Method for preserving mammalian organs

Details Method for preserving mammalian organs Method for preserving mammalian organs

2001-03-06

2002-11-05

Saucier, Sandra E. (Department: 1651)

Chemistry: molecular biology and microbiology

Differentiated tissue or organ other than blood, per se, or...

Including freezing; composition therefor

C435S001100, C435S001200

Reexamination Certificate

active

06475716

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
Japanese Patent Public Disclosure No. 72601/2000: This application was filed with the Japanese Patent Office on Aug. 31, 1998 as Japanese Patent Application No. 245052/1998. The title of the invention was “a method for preserving extracted mammalian organs” and the inventor was Kunihiro Seki, D. Sc., the same as the inventor of the present invention. The application was laid open to public inspection in Japan on Mar. 7, 2000 and is incorporated herein by reference to the specification and the drawings.
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a method for prolonged storage of extracted mammalian organs and such organs that have been preserved for use in transplants.
2. Prior Art
Clinical transplants of human organs such as lungs, heart, liver, kidneys and pancreas are routinely performed today. However, as the number of patients waiting for organ transplants increases yearly, the shortage of donors has become a serious problem and the waiting time to surgery is also increasing. Even if a donor is found, his or her organs cannot be effectively used in transplants since nothing like blood banks exist for organs that are fully equipped with the ability to preserve organs for prolonged periods and allow for efficient supply of organs.
Organs to be transplanted are most commonly preserved by cold storage but the preservation limit is about 4-24 hours (Cooper J D, Patterson G A, Trulock E P et al.; J. Thorac. Cardiovasc. Surg. 107, 460-471, 1994). In experiments using University of Wisconsin Solution (UWS) as a medium for cold storage of hearts from rats, rabbits and baboons before resuscitation, the time limit was 6-18 hours (Makowka I, Zerbe T R, Champman F et al.; Transplant Proc. 21, 1350, 1989 and Yen T, Hanan S A, Johnson D E et al.; Ann. Thorac. Surg. 49, 932, 1990). Transplanting of rat hearts (n=5) immersed in a combination medium of UWS and perfluorocarbon was found to be successful at both 24 hours (100%) and 48 hours (4 out of the 5 animals) (Kuroda Y, Kawamura T, Tanioka T et al; Transplantation, 59, 699-701, 1995). The reason for these short time limits is that when removed hearts are exposed to the low temperature of 4° C. or ischemic injury, their cell membranes are damaged to make tissue cell resuscitation impossible (Pegg D E; Organ Preservation Surg. Clin. North Am. 66, 617, 1986: Oz M C, Pinsky D J, Koga S et al.; Circulation 88, 291-297, 1993: and Heffner J E, Pepine J E; Rev. Pespir. Dis. 140, 531-554, 1989).
The technology for storing mammalian living tissues over prolonged periods before resuscitation have seen marked advances only in the area of single cells such as blood, sperm and ova. Efforts to develop practically feasible methods for the cold storage of living tissues which are aggregates of cells and organs which are composed of several tissues are also in progress but they have to meet the inexorable requirement that transplant be performed within 24 hours of storage (Kalayoglu M, Sollinger H W, Strarra R J et al.; Lancet 2, 617, 1988).
As regards the technology of organ preservation and resuscitation, trehalose (C
12
H
22
O
11
) is an interesting substance to mention. This is a nonreducing disacharide found widely in nature and it has been reported to have the ability to stabilize or protect the structure of cell membranes under various types of stress (Crowe J H, Crowe L M, Chapman D; Science 233, 701-703, 1984 and Wiemken A; Antinei Van Leeunwenhoek 58, 209-217, 1990). It was also reported that trehalose had the ability to protect cell membranes of the heart when it was exposed to the low temperature of 4° C. or ischemic injury (Stringham J C, Southhard J H, Hegge J et al.; Transplantation 58, 287-294, 1992 and Hirata T, Fukuse T, Liu C J et al.; Surgery 115, 102-107, 1994).
According to reports of experiments with tardigrades under high hydrostatic pressure, trehalose increased 10-20 fold in an anhydrous state (Crowe J H, Crowe L M, Chapman D; Science 233, 701-703, 1984 and Crowe J H, Crowe L M, Chapman D, Aurell Wistorm; Biochemical Journal 242, 1-10, 1987). Tardigrades are multicellular organisms composed of ca. 40,000 cells including nerve cells.
The present inventor previously found that tardigrades in a desiccation state had the viability to withstand high hydrostatic pressures up to 600 MPa (Kunihiro Seki et al.; Nature Vol. 395, No. 6705, pp. 853-854, Oct. 29, 1998 and Japanese Patent Public Disclosure No. 289917/1999 which is incorporated herein by reference to the specification and the drawings). Tardigrades become “desiccate” when they are in the “tun” state. The physiological mechanism behind their tun state has not been fully unravelled but it is at least clear that desiccated tardigrades have lost an extremely large amount of water in their body to become dehydrated.
SUMMARY OF THE INVENTION
As described above, the shortage of donors and the increasing time for which patients have to wait before surgery are two serious problems with organ transplants and a strong need exists to develop feasible techniques for preserving organs and later resuscitating them.
In the conventional storage of organs by refrigeration, the temperature of the organ is lowered so that its metabolism is suppressed to a level that maintains its viability. While the metabolism of the organ is suppressed by reducing temperature, water as a polar medium is a rich supply of ions which cause self-disintegration of cells, their death and necrosis over time. Hence, the longer the period of storage by refrigeration, the higher the frequency of the occurrence of serious thrombus formation and dysfunction. Organs cannot be stored cold for an indefinite period.
An object, therefore, of the invention is to provide a novel technique by which organs can be stored in vitro for a significantly increased number of days while preventing their cells and tissues from undergoing self-disintegration over time.
Another object of the invention is to provide a basic technique of such substantial utility that it can extend the duration of preservation of mammalian organs for use in transplanting into humans.
The present inventor found that the ability of desiccated tardigrades to withstand extreme environments in an inert medium could be applied to the purpose of preserving mammalian organs for an extended period. The organs preserved by the present invention can be later resuscitated for collecting viable nerves or stem cells. The resuscitated organs or the collected tissues can be used in transplants. For histopathological studies, it is quite significant that resuscitable biomaterials rather than necrotic specimens can be stored for a long period.
Animal tissue cells generally are not viable in the absence of water. One may readily imagine that organs of higher animals which are composed of heterogeneous tissues can never be resuscitated from a desiccation state. Techniques for preserving plants and various bacteria in a desiccation or dry state have already been developed but not a single experiment has been reported in which organs of higher animals were successfully resuscitated after storage in a desiccation or dry state.
To his surprise, the present inventor found that when extracted mammalian organs were deprived of much water under specified conditions and later stored at low temperature within an inert medium, they had apparent death of the same nature as experienced by tardigrades which remained viable in the tun state for a prolonged period.
Particularly surprising was that multi-cell and multi-tissue mammalian organs resuscitated from an extremely dehydrated state and that the resuscitated heart was found to beat. The cells of the resuscitated organ are believed to be in apparent death characterized by either an extreme drop in oxygen consumption (no greater than {fraction (1/1000)} of the normal level) or substantial arrest of oxygen consumption.
The method for preserving mammalian organs according to the first aspect of the invention comprises two steps, one of dehydratin

Affiliated with

Also associated with

Rating

Method for preserving mammalian organs does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method for preserving mammalian organs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for preserving mammalian organs will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2946197