-being is intricate, and has been distorted by pandemics such as coronavirus disease 2019 (COVID-19). This journal has come a long way since its first article was published, steadily contributing to the existing knowledge pool on general medical topics with a military slant. Only with continuous research and sharing, can we build upon the work of the scientific community, with hopes for the betterment of patient care.