The preservation of tissues for transplantation

Abstract

This paper is a written version of a lecture given during the celebration of Professor Rudolf Klen's 90th birthday. Dr. Klen played by far the major part in the introduction and the development of Tissue Banking in Europe. His concept of a tissue bank envisaged the storage of all types of cell, tissue and organ that physicians and surgeons might need for the treatment of their patients. There has been much progress towards this goal, but still the final objective remains elusive. This review of the current position starts with the recognition that some tissues are required to comprise or include cells that exhibit all the formal characteristics of life if they are to function as grafts, whereas other tissues do not. For some tissues, the preservation of mechanical properties is crucial: for others it is not. These considerations are crucial for the design of preservation methods for specific tissues: bone tendon and skin can provide useful grafts in the absence of living cells and this may even be true of cardiac valves: the crucial requirement here is that the mechanical properties remain intact. Simply freezing at around -80 degrees C may be sufficient. In contrast, many cell systems, and all metabolizing organs do require healthy cells to function. Cryopreservation is often an effective remedy for isolated cells, for example haemopoietic stem cells, but the damaging effects of the formation of ice are sufficient to rule out this approach for whole vascularised organs and for some tissues too. The damaging mechanisms are discussed, and it is concluded that the site of ice crystallization is crucial. Cartilage has hitherto been recalcitrant, but we have recently developed a method that permits this tissue to be stored at liquid nitrogen temperatures without any ice and with the recovery of living cells and intact mechanical properties after storage. Thus, many methods are available to help develop tissue banking originally envisioned by Dr. Klen.

Effects of decellularization on the mechanical and structural properties of the porcine aortic valve leaflet

“…It has been demonstrated that short term storage at low temperature has minimal effects on mechanical properties of connective tissues. [46][47][48] A study also showed that freeze storage in saline solution only significantly changes the mechanical properties of collagenous tissue (tendon) for duration longer than 40 days. [49] Recently, Schenke-Layland et al showed that certain local ultrastructural disruption was caused by one week cryopreservation using multiphoton laser scanning microscope.…”

Viabilidade celular da fração mononuclear da medula óssea e fração vascular estromal do tecido adiposo de equinos após o processo de congelamento e descongelamento

“…No congelamento gradativo, com decrésci-mo gradual e constante da temperatura, a formação de gelo será primariamente extracelular. No entanto, a formação de cristais de gelo no meio extracelular também é prejudicial, pois ocasiona desequilíbrio osmótico entre os meios intra e extracelular (Pegg 2006). O desequilíbrio osmótico tem como consequência a lesão da membrana plasmática, podendo resultar em ruptura e morte celular (Meryman 2007).…”

“…Estes eventos podem ocasionar prejuízos às célu-las por mecanismos diretos ou por intermédio do desequilíbrio osmótico (Sumida 2006). Segundo Pegg (2006), a utilização de crioprotetores e protocolos com controle de temperatura visa diminuir as perdas celulares inerentes ao processo de congelamento. A adição de agentes crioprotetores penetrantes, tais como o dimetilsulfóxido (DMSO), visa diminuir o volume de água para formação de cristais de gelo.…”

Issues of banking breast cancer cells to generate mammospheres

“…Tissue frozen at around -80°C may not yield functioning healthy cells that can be required for transplantation purposes (Pegg 2006), although living cells have been described in non-processed tissues frozen at -80°C (Heyligers and Klein-Nulend 2005). Cellular functions are arrested and no chemical reaction is generated at the liquid nitrogen temperature of -196°C.…”